eSeM

Around 6 months ago I had a set of rear calipers refurbished by Bigg Red and I have been having continuous problems with them sticking.

A couple of months back I replaced the pads and found that I could compress the near side caliper without any problems but the only way I could get the off-side caliper to compress was by releasing the bleed screw.

Over the weekend I had both calipers sticking and smoke from the brake pads.

This evening I have found that neither of the calipers will compress and I am using quite a bit of pressure on them. Both pistons rotate quite freely.

Never had this problem with any of the other sets of rear calipers I have had on the car, they have tended to seize through not being used regularly.

Any ideas?

martin j

I would have contacted the refurbisher when the problem first occurred,but anyway, could the piston come too far out and are not engaging to screw back in? also a customer of mine always has an apprentice at college and tells me they are now trained to open bleed valves when screwing rear caliper/pushing in front caliper pistons, something to do with not forcing fluid back through the abs unit.

eSeM

Piston is only protruding by about 7mm so not too far out.

I was reading quite a bit about opening the bleed valves to avoid pushing crud back though the brake system, however I have never needed to do this in the past with any other calipers and I think that my problem of not being able to compress the pistons is related to the constant sticking problems.

chrispayze

Even if the system is full, you shouldn't have to release the bleed screw to screw the pistons back in. Worst case, the reservoir just overflows (come on, we've all done it at some point!). Sounds like there's an issue upstream. If the pistons are turning ok though, then they should be retracting ok as they can't turn without extending/retracting. Odd.

chrispayze

Maybe something to try is to open the bleed screw and press the pedal (like you're bleeding it). Compare the pressure required with other calipers on the car, see if there is an obvious upstream blockage? If there isn't any discernable difference, then the problem is almost certainly caliper related.

chrispayze

Maybe they were built without the correct grease on the seals? But then I'm confused why they turn easily. Sorry, a few ramblings from a curious engineer, hopefully some of it will help!

unclefester

Almost sounds like they aren't on the wind back thread properly - if it turns but doesn't screw back in then surely that's the only possible cause of the problem? Or is the handbrake spindle not functioning somehow?

eSeM

Handbrake appears to work ok.

Nearside caliper did retract OK a couple of months back, now it wont. Off-side has always been a problem. Both calipers have new pistons.

I have another set of rear calipers in the garage which I plan to rebuild sometime this week. I am hoping that could give me an idea of what could be going wrong.

Front calipers are non-OEM (Wilwood) and are going to be replaced this weekend but for completely different reasons. I changed the pads on these and compressed the pistons a couple of months back without any trouble.

richmc

This is strange, what I would do first (cheap & easy) is to change the brake fluid first to try and dislodge any blockage if there is one. If there looks like a mecanical problem with the calipers I'd bite the bullet and change them, I've just done mine as one was sticking and the other leaking. I found these on eBay brand new Nissin ones so no worry about the quality of any refurb.

http://www.ebay.co.uk/itm/2-REAR-BRA...ht_3094wt_1037

If you can get it to compress with the bleed screw open, and it is only on one corner I'd remove the brake hose from the caliper and with the bleed screw closed see if it will push back, if it does the blockage is in the pipe work and you can then send loads of fluid through, if it still wont push back its in the caliper.

eSeM

This sounds like a good plan to isolate the problem

As I am changing the front calipers at the weekend it is probably a good time to completely flush the system.

Hopefully I can refurbish my other set of calipers before the weekend, both of the these calipers are in pretty good condition.

This is extremely annoying as the refurb from Bigg Red was about £180 all in and was supposed to stop the sticking problems that I have been getting with the calipers over the past few years.