405 rear brakes

[subhuman]

Hi,

Well, my 405 (92 GTDT saloon) recently failed MOT on NSR footbrake. Cause seemed to be a badly worn disc. Swapped both rear discs. Pads are only a couple of months old and still level so I didn't swap those. At the same time, I did the following:

* Checked caliper pistons and seals, both OK and not seized.
* Replaced and regreased guide upper and lower guide pins on both rear brakes.

Now, as I'm only an amateur mechanic, I don't have too much experience with brakes. My Haynes manual doesn't really go into much detail on how to 'set' the brakes up once the pads have been reinsterted etc... I can't seem to stop them binding (I haven't taken the car for a drive yet, just rotated the wheels while the car was up on the axle stands)

I've adjusted the hnadbrake cable and this seemed to help a little bit (even if the handbrake didn't feel as 'solid' afterwards)

Also, even though I've replaced and regreased the guide pins, the caliper doesn't seem to move all that 'freely'.

One thing I've been told to try is clean up the trough that the pads sit in, make sure the spring/pins which hold the pads are positioned correctly (although I'm not sure how to check this) and to file away any corrosion where the pad is seated.

I'd appreciate any insight into what I'm sure is a fairly simple fix.

Cheers,
sub.

[fireman2203]

Sounds like the piston is seized in the brake caliper itself mate. i suggest you get a caliper service kit or else replace the caliper with a new 1 (or scrap yard).
Note: I you have replaced the pads last time yourself and didnt use a windback tool to push the piston back instead of a G clamp you may have damaged the caliper itself.

[subhuman]

Thanks for your reply.

I used a proper piston retraction tool, and with the the wheels off and the pistons down, they do pump out and then retract fairly smoothly.

I've spoken to one mechanic who seems to think a steady half hour drive might do the trick, as well as bedding the new discs in.

The car itself is driveable and doesn't seem to drag, but I won't know for sure until I pull off the driveway.

Cheers,
sub.

[subhuman]

Well, took the car for a drive and it wasn't too bad. Pedal travel was a bit scary, but I haven't done a proper 4 wheel + ABS bleed yet. Hopefully that'll solve that.

The rears pads and discs did bind for about 2 minutes, but after a short 40mph run, they seemed to be OK.

Examining the discs after the 15 minute run showed that the pads had left two 'parallel' lines on the inner and outer rings of the discs. I presume this is due to the way they wore with the old crappy discs (new pads were put onto old, scored discs a couple of months back)

Anyway, once I get the system bled, I'll very probably take it to a garage to get a once over before the MOT. Can't be too careful where brakes are concerned.