Help! I'm replacing the rear disk and I've managed to get the spline bolts out but I can't get the cylinder to screw back in. I've got a kit for it but the cylinder is too far out. I can't get the slotted plate in. I've tried putting the adapter on an extender bar and ratchet but I can only get it to budge a tiny bit. Any ideas out there?

Could be the calipers are seized as I had a similar problem with mine and ended up getting some new calipers.

Nip the rubber brake line with locking grips and crack open the calliper bleed screw, you should find without back pressure the piston will screw in easily enough.

As an aside, why do I see so many posts on here mentioning replacing callipers due to seizing...

They are a doddle to dismantle and all you need is wire wool, old toothbrush, toothpick and brake cleaner aerosol to make them good.

A pair of OE brake cylinder/dust seals is £20.

You don't even have to remove them from the car, just be careful how you manipulate the brake hose.

I found securing the calliper by one bolt, lower hole in upper bolt location gave good steady access for doing work.

Edited 14 February, 201610 yr by MicMac

Help! I'm replacing the rear disk and I've managed to get the spline bolts out but I can't get the cylinder to screw back in. I've got a kit for it but the cylinder is too far out. I can't get the slotted plate in. I've tried putting the adapter on an extender bar and ratchet but I can only get it to budge a tiny bit. Any ideas out there?

Possibly obvious question but have you unscrewed the lid of the brake reservoir in the engine bay?

Nip the rubber brake line with locking grips and crack open the calliper bleed screw, you should find without back pressure the piston will screw in easily enough.

As an aside, why do I see so many posts on here mentioning replacing callipers due to seizing...

They are a doddle to dismantle and all you need is wire wool, old toothbrush, toothpick and brake cleaner aerosol to make them good.

This^

I would invest in some hose clamps rather than using locking grips to avoid damaging the pipes.

Also agree with the servicing of the calipers. A complete service including replacing seals and o-rings (on rear) is very simple to do. Getting the piston out is the hard bit but find using an air compressor where the bleed screw goes pops it straight out. Even if you don't have a compressor a bike pump will still do the job quite easily. The rest is cleaning, re-assemble and a quick bleed and as good as new.

@CWARD

I did say NIP with locking grips, not crush, you don't need mongo pressure.

I pump the brake pedal to remove the piston, one pump at a time until the piston can be manually wiggled out by hand or drops out.

For those still unsure of which end of a screwdriver you hold, don't clamp the hose before pumping the brake pedal. Do it immediately after the piston is free.

Personally I wouldn't clamp or nip any of the flexi hoses. They are internally braided and don't like being messed about with.

There's no need to clamp it anyway, just open the bleed and place a piece of tube on it into a container to catch what you are pushing out. There isn't enough head pressure for it all to pour out

I've had the bleed nipple undone with a one-way hose on it so there was no fluid pressure. There was nothing left on either pad and the disk was left a bit thinner than design. Is is possible that it has come off the end of whatever it can come of the end off. I'll go with MicMac's idea tomorrow and see if I can pump it all the way off, clean it up and put it back on.

Rear caliper piston is on basically a long screw which travels along to compensate for pad wear which a cable can't adjust for. If you've unscrewed it completely from this the piston would nearly fully out of the caliper. Are you sure you're winding it in the right direction.

Be careful not to let the master cylinder fluid reservoir run too low, air in the ABS pump is a can of worms you don't want to open.

Experience has shown you can get away with a good calliper clean and not even have to replace seals as long as they aren't damaged.

Just remove the outer dust seal and use a small pointed implement to pick out the inner fluid seal (be careful).

Be sure to clean the seal seats out properly, wash the seals in hot soapy water and rinse well, dry with a hair drier to avoid lint from cloths.

You want to be sure everything is scrupulously clean on reassembly.

Wash out the calliper with a brake cleaner aerosol and allow to dry after cleaning out the internals.

Apply a small amount of new brake fluid to the inner fluid seal to aid reassembly.

Fit the outer dust seal to the piston and offer it to the calliper to seat the seal, the trickiest part.

Once fitted carefully screw the piston back into the calliper until it bottoms, be sure to observe the correct direction of rotation.

All that's left is to reassemble everything using a wire brush to clean rust/dust off the various contact points and smear copper grease where appropriate.

Don't forget to bleed the calliper thoroughly.

Thanks for you help guys. I didn't have a spare car today so I bottled it and called in a mobile mechanic. He fared no better than me as he pronounced that both rear cylinders were frozen and he replaced them. Also, one of the new rear disks was binding against the caliper bracket and we had to put the old one back on until I can get it swapped.

Frozen (i.e. temperature) or seized?

Yea, it was a bit nippy. I've still got two numb toes. They were both mechanically seized.

 

Err... that is the pistons, not the toes.