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Brakes locking on
Kitlooney1000 - 16/8/03 at 09:36 PM

My freinds locost is on the road, running fine. after about 15-20 mins of driving, the front brakes gradually start binding and ultimately lock on. he has stripped and rebuilt the calipers twice, replaced the master cylinder to no avail. Any ideals?

chrisg - 16/8/03 at 09:48 PM

How close is the M/c to the exhaust?

Could be the fluid expanding due to the heat and applying the brakes.

cheers

Chris

Kitlooney1000 - 16/8/03 at 09:54 PM

The engine is a x/flow, the exhaust is on the other side

Mark Allanson - 16/8/03 at 10:16 PM

I have had this before on production cars, it is probably the rear adjusters failing, as you drive along, the rear adjusters gradualy creep back and displace the fluid back into the system and start to bind the front brakes. Its definately worth a look

Peteff - 17/8/03 at 12:17 AM

Has he got a return spring on the pedal? The master cylinder spring is not strong enough to push it back. Does it come off if he pulls the pedal back?

yours, Pete.

Rorty - 17/8/03 at 04:31 AM

Sounds like he built the car using Gremlins v1.4.

leto - 17/8/03 at 08:04 AM

An old brake hose can, with some bad luck, turn into a very efficient one-way valve. But then the wheel usually locks at first attempt to brake.

Cheers Leif

Jasper - 17/8/03 at 09:28 AM

Does he have any play in the brake pedal - I didn't on mine and it started to bind after about 15 mins.

Dick Axtell - 17/8/03 at 11:07 AM

quote:
Originally posted by Kitlooney1000
...the front brakes gradually start binding and ultimately lock on.


Q!: What pads are you using? Are they correct application for the caliper?
Q2: Which mcyl are you using? E.g. tandem (Sierra) type, or the dual, binocular-style?
Q3: Are you using any form of booster (servo)?

Assuming that the pads are correct, and that your fronts start in the free condition, brake binding will be caused by either brake fluid (heat) expansion, or by fluid displacement.
If it's caused by heat expansion, why is there insufficient recup flow to the reservoir? Suggest you carefully check (i) the brake pedal return position, (ii) the clearance between the mcyl input rod and the mcyl primary piston, and (iii) the condition of your brake pipes (for any restrictive kinks etc.).
It'll be very interesting to hear how you get on, so please keep us updated on any progress.

Kitlooney1000 - 19/8/03 at 08:56 PM

Thanks for all the replies, looks like the back brakes were the problem, the slaves were sticking.

Thanks again.