Good brakes but soft-ish pedal & groans.

[AAH!]

I have been noticing recently that my brake pedal often has different levels of travel before the brakes really bite and also at times the pedal seems to requires different amounts of pressure. The actual brakes seem to be working extremely well and it is not too much of a problem.

The bomb was changed 7 months ago as were the pads, calipers, disks and brake fluid. The brakes were bleed a couple of weeks ago when I had the two front wheel bearings changed.

Yesterday just to make sure the bomb was ok I did the bomb test and got 38 pumps before it went hard.

When I drove the car later in the day the pedal felt the same but after a short time on the motorway I noticed I was getting a groan/vibration form the front o/s wheel, which would go away when the brakes where dabbed or the steering wheel turned. (just like before the wheel bearings were changed! ). The last time this happened was on my way home from the garage meet where I had drained and renewed the hydraulic fluid. I thought it was the wheel bearing.

When I got home I gave the o/s brake pads a good clean out and bled the caliper and fond a bit of air lurking on one side.

There also seems to be a bit of weeping of hydraulic fluid from the crimped metal section of the high pressure hose that leads from the hydraulic pump to the bomb. There is also a bit of weeping from the banjo bolt on the hydraulic pump that leads to the steering box.

I took the car out and all seems to be well, although it wasn't long enough to be able to judge properly.

Could the pedal issue be a master cylinder thing or servo thing? What normally happens when the master cylinder or servo starts to fail?

It may be that a bit of dirt got stuck in the pads or maybe the new wheel bearing is no good, but is it possible for pressure to build up in the system and just one caliper to start pushing the pads towards the disk by it self and cause the groan/vibration ?


Thanks ...Angus

[newsh]

Hi Angus, I've had this happen a couple of times since I did my 996 conversion, you just have to clean the pads and reassemble, last time I chamfered the leading edges of the pads with a file, about 3mm, and used copperslip on the backs of the self adhesive shims where they fit to the pistons and edges where they contact the calipers, the groaning has not reappeared yet..
Dan mentioned yesterday that he has had the same problem.

[maRS2]

check this their is a way to test the servo also look what they say about faulty abs senssor.

[AAH!]

Thanks guys.

I will try chamfering the edges of the pads if it happens again and also try the servo tests.

So i may have changed my wheel bearings for nothing But at least that may be one thing I wont have to worry about for a while.