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By peeeot - 10 Years Ago
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I am trying to take a fresh look at my high fuel consumption and would welcome the forum's input.
I log my odometer and fuel consumption on a spreadsheet. My cumulative average since 2013 is 10.8 mpg. On most tanks, I do between 10.2 and 11.2 mpg regardless of driving style or speed. I usually drive economically.
Using google maps on a recent 53 mile trip, I calculate my odometer error at 1%, so I believe my fuel economy numbers are accurate.
I have tried many things, made many improvements to the car such as rebuilding the front suspension and getting an alignment, altered timing, advance curve, carburetor settings, etc yet tank after tank I see 10-12 mpg.
Performance is good. The car feels responsive, smooth, quiet. There are no drivability problems. All the numbers I have checked (compression, vacuum, timing) at various points over 2 years have been in the prescribed range either by the manual or this forum. So, I am pretty stumped as to why I am not seeing the more typical 14-16 mpg out of my Fairlane.
I'm not quite ready to accept that this is good as it's gonna get. I am hoping this discussion will either improve my economy or show me I'm going to have to accept it as is.
Where should I start?
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By LordMrFord - 10 Years Ago
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What about one or two bended pushrods or clogged valves?
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By miker - 10 Years Ago
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How do the plugs look?
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By Kahuna - 10 Years Ago
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I would start by noting the rear axle ratio, tire sizes. Then the tune up.
If everything is in order (Compression/Timing/Carb jetting)?
Automatic? Loose torque converter?, Trans slippage?
Tire pressure?
Things I'd start to look at
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By peeeot - 10 Years Ago
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Here is the requested information:
Axle: 3.10:1 original 9".
Tires: I have done many miles with both 225/70r14 radials at as much as 40 psi AND 7.50x14 bias plies at 24 psi. No difference in economy.
Compression: checked a couple of times since re-ringing engine, though not recently. All cylinders were within a few psi of 150.
Timing: I've been all over the map with this, checked the curve, changed vacuum advance rate, tried running with and without vacuum advance, road tested different settings with a vacuum gauge, etc. I could tell a difference in power, responsiveness, smoothness, pinging based on the different settings I tried, but none ever gave me a tank better than 12.5 mpg.
Carburetor: original carter afb with vacuum secondaries, correct stock jets and metering rods, correct float settings. I have tried 2 of these units, tried small adjustments to float level, made sure choke works properly, air bleeds are clear, etc. with no change in economy.
Transmission: original fordomatic. Bands adjusted, fluid type fa, removed torque converter and replaced seals a while ago because the converter was leaking badly(it's a bolt-together unit). Trans shifts well, no performance complaints, no slipping, tachs 3000 rpm at 70 mph, I don't think the converter is slipping more than normal for a non-lockup unit.
Engine: running 20w-50 oil. Engine runs hot at highway speeds, I believe due to poor flow through radiator which has clearly been patched up. Always stays in the normal bar on the gauge though.
Spark plugs: here are some pictures of 3 different plugs I pulled. Most show a pink residue which I'm told is from a fuel additive (I usually run shell regular). The first 3 are one plug at different angles, the next 2 are of a second plug, an the last 2 are a third.  
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By peeeot - 10 Years Ago
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By Rono - 10 Years Ago
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Here are just a couple of things to consider; My wife and I just finished an 1,800 mile motorcycle trip. Up from southern California to northern Idaho and back. You can't feel it in a car, but on a bike, head winds and tail winds affect gas mileage. Stop and go driving as opposed to cruising on the interstate for 200 miles will give you different mileage results over the same distance. Also, ethanol blends in the fuel will vary, but in Idaho we could buy premium gas with NO Ethanol and got great fuel mileage. "I'm just sayin'"
Rono
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By peeeot - 10 Years Ago
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It's true that all of the pumps at normal stations here in NC have 10% ethanol. You have to go out of your way for pure gas.
My car has a lot of surface rust that has been painted over. The hood, roof, trunk, and fenders have a coarse texture, like 60 grit sandpaper but not as sharp. I'm sure that doesn't help with aerodynamics, but do you think it could hurt to the tune of 3-5 highway mpg?
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By hotdoger1 - 10 Years Ago
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my story have 272 with g heads in 56 crown 3 speed overdrive. engine has protronix spark autolite carb with 1 inch spacer timing set 10 degrees plugs are ngk split vtips steel wires. always use 10% gas.mpg is always around 20. this year went on 700 mile trip first tank got 22 mpg. just made another car with 292 with the same setup. car has auto trans. will let you know what it does.
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By Ted - 10 Years Ago
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If you’re not checking the actual content of ethanol in the fuel, then you really don’t know what’s there. The gas pumps typically say ‘May contain up to 10% Ethanol’ meaning it does not have to be there at all to meet that criteria. Premium fuel typically is maxed at 5% ethanol while you will find the 10% amount in the 87 and 89 octane grades. I do check the fuel content regularly here at the shop simply due to dynoing a number of engines on pump gas. An engine ran this last Tuesday found that the customers supplied Valero fuel had 3½% ethanol rather than the normal 5% so unless you check, you simply don’t know. Up to 30% ethanol has been found in fuel that’s been checked here and there are a variety of reasons that can help to explain how the ethanol content can get that high. That 30% fuel obviously didn’t run well and once the percent content was recognized as the problem, the fuel was simply changed out for a 5% blend and all was well.
