[tim b]

So I've just spent all day overhauling the brakes on my R32. The reasons for this were excess pedal travel and a scuffing noise from one of the brakes.

I've had all the calipers off the car and cleaned out all the pistons under the seals etc. Discovered the scuffing was one rear pad being tight in the caliper. Freed that up, and bled the entire system through with brand new DOT 5.1 fluid. :smokin:

Trouble is I've still got lots of pedal travel before the brakes do much. I have to push the pedal about half way through its travel before the brakes start to bite.

The feeling for the first half of the movement is like when you put new pads in and the pedal moves loads as it takes up the slack in the system, (i.e. there is some resistance as if its moving fluid about, but its just that the pads aren't at the disks yet). This feeling is always there though, the brakes don't seem to take up this 'slack'.

Once you're through this travel the brakes work well enough, but with the position of the pedal when the brakes start to work you've got no chance of heel and toe braking due to the pedal positions. Setup is stock calipers and hoses, with uprated pads and disks, and the ABS removed.

So do other people's R32 brakes, (with stock calipers), have loads of pedal movement, or do they start to bite as soon as you touch the pedal? I've got the service manual with the measurements in for reference which I'll check tomorrow, but wondered if they're all like this, or if anyone has had the same problem and managed to fix it.

The brakes on my S13 are loads better, biting really early and having plenty of power.

Sorry for the long post, wanted to mention everything I'd found in case it made a difference to the diagnosis.

 

[Chris Wilson]

I'd look to overhauling the master cylinder, or even ensuring it's the correct bore size. if it's had one with too small a bore you will always have excess travel, but the pedal should be light once the brake pads contact as hydraulic advantage has increased.

 

[Mirage]

same on my 32 i bought a master brake cylinder stopper kit, improved brake feel loads.

 

[tim b]

I'd look to overhauling the master cylinder, or even ensuring it's the correct bore size.

Hmmm, interesting. That's probably a good thing to check out, as it may have been swapped, (perhaps for a GTS item), when the ABS was removed and the brake hoses re-plumbed. I'll try to confirm its the correct part. Thanks for that input.

i bought a master brake cylinder stopper kit, improved brake feel loads

I've been looking into this as I've heard very positive reviews from many people after fitting these, but E-bay seems all out of R32 ones at the moment. I'll give Sumo Power or Abbey a call in the new year and see if they can supply one. Cheers for the help.

 

[Ross]

Tim,
It sounds to me that you have not got all the air out of the system?
Once you have bled the ABS system then bleed the brakes diagonally back and front using two autobleed kits and ensure the master cylinder never empties. My brake pedal is right at the top of the travel and is rock hard with instant braking. It has improved though with the use of braided hoses from Earls which took away the minimal sponginess I had.

 

[fabianGTR34]

I'd bleed some more, sometimes it is quite hard to get all the ait out of the system, especialy when you have removed the calipers for example.
I would bleed the system a few more times verry well before buying new things, it should brake reasonable with the standard setup.. improvements can be made when the the stock sytems works ok.

 

[tim b]

It sounds to me that you have not got all the air out of the system?
Once you have bled the ABS system then bleed the brakes diagonally back and front using two autobleed kits...

Could be. I've got no ABS anymore, (pump thing removed and system re-plumbed), so I'm confident its not that causing the problem. I didn't bleed the brakes in the sequence you described however, I followed the workshop manual sequence of working from the furthest caliper, (i.e. rear left, rear right, front left, front right). Why do you bleed them diagonally?

To make sure I'm not missing something obvious, its only the R33s that have two bleed points per caliper isn't it, as there appeared to be only one on my R32 calipers?

I didn't use an auto-bleeder either, wonder if that would have made a difference. Instead I kept the reservoir topped up, and I sat at each caliper with a pipe on the bleed point feeding into a pot. I'd open the nipple, shout to my Dad who was working the brake who'd then depress the brake pedal, and when it was at the bottom I'd close the nipple. He'd then release the pedal, and we repeated the sequence until about half a tea-cup full of fluid had passed through the caliper, (after the air had come out).

I wonder if my frequent trips back to the master cylinder reservoir to top it up allowed any air that was coming down the pipes to rise back up, meaning it never made its way to the caliper and got bled out. Perhaps fewer pauses during the process is the answer, but without an auto-bleeder or a third person topping up the reservoir it could be tricky, (could get my sister to do it actually, if it would help keep the process going and be a benefit).

I'd bleed some more, sometimes it is quite hard to get all the ait out of the system, especialy when you have removed the calipers for example.

Yep, I'd removed the calipers and pressed the pistons about on the bench which made loads of fluid come out. Perhaps a second bleeding session is the first thing to try.

Its wierd though because the initial pedal travel I'm describing isn't spongy, (as I'd expect of there was air in there), but a constant linear movement with a small but constant amount of resistance.

I know from experiences with my hydraulic mountain bike disk brakes that air in the system can make the lever movement feel wierd, so perhaps another go at bleeding is the way to go. :thumbsup:

 

[Chris Wilson]

Clamp off both rear flexi hoses and try the pedal, do the same for the front. Whichever circuit being clamped off restoresd the pedal is the one giving the problem. Your bleeding system sounds fine, I still suspect the master cylinder. Son't damage the liner on the hoses by clamping ludicrously hard, ideally use proper brake hose clamps. DO NOT try and clamp braided (Aeroquip / Goodridge type hoses), only stock type "rubber" ones.