|
By Duck - 11 Years Ago
|
|
I'm wondering if anyone here could shed some light on what ( after hours spent w/ Google) appears to be a very convoluted topic- converting a '55- '57 'bird to a dual (split) reservoir brake system. I DON"T want to convert to discs, as I have no problem with the existing drum/ drum factory setup. I just would like the peace of mind afforded by splitting the system. If anyone has experience with this specific changeover, may I inquire as to how you did it, how did it turn out, and the components used?Also, whom did you purchase the parts from? From all I've read, seems many folks confuse residual valves w/ proportioning valves. (What did you use successfully?) Also what M/C is/was the proper choice. I'll be re-using the factory booster after Cardone rebuilds it again, due to it allowing my current M/C to be sucked dry of fluid. (That's a story for another day, though) Any thought are appreciated, & Thanks in Advance /Duck
|
|
By The Master Cylinder - 11 Years Ago
|
|
Duck (11/17/2013)
I'll be re-using the factory booster after Cardone rebuilds it again... Duck
Duck, Just so I understand your plans, You want to used drum brakes all around with a dual M/C using your factory booster on the fronts only?
If that's the case you should used an adjustable proportioning valve since your using power on the front but not on the rear. I'd use a dual M/C off a drum brake car (Granada or similar) with no residual valves.
Not an expert, just my opinion and it's worth just about how much you paid me for it…
|
|
By Duck - 11 Years Ago
|
|
Right- keeping drums @ all 4 corners. I've seen that '67 - '70 Mustang master cylinders had been mentioned in several occasions. as an appropriate donor. I surmised that a few of them came w/ drums fnt & rr. I haven't a clue as to if that particular M/C had internal valving or not, however. I have a suspicion that the booster being a player only at the front brakes will be the fly in the ointment. I don't want to swap in a different booster, if it can be helped though, as I already have this one, and also due to the constraints of available under hood free space.
|
|
By The Master Cylinder - 11 Years Ago
|
|
Yes, a mustang M/C may be better for a 'Bird. For some reason I was thinking car.
|
|
By simplyconnected - 11 Years Ago
|
Duck, this would be a lot easier if you could move your battery to the trunk, and install a firewall booster. You can get a two-stage 8" booster and dual M/C from MBM for under $200.
Not that it matters because Ford and GM never made Combination Valves, but I like the GM style better. It comes with two mounting holes in the valve body.
You're right, some folks fight about the proper name, and vendors use 'proportioning valve' to mean a host of different things, including flow controls (which don't proportion anything).
To save confusion, I call OEM-style, "Combination Proportioning Valves" while others simply call them, Combination Valves. They come in two flavors: Drum/Drum and Disc/Drum. If you do the firewall booster, you should use the Drum/Drum to equalize flow between the front and rear systems. This is an easy setup and not high in cost. - Dave
|
|
By kevink1955 - 11 Years Ago
|
To make it even more confusing I have heard that you must use the brake failure switch (4 ports) as it contains a shuttle valve that not only turns on the brake warning light but blocks the line to the failed system to maintain almost normal pedal hight during a system failure.
Nothing says you have to wire the warning switch but a cutaway view of the switch I have seen looks like it does block the failed ports on activation. If you have ever bleed a dual master right at the ports the pedal drops almost all the way to the floor when any line is cracked so there may be something to using the switch.
|
|
By charliemccraney - 11 Years Ago
|
There is a lot of mis-info related to brakes. Mine with the dual master cylinder is no safer than a single. That I can tell you as a fact. Something that was mentioned to me is perhaps the pedal travel is not sufficient to engage the safety feature. I haven't taken the time to research this for myself but it should be easy to get an idea if yours is sufficient by finding a travel spec for the vehicle that the master cylinder is intended for and then verifying that yours can achieve the same.
At this point, I'd advise you to not expect the "safety" that everyone claims of a dual mc on a vehicle for which it was never intended. If you install it, maybe it will be safer and maybe it will not. I guess that chance could make it worth the cost.
Here's a fairly recent thread to give you a little more to think about.
http://forums.y-blocksforever.com/Topic90139.aspx
|
|
By slick56 - 11 Years Ago
|
|
If i ruptured a brake hose, i'd like to think that with a dual circuit master cylinder, two wheels would at least slow me down.
|
|
By charliemccraney - 11 Years Ago
|
I like to have thought that, too. But that's not what happened. A, fortunately, very low rate of speed in my driveway and the parking brake stopped it. Hydraulics were doing nothing.
