Hydraulic Brakes
 

I know I should post this on the V8 or Hot rod forum but I thought I would ask among friends first.

A prospective new member to the club told me he had hydraulic brakes and after driving some miles they build up so much pressure they lock the wheels. I had a little experience with hydraulics 50 years ago but never ran across anytning like this.

Is this something common? Is there an easy fix? I already offered a complete set of mechanical brakes but he turned me down:D.

Thanks,

Richard
Anaheim CA

Re: Hydraulic Brakes
 

There's something radically wrong with his master cylinder if pressure does indeed build up.

Re: Hydraulic Brakes
 

Adjust the link between the pedal and master cylinder.
It sounds like the piston is not coming back far enough
to clear the port.

Re: Hydraulic Brakes
 

It is possible that there is a problem with the residual (check) valve, if there was one installed. The purpose of the residual valve is to keep a little hydraulic pressure on the wheel cylinders when the brakes are not applied. This prevents the wheel cylinders from "sucking" air back into the wheel cylinders. If the residual valve is faulty or is not the correct one for the application then it could cause the brakes to drag or even lock up. It could also be some foreign matter in the system that plugs up the system that blocks the fluid returning back to the master cylinder.

Just my 2 cents.

Bob

Re: Hydraulic Brakes
 

Can't hurt to post on both of the other sites as well.

Re: Hydraulic Brakes
 

make sure the brake pedal hasn't been adjusted with no free play. there should be
some play in the pedal to give the fluid a place to expand.
If all that is ok I would suspect bad front brake lines colapsing on the inside and acting like a one way valve causing the brakes to drag.

Re: Hydraulic Brakes
 

Re: Hydraulic Brakes
 

dot5 i'm told with it's silicon may heat up and expand.

Re: Hydraulic Brakes
 

Dot 5 silicone is the only thing I use on my old cars that have hydraulic brakes. I don't know that it expands with heat, but even if it did, it would simply raise the level in the reservoir. I'd bet the problem is the master cylinder piston isn't coming back far enough to uncover the hole.

Re: Hydraulic Brakes
 

Everyone has had good suggestions so far but I would like to ask if this is a newly installed system on an older one? If it is new it is possible the linkage is not allowing the master cylinder piston to retract far enough.

Charlie Stephens

Re: Hydraulic Brakes
 

Pete's post nailed it! The piston is not returning far enough to uncover the port and as the heat builds up and expands the fluid it applies the brakes.
Shorten the pushrod until the piston uncovers the port allowing the fluid to return. Bill

Re: Hydraulic Brakes
 

Thanks everybody. Thats great information and reallly quick.

I have printed all the replies out and will deliver them to him this morning

Thanks Again,

Richard
Anaheim CA

Re: Hydraulic Brakes