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By Ted - 10 Years Ago
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Peeeot. I’ll suggest just adding some initial advance in increments to what you already have. There’s the chance the damper has slipped or simply isn’t reading correctly against the timing pointer. If you see some gains in the mpg numbers doing this, then it would be worth the effort in verifying that TDC on the damper is indeed correct. When doing changes for fuel mileage gains, it is recommended to run at least three tanks of fuel for each change so that any detrimental variables can be buffered out of the numbers when averaging.
I’ll add that a retarded camshaft can also be a hindrance to the fuel economy but your compression readings are high enough to have that as a minor player. Might be worth checking the cam timing when all other areas to look at are exhausted though.
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By 57RancheroJim - 10 Years Ago
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I have to use California blended gas which is different the the other 49 states, God only knows what it is but I'm sure it's crap LOL. I've made 4 long distance trips of 280 miles round trip to visit the grand kids and averaged 17-18 mpg in the Ranchero. 292, E4 cam, 390cfm Holley, 3.89 gears, three speed overdrive trans, 215x70x14 radials. I know comparing this to a 312 with auto is like apples and oranges but I think the your 312 should be doing better then what it's getting.
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By charliemccraney - 10 Years Ago
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I haven't experienced any issues since ethanol became a big deal. No decrease in mileage, no decrease in performance, no rubber or metal parts deteriorating prematurely.
I did tune my carb with an O2 sensor. I even erred on the rich side, as indicated by the gauge, and my plugs are always white. . If I hold one next to a brand new plug, the new one is brighter, but it's not a whole lot of difference. My thought, given the color of your plugs, maybe you are too rich for ethanol blended fuels.
While I haven't experienced problems with ethanol, it may still be worth a shot for you to experiment with that. Premium fuel is suppose to have less ethanol than the lower grades. You could try a tank of premium. But, that doesn't mean a whole lot, unless you can know that there is less or none, so you need an ethanol test kit. That way you can test a sample of fuel to know the percentage of ethanol it contains, and therefore determine if there is any correlation between the percentage of ethanol and fuel mileage. You can get ethanol test kits at places that sell lawn mowers, and yard equipment like that.
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By 2721955meteor - 10 Years Ago
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I would look for a rear ratio in the high 2s,with a 312auto any thing in the 3s is to low geared. i have a 57 292 with 3,25 3spd standerd and it is to low geared,ys have great low ent torqe and with a auto trans need gearing in the 2s eith,i run a holley 4v 550 vacume seconds.
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By FORD DEARBORN - 10 Years Ago
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Greetings to all: I have found a fast and simple way to determine the alcohol percentage of gasoline. A good accurate glass 100ml graduated cylinder and a good jar with a tight fitting lid is all that's needed. Fill the cylinder to 50ml and to that add 10ml of water. Pour this 60ml concoction into the jar and shake it for about 40 seconds or so. Pour this back in to the graduated cylinder and see how the 10ml of water "grew." Probably will look like about 15ml which means it pulled out 5 ml of alcohol from the fuel indicating 10%. Recently, samples from my local BP station here in Michigan showed 10% for regular, 6% for mid grade and 8% for premium. I purged the gas pump hose first by pumping a couple gallons in my car, then pumped a gallon in a clean empty sample can. This method served well when burning auto fuel in aircraft approved (stc'd) for auto fuel. That is, before the days of alcohol in pump gas. This mileage discussion is very interesting as I consider it a quick indicator of vehicle health and efficiency. I rebuilt and made my 292 into a 1957 312 for my 64 F100 including a custom cam ground by Oregon Cam to 57 specs. So far I've had to advance the cam 4* and I'm getting 14 to 16 mpg. The truck has a 3.5 rear gear and 3 speed overdrive. Next thing on the list is to dial in the 450cfm Quick Fuel carb with a wide band air fuel meter as the plugs are a bit on the dark side and the exhaust smells a bit rich also. Hope this helps, JEFF..........
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By Kahuna - 10 Years Ago
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Given your input, in your early posts:
All my calculations, using your data for rpm & tire size, tell me that your rear axle ratio is 3.70 to 1.
If you really had a 3.10 axle ratio, then at 3000 rpm you'd be traveling at near 84 mph.
This, I think, is really a big part of the problem.
With a 3.10 axle, at 70 mph, you'd be at 2500 rpm. A much better ratio.
Just some more food for thought. Hope it helps.
Jim
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By charliemccraney - 10 Years Ago
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That is a great observation. I have a slightly taller tire, 28", and a 3.70 and 70mph is right around 3000rpm. Given how easy it is to swap 9" center sections, that could be the reason.
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By MoonShadow - 10 Years Ago
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I'm also running a 370 but with an AOD. It's great on take off but when in 4th the rpm is a little low for performance. It cruises just fine but a bit out of the power range. About 2600 at 65. The AOD is in need of adjustment of the shift points but I can't find anyone local that can handle it. Right now it upshifts to 4th at about 48. The rpm drops below 2000 and it barely will pull hills. At higher speeds it is better. I'm thinking of installing a 410 gear. That should bring the rpm up a bit. I am still running the stock 56 rearend but with a posi. Chuck
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By charliemccraney - 10 Years Ago
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You might be ok once you get that supercharged motor in there.