There is more too it than simply the master cylinder. I don't know enough about it to say what, and I don't want to contribute to the mis-info.
|
|
By paul2748 - 11 Years Ago
|
|
I had the same situation as Charley, on two different cars. Both have combination valves and dual master.
|
|
By MarkMontereyBay - 11 Years Ago
|
Here is a good description of the brake system function including the pressure differential switch/isolation valve.
http://www.classicperform.com/ShopTalk/
There is a tool to use when bleeding or servicing the brake system to keep the pressure switch/isolation valve centered. Before the hydraulic system is opened, the pressure differential switch connector on the combination valve is removed. In its place, the tool is threaded into the port which has a small pin on it to hold the isolation valve in the centered position.
http://www.npdlink.com/store/products/tbird_brake_pressure_differential_valve_switch_lock_tool-178818-6444.html
|
|
By MarkMontereyBay - 11 Years Ago
|
|
If the brake system has been opened not using the lock out tool and the isolation valve has gone off center and either the front or rear brakes won't bleed, here is the way to recenter the pressure differential valve. Make sure all four bleeders are closed. Have a helper sit behind the wheel with his foot on the brake but not pushing it down. Open a bleeder on the system that system that will bleed (front or rear) while having the helper very slowly press the brake pedal down until a pop is heard or felt in the brake pedal travel and hold it in that position without moving it. Close the bleeder. The isolation/differential valve is centered and the warning light should be out. I had to do this as an apprentice a few times before I listened to the journeyman explain, once again, how and why to use the lockout tool. I still have mine from 1979.
|
|
By kevink1955 - 11 Years Ago
|
So the brake warning switch (isolation valve) does most of the work protecting you from brake failure, that's what was told to me and is now confirmed by the link provided by Mark.
I wonder what would happen if you installed an isolation valve (see I learned a new term today) on a single master, split the brake system front to rear and pipe it to the outlets then connect the 2 inlets to a stock single master cylinder. Would that protect from any failure on the down stream side of the valve?
Sure you could still have a master cylinder failure but I have never seen one fail without warning such as sinking pedal or leaking at the pushrod
|
|
By Duck - 11 Years Ago
|
|
Seems that anything short of a full-on disc conversion is a 50/ 50 proposition, at best and would come at the expense of losing my power assist. I'm not really in a position to let go of all that $ to do a conversion right now, either. I think I'll just have my booster rebuilt, and buy a big anchor w/ 50 ft. of good heavy chain, in the meantime 'til I can scrape up the coin to do it right. I am still going to send my wheel cylinders out to be sleeved w/ .304 this week however. /Duck
|
|
By GREENBIRD56 - 11 Years Ago
|
Hey there, Duck cruzin' with a heavy foot again? Wear the boots with the brake linings...........
Stargazer had a note on here (I think?) about using a different divorced brake booster. Apparently, we are (as usual) being victimized by vendors on account of wanting the "original" parts - when another nearly duplicate part is available for less (and looks just like it).
|
|
By skygazer - 11 Years Ago
|
I think this is the tread Steve is referring to... http://forums.y-blocksforever.com/Topic84997.aspx#bm86383
This doesn't answer the dual circuit/single booster question for drums. Boosted front-only seems to work well for disk-drum setups, but I don't think I would want to boost only the front of an all drum setup.
|
|
By Duck - 11 Years Ago
|
|
Steve- no, this thing's an expensive paperweight until either I can 1) get the brakes sorted or 2) the return of nice weather (whichever comes last) I also smell subterfuge inasmuch as vendors "whitebox" parts. Nothing new there though, I suppose. Seems if anyone had ever successfully accomplished what I had hoped to do, I'd have found a trace of it on the interweb, by now. After reading about M/C's & distribution valves/ switches not working as intended, I'll be more conservative in my thinking for safety's sake. Thanks for the head's up. /Duck
|
|
By The Master Cylinder - 11 Years Ago
|
There appears to be a lot of misinformation and misunderstanding of how a dual master cylinder works. There are two separate braking systems, they never share fluid. The isolation valve is just that, to stop leakage from the system that has the leak. It does nothing for the fluid in the system that is working. I find it odd that the link Mark provided doesn't mention anything about the internal safety devices in the M/C.
