front brakes keep jamming solid, oh and catching fire!!!!! please help!!

hi guys, my apologies for not being on in a long time, i need help asap meant to be racing this weekend but i've developed a slight problem with the front brakes. so far i have disconnected everything to do with the abs, i've unplugged the abs unit, removed the relay and any fuses, i've replaced both front flexi hoses thinking the pressure wasnt releasing from the calipers, it has wilwood four pot calipers & braided hoses, any help would be extremely gratefully apreciated

Sure its not the pistons sticking in the caliper themselves ???

Have you changed the bias valve to a single  or just looped before the abs unit ???

hi thanks for the quick reply, all the pistons work freely, i've taken most of the inlet manifold off to have a look at the bias valve, to be honest i'm in unknown territory, it looks like the original bias valve with two pipes in and four out i think.

Is it both front brakes? is it after you have driven it for a few miles?
Do they both spin freely by hand when it's jacked up?
Could be a sticky master cylinder if it's both front brakes, how does the pedal feel?

yeah it's both front wheels, usually after its done 9 laps which is about 1 mile each lap, the other day it didn't even manage a 2 mile roadtest, after 20 minutes you could hear them releasing once they had cooled down a bit, pedal has about 10mm travel then its solid.

have just bypassed the abs unit & it seems to be working so far, brake pedal is solid, i won't know for definate until i roadtest it tomorrow now.

My breaks were sticking on solid and it was the slave cylinder. Pressure went in but wouldn't release, took it apart cleaned it and hey presto. Dead quick and easy so probably worth doing anyway

Logic points to the caliper seizing when hot, but both at the same time indicates something else, gut feeling would be the master cylinder sticking causing the front brakes to bind slightly and after a few miles the calipers overheat and stick on.
When they stick what happens if you undo the bleed nipple, do they then free off?

Have you recently replaced the brake pads or something else? grabbing at lots of straws!

thanks for all the replies, i'll start from when i think it all began i'll try and keep it short so bear with me.

a few years ago i was doing a track day and the n/s/f brake wore down quite quickly due to crappy pads, the pad wore that thin that one of the pistons came right out of the caliper, removed the caliper refitted the piston, fitted new pads then bled the brake. this was fine for that year then the car sat off the road for a couple of years.

at the start of this year before the racing season started i ordered new seal kits & rubbers for the calipers stripped them right down & cleaned them out, fitted new bleed nipples & new braided hoses. i also fitted ebc yellow stuff pads & new brake rotors which were long overdue, bled the whole system with dot5 brake fluid, no air at all in system. i've now done 4 events this year and nearly everytime the drivers side has always got hot then started to stick but if it is left and cools down it free's itself off. the other day i had it to my mates garage for him to set up the apexi boost guage, once that was done he took it for a roadtest which was approx 1 mile possibly even 2 at the most and when he came back the front brakes were both locking on & the passenger side caught fire.

yesterday i looped the brake pipes at the abs pump and so far it seems ok, the wheels spin quite free so i'll roadtest it this afternoon and see what happens.

i hope you've not fallen asleep reading this!!! all your help and advice is greatly appreciated.

dot 5 fluid not really compatible with abs & also an issue on old systems. I would use dot 4 or dot 5.1 unless dot 5 is requirement to your racing regs.
If was not abs system I would be looking at master cylinder next, new cylinder can be cheap too: http://www.gtir-motorsport-club.com/t2843-brake-master-cylinder-upgrade

Yeah keep us updated ....i wouldnt of used dot 5 .... dot 5.1 is better in our old car brake system ....

Damn must type quicker ... you beat me to it mr b

sorry my mistake it is dot 5.1 that i used not dot 5

nomad wrote:Damn must type quicker ... you beat me to it mr b

more replies the better my old notebook keyboard is king
5.1 is the good stuff & not silly money these days, not much more than 4 unless going for top brands.

How tight are the pads to the discs when cold ???  How did you get on with your test drive ???? 
Of course mr b the more view on the problem the better ...

Maybe I missed it whats the regs for your class or racing ? What calipers and discs you using ? I recomend ate blue brake fluid. I personslly have not used the ebc yellow but there other pads are crap in my opinion. Are you aloud to run any pad ?

just an update to the situation, been flat out with work so my apologies for the delay, i looped the pipes at the abs pump at the weekend then bled all the brakes again, pedal now has very slight travel then pedal is solid, brakes are working fine for the moment and both front wheels are now spinning more freely not like before as they were slightly binding.

just to answer a few questions the car is running a wilwood four pot set up on the front with 320mm rotors and bells, i'm using ebc yellow stuff pads at the moment (only cause they were free!) there is no restriction to the brake pads i can use in my class which is the road production class over 2000cc. i think to be on the safe side i'm going to fit the upgraded master cylinder to avoid this happening again or i'll end up with warped discs the amount of times they've been heated.

sorry guys forgot to say i really appreciate all your help and patience with me on this, i'm not that great on the old computer but i'm getting there

Your welcome ... thats what its all about trying to help each other ... anyway glad you made some head way with it ... and atleast i pointed you in the right direction lol ....

And great for replying so anyone else can see how you made it at least better