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By RJ Palmer - 4 Years Ago
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Has anyone done that? Thinking of doing that and would like to call on anyone who has and what problems I could encounter.
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By 55blacktie - 4 Years Ago
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The OEM booster is not sufficient for all four corners, when converting to disc brakes. It can be used for the front or rear, if you are converting to a dual-circuit master cylinder as well. you will need an aftermarket booster for all four corners, which will require relocating the battery.
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By Vic Correnti - 4 Years Ago
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I can't speak for the booster but can say that I have front discs and rear drums on my 55 Bird for the last 25 years. My pedal is hard and the effort is way less then the original with all drums and stops way better. So I would say try it without a booster and you can always add one if you need to. You can always size the master cylinder and calipers to increase force also.
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By miker - 4 Years Ago
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I bought a front disc/power booster kit from one of the Thunderbird supplier (they retired, I think Hill’s acquired them) back in 1999. It used a disc/drum dual master and the booster on the front disc only. I don’t recall if there was a different rear wheel cylinder (for balance adjustment) or if it would be different with the front booster. But most of the bird suppliers would know.
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By 55blacktie - 4 Years Ago
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Vic, glad to hear you are happy with your brake setup. I bought Wilwood 4-piston Dynalite calipers and 1 1/2 drop spindles from Dave (Drop em Stop em), Wilwood 15/16ths master/w proportioning valve, retaining OEM 11" rear drums, but no booster. I'm still working on put my 55 back on the road, but it sounds like I'll be happy with my brakes. I do intend to put automatic adjusters on the rear and can provide parts list for same if you're interested. PM works for me.
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By DryLakesRacer - 4 Years Ago
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Not on a Thunderbird but I installed the Wilwood 7/8” MC, prop valve, and 4 piston calipers on my 56 Victoria and 11 x 2-1/4” F-150 rear drums on the 8.8 rear I installed. No booster and it stops great. Pedal pressure is less than all drums.
At a Thunderbird gathering I noticed quite a few with front discs and a Bendix Booster on the left fender and found out Prestige Thunderbird in Sante Fe Springs Ca. does this installation. They use the 4 piston front Mustang calipers. The owners I talked were very pleased. I see no reason not to add this style of assist if you feel it’s necessary with the Wilwood calipers.
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By paul2748 - 4 Years Ago
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I have heard that running the stock booster on just the front brakes (disc) is something many people do.
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By RJ Palmer - 4 Years Ago
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According to Gil Baumgartner ay CTCI , using the stock booster for the front disc brakes wont help at all because it can provide a 600-800 psi assist and front disc brakes require a boost of at least 1200 psi to provide a noticeable assist.
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By KULTULZ - 4 Years Ago
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Disc brake calipers are designed to operate at higher hydraulic line pressure than original drum brakes, as a result it is very beneficial to have a power brake booster. These steps are written presuming you have a power booster on your car. If not, the brake fluid lines would be slightly different. A booster is highly recommended. Even with a booster these brakes will not give you the feel of the disc brakes on your new vehicle, it still takes a bit of pedal pressure. The biggest advantage is the straight, true stopping, and the resistance to fade.
SOURCE - https://www.ctci.org/disc-brake-conversion/
A MIDLAND BOOSTER is designed for one circuit only as was common in pre-1967 cars (SGL RESVR MC). To keep the disc conversion somewhat OEM appearing, the front disc circuit (primary reservoir) will be plumbed through the BOOSTER HYD CYLINDER for disc power assist and the rear drum circuit plumbed straight from the MC secondary reservoir as they require less line pressure their being self-energizing.
The original kit design included different size rear wheel cylinders and was later changed to a universal PPV. Both methods seem to be hit and miss on brake bias. The booster will give enough assist to be noticeable.
The nice thing about this conversion is that the KH 4-Piston Caliper can be adapted to the OEM spindle (and keep original 14" wheels - 57 BIRD) and can be easily changed back to 4-wheel drum if the car goes to a dedicated restoration.
CTCI Install Photo Showing Rough Plumbing -
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By paul2748 - 4 Years Ago
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I did a Granada conversion on my 54 Ford. Went non power. Used the Granada dual master for non-power brakes. Brakes improved with stopping and don't miss the power set up at all.
A friend with a 56 Bird just went to front discs, non power. As far as I know, he is very happy with it. I think he used the 4 piston calipers.
