rear caliper sticking

loadswine · December 30, 2006, 13:04

I took the 2 out the other day for a quick spin, when I got back the offside rear disk was very hot compared to the others.
Investigating today, it seems the handbrake activates, but the caliper is not releasing properly when off. Caliper now swung out of way of disk and it seems to be inside where the bother is.
Next thing to try is to rotate the piston back into its housing and hope that that frees up the mechanism.
Anyone got a quick and easy way to screw the piston in without the service tool?

markiii · December 30, 2006, 13:15

I have a tool which should fit, Stu has it at teh mo, from meory you guys are quite close?

if so feel free to borrow it

loadswine · December 30, 2006, 13:30

Excellent Mark, I'll give Stu a ring. s:)

s:)

Anonymous · December 30, 2006, 15:02

Quote from: "loadswine"Anyone got a quick and easy way to screw the piston in without the service tool?

Does it have to be screwed back in? I've used a valve spring compressor before to push the piston back into the caliper.

aaronjb · December 30, 2006, 15:24

Quote from: "Moleshome"
Quote from: "loadswine"Anyone got a quick and easy way to screw the piston in without the service tool?

Does it have to be screwed back in? I've used a valve spring compressor before to push the piston back into the caliper.

The front calipers push in, but the rear caliper has to be screwed back in as per the service guide. Forcing it straight back in carries a high risk of breaking the handbrake mechanism.

If you don't have the proper tool to hand then a largish open-ended wrench with it's points in the notches on the piston, plus a second smaller wrench as a handle in the ring end of the main spanner works quite well.

firepower · December 30, 2006, 16:53

is it definitely the caliper that is causing your problem s:?: :?: s:?:

i used to own a mk 1 mr2 and the hand brake cables caused problems by siezing on, so i would check the cable as well

i dont think there is any reason why the caliper should have over adjusted as it should lock in to a notch on the back of the brake pad which stops it from rotating.

loadswine · December 30, 2006, 18:42

Its definitely the caliper that has the problem, as it was still stuck with the handbrake cable disconnected. I've picked up the tool from Stu, but it was dark and raining when I got back, just had a chance to offer the tool up to the piston, it wasn't about to move in a hurry.
As soon as its dry and light, I'll go and have a proper go.
If it is still sticking, after the fiddling, I guess its a new caliper... s:(

s:(

markiii · December 30, 2006, 18:44

if it's teh caluiper let me know before you spend cash, may have an interesting idea for you

loadswine · December 30, 2006, 18:46

Mmmmm, sounds intriguing!
One good thing I did find while grubbing about, is that the car has stainless steel reinforced brake lines fitted. At least that was a nice surprise.

loadswine · December 31, 2006, 15:20

I wound the caliper back in a bit, took some effort which wasn't a good sign. Refitted all the bits and it doesn't seize on the handbrake operation at all, mechanism releases well.
Took it out for a quick test and it seems as if the caliper is still sticking a bit, from the operation of the footbrake. Definitely a problem inside the caliper. I'll try winding it back in again, but I am beginning to think the caliper is up for replacement. Mark, I might need your interesting idea after all.

Anonymous · December 31, 2006, 15:26

hav'nt done the 'two' before Nige, but the screw in pistons can be very stiff anyway mate.

Assume you left he lid off the brake fluid resovoir so you not trying to push against pressure? (sure you did, just a thought)

loadswine · December 31, 2006, 15:53

A good thought Perry, first time I attempted it, I forgot until my eyeballs popped! Then I thought "Ah the reservoir lid!" or words to that effect. s:lol: :lol: s:lol:

Anonymous · December 31, 2006, 15:53

One other thought - hope it isn't too obvious.

Has the sliding pin on the caliper been properly lubricated with a lithium soap base grease? Use of common axle/wheel bearing grease can prevent the caliper from sliding in/out properly.

loadswine · December 31, 2006, 15:56

Pins are well lubricated and move quite freely as far as I can see.
Thanks for the idea , we might find a cure yet!

normanh · January 2, 2007, 09:32

Question, has anyone a detailed drawing/parts breakdown on the rear caliper? As I suspect I am having a few problems here as well. Better to see what I intend to clean up before I attempt the job. Had one disc corroded on the iniside which I cleaned up on fitting new pads but the had brake still does not feel right. Does anyone know if the handbrake mechanism in the caliper needs lubricating? I have had one new cable fitted as the old one was total siezed.

normanh

loadswine · January 2, 2007, 10:42

The only external handbrake parts that could need any lubrication are the crank and spring, if they are free from corrosion and move freely, then the problem is likely to be inside the caliper assembly.

loadswine · January 4, 2007, 21:38

Just an update. I wound the piston back in for a second time today and it seems to have fixed it, at least for now. There is no apparent sticking after applying the footbrake and after a run of about 8 miles the disc was no hotter than any of the others.
I will test it some more when I get a chance over a slightly longer distance and see if I get any issues with it then.

aaronjb · January 4, 2007, 21:51

Good news then Nigel s:)

s:)

Anonymous · January 5, 2007, 01:26

great news bud ! s:)

s:)

loadswine · January 5, 2007, 11:22

Yep! Pleased so far! s:)

s:)

firepower · January 5, 2007, 15:22

how does screwing the piston back in to the caliper housing stop it from sticking s:?: :?: s:?: as soon as you apply the brakes the piston will move back out of the caliper housing in to contact with the pads unless the piston was over adjusted to start with s:? :? s:?

Anonymous · January 5, 2007, 18:46

why is a nut easier to undo the second time around? s;)

s;)

probably cleared the obstruction (grit or the likes) and now its no longer siezed (fingers crossed)

kanujunkie · January 5, 2007, 21:45

plus he hasn't said wether he lubricated the piston with a wipe of oil

heathstimpson · January 6, 2007, 07:08

Quote from: "kanujunkie"plus he hasn't said wether he lubricated the piston with a wipe of oil

Yes that normally helps and don't forget to put a small bit of lube on the seal around the piston preventing damage as you screw it back in s:wink: :wink: s:wink:

loadswine · January 7, 2007, 17:08

Actually I didn't do anything to the piston other than wind it back in and let the internal mechanism adjust it back to normal.
I am guessing that as I don't use my car a lot in the winter it got a bit stuck through non use. I am only just guessing here. Sometimes things that become stuck in those circumstances do free up after moving them around in some way.
I don't know all the whys and wherefores I'm afraid, I just know that it seems better now than before I did it. s:)

s:)
Lubricating the seal does sound like a good idea. What to use though, don't want to rot anything.