Caliper Pistons Stuck

[RickS1K]

I tried to swap my brake pads today, and so far I'm failing. I took out the old pads and started cleaning everything (first time I've done this on non-OEM pads - using Bremo SCs now - and **** they were a mess of baked in dust (OEM pads/dust have always cleaned up nicely, not sure I'll get them back to normal). Naturally, I also checked the pistons, and they're not all working properly. On the same caliper, two pistons on the same side are barely moving. They weren't moving at all initially, but after 7/8 cycles of disassemble, clean, reassemble, pump brakes & repeat they started moving but then seemed to plateau. I've tried blocking two pistons and then pumping the brake, but whatever I try, I can't stop the 'working' piston doing all the work.

Any thoughts? Is there a way to release them without removing the pistons (and associated fun with brake fluid...).

Cheers

Rick

 

[alex]

2 of 4 will always move first in my experience. Only once light pressure is used to hold them back do the other 2 move.

That may be wrong but its what I have experienced.

- Alex

 

[RickS1K]

On the other side they don't all move together...but they do move. On the side I'm posting about both calipers on the same side barely move at all. Surely that can't be right?

 

[Flyingscotsman]

Are you holding back or clamping the 'moving' ones when the other ones don't move?

 

[RickS1K]

As far as I can yes. I can stick something between the top two, but with the bottom two I'm not sure what else to do when I'm pumping the brake other than just trying to stop the one that moves with my other hand?

 

[Flyingscotsman]

You could try using a g-clamp to hold back the moving piston. If the other one doesnt move then, it may be time to strip down the caliper.

 

[phil]

You could try using a g-clamp to hold back the moving piston.

Or, a small block of wood cut to fit will do the job.

 

[fast_ryan]

Brake Calipers

It might be worth removing the brake calipers from the bike and giving them a good clean.

 

[bananaman]

In my experience (twice) if you need to free off the pistons at all for a clean, they will soon return to the origonal problem.
Only way I could solve it was replace with new piston/seal kit. If you're gonna strip it you may as well replace....

 

[RickS1K]

In my experience (twice) if you need to free off the pistons at all for a clean, they will soon return to the origonal problem.
Only way I could solve it was replace with new piston/seal kit. If you're gonna strip it you may as well replace....

Yup, that's what I feared. Taking out the calipers cleaning them and replacing them seems easy enough, but not something I've done before. Doing the fuller job means changing some seals too - Is it complicated?

Also I've check a few places for the replacement pistons and the parts look different. Apart from just getting the BMW kit (any idea how much), what is the right set to order?

Cheers

 

[Flyingscotsman]

I think this is what you need:

https://www.reactiveparts.com/alpha-racing-bmw-s1000rr-repair-kit-front-brake-caliper.html

 

[phil]

Yup, that's what I feared. Taking out the calipers cleaning them and replacing them seems easy enough, but not something I've done before. Doing the fuller job means changing some seals too - Is it complicated?

You could get a quote for a local mechanic (not BMW) to do it for you?

 

[RickS1K]

Rob - yup that's one of the ones I found, looks right.

Phil - yup done that: 1 hour per caliper + parts = ?200+

I have a track day at Donny at end of month so might have to do it, as I'm travelling a lot this month...not a lot at the end of the day but would prefer to learn to do it...

 

[phil]

Yeah, give it a go Colin.

 

[fast_ryan]

Parts

I think this is what you need:

https://www.reactiveparts.com/alpha-racing-bmw-s1000rr-repair-kit-front-brake-caliper.html

It will be far quicker and cheaper to order new pistons and seals directly from BMW.

 

[Flyingscotsman]

It will be far quicker and cheaper to order new pistons and seals directly from BMW.

Good point Ry! I've not used Reactive but have heard on here they can be less than 'reactive' in delivery times.

 

[IMORTAL_Indian]

Give DR bikes a shout too.... they are quick and prices are good... tell Daniel that you know me....

 

[RickS1K]

Re: Parts

It will be far quicker and cheaper to order new pistons and seals directly from BMW.

The idea that a dealer might be cheaper was such a novel concept that I had to check it out

I didn't call Tim, just my local dealer, and they're ?141, with 7-10 day delivery lead time. Unreactiveparts are ?68 for what appears to be an official Brembo kit. Assuming the worst about the latter's delivery time means both scenarios put me a little too close to the track day for comfort if I cock it up.

I'll look at other places (Amit), but I have a caliper removal tool arriving today. I'm going to see what I can achieve by cleaning them and refreshing the brake fluid - @Bananaman how soon after cleaning did the pistons re-offend? I assume I'd be able to make the trackday before then (naturally with a good run in to make sure they work)

 

[bananaman]

Re: Parts

The idea that a dealer might be cheaper was such a novel concept that I had to check it out

I didn't call Tim, just my local dealer, and they're ?141, with 7-10 day delivery lead time. Unreactiveparts are ?68 for what appears to be an official Brembo kit. Assuming the worst about the latter's delivery time means both scenarios put me a little too close to the track day for comfort if I cock it up.

I'll look at other places (Amit), but I have a caliper removal tool arriving today. I'm going to see what I can achieve by cleaning them and refreshing the brake fluid - @Bananaman how soon after cleaning did the pistons re-offend? I assume I'd be able to make the trackday before then (naturally with a good run in to make sure they work)

After cleaning (pistons out etc), probably a few weeks. Leads me to believe it must be the seals.... When it happened again I just went straight for a new kit which solved it.
If you are half sensible it's quite an easy job, the careful bit is putting the pistons in square.

Vines of Guilford have been excellent for me, parts etc

 

[alex]

Try the part number in KFM-Motorrad.