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By RJ Palmer - 4 Years Ago
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Thanks for your input Paul, I too have the Granada front discs and dual master cylinder which I did 10 years ago. I'm not 100 % happy with that setup as I've had to make a few panic stops and thought car should have stopped sooner in that situation. I find that I have to pump the brakes to get a good firm hard stop. Of course , in a panic situation I don't have that luxury. I keep going back to Gil Baumgartner's comment where he stated to me in an email that disc brakes need approx. 1200 psi to be fully effective. I have talked to Master Power Brakes in No. Carolina and they recommend a 7" dia dual booster with a 1-1/8 " bore master cylinder for my application of front disc and rear drums. They also recommend a combination valve which I already have. I have already relocated the battery to the trunk to make room for the booster tank. Master Power has stated that rework to the booster tank mount bracket will be required to ensure the booster tank does not contact the tbird aluminium valve cover..I should have said the tbird under dash mount channel / firewall master cylinder mount will have to be reworked. So I'm going to go for it ! Thanks again RJ Palmer
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By KULTULZ - 4 Years Ago
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I too have the Granada front discs and dual master cylinder which I did 10 years ago. I'm not 100 % happy with that setup as I've had to make a few panic stops and thought car should have stopped sooner in that situation. I find that I have to pump the brakes to get a good firm hard stop. Of course , in a panic situation I don't have that luxury. I keep going back to Gil Baumgartner's comment where he stated to me in an email that disc brakes need approx. 1200 psi to be fully effective.
It sounds more likely you have a mis-match of parts and/or incorrect adjustment/system bleeding. That line pressure is generated by caliper style/piston size chosen, MC type, pedal ratio and amount of pressure you can put on the pedal. Power assist only makes it easier to achieve that brake line pressure. Factory cars also came through with manual disc/drum.
You have a GRANADA disc swap on your BIRD now? What size wheels?
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By DryLakesRacer - 4 Years Ago
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I agree, pedal ratio makes a big difference. 6 to 1 and a MC of 7/8” or smaller normally do not need a booster. I remember my dads new 55 sunliner he had the dealer add a Bendix booster. It was a lot more sensitive than the 56 Victoria which he didn’t add one.
When I changed rear ends in my 56 the brakes came off a vehicle with power brakes and I changed the wheel cylinders to a smaller size. Also 4 piston or 6 piston calipers seem to work fine without one. There are a lot of options and opinions.
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By RJ Palmer - 4 Years Ago
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14" wheels
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By 55blacktie - 4 Years Ago
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1st-gen. Mustangs/w 4-piston KH calipers had 14" rims.
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By paul2748 - 4 Years Ago
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Fortunately, I have had only one panic stop - doing 65 when I came over a rise and found traffic dead stopped in front. Brakes worked very well. I might add that I have a 9 inch rear with later TBird/truck brakes
RJ Palmer (4/23/2021)
Thanks for your input Paul, I too have the Granada front discs and dual master cylinder which I did 10 years ago. I'm not 100 % happy with that setup as I've had to make a few panic stops and thought car should have stopped sooner in that situation. I find that I have to pump the brakes to get a good firm hard stop. Of course , in a panic situation I don't have that luxury. I keep going back to Gil Baumgartner's comment where he stated to me in an email that disc brakes need approx. 1200 psi to be fully effective. I have talked to Master Power Brakes in No. Carolina and they recommend a 7" dia dual booster with a 1-1/8 " bore master cylinder for my application of front disc and rear drums. They also recommend a combination valve which I already have. I have already relocated the battery to the trunk to make room for the booster tank. Master Power has stated that rework to the booster tank mount bracket will be required to ensure the booster tank does not contact the tbird aluminium valve cover..I should have said the tbird under dash mount channel / firewall master cylinder mount will have to be reworked. So I'm going to go for it ! Thanks again RJ Palmer
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By FORD DEARBORN - 4 Years Ago
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There is, in the case of a 65 Mercury Comet I'm helping restore,, a difference in pedal leverage if that vehicle was built with power breaks, or manual brakes. That is, the MC push rod is positioned much higher on the brake pedal arm than if that vehicle was equipped with power brakes. I just wanted to say there can be some not so obvious design differences. Also, after a panic stop in my 64 F100 which has manual/drum brakes, a sound was produced I haven't heard in decades,- screeching tires from hard braking. Antilock brakes are the other piece of the modern brake equasion. The truck stopped very well and straight with out incident and it doesn't take a lot of pedal pressure/effort with the stock design. Just some more food for thought....
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By KULTULZ - 4 Years Ago
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RJ Palmer (4/23/2021)
What I am trying to find out is that you have a 57 BIRD w/ GRANADA front disc swap with what 14' wheels, original BIRD steel wheels or another wheel? Your BIRD is not a dedicated restoration but a daily driver/resto-mod and has several upgrades? Just curious.
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