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By Kahuna - 10 Years Ago
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Re rear end ratios:
Moonshadow
On my 32 Ford, I have a large flathead (290 CI), a Ford toploader four speed, then a Gear Vendors O/D behind the transmission.
The rear axle ratio is 4.11:1. Tires are 29" in diameter. The overdrive drops the final ratio to 3.21.
The engine has a Potvin 425 cam with 245 degrees @ .050".
The engine has (2) 4 bbl teapots, linked together, not progressive.
On the road, car will exceed 21 mpg. I've often thought about going to a 3.78 ratio, but then would lose a bit of the performance.
This is in a Tudor sedan that is shaped like a cardboard box going down the road.
IMHO, lower rpms mean better mileage.
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By MoonShadow - 10 Years Ago
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I've looked at the gear vendor setup but I would have to cancel work on my roadster to buy one! I'd love to get 21mpg but will have to get through the learning curve on the 4-71 blower and 325 cubes. Chuck
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By Kahuna - 10 Years Ago
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I'm guessing you won't be too concerned with mileage with that new setup.
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By peeeot - 10 Years Ago
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I am confident that I have a 3.10:1 gear. I got my revs/mile for each tire from this page: http://www.carnut.com/specs/tires.html It gives a 7.50x14 tire at 750 revs/mile. That comes out to 2325 rpms at 60 and 2712.5 at 70; it will be more with the radials I mentioned because they are 764 revs/mile. That 2712.5 at 70 assumes no slip whatsoever. It's what a manual transmission or lockup converter would give. I have an open torque converter so I expect higher revs than that.
My converter is showing a 10% rpm gain relative to that "lockup ideal." According to my internet snooping, most converters give 3-5%--but it is referring to modern converters, not 50-year-old designs. Can anyone here with a stock Fordomatic verify less than 10% slip?
Also, I can post in detail my current advance characteristics if anyone thinks that would help clear up the picture.
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By Kahuna - 10 Years Ago
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I'm all out of ideas
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By 2721955meteor - 10 Years Ago
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what is the torqe stall # ,if it is higher than spec,you may have to increase torque charging pressure,if low torque pressure it will increase the slippage.all torque
converters have some slippage,high stall tells you ther is low charge or internal issues with converter.still think your ratio in diff is to low for decent fuel economy. if memory is correct the torqe pressure can be increased with new spring ,located along side of trans pressure spring. throtel pressure seting is also critical as well. if you can find a older motors repair manual ther is good info on tp adjustemnt as well the rest of transand valve bodey
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By miker - 10 Years Ago
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My last shot in the dark. The plugs look rich to me, and Charlie's post would indicate that. Do you have the right springs on the step up rods, or would a change help. It's been too long since I tuned an AFB, but IIRC, the rods determine the enrichment, and the springs the vacuum level they come in at. If you're running on the "rich" circuit at cruise that would do it.
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By DryLakesRacer - 10 Years Ago
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My milage is crap. Stock 292, fordomatic, 3.21 gears, 57 dist, and of course dual quads. The best it ever did with a single WCFB was 12 mpg all in town driving. Tail pipes were spotless; now with dual quads it's 10/11 with the same in town driving ( I drive like a grandma and a max of 65 on the Ca. Freeways ) tail pipes are still spotless. Mostly I blame the automatic as our 56 in 56 didn't do much better new. To me the best improvement would be a fuel injection unit like the one MSD makes. It a long with one of their dist. and a cut up stock air cleaner to hide it all would be pretty cool, but not as cool as the 2 quads. A better automatic would help too.... Good Luck
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By Kahuna - 10 Years Ago
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How about tuning with an Air/Fuel meter?
That's how I did my 32 and it made a huge
difference in both performance & mileage.
Then, a Ford AOD
There, I'm almost done.
Except 1) I don't believe there is a 10% slippage in the torque convertor
Except 2) to say that the dual quads are the COOLEST
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By Tom Compton - 10 Years Ago
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My tires are 28" IIRC. With 3.73 gears in 4th (I have a T5 but 4th is 1:1) at 70 MPH the tach shows 3000 RPM. Sounds like your rear end ratio calculation is off.
TC
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By peeeot - 10 Years Ago
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I'm not sure whether 10% is normal for the Fordomatic converter or not, but I do recall my '59 Galaxie with a 3.10 gear being within 100 rpm of the numbers I am seeing with my Fairlane. The Galaxie had the 2-speed aluminum case Fordo.
Miker, if you think my plugs look rich, I'm thinking I will not invest any more time or energy on the AFB and finish putting together my Autolite 4100 instead. I haven't heard of anybody else running that early AFB, perhaps it was extra inefficient. I know the high-speed air bleeds tend to get a film across them which could contribute to rich running. I had a 2100 on my '59 and was very pleased with it.
I'm going to replace the read brake shoes as well. The linings are very old and they look fine but sometimes I suspect they are hanging on a little bit after they are applied. For example, when I release the parking brake after the car has been parked for a while, it does not start rolling when I drop it into reverse without a little throttle.
