I installed a universal master cylinder and brake booster into my 1955 Ford F-100. Everything was working fine until yesterday when all four wheels locked up. A small amount of brake fluid leaked from the lid of the master cylinder. I broke the seal between the master cylinder and brake booster which released the brakes. One I tightened it up again the brakes locked. I think I have a bad brake booster but I’m looking for advise.

thanks,
Jon

 

It sounds like your pushrod is too long and not allowing the master back enough . Where is your booster mounted , 4 wheel discs and do you have a residual valve ?

 

I second the pushrod length. I too swapped out the master cylinder on my truck this fall, took it on a few test drives and everything seemed fine. First longer distance trip my brakes were dragging bad. Got to my destination and noticed that the brake lights were also staying on, which meant the sensor right at the back of the master cylinder was sensing pressure. A few turns backing down the pushrod to the master and everything has been fine since!

 

That makes sense. Can I put a couple washers between the master and the booster?

 

Or make a heavy gasket.

 

Take the master cylinder off the booster, the length of the pin from the booster can be adjusted for length ..no need to disconnect any brake lines in case you're wondering..

 

How do I adjust it?

 

 

It is a threaded sleeve, you should be able to just screw it in. Here's a link to a thread where John Niolon had a problem when it wasn't long enough. It may be of some help
https://www.ford-trucks.com/forums/1...akes-dont.html

 

I got it figured out. I really appreciate the help!

Jon



QUOTE=56panelford;19022513]It is a threaded sleeve, you should be able to just screw it in. Here's a link to a thread where John Niolon had a problem when it wasn't long enough. It may be of some help
https://www.ford-trucks.com/forums/1...akes-dont.html[/QUOTE]

 

After I adjusted the push rod brakes were working well. I started my truck the other day just to move it so I could sweep my garage. It sat running for about 10 minutes. When I got back in the truck to put it in the garage, the brakes were locked up. I loosened the bolts that hold the master cylinder to the booster just two turns and the wheels freed up. I removed the master cylinder completely to look at the booster again more closely. I have the push rod as short as it can go. There is no pressure on the brake pedal clevis. Then I noticed that after I push in and release the brakes the push rod did not return all the way. It stuck out maybe an 1/8" and I could push it in with my finger. I think this is the real problem. It is a brand new booster. I hit it with a shot of WD40 but it is still sticking. Can you rebuild a brake booster or is there another way to remedy something like this? Or do I need to buy a new booster? I really would prefer using the brand new one I have. Thanks for the help in advance.

Jon





QUOTE=56panelford;19022513]It is a threaded sleeve, you should be able to just screw it in. Here's a link to a thread where John Niolon had a problem when it wasn't long enough. It may be of some help
https://www.ford-trucks.com/forums/1...OTE][/QUOT