VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1940 Chevy Master Cylinder Brakes

I just replaced the Master Cylinder, all four wheel cylinders and brake shoes. I adjusted all the brake shoes, and bleed the brakes, LR/LF/RR/RF. The pedal is still low. It builds up a little after pumping, but still low. The brake pedal doesn't return when I release it. What am I missing?

I know you don`t want to hear this reply , but it sounds like there is still air in the lines.....not sure about the pedal not returning ?? I know mine will scrape a little on the floor board and can be adjusted to come back freely .....I went through my entire system last summer and had to bleed a few times to get it right ....good luck David

If re-bleeding does not solve the problem I would suspect some parts in the "new" master cylinder ae not installed correctly or missing.

Sorry to hear that things are not working as expected. That can be very frustrating.

I noticed that you said that the brake pedal was not returning completely. I agree with the suggestion to make sure there is no physical interference with the brake pedal linkage. I suggest that you disconnect the pedal from the master cylinder and move it through the full range of travel.

There are 2 other items that I expect you have checked but will mention them. 1) Make sure that you have adjusted the eccentric in the pivot in the linkage to set the free-play correctly. 2) Make sure that the vent in the cap on the master cylinder is open. If that vent is blocked the pedal cannot return to the up position. The fluid returning from the cylinders has no where to go.

I also have to agree with Gene that there could be problems with the master cylinder.

Keep us updated.

If the master cylinder is new ignore this:

There are two holes in the bottom of the master cylinder resoroi. Both must be open for it to operate properly. Use a needle and plyers to open the tiny one. Then a suitble device to make sure the bigger one is open as well.

The two holes may be the culprit but should not be if the MC is new.

Good luck,

Charlie

BTW: Adkist tje brale linings to where the lock in place and you can't turn them with your hands. Then back off the adjusting wheel 5 increments or until you can just turn it (the wheel). When driven around the block a couple of times it (internal brake mechanism) will free up and adjust itself to the drum.

To tighten the shoes to the drum: Facing forward the rear adjuster should be turned clockwise to tighten. Facing reward the forward advuster wheel clockwise also. (I'm going by memory here so if I've got this advise on the adjusters wrong someone please correct me. Thanks)

BTW: I believe you will find that the left front is farthest from the MC. In other words following the length of the lines coming off the MC.