Master Cylinder replaced, calipers replaced, still have squishy pedal
 

Hi All

Really struggling with this problem. I have a MY95 GL (non turbo) and have had 2 pots from a 98 WRX for a couple of years, these originally gave good performance. Over the past few months the pedal feel and travel has got progressively worse, nothing was changed in the braking system to set this off.

I replaced the fluid and bled thoroughly but this made no difference to pedal feel. All lines and flexi hoses look fine and it's not been leaking any fluid.

Offside 2-pot caliper was found to have a sticking slider which was lubed and new pads fitted, this made the pedal feel worse!! All I can think is that the action of forcing the pistons back into the calipers aggravated a problem somewhere.

Replaced brake master cylinder and pressure bled system (had this done by local garage as a bit out of my scope) no difference to problem.

It was suggested to me that I should clamp each flexi hose in turn to isolate each caliper (and drum cylinders on the rear), I found that clamping the offside front caliper (NB same one as had sticking slider earlier) gave much better pedal feel with engine and servo off, unfortunately I didn't check with engine on as I thought I'd cracked my problem. Clamping the other flexis didn't make the same difference. Went on to swap back to the original 1-pots on the front and still had good pedal feel with engine off, but with engine on the feel is still poor (possibly slightly better, but still far from right).

One thing of note is that the pedal feels a bit better when the clutch is pressed. Non-turbos have a hill-holder-clutch device which, if you press the brake and clutch at once, maintains hydraulic pressure in the brake lines even if the brake is released, until the clutch is released - i.e. for hill starts if you're too lazy to use the hand brake. Chap at the dealer thinks it's unlikely a faulty hill-holder would cause these symptoms but I can't think what else could be at fault.

Cars eh :rolleyes: If anyone has any suggestions I'd be very appreciative.

Cheers,

Ben

Don't know anything about the hill holder system. Had a similar problem a few years ago when I rotated the pads on my Renault 19. Good brakes before i started, good brakes after with engine off & NO brakes when engine started. Tried blleding no change, even stripped the master cylinder to check seals. In the end it was sticking slider pins on the calipers, stripped them down, cleaned and lubricated with a light smear copper based grease. Problem fixed. hope this might help if no one else has a better suggestion steve.

I concurr.....

A full stripdown. Check for seizing pistons and sliders.
Also make sure that the pads are not seizing in the caliper body - preventing them from sliding freely.

A pain in the backside when its freezing outside.....but when needs must....


Tim.

Thanks chaps, you were right :) Now much better after freeing and lubing the sliders and backs of pads etc. Still not as good as I'd like though. I guess sitting in my garage for 2 years had done the 1-pots no favours. Will try to give the 2-pots a really good strip down and refurb and switch back to see how they behave then.

Many thanks,

Ben