I am guessing (hoping?) that this poor economy is the sum of several minor contributors adding up to a noticeable impact.
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By miker - 10 Years Ago
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Well, my comment was based on Charlie's comment, after tuning with an O2 sensor. I'm normally looking at a light tan with a carb, but I was always looking for power, not economy. My EFI setup, tuned for power, still runs white. But at light load it's pretty lean, and the fuel shuts off on trailing throttle.
Those Autolites are really well spoken of. But my comment still stands. Put a vacuum gauge on, and make sure the enrichment circuit isn't used at cruise. Whether it's the rods, or a power valve, or whatever, if the gearing-weight-hills put you into the power circuit, the mileage will suffer.
Under the heading of "young and dumb" (as opposed to now, old and dumb), we did a lot of dumb things with power valves, and springs and oil in SU's, thinking we were race car drivers. All we did was buy more gas, and wash down the cylinder walls.
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By Park Olson - 10 Years Ago
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Can the secondaries on that carb be deactivated to run as a two barrel for comparison?
That might atomize the fuel mixture better.
I run a 1.01 Ford flat top on a 292 in an F600, (7500#) ,and get about 10+ mpg, It has a 11/2" riser block
JOT
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By Ted - 10 Years Ago
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As a general rule, four barrel carbs will get better overall fuel economy than will a larger sized two barrel carb. Part of that has to do with the primary venturies in the four barrel carb being smaller than the venturies in a two barrel carb thus promoting increased atomization of the fuel. Vacuum secondary carburetors will only be running on its primary side circuits during normal driving operation but the secondary side is still a player in that there is an idle circuit still active there to allow fuel to be constantly refreshed in that end of the carb. On the Holley and Autolite carbs, that’s to keep the fuel from going stagnant if not using the secondaries very often. On these carbs, the secondary float level is also important and if too high, can be contributing to increased fuel consumption. On the flip side of this, the Carter 4V carb has a common fuel level for both the primary and secondary fuel supply but the left and right side of the carbs are independent of each other in regards to float levels. On the Carter carbs, it’s possible for the outer two cylinders on one bank and the inner two cylinders on the other bank to run at a different air fuel ratio than the other four simply due to the left and right sides of the carburetor simply having different float levels.
But beyond all that, there are lots of variables involved to get that fuel mileage up. While the engine combination and its tuneup is at the top of the list for the fuel mileage, the remainder of the car must also be looked at. Gearing and tire size are two of the obvious things to consider but in the background is the front end alignment, tire inflation pressures, brake drag, driveshaft angles, and transmission drag. If running an automatic trans, then this is an area much overlooked as there is a considerable amount of variability within the transmissions both in the clutch packs and the converters.
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By peeeot - 10 Years Ago
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I took the Fairlane out for a drive today for the first time in a couple of weeks. When I first put the transmission in gear to leave the driveway, it felt like the parking brake was engaged: I had to put my foot on the gas to get the car to roll, and it was very sluggish. I assumed the shoes were sticking to the drums and a little exercise would clear that right up. Everything felt pretty normal after two stops. When I reached my destination, I checked how rollable the car was by shifting into neutral with the engine off. The car immediately started rolling by gravity and I thought I was on flat ground! Additionally, it wanted to creep at stoplights. So if the brakes are contributing to bad mileage, it would seem an intermittent problem.
I have thought more about whether the transmission could be the weak link. Aside from the poor economy, I also feel like there is more engine braking than should be. I had the converter apart a couple years ago and began to wonder whether I could have installed the stator backwards. This is the way I assembled it:
From what I can tell, that was the way it ought to go. And I remember checking the one-way clutch and not finding a problem there. Ted, how would one assess transmission drag?
What about oil? I use 20w-50.
Front end alignment is fresh with the front end rebuild. Tires are 225/70/14s and I tried running them as high as 40 psi; also tried 7.50x14 bias plies at 24 psi with no difference (except much easier steering! No power steering on my Fairlane).
I'm going to replace the old rear brake shoes this weekend and will see whether there is any perceivable change with that improvement.
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By 57RancheroJim - 10 Years Ago
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Unfortunately the FOM has always been a MGP killer. If I recall they take close to 50 hp as compared to other makes that are around 20-25..
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By Kahuna - 10 Years Ago
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I don't believe that for a second
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By charliemccraney - 10 Years Ago
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Transmission efficiency is irrelevant if similarly equipped vehicles routinely get better mileage
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By Ted - 10 Years Ago
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peeeot (11/13/2015)
I have thought more about whether the transmission could be the weak link. Aside from the poor economy, I also feel like there is more engine braking than should be. I had the converter apart a couple years ago and began to wonder whether I could have installed the stator backwards. This is the way I assembled it:
From what I can tell, that was the way it ought to go. And I remember checking the one-way clutch and not finding a problem there. Ted, how would one assess transmission drag?
That’s a tough one. A chassis dyno with the engine simply running at a specific rpm and throttle opening would give an idea of how much horsepower is being required for normal driving. But that means having a baseline for a normal drag within the transmission and/or driveline in which to compare. I have run across this in the past on Turbo 350 trannies and the transmissions were simply swapped out for another when the problem cropped up.
