Yet another brake breeding problem

[patrics]

Hi Stuart
Are you sure you still have a problem what?s the pedal like when you are driving - does it still feel long?
I think that the brake system is probably bled and the pump up your experiencing might be down to the rollback on the new calipers ? gently put a feeler gauge between the pad backplates and the caliper pistons and tell me what they are for each - but make sure you don?t push the pistons back and get the wrong measurement.
Where are you anyway?
Regards
Steve

[stuartgb100]

Hi Steve,

Had a night off, last night, so just pumped up the pedal and confirmed there is still air in there somewhere (I believe).

Nothing done since then so here are 'cold' readings:

n/s front: inner piston clearance to back of pad plate is 30+ thou
outer is < 3 thou

o/s front: inner 6 thou
outer is 10 thou

Despite a rebuild .......... sticking piston ? Bear in mind this is not a fully refurbished set of calipers, just seals etc.

Haven't driven the car for 10 days, since gingerly testing it and discovering the brake problem. Certainly if I start it up, there appears to be extra travel on the pedal.

As regards my location, near Cambridge, East Anglia.

Regards,
Stuart.

[iain.hamlton]

I think extra travel with the engine running is typical even when the problem is not directly related to the servo. At least that is what i have found. The logic is that servo adds extra force, making the pedal sink more easily. My money is still on the master cylinder, probably air caught in it. I like the idea of loosening the union on the output of MC and trying to bleed the air out like that. Otherwise, how about one of those desperate kits that pressurizes the MC resevoir? Gunson Eezibleed?(careful you don't get brake fluid everywhere!)

best of luck,

iain

[stuartgb100]

Iain,

I am already using the Eesi-bleed kit. If there is air in the master cylinder, then it doesn't seem able to shift it.

I think I'll connect the eesi kit up, then try to concoct some sort of plastic bag type of arrangement around the exit pipe from the m/c, and open it up a little. If I can contain the fluid enough, then I think a pump or two on the pedal might help.

Regards,
Stuart.

[patrics]

Well Stuart, looks like you have found your problem, no actuation can cope with clearances like that! Get them all down to 0.003? and the pedal feel will be okay

Cheers
Steve