Rear Brake Caliper Issue

[Michael Fernando]

Hi Guys

I've Recently been doing the brakes on my newly purchased 197 cup and for the life of me cant get get the rear brakes to rewind, the caliper is a second had part bought off of eBay. I've taken all of the fittings off(handbrake cable, bleed nipple and brake hose) and It still wont rewind. I feel like its a seized caliper but is there another way of checking before I go back to the seller and ask for a refund.(the handbrake function works, but I assume that's a different mechanism which moves the entire assembly)

Thanks in advance for the help

 

[J90RDN]

Are you using a rewind tool? i.e. rotating and applying pressure at same time.

 

[Siliconsteve]

As above, if not using the tool you've no hope

 

[turkie172]

Check the seal around the rubber boots on the piston they tend to bind to the piston but be very carful not to rip them the piston needs to come out to replace the boot. I bought the tool Laser Brake Calliper Piston Rewind Tool 3/8" model number 1314 it was about £18 and has an adapter with different pin spacing's so it can be used on multiple cars. Its still a little tricky to use as the backing plate does not sit completely flush against the casting to push off from and be carful of the brake pipe moving the calliper about can bend the rigid part of the pipe and split or crack it £29 for a new one and a week and a bit to wait for it.


Put a little brake fluid (dip your clean finger in the bake fluid bottle under the bonnet if you don't have any around) under the lip to lube it (I don't know what WD40 or other fluids will do to the seals otherwise) if it's a complete emergency you can afford to scratch the part from the grove to the front face using plumper's pliers over a good cloth only touching that part.

 

[Michael Fernando]

Are you using a rewind tool? i.e. rotating and applying pressure at same time.

Yes I'm using this rewind tool I got from amazon.

 

[Michael Fernando]

Check the seal around the rubber boots on the piston they tend to bind to the piston but be very carful not to rip them the piston needs to come out to replace the boot. I bought the tool Laser Brake Calliper Piston Rewind Tool 3/8" model number 1314 it was about £18 and has an adapter with different pin spacing's so it can be used on multiple cars. Its still a little tricky to use as the backing plate does not sit completely flush against the casting to push off from and be carful of the brake pipe moving the calliper about can bend the rigid part of the pipe and split or crack it £29 for a new one and a week and a bit to wait for it.
View attachment 18309

Put a little brake fluid (dip your clean finger in the bake fluid bottle under the bonnet if you don't have any around) under the lip to lube it (I don't know what WD40 or other fluids will do to the seals otherwise) if it's a complete emergency you can afford to scratch the part from the grove to the front face using plumper's pliers over a good cloth only touching that part.

So if the rubber boot is sealed to the piston does that mean the piston is seized in the caliper or is it just a way of trying to free it?

 

[Siliconsteve]

Sen

So if the rubber boot is sealed to the piston does that mean the piston is seized in the caliper or is it just a way of trying to free it?

Send it back for a refund before you can't and buy a new one. Problem over in about an hour as opposed to a day mucking around

 

[J90RDN]

Depends how much you paid for it. Biggred will recondition yours for £99 a side. If you paid pennies then perhaps persevere. I had to give mine a little bit of persuasion last week with some molegrips on the outer lip to loosen them slightly. Got the piston out and wasn't corroded, so assume it had stuck in as suggested above. Damaged the outer boot in the process, but again, Biggred has the rebuild kit for £17.99 delivered within a few days, and that's for both sides.

 

[turkie172]

No the boot is just stuck to the piston you will find as you try to wind the piston back the boot will get twisted that just means the rubber boot is not letting the piston rotate inside it so it needs a little lubrication there is always the possibility the calliper is seized or the tool is not being used correctly it needs inward pressure as well as rotated it in the right direction. It's just that the boot sticking to the piston can make the wind back so much harder that you might think the calliper is seized. I admit that I had to add a ring spanner to get the extra leverage for the windback but the car past the MOT brake and balance test and the handbrake is working fine just make sure the pads move freely but don't slap around the boot is something to look out for as I nearly ripped mine with all the pressure I was using and was not looking carefully enough.

 

[Foxspeed]

as said needs some pressure to get them to wind back ie clockwise

 

[Michael Fernando]

Thanks for all the advice, ive ordered a new caliper now. Im pretty sure the old one was seized as it wasnt moving in at all and we started to bend the tools we were using for the rewind.