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By peeeot - 10 Years Ago
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I see. I have changed the rear brake shoes and adjusted all brakes. I set the fronts to where the wheel will spin one full revolution before stopping when spun by hand. The rears are much trickier, I set them to where I could feel a little brake drag but still turn the drum easily by hand. I erred on the tight side since the shoes are new and will need to wear in. I will not try to assess economy again until they have time to wear in.
In the mean time, I have been studying my FOM supplement and intend to do control pressure checks and, most importantly, a stall test. But given the behaviors they describe when troubleshooting converter issues, I suspect I will not find any problems. And now I'm sure I installed the stator correctly. Updates as I have them.
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By 57RancheroJim - 10 Years Ago
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Kahuna (11/13/2015)
I don't believe that for a second Here are some examples of parasitic hp loss with auto's. This one doesn't include FOM but they are right up there with the worst ones.
thought some of you might find this interesting.............
Just in case you're curious, power loss for various auto transmissions:
Please remember these are approximate values, and were provided by Car Craft Magazine.
Powerglide_____18 hp
TH-350________36 hp
TH-400________44 hp
Ford_C-6______55-60 hp
Ford_C-4______28 hp
Ford_FMX______25 hp
Chrysler_A904__25 hp
Chrysler_727___45 hp
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By PF Arcand - 10 Years Ago
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At a guess, I'd presume that a Fordo is about the same efficiency as the FMX at about 25 h.p., but it would be interesting to know for sure..
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By 57RancheroJim - 10 Years Ago
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I had the info on the FOM at one time and just can't find it, but I was amazed at how high it was, much higher then a FMX. I'm not an auto trans guy so I don't why.
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By 2721955meteor - 10 Years Ago
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have you tryed doing a complete trans presure test,also throtle presure adjusted to book specs.to much tp gives late shifts, to litle gives slushey shifts. useing the old bolt together converter may result in over heated oil in trans.i would also try mercon fluid. is the trans a older fm that matches the 55 torque.
it apears your engine is not the isue, rear axel is close to corect. tho with the torque of a y you could try the high 2s for a ratio.. do you use a heatriser valve.
i have poor fuel econemy ,but have no heat riser,mostly short runs,to much on the throtel, run a 3.25 rear,use reg fuel frome blain wa, .it improves when i use mid grade,but with cn doller worth zip. you may have same isues as me love theresponce and sound,drive a bit like a 18year old(at age 75). we have a mazda2 for econemy, ichose to burn the fuel and drive the 57 ranchero.I like the reaserch you have ,as well as the way you layed it out. keep us filled in when you find improvements
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By FORD DEARBORN - 10 Years Ago
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Greetings to all: If memory serves me correctly, the FMX did not have a rear pump as opposed to the COM and FOM trans.. This may explain the better power consumption number for the FMX. Not pumping fluid when ever the drive shaft is rotation meant the vehicle could not be push started which became less important as vehicle reliability increased. This is a very interesting thread as I too monitor fuel consumption religiously. If winter can hold off a little longer I should be trying out an Innovate air fuel ratio meter to better dial in a small 4bbl on my 312. Will report the results. Good luck, JEFF..........
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By 57RancheroJim - 10 Years Ago
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FORD DEARBORN (11/15/2015)
Greetings to all: If memory serves me correctly, the FMX did not have a rear pump as opposed to the COM and FOM trans.. This may explain the better power consumption number for the FMX. Not pumping fluid when ever the drive shaft is rotation meant the vehicle could not be push started which became less important as vehicle reliability increased. This is a very interesting thread as I too monitor fuel consumption religiously. If winter can hold off a little longer I should be trying out an Innovate air fuel ratio meter to better dial in a small 4bbl on my 312. Will report the results. Good luck, JEFF.......... Thats a good point about the pump difference..
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By peeeot - 10 Years Ago
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I was aware that the FOM had a rear pump but had not considered how it might affect economy, particularly if there was a malfunction.
I am increasingly growing to believe that I have drag issues somewhere. Today I noticed that I was LOSING speed while coasting down a moderate hill in my neighborhood. I have noticed that shifting into neutral improves coasting but not as much as I would expect. Is it possible that I'm getting some kind of hydraulic resistance from the rear pump?
I just replaced my rear brake shoes and am definitely getting some drag there, but I don't understand it. When I first installed them, I could turn the drum (without wheel) by hand pretty easily, so I figured they were adjusted loose enough to get started. Well, they got hot enough that I could smell them when I drove it so I pulled the drums off to inspect. Linings looked ok, drums looked shiny. I went over the drums with coarse sandpaper enough to break the glaze, and then carefully adjusted the brakes again, this time following the same rule as for the fronts: when I gave the wheel a hearty spin, it would rotate about 1 full turn before stopping. Well, the rear drums are still noticeably hotter than the fronts. How could that be, when I adjusted front and rear the same way? Is it because the shoes are new/not seated in yet?
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By 57RancheroJim - 10 Years Ago
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That could be a possibility that the new shoes are heating a little but it shouldn't be much. Are you sure your emergency brake is releasing completely? Always adjust the brakes when cold.