Here's is an interactive explanation on how the dual M/C works to prevent total loss of your brakes. As said before if your brakes are not set up correctly to begin with or your travel is insufficient then the safety factor is not going to work.
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/master-brake.htm
My own brake system on my '55 is out of a '72 Granada, M/C, power booster, disk brakes and rear brakes. I don't even have the "isolation valve/warning light installed, nor is it needed. It is just an another safety item in ADDITION TO the dual M/C.
Am I a brake specialist. No, but I have done quite a bit of research on brakes.
|
|
By MarkMontereyBay - 11 Years Ago
|
|
The link I posted deals with the design and operation of a typical combination valve. The dual circuit master cylinders are two separate braking systems in one master cylinder body. The weak point of the design is pedal travel related to incorrect rear drum brake adjustment and/or worn linings. If the front brakes are lost do to a hydraulic failure the pedal needs to travel enough to move the front master cylinder piston to make contact with the rear brake piston engaging the rear brakes. If the rear brakes are not adjusted correctly or a combination of worn linings and poor adjustment, the pedal may hit the floor/carpet before making adequate movement to engage the rear master cylinder piston with enough pressure to initiate adequate braking. The brake warning light was designed for those less than "attentive" drivers who may continue driving with only one system working, particularly if the rear brake are inoperative due hydraulic failure. The isolation valve closes off the master cylinder from the failing system minimizing fluid loss.
|
|
By The Master Cylinder - 11 Years Ago
|
|
MarkMontereyBay (11/24/2013)
If the rear brakes are not adjusted correctly or a combination of worn linings and poor adjustment, the pedal may hit the floor/carpet before making adequate movement to engage the rear master cylinder piston with enough pressure to initiate adequate braking.
Haha, Mark, You said it all right there... If your braking system is borderline due to lack of maintenance or you installed it improperly and didn't check it in the first place, how can it be blamed on the dual master cylinder/dual brake system when it doesn't work properly.
One thing I learned in class (way long ago) is you can't design for "Double Jeopardy". For one example, lack of maintenance and failure of a component.
Bottom line I feel when set up properly and maintained a dual braking system is way safer than a single M?C system.
|
|
By The Master Cylinder - 11 Years Ago
|
|
Mark, all that said I hope you get your brake "problem" worked out to your satisfaction.
|
|
By MarkMontereyBay - 11 Years Ago
|
|
I put that info up for Duck to help explain the dual circuit brake system. I am running Granada manual front discs and stock rear drums on my 57 Bird. Used the Granada master cylinder and a Wilwood combo valve. I don't miss the power brakes at all, they work great. Much safer and effective over the often scary front drums. Finishing up an alternator conversion this week if I can and after the holiday it's back to finishing the 445 Survival Motorsports stroker for the 65 Galaxie.
|
|
By lowrider - 11 Years Ago
|
Just to add fuel to the fire, I read over on the HAMB (more than 1 post) that if your running just the stock drum/drum set up a proportioning/combo valve isn't needed.
I agree with Charlie too. After working on cars 40+ yrs when I would pull one in with a blown line, cylinder etc. you still needed a boat anchor to stop it.
|
|
By slumlord444 - 11 Years Ago
|
|
Had a rear break line blow on my '74 Ranchero back in the day. Brake line rusted through and blew when I tried to make a rapid slow down to make a left turn. Had a tough time getting it stopped. Missed my turn. Would have hit anyone in front of me if there had been anyone close. Emergency brake on my T Bird could have not been much worse.
|
|
By 312T85Bird - 11 Years Ago
|
Dorman Products Part # MC 73323 fits a '66 to '71 Mustang with manual Disc Brakes and works Great with Drum Brakes on Baby Birds and does not need a Proportioning valve as it is self equalizing. The master cylinder with Power brakes Does need the proportioning valve however. Nice bolt up, however I suggest a 1/8" thick plate faced like the Original master cylinder to bolt between the new master cylinder and the firewall to stiffen the firewall when you install it and the push rod will need to be 1/4" longer then stock. You will be amazed at how well the Bird will stop still using drum brakes.
Tom
|