brembo brake callipers- wtf

MEB · May 4, 2013

my f650gs twin is defiantly in need of new pistons and seals (and yes pistons, as they are actually cracked in places).
I was absolutely flabbergasted to hear (from my friendly bmw dealer) that it isn't possible to purchase the pistons. you can buy the seals.. but not the pistons. I have rang motoworks and they have said the exact same thing.
any other bike and you can replace pistons and seals for around £30-£50 depending on your bike and whallah!- 'like new' callipers. yet bmw seem insistent to sell me a new calliper for £250 or motorworks a used one (with used pistons) for £160.
I've asked this question to bmw and motorworks but i thought I'd ask the Beemer fanatics as so far i've had no luck; are there pistons out there somewhere which can fit my calliper? or indeed an aftermarket caliper which i can install and then later just replace pistons and seals? and before anyone sparks up about brakes being the most important aspect of a bike and that aftermarket is bad- i'm not after the cheapest callipers, just ones that i don't have to constantly replace every 12-18 months.
thanks in advance

dpm · May 4, 2013

don't some Hondas use the same caliper? A cross-reference might be in order...

JayC · May 4, 2013

I just rang CW (Dorchester) on your behalf because I find that to be bloody outrageous!
The parts list apparently shows a seal kit for £15.00 , which at that price is unlikely to include pistons, he agreed. He said he could ring BMW to find out but it may be that you have to buy a new caliper if going through BMW. He also said he'd never come across such request before and asked if they'd been prised out with a screwdriver, or similar. Not having any idea of how you got to notice the cracks I then told him I'm ringing on someone elses behalf.

In your situation I'd be inclined to remove the pistons and buy them on their own elsewhere, something the parts guy also suggested. I don't know where from but I know I certainly wouldn't be buying new calipers unnecessarily.

Good luck!

MEB · May 4, 2013

dpm- i'll start cross referencing now, thanks

jayc- i really appreciate you going through the bother of ringing your BM dealer. the cracks are actually cracks/miniature rough holes (1mm in diameter) on the face of the pistons. they're an absolute eye sore and i would take a picture but it would mean taking the caliper off at this late hour with work in the morning. i too was quoted the £15 which doesn't include pistons.
I've already attempted sourcing them elsewhere and even flea-bay doesn't yield answers. utterly frustrating to say the least.
thanks again to both of you =D

dpm · May 4, 2013

Try CB500s and NT650 Deauvilles; the calipers are gold but I have a niggling notion they're otherwise the same...

Smythson · May 4, 2013

I had exactly the same problem when trying to replace a pin seal. I popped down to a KTM dealer. Same caliper as a KTM 690 Enduro 2009 and quite possibly these too -

http://www.advrider.com/forums/showthread.php?t=755569

If you've a Honda near you -

http://www.lingshondaparts.com/hond...ck_01=13MAKVS1&block_02=F__0900&block_03=4652

- looks very similar though i haven't checked in store.

Also this site says this suggests the caliper is used on a few more bikes -

http://www.ebcbrakesdirect.com/sear...hh&v1=car&t1&gclid=CNWCuIqIubYCFVDMtAodygwAmA

Best,

S

MEB · May 6, 2013

cheers guys. so far i cannot find anything from what smython and dpm have recommended that tell me the calipers are definatly the same.
i have however found a site that sells pretty much every size motorcycle piston and seals
http://www.motorcycleproducts.co.uk/catalogue/brake-caliper-piston-kits-c-108_233.html
so... does anyone know what size of pistons are needed? I remember motorworks telling me it's probably a certain size (although i forget the size quoted) but they cannot be certain.
Max

MEB · May 6, 2013

actually nevermind, just checked one of smythsons links and it reckons 32X28.5 and 30X28.5.
gunna take the plunge i think and buy these tomorrow when i get paid.
thanks to those who have helped- and i'll make sure i post back after i try fitting them :thumb2

JayC · May 6, 2013

MEB said:
actually nevermind, just checked one of smythsons links and it reckons 32X28.5 and 30X28.5.
gunna take the plunge i think and buy these tomorrow when i get paid.
thanks to those who have helped- and i'll make sure i post back after i try fitting them

I was about to give you the sizes but now see you have found them.

When I rang on your behalf I was told that the 32 and 30mm dimensions are the bores, not the OD! It seemed an odd way to provide info. It is of course possible the shop guy got confused and offered me the caliper bores as a ref to the correct pistons but that certainly wasn't how he worded it to me, especially as it was only the pistons I was enquiring about when he stated the bore dimensions. Best bet is to remove them and measure to confirm, if you haven't already :thumb2

MEB · May 11, 2013

hey guys. been longer than expected to get the parts and that's down to being paid two days later than normal and waiting for parts to be delivered to the honda dealers.
well then...
only just got round to doing my calipers and i've already hit a wall... well two really. :hide

wall numero one- bracket completely stuck to the caliper (see image)
wall 2- the top piston is well and truly seized.

oh and the pictures should help describe the holes in the pistons. they were not that bad when i last changed the calipers and the top one i have just damaged a little bit further as i thought (silly me) that i could wedge my pliers in the hole to help extract the piston.
any ideas or is it new caliper time?

dpm · May 11, 2013

connect it back up, block the free piston, pump'er out.

where's the bracket seized?