In some rare instances I have seen the rear rubber brake hose deteriorate on the inside a loose piece will act as a one way valve and keep pressure on the wheel cylinders..
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By FORD DEARBORN - 10 Years Ago
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Greetings to all: As mentioned above, the parking brake cable has been a source of trouble many times and would be 1st on my list. Also, make sure that there is proper free play in the brake pedal as it's necessary for the master cylinder piston to completely return home. Otherwise some residual pressure may remain in the hydraulic system. Peeeot, do you have a dual master cylinder? It''s one thing to have a slight drag with slight warming of the brakes and quite another thing when one can smell the brakes. I think you are on the right track in solving this brake issue first. Hope this helps, JEFF.................
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By peeeot - 10 Years Ago
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I have a bit more info on the brake issue. Yesterday I needed to drive about 90 miles so I jacked the rear end up and backed the adjusters off something like 20 clicks, enough that when I spun the wheel I heard little to no contact between the shoes and the drums. As expected, the pedal action was much lower but still firm, still stopping the car ok. I applied the brakes several times and rechecked for drag and there was none, so I hit the road.
When I arrived at my destinations, once again the rear wheel rim and brake drum were quite a bit hotter than the front. In fact, the front wheel didn't feel warm at all. There was a detectable odor at the rear but not as strong as it was before loosening the brakes up. After a few minutes I cold hold my fingers on the front drum no problem but the rears were still too hot to touch for more than a few seconds.
Even so, if I took my foot off the brake in neutral, the car would start rolling, and this on a very shallow incline. To date, I have checked for a hydraulic hold on the brakes (failure to release) dozens of times under different circumstances and have never found the brakes to be holding.
I made a point on my drive home of finding a few miles without stopping so that I could coast to a stop and check for heat indicating brake drag. When I pulled over and checked them, without braking at all, they were not as hot as they had been when I arrived at my destination, but they were still definitely warmer than the fronts, enough to indicate (to my mind) some amount of drag--yet once again, the car easily rolled when placed in neutral.
One other observation: After this last adjustment, the pedal height was much lower, and it took some mental getting used to because my foot would move to where it expected to stop without meeting resistance. It was enough to give me a flash of that "oh crap" feeling you get when you think your brakes have failed, until I hit the firmness and the car stopped fine. Well, over the course of my trip I noticed that these "oh crap" moments had stopped. I figured I had just gotten used to the new hard pedal height. Then, when I was near my destination, as I approached a light to stop, the same thing happened: the pedal felt much lower than my muscle memory was anticipating. I paid special attention to this on the way back home, and without measurement it's hard to be sure, but I suspect my actual hard pedal height changed intermittently. This would suggest something like the brake shoes hanging up on the backing plate.
Today, weather permitting, I'd like to get the drums off again and resurfaces the backing plate pads to make sure they are smooth. I will probably bleed the brakes too to make sure I don't have any boiled fluid in the rear lines. Beyond that, I'm not sure where to head with this. It's almost like the rears are doing more of the braking effort than the fronts, but with a single-line master system, I don't know how that would be possible.
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By chiggerfarmer - 10 Years Ago
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There should be one rubber brake line from the body to the rear axle that serves both rear brakes. Sometimes these lines can fail inside and not release properly. I have never yet seen one that did this intermittently, but if all else fails I would be suspicious of it.
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By 57RancheroJim - 10 Years Ago
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Wear on the backing plates could be a possibility as you mentioned but you said the wheels turn fine after applying pressure and releasing so it doesn't sound like the shoes are hanging up. I'm not sure if there would be more heating if the primary shoes and secondary were on in reverse? Just a wild guess but could it be possible that the rear brakes are working fine and trying to do the most of stopping because the fronts aren't working properly?
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By 2721955meteor - 10 Years Ago
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wheel cylenders could be sticking. had that isue with my ranchero,replaced bothe the fronts, had to drive them apart with hamer and punch, the worked but never quit draging.
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By peeeot - 10 Years Ago
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I took the driver rear brake back apart and though there is some wear on the backing plate pad, I really don't think it's enough to cause a problem. I actuated the brake with the drum off and watched the shoes expand and return. It appeared to me that as long as the range of motion was small the shoes would always return. They did not snap back into place; when the pedal was released they returned steadily over about a second or so. I flushed and bled the brake line and adjusted the brake according to the shop manual.When I was done I could hear some contact with the drum but the wheel spun freely. Apparently the adjustment has not been my problem though. I verified that the wheel cylinder was 7/8 ID and that the pistons both moved freely. There was a LOT of brake dust in the drum on the driver side and a normal amount on the passenger side. That was surprising because both sides get hot. I haven't finished checking out the passenger side yet though.
I will be checking the fronts too as I get time, perhaps there is indeed a problem up there forcing the rears to take up more than their share of the stopping duty.
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By PF Arcand - 10 Years Ago
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Your problem is perplexing? Grabbing at straws here.. but you say the rear brakes are overheating, so is it possible your rear axle fluid is to low & the wheel bearings and so on are overheating?..
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By 57RancheroJim - 10 Years Ago
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Brakes not snapping back is normal, the wheel cylinders are trying to push all the fluid back into the master cylinder. They can't do that at the same speed as the master cylinder piston is released, thats why there is two holes in the master reservoir, the small one compensates for this. BLA BLA BLA, I'm sure you know that...
