chrysler75 Posted May 25, 2019 Share Posted May 25, 2019 (edited) The master brake cylinder of our 1929 Chrysler series 75 roadster is overhauled, but since we have a problem. after a while the brakes lock up , when I wait half an hour it releases, but after a while it locks up again. We drive on silicone brake fluid. A new original master brake cylinder is impossible to find. Does anyone know if I can mount the master brake cylinder of a Dodge WC 1940 for a 1929 Chrysler series 75 roadster? Does it fit and is the brake capacity enough for the roadster? Edited May 25, 2019 by chrysler75 (see edit history) Link to comment Share on other sites More sharing options...
stvaughn Posted May 25, 2019 Share Posted May 25, 2019 Do the brakes lock up, or is it just the master cylinder? Does it do it when driving or when bleeding? How many pumps to lock up? Did you bench bleed the master cylinder? More information please. I’m using DOT 5 also and have spent several weeks getting my brakes sorted out. Link to comment Share on other sites More sharing options...
keiser31 Posted May 25, 2019 Share Posted May 25, 2019 Photo of the master cylinder would help. Does it contain the reservoir or is the reservoir a separate can above the master cylinder? Link to comment Share on other sites More sharing options...
chrysler75 Posted May 26, 2019 Author Share Posted May 26, 2019 Thanks for the replies! the brakes just lock up after a while driving, when I want to stop the car. Yesterday I drove 30 miles without any problems, but when I came home and wanted to drive her in the garage, this problem occurs, and it locked up so fearce that I was afraid to break a drive shaft. I already gave the pedal more space before it realy brakes, but this space is gone when the master cylinder locks up. It is surely the mastercylinder, when I jack up the car all four wheels are locked up. I drove the Chrysler for several years without any problems on silicone with new wheel cylinders, new lines and an overhauled mastercylinder and the car always really braked very well. The mastercylinder is the round type with the reservoir separate , but I think that I can shut up this reservoir when I use the master cylinder with the reservoir on top of it., like the one on the Dodge WC. The holes to mount the cylinder seem to be the same . Link to comment Share on other sites More sharing options...
mobileparts Posted May 26, 2019 Share Posted May 26, 2019 The applications are 1929 - 1936 is the same, And then 1937 - 1942 is the same, But the two are Very Very different. I have both of them, BRAND NEW.... Always best to simply call me -- Craig -- 516 - 485 - 1935... New York. 1 Link to comment Share on other sites More sharing options...
chrysler75 Posted May 26, 2019 Author Share Posted May 26, 2019 hello Craig, Thanks for your answer! Can I use the original for our 1929 Chrysler with silicone oil? If yes, please sent an email with price and shipping to the Netherlands regardPete Link to comment Share on other sites More sharing options...
mobileparts Posted May 26, 2019 Share Posted May 26, 2019 Yes -- my Master Cylinders -- are DOT 5 / Silicone brake fluid compatible. The master cylinder is $ 149.00 USA dollars .... I would have to have your address to find out what shipping is...... Link to comment Share on other sites More sharing options...
ply33 Posted May 27, 2019 Share Posted May 27, 2019 If the push rod from the pedal to the master cylinder is adjusted too long then you will have this behavior. There should be about 1" of free travel at the pedal before the push rod contacts the piston in the master. I suppose the same thing could happen if an incorrect piston was installed. Basically, the piston has to return far enough to free a pressure relief hole that exists between the cylinder and the reservoir. Link to comment Share on other sites More sharing options...
plk Posted May 27, 2019 Share Posted May 27, 2019 I agree; piston is not coming back far enough to clear the pressure relief hole. I have seen the same thing on a Cord Link to comment Share on other sites More sharing options...
ipeeforward Posted May 27, 2019 Share Posted May 27, 2019 Hi Pete, I had the same problem on a Lockheed master cylinder I overhauled. I switched to silicone brake fluid as it seemed a good idea however the new old stock seals I used swelled up in service and as has already been pointed out blocked the tiny compensation hole when the master cylinder was at rest causing the brakes to drag after a few applications. As I couldn't get any brand new seals I went back to dot4 fluid with some more old stock seals and haven't had any problems since. I also have a 1929 Chrysler 75 happy to chat if needed. John F Link to comment Share on other sites More sharing options...
mobileparts Posted May 29, 2019 Share Posted May 29, 2019 Hi, P.A. (Peter), Gave you all the information --- it is in your in box of messages. Yours, Craig.... Link to comment Share on other sites More sharing options...
chrysler75 Posted July 4, 2019 Author Share Posted July 4, 2019 Problem solved, I visited the company that overhauled the master break cylinder, they found out that the seals were swelled up and did replace them. Since I drove about 300 miles and the brakes did not lock up anymore. So I ordered three new sets of seals for eventually solve this problem if it occurs in the future. Many thanks to all for the help and support on this matter! Pete 1 Link to comment Share on other sites More sharing options...
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