[1932 Roadster]

I have a 32 Roadster with the power brake master cylinder under the floor. I'm having an issue with the brakes where they begin to drag after about 5 minutes of driving. I noticed that there is no residual valves in the brake lines? could this be the issue?

 

[MecGen]

Hi there
The first thing I would do is find out exactly what's dragging, all wheels, front, rear, or just one wheel? The way I do this is to drive your rod till the brake start to drag, then jump out and check the wheel temps with a inferred gun, this will pinpoint which (or all) wheels are sticking. Remeber to stop the car before jumping out:thumbup:

The residual valves that I know of would make things worse as their job is to hold a little bit of pressure in the braking system...its been along time since I have seen them used, so I can't comment for sure

Do you know which/how many wheel are dragging? Have you checked it? I have seen everything from bad m/c to brake lines cause this issue.

Regards

 

[1932 Roadster]

Its definitely front brakes that begin dragging after a short drive. I figure it could be the exhaust being to close the master and booster. Its only 1/2 inch from the booster and just over an inch from the master. I'm going to wrap the exhaust with header wrap and see if it continues. I will get the pipe moved slightly at a muffler shop.

 

[Irelands child]

I would lean first towards the master cylinder push rod being adjusted out too far, holding the MC spool from retracting completely. There should be a very small amount of play. Also along that line, your pedal is routed though the floor and may not be returning easily (carpet or floor board drag also possible). Then the MC may be internally snug. There are aftermarket return springs you can add - here's one I dug out BRAKE PEDAL RETURN SPRING KIT | Hot Rods by Dean

Yes, you should have residual valves in the lines for a below the floor MC

As far as exhaust being a 1/2" from the booster - mine is as well, but have not had a problem in 4 years of driving the car:



Dave W

 

[1932 Roadster]

Thanks Dave. I installed both front and rear residual valves, as well as an adjustable proportioning valve for the back brakes. I'll look into the return spring option too. Cheers, John

 

[1932 Roadster]

Problem solved! Both the pedal pushrod and the one between the master and booster needed adjustment. I also put header wrapping on the exhaust pipe for good measure. All is good now.