Stuck rear caliper acting on the opposite side?

Hey everybody,

I found a new issue. I had to replace the rear left brake disc splash shield as it was completely rusted through. Now I found that the caliper on this side was a bit stuck. Not too bad but the wheel was hard to turn (much more than on the right side). I thought maybe I should drive a bit for them to redo the clearance.

So I went for a drive and the wheel was still a bit hard to turn. I disassembled the caliper and tried to re-screw the piston but I did not have the rotating tool so I couldn't. I greased everything (piston/pins with silicone grease), rear of pads with and sliders with ceramic grease.

Reassembled and went for a drive. I took an infrared thermometer with me to gauge how bad it was. I stopped after 4 miles and took the measures. Front brake was at 35°C, rear left (on which I worked) 56°C and rear right (didn't touch it, wheel was apparently more free) was at 200°C!

This caliper never stuck to my knowledge and now it sticks much more than the other side just after I worked on the opposite side??? I have not explanation for this, can it be that the "left one" interfere through the handbrake or master cylinder?

Have you checked the parking brake cable clearance at both calipers? Should only need adjusting when cables are replaced or calipers removed but its easy enough to check the air gap.

Thanks for your answer. Yes, I did tonight. The handbrake cable more or less rests on the support, there is no tension or very minimal tension (gap 1-2mm). So it's probably not coming from there.

Temperature of the rear right brake after driving at 30 mph is between 160-250C, the rear left is about 50-60C and both fronts always about 30C. So I get that the two rears are now sticking, I just don't get how the rear right, on which I didn't do anything got sticky after a repair on the rear left (I am sure it's a new problem because it smells a lot now which was not the case before)

Maybe a brake line blockage, try bleeding the line to check the flow.

And the RR is still turning freer than the LR, but the temp of RR is at 400°F+/-?

doc280 said:

Maybe a brake line blockage, try bleeding the line to check the flow.

Click to expand...

Yes I will try that, thanks. Will see if releasing the pressure allows the piston to retract. From what I saw the piston/boots/guiding pins seem all to be in good condition and lubricated.

GTI's said:

And the RR is still turning freer than the LR, but the temp of RR is at 400°F+/-?

Click to expand...

Not anymore or at least not when hot. I jacked the car when it was hot and the wheel was definitely not turning freely, could turn it by hand but it sticks a lot.

Also I tried to hit the caliper with a mallet and to activate foot brake + handbrake several times and it seems it improved the things a little (still around 140-160C during the return trip, almost without hitting the brakes) but definitely a tiny improvement. So I think the piston is able to move partially at least.

So you were right GTI's, I had a look again today. I tried to open the bleeder, some fluid poured out but the disc wouldn't budge. Removed the parking brake cable and voilà, the disc is free (rear right side) so even that 2mm gap were creating such a drag. I feel dumb not have tried that the other day.

On the RL side however, removing the parking brake cable didn't change a thing, letting some fluid out either, I tried to retract the piston using a homemade tool and the bleeder open but it wouldn't budge. So on this side it seems clear that the piston is in fact lightly stuck (it's not free but it's not so bad, it locks the wheel if I press the brake and unlocks it if I release, just not as much as the other side). Having already replaced the brake fluid 6 months ago, I will have to rebuild it I think.

For now I disconnected the parking brake on the RR side because I don't know why it locked the brake caliper after my work on the RL side? Auto-adjustment with the frozen piston? But at least the car can be driven for now and it's not a defective ABS unit

PS: Not sure about the best thing to do regarding the RR side, should I re-adjust the parking brake cable for this side or do something on the caliper side? Not sure why it is too tight now and not before?

If you do not have the spec for parking brake here it is

Ok so mine was a bit too tight it seems. Will adjust it for both once I rebuild the other caliper as it seems to be quite a hassle.

Thank you guys

So I rebuilt the left caliper put the parking brake cable back on the right caliper and adjusted the tension. Everything is fine now. They react the same to the parking brake now.

However after the rebuild the parking brake worked very differently on the left caliper (it was only connected to the left side). With the cable disconnected on the right side, I had to go like 7 clicks to tighten it and it felt like "on/off". After the rebuild and before adjustment, 4 clicks were enough and it felt like much more progressive. Probably due to the stuck piston before.

After adjustment, on both caliper I made it so that there is no gap between the cable and parking brake support to be sure it is fully released. Even like this, 3 clicks are more than enough to get it very tight.

Thanks for your help.