Brake pedal requiring double pump

[caspros]

Hi All,

Ok, so before the last track day, fitted new pads, new fluid, etc, and brakes were working fine.

For some reason, recently, I have to pump them once before they'll grab properly like in their former glory.

Today we re-bled all the brakes, filled with MBF600, and still, the same problem.

They're Subaru 4 pots on the front, 1 pot's on the back.

Please note, this is a recent thing.

I am planning on going in the winter series this Sunday, but I can't really drive it like it is.

Thanks for your help.

[Guest boostcut]

it could be a bit of pad knock off. or maybe the master cylinder is bypassing. with the car off does the pedal creep to the floor?

[madmike]

Does the handbrake still work?

If it does no problem just go race her!!!!!

Could it be that your pistons are sticking?

[caspros]

Hmm, nope the pedal doesn't creep to the floor. And, ha ha, imagine that. 200km/hr, handbrake on.

It could be the piston sticking, not sure how to check for that.

A smart man said it could also be a wheel bearing, which could've knocked the pads out.

[Guest boostcut]

pull your caliper off one at a time and SLOWLY push the pedal down and watch the pistons come out evenly... if not id start by rebuilding the calipers esp if your racing...

[BC5RA]

A bit out there but; check your Hub nut hasn't loosened and the first pump gathers the assembly.

[Guest]

2 main causes of this are

1, play in hub causing pad knock off

2, pads wearing unevenly (tapered) this causes excessive piston push back as the pad tries square up to rotor when pedal released

Hence why when you pump the brakes all is good

[caspros]

Damn, so it actually sounds pretty serious. I guess that's no racing for me then. Stink.

[madmike]

Don't be a girl.... go out an give it shit...

PS Don't listen to me. I'm a gravel boy..

[caspros]

Is there an easy way to test for this play in hub ? (<---novice)

Take off the wheel and try and wobble it ???

[viperguy]

if this issue comes up with 2-pot fronts, check/grease the sliders...fixed the problem in my wrx

[Guest boostin]

Clamp off all 4 brake lines (with proper brake line clamps so you don't damage the hose!!) and release one at a time pumping the pedal in between. When the pedal drops away, you found which one/s is causing the problem. Just gotta find the cause after that.

[caspros]

Heyyy, that's a really good idea ! Will try to do that this week. Thanks !

[leggyfreak]

 caspros said:

Is there an easy way to test for this play in hub ? (<---novice)

Take off the wheel and try and wobble it ???

i got this in my car atm just wondering weather the play in the hub could be caused by wheel bearing???

or is there any other things that cause it