The near-side rear brake calliper on my mk1 roadster doesn’t seem to be working properly. Surface corrosion that has developed due to moisture does not wear off after driving it around, suggesting that the pads are not contacting on the outer side. However, the handbrake does work on that side as the wheel cannot be rotated when up in the air with the handbrake on. The disc is also warm after driving, so there must be some contact at least with the other side.
I’ve taken the lower calliper slider pin or and given it a coat of copper grease but this hasn’t helped. Whilst the bolt was out I had a look and apart from looking a bit old there wasn’t anything obviously wrong with it. It seemed to move freely too.
Could the non-removal of the surface corrosion be down to worn pads alone, or does it suggest that the calliper itself needs replacing?
This is a problem when there is damp in the air and car not used regularly.
Corrosion builds up on the discs and reaches the point where it abrades the pads down and reduces the contact area. Uusally part of the contact surface clears throughout the circumference but there is an area that will not polish up with brake use however hard you try.
Assuming there is no problem with the caliper, the remedy is new discs and pads on both sides. Don’t panic these are really cheap nowadays.
Two things go wrong with Mk1, 2 and 2.5 rear calipers.
1 The handbrake does not work. Can you confim that both sides work ie stop the wheel rotating with the hand brake on and rotate with the handbrake off.
If so both handbrake mechanisms are fine.
2 After a good mileage anywhere between 30k and 100k miles the caliper seals can seize the brakes on.
It appears you believe that the nearside disk is noticibly warmer than the offside disc after a drive.
If my reading of your comments is correct then the your nearside caliper is starting to seize and will only get worse.
If you have greased the sliding pin with red rubber grease or ceramic grease not copperslip as copperslip does not lubricate and you have removed both disc pads and cleaned the metal backing plate wings where it rubs against the caliper and greased that with ceramic grease rather than copperslip as again it does not lubricate. After that if one disc is warmer than the other after a drive with no hard braking it is time for a reconed caliper.
Only rerubber if the caliper has done less than say 60k miles others will say it is cheaper but life is a bit too short.
If the disks and pads are even slightly worn just change them and do a full brake bleed front and rear if that has not been done in the last two years.
I was planning on replacing the pads and discs anyway, so this sounds promising. I’ll update this thread once they’ve been installed.
The handbrake does work (another thread said that it didn’t, but I hadn’t pulled it up all of the way, embarrassingly), and does stop both wheels. Wheels can both rotate with the handbrake off, too.
What I meant was that the nearside disc is also warm, along with the offside disc - they both heat up, but I didn’t check whether they were as hot as each other. I’ll check this next time.
I’m currently at 80k so I may as well go for a reconditioned caliper if new discs and pads don’t solve the problem.