Had the car on the road 1 month now and I have had about 10 occurances of the back brakes binding/sticking on !

All it takes is a few pumps of the pedal the they release, strange thing is they dont stick after being used... most of the time I will be driving on a straight and all of the sudden the car goes slugish and I have to pull over, pump the pedal and they release.

I have checked all the mechanics, hand brake and they are all free when they stick on so do I just need to bleed them again ?

Cheers,
Kosmo.

eh? thats a weird one. they'll need some pressure to start them working to be able to stick. air in the system would mean they'd struggle to build up pressure to make the brakes work i'd have thought.

Maybe servo related? (if you have one)

Brakes are Wilwood powerlights on seperate circuit to the fronts with Wilwood master cylinder.

Even checked the balance bar, thought it had jammed but all OK ???

No servo....

[Edited on 20/6/09 by Kosmo]

Sounds like a prime example of the m/c not having sufficient free play to return correctly or a sticking m/c cylinder.

How much free play should there be and how do a measure it ?

Cheers,
Kosmo.

Enough so that there is no pressure on the piston when the pedal is returned - I would say a couple of mm should suffice.

Measure free play by feel.

But I guess if the pedal ratio is 5:1 10mm of free movement at the pedal pad before anything hits an m/c piston.

Andrew

[Edited on 20/6/09 by Andy S]

Thanks.... I will take a look tomorrow.

might sound a bit wierd, but are the floor mounted or hanging pedals? does the wieght of the pedal somehow push the master cylinder in?

could some pedal return springs help?