what did you do with your fazer today ?

[ChristoT]

Went to fit my nice new braided lines and came to realise that my rear caliper needs a major overhaul as both pistons are seized. One is moving ever so slightly and the other is completely jammed

Time to try and find some genuine seals and spend more money

Well, now we know why your rear brake felt like a brick outhouse!! )

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[Dead Eye]

Yeah, going to go and buy a clamp and try to free the pistons. Hopefully I can restore them without having to replace them, but I'll definitely do the seals whilst I'm there.

I was sensible enough to only do the rear caliper to start with and it's useless anyway so I can probably get away with using the bike to fetch the bits I need. Failing that I guess I'll have to take out the fuel guzzling cage

[Dave48]

Deadeye-was faced with same prob with rear caliper @ weekend. Good news is that if you've lost system pressure by removing brake line, you can split the caliper in two by removing the 2 bolts @ rear. CAUTION-don't lose the black rubber type washer that sits between the two halves to seal brake fluid internal passageway..Ask your local friendly bike shop to apply compressed air to each caliper-leave bleed nipples in for this. My pistons popped straight out, allowing me to clean up pistons & bores. When reinstalling use a thin smear of red rubber grease to new seals & piston sides to ease insertion & help prevent future ingress of dirt,water etc. Its a bloody silly location for the rear caliper-right where it gets a constant stream of dirt/wet/salt etc :eek  Good luck!

[stevierst]

Got mine to do today, not looking forward to it. >

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[Dead Eye]

Dave48 - Thanks for the advice So far most people seem to have suggested that splitting the caliper is absolute pain the ass and that the gasket on the inside is no longer available from Yamaha (but there is a part from another manufacturer, I forget which). I'm going to try and do it without splitting the caliper if I can - I'll re-attach the brake hose and use that to pressurise the caliper. Then, clamp on piston and force the other out, clean up that side, replace everything, then swap the clamp around and do the other side

Hopefully the fronts will be ok and won't require quite so much work.

Edit: For the seals, am I right in saying the kit is one per piston, not one per caliper... if so this is expensive

[ChristoT]

Dave48 - Thanks for the advice So far most people seem to have suggested that splitting the caliper is absolute pain the ass and that the gasket on the inside is no longer available from Yamaha (but there is a part from another manufacturer, I forget which). I'm going to try and do it without splitting the caliper if I can - I'll re-attach the brake hose and use that to pressurise the caliper. Then, clamp on piston and force the other out, clean up that side, replace everything, then swap the clamp around and do the other side

Hopefully the fronts will be ok and won't require quite so much work.

Edit: For the seals, am I right in saying the kit is one per piston, not one per caliper... if so this is expensive

The gasket isn't available, there was a Foxeye in Twist ad Go (local bike shop) a few weeks back, and the mechanic spent a good 45 minutes looking for the right part.

[Chris]

Sure there was one from a suzuki that wasn't an exact match but was close enough. However I've reused the original small rubber ring between the caliper halfs and it's fine.

Chris

[stevierst]

Just finished the rear caliper seals. It was a but of a pain in the rs without splitting the caliper, but do-able. My seal wiper rings were completely shot, and these were chewed up, locking the piston in. Brute force and ignorance got them out in the end.
Putting the new seals in was a bit emotional, it always seems like they're too big until they finally pop in. Hopefully that's them done for the next few months!:

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[Chris]

Just finished the rear caliper seals. It was a but of a pain in the rs without splitting the caliper, but do-able. My seal wiper rings were completely shot, and these were chewed up, locking the piston in. Brute force and ignorance got them out in the end.
Putting the new seals in was a bit emotional, it always seems like they're too big until they finally pop in. Hopefully that's them done for the next few months!:

Ye, the bigger fluid seals weren't too bad but the dust seals were a right pain! I found them bad because they're so thin they just flex instead of popping into the groove. Guess you just have to make sure the grooves they sit in are as clean as possible and that makes a big difference. I'm glad I split the caliper to do it, would have been a complete nightmare if I hadn't.

Chris

[Dead Eye]

I'm a little more concerned about splitting the caliper as the bike has done 86k miles and it has sooo much crap on it that I expect the internal seal to just completely disintegrate if it sees the light of day...

Also, does anyone have an answer to the seal question? Do I need one or two kits for the rear caliper - I've started second guessing myself and can't figure out if I've gone completely nuts or I'm still just regular nuts :|

[stevierst]

I split a caliper a while back, and I thought it was just two 'o' ring seals between the halves not gaskets?

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[Skippernick]

oh god i'm not looking forward to this.
If i'm going to change the brake lines is it worth replacing the seals at the same time, or is a case of if it ain't broke don't fix?

[Dead Eye]

Depends on the condition of the caliper and pistons really - if its a low mileage bike that is kept clean you should be fine. If its like mine - high mileage and very dirty / poorly maintained by the previous owner then its probably going to need doing...

[Skippernick]

It will click through 19,000 very soon, i've had it since 6,700, he kept it immaculate but don't know about servicing.
I've used it through 3 winters this winter the most, its clean but not spotless, a fair amount of break and chain cleaner, when i checked the pads the other day the pistons had a little rust on them, most of it came off with a spray of brake cleaner.

[Dead Eye]

Sounds like they should be ok, but a good clean never hurts

[stevierst]

Sounds like they should be ok, but a good clean never hurts

definitely give them a good clean. If there's ANY little bits of rubber that poke out of the top of the piston, then the seals will need changing soon.

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[Dave48]

The "washer" is more like a flat rubber washer than an O-ring & so long as its not pinched/damaged should be fine to reuse-guess its made of a similar material to piston seals -ie brake fluid proof. Stripping/cleaning/reassembling with smear of red rubber grease will prevent future piston seizure as the position of caliper places it in the " line of fire" for all the wet & nasty stuff. Cheaper than replacing rusted/corroded pistons & damaged calipers!
Oh yes to get back to subject of thread.......... Collected my gear pedal/footpeg shaft with nice new bush fitted (£5). All side play now gone & gear change crisp & positive. Theres still one or two good "old skool" engineers in Brum! :lol

[Dave48]

ChrisoT you are right- there is one dust seal (thin) & one piston seal(thicker) per piston so you need two of each for back caliper  as it has two pistons.

[Dead Eye]

Ordered new rear caliper seals and got one of the pistons out - old dust seals literally fell apart in my hand :\

Tried to split the caliper but it was having none of it! Had the caliper attached to the caliper bracket backwards (so I could get to the two bolts) then used a good fitting socket and my 750mm breaker bar and nada. I was able to lift the front wheel with the breaker bar whilst the bike was on the centre stand :| Looks like I'm doing this the fiddly way!

[Dave48]

Deadeye-Put your caliper in a decent sized bench vice(suitably padded)-you will have better access/leverage. If it is impossible(corrosion) to split caliper then pop the piston you already removed back into its bore(without the old seals), clamp this in place & apply compressed air to remove stuck piston. You might have to visit your local friendly bike shop for this & tip the mechanic! Whats the saying?---Do it right----Do it once! :lol Seriously though, once you have new seals & red rubber grease applied its easy to keep caliper clean & working well. Good luck,Dave