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By Ted - 10 Years Ago
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There’s a good chance the springs are simply not pulling the shoes and wheel cylinders back as they should. As a general rule, brake springs are typically only good for ten years and then should be replaced. Brake spring kits are readily available for most applications.
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By peeeot - 10 Years Ago
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PF, that's a good thought. I figured if the wheel bearings were bad I would hear it/feel it in some way other than the heat. Then there's the fact that the drum itself gets very hot, not the brake backing plate, and all that brake dust on the driver side. Next time I drive I will check the axle tube for heat in the area of the bearings.
Ted, springs are cheap, I'll look into replacements. I know that when self-energizing brakes apply the "servo action" uses the primary shoe to increase the application force on the rear shoe. Maybe the springs aren't pulling the primary shoe off with enough gusto after actual braking and I have been unable to observe it since I can only check for shoe release when the car is already stopped.
I feel like I'm grabbing at straws too! Just have to be more stubborn than the problem...
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By peeeot - 10 Years Ago
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I contacted Charlie of charlietranny.com about the torque converter slippage. He said that 5-10% slip is considered normal, so the 8-9% I'm seeing at highway speeds is normal and therefore it seems unlikely that my transmission is what's eating up my MPGs.
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By 57RancheroJim - 10 Years Ago
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It will be interesting to see what you find in the end. I think we are running out of guesses..
If all the heat is being generated on the driver side, is the passenger side not working properly causing the problem?
Can you brake hard enough to see that both lock up?
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By MoonShadow - 10 Years Ago
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I had a problem with one caliper dragging on my Dodge van. I followed some advice on digging in to it and was told to jack up the vehicle and find the wheel(s) that seems to be dragging. Open the bleeder screw until a little fluid comes out then check to see if the wheel turns easier. Problem turned out to be a bad rubber brake hose. Apparently they can develop loose tabs of rubber inside that act like a flapper valve and don't allow the brake shoes to retract fully. Worked for me. Chuck
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By peeeot - 10 Years Ago
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Updates!
I have now gone through all the brakes and bled them and adjusted them per the shop manual and found no hydraulic or mechanical problems. After a nice little test drive, I found once again that I could touch the front drums as long as I wanted to but the rears were too hot to be touched for more than a second or two. I did find (or rather, rediscover) that the front drums are both pretty deeply scored from where the brake shoe rivets dragged on the drum who knows how long ago. The grooves are deep enough that the linings have not worn into the grooves yet. What that means is that the actual lining-to-drum contact area up front is something like 25-30% less than it should be. My theory is that this reduced lining area reduces the effectiveness of the front brakes and so I have to push the pedal harder which makes the rears carry more of the stopping work than they are designed to. Does this sound like a plausible theory? If not, I will try replacing the rear brake hose. I replaced it just a couple thousand miles ago but I know that doesn't guarantee it isn't defective.
In more exciting news, I thought the car felt a little lighter on the test drive and noticed two tangible indicators of improvement: RPMS at 70 mph were 2900 and the temp gauge never reached the halfway mark. Normally, 70 comes in at 3100 RPM and the temp at 70 is a little over halfway. True, it is a very cold day, but assuming both of these changes prove to be consistent, I will expect my fuel economy to improve. Dropping 200 rpm at 70 means there is considerably less rolling resistance! Now I just need to drive it more and see if this wasn't a fluke.
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By MoonShadow - 10 Years Ago
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You really should have the drums turned or replace them. The grooves will cause premature wear on the shoes and reduce braking efficiency.
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By 57RancheroJim - 10 Years Ago
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Besides the fronts being grooved they may be worn or have been turned to far oversize. Next time you have the drums off take a brake shoe off and place it inside the drum and compare the arc, you may be getting a very small contact area. I miss they days when they would arc the shoes to the drums so you didn't have to wear them in..
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By Lucky'57 - 10 Years Ago
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I haven't read the whole post here but for what it's worth, my 57 Fairlane 500 had similar problems. Brakes would heat up and drag, pedal would come rock hard. Talked to the guys on 57fordsforever and come to figure the master cylinder wouldn't retract all the way allowing the fluid to bleed back. As the brakes generated heat the "trapped" fluid would expand to the point where I had to bleed fluid just to keep going.
There is an eccentric adjustment on the brake pedal, you need to set this up so it has at least 1/16" or so of play. Hope this helps. My stock brakes have no proportioning valve, did someone throw one into your car? That could also be an issue (if it's stuck just tap that pin back in).
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By DryLakesRacer - 10 Years Ago
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I worked in a brake shop for a few years and the raised spots on the backing plates must be smooth. We would flat file them as necessary. No high spots. We always replaced the springs no matter what and always put lubriplate on every raised place where the shoes rode. I could tell when doing a brake job if the last shop knew what they were doing by the chamfering of the shoes and the evidence of lubriplate on the backing plates and the adjusting screw... Good luck.
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By junkyardjeff - 10 Years Ago
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I was watching the Andy Griffith show when aunt Bea's sister and family came to visit in a 55 Ford and her husband was saying he got 15 miles to the gallon on the trip so I do not think they are gas misers.
