Has anyone had experience converting a 57 Tbird to front disc/drum rear using the OEM power booster? I don't want to relocate the battery. I can't see how to plumb a dual reservoir master cylinder into the system. I have heard of sending power assist to the fronts only and leaving the rear drums attached directly to the master cylinder. I am skeptical about that set up. Also looked at hydroboost but don't want to upgrade to a modern P/S pump because I think the original would be stressed too much.

57 Black Tbird 312/auto

Hey Mark;  i put in an Electric master cylinder in My 55 bird. works great,   ABS Brakes. com--- they are in Orange, Cal.   Also have Mitchishi power steering box with remote resevier.  Also using John mummert's brackets and small GM pump.  Good road feel and very comfortable-- not too fast.  Hope this helps    God Bless   Eddie

Eddie

Lake Forest, Ca. 92630

I did that conversion some years ago, and the booster on the front only worked fine, with a separate proportioning valve to the rear. If I remember the explanation correctly, it has to do with higher pressure for the disc as they do not "self energize" as the drums do. I think a Volvo I owned in the late 60's did that from the factory. I also know someone who's used the electric brake boost, and they thought highly of it also.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Miker,



I am leaning toward a set up like yours. What I don't quite understand yet is how the dual braking system is applied to it. That is, with a dual reservoir master cylinder, there are actually two braking circuits, front and rear. If the pressure is lost in one of the brake systems, front or the rear, the proportioning valve should move to isolate the leaking system and maintain fluid pressure for the other brakes. That is the reason I want the dual system. Have you plumbed yours this way?

57 Black Tbird 312/auto

I'm going to try to get this right, but it's been a while. Most disc/drum masters have a large and a small reservoir.  That's because the disc require more fluid volume to work than the drums do.  These are normally run to a "combination valve" that contains both a residual pressure valve (10lbs drum/2lbs disc), a switch (which when pushed off center) gives a warning light of system failure, and sometimes a proportionting valve to control pressure, typically to the rear. These aren't adjustable, they're preset for an individual vehicle.  I used an adjustable proportioning valve to the rear when I went to rear disc (don't waste your money like I did).  When I had the drums in back, I used a kit from one of the t bird guys, and they did the engineering on the combination valve.  The front disc brake circuit went in and out of the booster in it's stock location, and the rears went straight to the drums.  It seemed like it had a little more rear brake than I needed, but it worked fine and I drove it for years with no problems.  I have no idea how you calculate which comb. valve you need, but I suspect that an early Mustang would be close, at least in my case, as the kit had modified Granada disc and Mustang calipers.  It fit the stock spindle using different bearings and races that came with it.  There may be better solutions out there now, as this was at least 10 years ago.  but like I said, it worked fine for years, and if the rears locked up too badly, I could have always put a second adjustable valve in that line and turned them down.  I don't know if there would be a problem with two valves in line, but since iI never did it, I didn't find out.  I know Larry's thunderbird still sell these, and probably Casco and others, so shipping is the main price difference.  If you're in Texas, I think Amos Minter installs a kit, and they will either sell it or refer you to their supplier, who's name is escaping me.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Miker,



I think we are on the right track. In the Ford combination block (valve) is a pressure differential valve. This maintains correct hydraulic pressure needed for the front and rear brakes; disc/drum or disc/disc or drum/drum. This valve's position is normally centered to allow fluid pressure from both reservoirs of the master cylinder to pass through the ports in the combination valve to the front and rear brakes independently unless the pressure on one side is lost. For example the if a wheel cylinder on a rear brake blows out, the pressure differential valve will move from pressure on the front side of the valve to block the port going to the rear brakes. This closes off pressure from the rear brake reservoir of the master cylinder and keeps the hydraulic pressure in the master cylinder and allows the front brakes to operate as normal. This kind of system was mandated in the late 60's for all car manufacturers. There is a brake warning switch threaded into the valve which lights the brake warning indicator on the dash when the valve moves to one side due to pressure loss to one of the systems. There is a tool to keep this valve centered when doing brake bleeding and/or brake work. I still have mine from when I was an apprentice. For brake work, the warning switch is removed before any brake line is opened and this small tool threads into the same hole where the brake warning switch sits. The tool has a small shaft on the end that will hold the valve in the normal centered position so it doesn't shift when the brake lines are opened for bleeding or parts replacement. What I didn't see in the Tbird kits being sold was anything to accomplish this safety issue. There was no pressure differential valve to save the brakes if a wheel cylinder or caliper failed losing pressure. A simple proportioning valve doesn't do this as far as I can tell. I talked with a couple vendors several years ago and they really didn't understand or didn't want to talk about it. I have used the Ford combo valve for disc conversions on both my 65 Galaxie and 66 F100. I am trying to figure out how to plumb one of these into the TBird with power brakes on the front only and manual on the rears. I am not sure if the added power function to the fronts only would upset the balance in the pressure differential valve or not.


57 Black Tbird 312/auto

I used the 10 psi residual valve for the rear drums.

recommended 2 psi for the front disc brakes.



I only used the rear valve. My car has great stopping power with a good pedal feel. No power boost is needed.



Here is a link for the rear valve, they also have the 2 psi front.

http://www.speedwaymotors.com/Speedway-Drum-Brake-Residual-Valves-10-PSI,7502.html



Jim

  Jim Rowe Elkhorn, NE

Mark, my current set up is disc/disc, and does not have a comb. valve, just an adjustable to the rear circuit. The old disc/drum is stored somewhere, but as I remember it had the switch, but I never connected a warning light. I've lost the brakes a couple times over the years (other cars), and you know immediately that something is wrong as stopping takes on a whole new meaning (panic, resulting in pushing real hard and then stopping). These were unmodified factory systems, including the Volvo. Since the booster comes after the master, I don't think it would have had an effect on the "fail" switch, but I'm on thin ground here as my engineering skill isn't that hot.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Brake failure is the reason the parking brake function should be a higher priority than many of us make it. That "emergency brake" can be a savior. Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Miker,



I could remove the original Midland power booster and use a Bendix Dual reservoir master cylinder/booster. The Tbird vendors have them for about $600 or I also could remove the stock booster for a manual brake arrangement and use a dual reservoir master with the Ford combination valve for either set up. This would give me the safety of having the dual system in case of failure. I want to use the original Midland booster to keep the Bird as stock appearing as possible but having the advantage of "modern" power disc/drum brakes as well as the safety. I drive the Coastal Mountains here and each time I start down a steep hill , I cringe at the thought of a wheel cylinder giving up, etc. The Ford combination block is an obsolete part from the dealer. They sold out of the left over stock quickly. I have found some aftermarket suppliers who make them.



http://www.autokrafters.com/v4/go.gnf?session=732bc62f4ca94c27a573a90d8185cd9f&s=autokrafters&t=&n=default&d=products&show_product_id=853162&product=23841



I used one of the last Ford valves on my Galaxie and an junkyard piece on the F100. They junkyard parts have to be untampered with. If they have been open to the weather; master cylinder cover left off and the system drained of fluid, corrosion and contamination gets in. Rule of thumb is to pick a car with similar weight and wheelbase to salvage from. I used 79 Thunderbird stuff on my Galaxie and 76 F150 parts on the 66 F100, both work great.

57 Black Tbird 312/auto