[Zute]

So today’s the day when I finally get round to fitting my R56 brakes. All was going swimmingly until I tried to install the first caliper - it won’t fit over the pads! The piston is as far back as I can get it - can’t see that it could go back more.

The discs are brand new Nitracs and measure 22.1 mm thick. The pads are Ferodo DS2500 - each 17.9 mm thick including the 5.1 mm backing. The calipers are brand but were blasted and painted by a brake specialist who shall remain nameless and then stickered and clearcoated by me.

What’s the next step? Do I have bad pads or discs? Is sanding the friction material on the pads down a bad idea? As it stands, I can’t even get the claws and piston of the caliper over the edge of the pad, let alone the little bump in the middle of the backing! By my reckoning, I need at least 2mm more clearance.

All help appreciated!

 

[Green Hell]

Pad number is fine, that's sure. Got the same on mine. Your piston looks like it's not fully in tho. Normally it should be flush with the seal if fully in. Have you had the piston out when getting them painted / blasted? Wouldn't be surprised if there's a tiny layer of red below the piston.

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[Maccmike]

Pistons not all the way in.

 

[Zute]

Pad number is fine, that's sure. Got the same on mine. Your piston looks like it's not fully in tho. Normally it should be flush with the seal if fully in. Have you had the piston out when getting them painted / blasted? Wouldn't be surprised if there's a tiny layer of red below the piston.

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I’ve tried to force them in with a large g-clamp without success. I sent them in full assembled - judging by where else they got paint (such as in the slider bores), I guess it’s possible that they got some in the piston bores. They SAID they’d reused my existing pistons since they were new, but I guess they could have swapped them for ones that are slightly too long?

What’s the best thing to do now? Remove the pistons and check for paint? Presumably I need new dust boots if I do that?

 

[RT2002MCS]

Use a long pry bar to lever against the piston and caliper body, obviously get your freshly painted calipers wrapped up. This is how I over came the same concern after I painted mine.


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[bidsy26]

Lads should be 18mm and discs 22mm

 

[bidsy26]

*pads

 

[Maccmike]

Thats what hes measured.
The piston has to sit flush, simples.
Take the piston out and tell us what you find.

 

[bidsy26]

Thats what hes measured.
The piston has to sit flush, simples.
Take the piston out and tell us what you find.

Well done. Just confirming for him......

 

[Weltz]

lads should be 18mm and discs 22mm

lads lads lads

 

[Zute]

Well, I pulled one of the pistons tonight to see what’s what.

Inside of the bore looks clear:

Some sloppy painting around the rim though:

Piston looks fine:

This might be the problem:

Correct me if I’m wrong, but shouldn’t the piston only be 50mm long?

 

[bidsy26]

lads lads lads

Haha exactly what I said to myself.....

 

[cooper a]

Well, I pulled one of the pistons tonight to see what’s what.

Inside of the bore looks clear:

Some sloppy painting around the rim though:

Piston looks fine:

This might be the problem:

Correct me if I’m wrong, but shouldn’t the piston only be 50mm long?

Yes, It should be 50mm.

 

[Zute]

Sent my findings to the brake company this morning and the pistons are indeed incorrect. They’re having them collected so they can put the right ones in.

I’d call that a result - thanks for your help everyone.

 

[Undiez]

Sent my findings to the brake company this morning and the pistons are indeed incorrect. They’re having them collected so they can put the right ones in.

I’d call that a result - thanks for your help everyone.

I just had the exact same experience. Had the brakes fitted for me two years ago, then, when I tried to fit new pads the piston wouldn’t go back far enough.

Grrrrr!!!

Still, quite a learning experience swapping out the pistons. You live and learn eh?