MEB · May 11, 2013

i took it off as a last resort as i've already tried blocking off the moving piston- the other is well and truly seized.
the bracket is outlined. it is attached at two points and haynes manual reckons it should simply slide off. i have reomved rubber boot (RB) but S is where is is just stuck. no amount of twisting (which is limited) or pulling or levering will free it up. -and i've tried lubing it with brake cleaner too

JayC · May 11, 2013

First thing I'd be doing is putting some soft jaws (cushion) in that vice for when you attack this problem again! It won't hide the jaw marks you have already put on the calipers but it will prevent the imprint from getting worse.

As the pistons are shot then I'd be inclined to Araldite a plate covering all holed surfaces, lube the pistons and push them back home. Use compressed air to free the pistons off but ensure you place a packer between the caliper arms and the piston to both cushion the force when the piston is finally released, and to prevent it shooting out of the caliper, onto the shed wall, off your fuel tank and the cats head before striking you in the face, because it will fucking hurt if it does hit you! :rob

Judging by the state of the piston walls it looks like your caliper may already be past it.

There is next to no clearance between the piston and the bore and any amount of misalignment will be enough to seize it in position. The pistons need to be inserted/removed dead square to the bore. It may just be that they are not seated squarely and so feel permanently seized. So, if you do want to try to salvage your caliper, or at least inspect it before throwing more cash at it then try the method above.

MEB · May 11, 2013

yeah... i kind of though about cushioning the clamp after i'd tightened it. :blast

...and I don't have a source of compressed air. well, not today at least. corr blimey i hate all things breaky- no job has ever gone straight forward for me :tears

thanks anyway pal

MEB · May 11, 2013

back again and with some success.
this may be interesting to those who have been posting as now i really could do with some opinions/advice.
i managed to free the bracket. had to undo and remove a bolt that i probably shouldn't have (but i'll locktite it back in after), but that was enough to give me some extra leverage.
then the pistons... mole gripped them out. and before anyone screams at me- i was pretty much stuck without compressed air and one in particular wouldn't come out with braking. i did it very gently and there is very (very) little damage to the pistons so i can presume there is none to the calliper/bores.
but this is where it gets interesting. i've just compared the brembo pistons i bought with the old ones. the new ones are exactly the same diameter and depth but much lighter, have no cap on them and are exactly 1mm shorter. (see image)
so... i'm thinking to fit the new ones or is there something you guys know that i should?

(image 1 & 2 are the reasons why the bracket was stuck, image 3 is the pistons)

JayC · May 11, 2013

MEB said:
back again and with some success.
this may be interesting to those who have been posting as now i really could do with some opinions/advice.
i managed to free the bracket. had to undo and remove a bolt that i probably shouldn't have (but i'll locktite it back in after), but that was enough to give me some extra leverage.
then the pistons... mole gripped them out. and before anyone screams at me- i was pretty much stuck without compressed air and one in particular wouldn't come out with braking. i did it very gently and there is very (very) little damage to the pistons so i can presume there is none to the calliper/bores.
but this is where it gets interesting. i've just compared the brembo pistons i bought with the old ones. the new ones are exactly the same diameter and depth but much lighter, have no cap on them and are exactly 1mm shorter. (see image)
so... i'm thinking to fit the new ones or is there something you guys know that i should?

Yes, I know that aluminium is softer than steel and if you have been wriggling the piston with mole grips then there is a good chance you have damaged the aluminium bores.
I am not going to suggest how to approach putting the pistons in because I truthfully don't feel you're the right person for the job! :aidan

Hopefully somebody less mechanically sympathetic than me will be along shortly with further destr....instructions.

MEB · May 11, 2013

JayC said:
Yes, I know that aluminium is softer than steel and if you have been wriggling the piston with mole grips then there is a good chance you have damaged the aluminium bores.
I am not going to suggest how to approach putting the pistons in because I truthfully don't feel you're the right person for the job!

Hopefully somebody less mechanically sympathetic than me will be along shortly with further destr....instructions.

thanks pal, probably the first time i've laughed today (and not sarcastically). will keep you informed with the end result

MEB · May 11, 2013

dear thread readers. the caliper is all back on the bike with all new brake fluid pumped through. have not long since come back from a test ride and she's braking like new. :bounce1

because of having to mole grip the pistons out i'll have to inspect tomorrow and see if any leaks or problems have occurred.
thanks to everyone that helped and for anyone else with the same problem; i just overhauled the caliper with slr650 pistons and the bmw seals (as they were cheaper than honda).

Bendy toy · May 19, 2013

A 1mm shorter piston will make no difference to how the brake works - pads vary in thickness by much more than that.
Clean the caliper bores paying special attention to the seal grooves. If anything alloy is cracked you need a new calliper.

Clean the whole calliper to remove ALL dirt and grit. Fill the seal groove with red brake grease and fit the main seal. Fit the dust seal and fill the space between with red grease. Wipe off the excess - don't need grease shoved behind the piston.

Carefully fit new piston keeping it square.

It will be a loose fit in the caliper held central by the seal.

Neiljohnuk · May 24, 2013

MEB said:
oh and the pictures should help describe the holes in the pistons. they were not that bad when i last changed the calipers and the top one i have just damaged a little bit further as i thought (silly me) that i could wedge my pliers in the hole to help extract the piston.
any ideas or is it new caliper time?

Hole in the plastic fillers, when I broke one of my K's fillers I simply filled the hole with JBweld and smoothed it off!

Looks like you needed new pistons and seals anyway, what sort of mileage?

brembo brake callipers- wtf

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