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By 2721955meteor - 10 Years Ago
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seems you have not checked a verry critical part of the power train. trans throttle pressure adjustement. Torque stall,must have a acurate tack. if torque stall is high,check trans presures,and torque charging presure. a poorly set up trans will acount for 5 or so mpg. torqe stall will tell you the health of the engine as well
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By peeeot - 10 Years Ago
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You're right, I still have not checked the trans throttle pressure. I got sidelined on this issue by some fuel delivery problems that made the car unreliable for a few days, but it's back in action now. The trans throttle pressure & stall check are next on the list of things to look into.
Meanwhile, I can report that something (I wish I knew what) has definitely changed. Throttle response has always been very linear and a bit soggy--I remembered my 292 '59 Galaxie feeling more punchy than this 312 car and figured it was a consequence of the CI FOM as opposed to the later aluminum one the Galaxie had. Well, now, the 312 is awake! If I am very gentle with the throttle, the first little bit of pedal travel gives light acceleration, but if I push it just a little farther (we're talking 1/4 throttle at most, by the feel), there is a surge of power stronger than what I have grown accustomed to with this car. The long shot of it is that I don't have to give it as much throttle as I used to to get the same rate of acceleration. I don't believe this to be caused by removing rolling resistance, though I can't say for sure. It just seems that when the throttle plates open enough to pull in the main fuel circuit, it does so with new strength. No carb settings have changed and I have been through this carb checking for blocked passages and the like many times with no trouble indicated. This is a new development so I haven't been able to tell whether it has helped or hurt economy. I will be driving the car a lot now so I'll post back when I know.
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By MoonShadow - 10 Years Ago
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What were the fuel delivery problems you dealt with?
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By peeeot - 10 Years Ago
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I was driving along and the fuel tank was low but I thought I had enough to get to a gas station. Car quit and I figured it was lower than expected so I added the gallon of gas I carry around "just in case" which has been enough to get it to a gas station in the past but this time I got about 200 ft. Got another gallon and another 200 ft, uphill. Repositioned so car was pointing downhill and got it running, made it to a gas station, put 3/4 tank in, thought I was good, got about a mile before more of the same.
First thing I did when I got it back home was change the fuel filter, which seemed to fix it but got me about 5-10 miles before it started to act up again, but not as badly. Took fuel pump apart, took carb apart, found a little sediment in carb bowls but pump was clean. Put it back together and no trouble since then. I'm not sure whether there was a problem with the fuel pump check valves or maybe it was sucking a bit of air at the hose junction to the fuel hardline.
Just to be clear, it was not an ignition problem. I disconnected the fuel line at the carb and verified that it was pumping intermittently.
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By MoonShadow - 10 Years Ago
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DIrt could have put a strain on the fuel system and could cause bad mileage. Time for another road trip.
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By Ted - 10 Years Ago
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56Roger (12/5/2015)
Your engine's rpm will always be the same at any given speed unless the gear ratios are changed somewhere in the drive train. Effective tire height must also be considered. But otherwise the only way for it to be different than it has ever been is for the tires to have lost traction (spinning/skidding) or the clutch/auto transmission to be slipping. The relationship between the tires rotating along the surface of the road through the drivetrain to the crankshaft rotating in the crankcase doesn't change no matter how well or poorly the engine is running. It's after the fact.
Good thing too, would pretty much make your speedometer useless if it didn't.
While that statement is true for a standard transmission equipped vehicle, it does not hold true for an automatic transmission. The torque converter by design does exhibit a given amount of slippage and where the rolling resistance is increased, the engine rpms will be higher versus where the rolling resistance is less. The exception to this is the ‘lockup converter’ design which gets around the built in slippage factor but that lockup only occurs when the engine is under its least amount of strain. Even within the manufacture of torque converters for the same application, there is a given amount of variability in the slippage between these. This among other factors helps to explain why some cars although identical in manufacture have better fuel mileage than others.
The speedometer gear runs off of the transmission output shaft which will not reflect rpm variances from the converter forward.
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By 2721955meteor - 10 Years Ago
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ted is bang on re the torque slippage,but torque charging pressure has a direct bearing on the slippage,which will never be eliminated toatley.shift quality and torque eficency are all controlled by pressure, via the control valve and the throttle pressure .adjustment. until these pressure are correct and to speck your search for better milage is like the dog chasing his tail.
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By peeeot - 10 Years Ago
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meteor, that's an interesting consideration. I hadn't really thought about it but would have assumed that as long as the converter was filled and the clutches/bands fully applied, converter slip would be the same regardless of throttle pressure because the converter elements would not "care" what the pressure in the shell was relative to atmosphere. I understand throttle pressure as balancing with governor pressure and influencing shift events (timing, quality, rate) and not having a significant direct bearing on converter behavior (beyond the effects of being in different gears).
I'm working on my first measured tank of gas still, gauge is showing 5/8 full and I've gone about 100 miles. That looks better than it's ever been but I also recalibrated the fuel gauge (so it wouldn't tell me I had fuel when I actually was empty). Consequently, I don't know how I'm doing relative to the norm and will just have to wait and see until it's time to fill up.
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