EvilSpike Posted July 20, 2011 Report Share Posted July 20, 2011 *Blown Seal Related, although not like a canadian version of Gretch Morning So deciding to make the front brakes all nice and properly working for the next owner of my ZXR 400 i thought I'd pop the calipers off, squeeze out the pistons and give them a good clean and a film of grease. I only managed one of the calipers yesterday and i found that only two pistons came out easily when the lever was pumped due to corrosion of the pistions. I gave them a good clean and a scrub but I think that one of the seals might be mullered. It looks like it is trying to escape the piston, you can see about 2mm of the seal poking out between the caliper body and the piston itself. Thing is though is that the piston slides in and out easily and i took the bike for a ride down the road and back and the brakes feel perfect now. There are no leaks of fluid and the lever feels fine. Am I kidding myself that the calipers don't need to be properly rebuilt? Ta for the advice, although the act of writing this has convinced me they need a rebuild. How expensive is this as I'm not confident of doing this myself couple of hours labour plus the seals? Spike Link to comment Share on other sites More sharing options...
EvilSpike Posted July 20, 2011 Author Report Share Posted July 20, 2011 Actually, is this just the dust seal poking out? If so, it won't be a problem in the short term no? Link to comment Share on other sites More sharing options...
thefatman Posted July 20, 2011 Report Share Posted July 20, 2011 That is just the dust seal so it won't cause any problems. As your selling it i'd be tempted to leave it. If you do have the time to strip the caliper it isn't a hard job, and you'd be able to reuse the dust seal so it doesn't need replacing, then bleed the brakes afterwards. Link to comment Share on other sites More sharing options...
lorenzo Posted July 20, 2011 Report Share Posted July 20, 2011 The dust seals can swell sometimes though, which means that they don't go back in properly. If the brakes work nicely and they're safe, I'd keep it like it is, especially if you're selling. The actual seal that the fluid is kept in, this sounds like it's fine, I've never known one go badly wrong; so long as the pistons aren't corroded to bits you'll be cool. Often the corrosion's just on the outer bit of the piston, which is as a result of the dust seal doing its job. Link to comment Share on other sites More sharing options...
EvilSpike Posted July 21, 2011 Author Report Share Posted July 21, 2011 Hmm, well I stripped and cleaned the other one yesterday and it too has one dust seal that is being pushed out in one place. Both are at the bottom of the lower caliper where you'd expect salty, crappy water to linger and it obvious it's the light corrosion thats causing it to lift. I don't think the pistons are sliding back properly as the disks are becoming hot to touch (not boiling, just hot) when riding a few miles at 30-40mph without using the front brake much. So do I remove the knackered dust seals completely on those two pistons and try and get rid of the bike asap, or see if i can find the time to do the job properly and keep hold of the bike? I've only got two weeks of holiday left before going back to sea so if i take too long I'm never going to sell the bike this year... Link to comment Share on other sites More sharing options...
selexon Posted July 21, 2011 Report Share Posted July 21, 2011 If the inner seals are all looking good, take out the dust seals. no problem running without them as long as u tell the next guy to clean them every oil change. A lot of racers that use billet Brembo's take out the dust seals to help the pistons retract easier/quicker... Link to comment Share on other sites More sharing options...
lorenzo Posted July 21, 2011 Report Share Posted July 21, 2011 If you were realy keen you'd pop the pistons out, split the calipers, clean the corrosion off both the pistons and the inside of the bores (especially where the seals sit, it can get really grotty in there), then reassemble them, bleeding them up with fresh fluid. That'd be about an afternoons work and would give you as good a set of brakes as you'll get, however, if the brakes are working and not binding on, then I'd say that on a 15 year old bike (can't remember what vintage your zxr is, mid 90's?) it's par for the course. About 50% of bike I've bought have had snagging dust seals, it's not the end of the world. Get a mate to pull it up on the side stand so that the front wheel's in the air and then you can spin the front wheel a bit. If it's binding then it'll stop almost immediately, if it's just its natural rubbing then you should get at least 2 turn out of it with a good spin. Don't expect it to keep going round and round, it'll never happen unless you take the calipers off altoghether. Your discs being warm after a gentle run isn't really a very good indication at all: If you can touch them then they don't really count as being warm, seeing as they can get up to a few hundred degrees or something ludicrous. Link to comment Share on other sites More sharing options...
gurninman Posted July 21, 2011 Report Share Posted July 21, 2011 Every used bike I've ever bought has had buggered dust seals.First job when I buy is to remove the bastard things. I tend to give the brakes a good going over on a monthly basis, so make sure the pistons etc are in good nick and clean. Link to comment Share on other sites More sharing options...
EvilSpike Posted July 25, 2011 Author Report Share Posted July 25, 2011 If I split the callipers, do I have to replace the seal that goes between the two? Thing is is that I've got a copy of the service manual and I can't see that there is a seal or gasket to go there although I figure there ought to be... See page 2 of this for what I'm stupidly bleating on about I've got them off the bike and drained the system, but my LBS says to just drop them in and they will give them back sorted to pop on the bike without splitting the calipers. (and knowing Ritchie it'll probably be only for a tenner or something) but I'd rather learn to do it myself. Link to comment Share on other sites More sharing options...
EvilSpike Posted July 25, 2011 Author Report Share Posted July 25, 2011 And thanks for the advice and help Loz, Selexon, fatty and Gurninman. Appreciate it muchly. I fuck about with stupendously expensive bits of kit at work but am timid about doing my own stuff, god knows why... Link to comment Share on other sites More sharing options...
lorenzo Posted July 26, 2011 Report Share Posted July 26, 2011 If I split the callipers, do I have to replace the seal that goes between the two? Thing is is that I've got a copy of the service manual and I can't see that there is a seal or gasket to go there although I figure there ought to be... . There should be a small seal between the two, but if you're working in a half tidy workshop and not on your lawn etc then you should be Ok, it usually sticks to one half and doesn't go missing. The key thing is to get a good allen socket; they're going to be on tight as fook, you don't want to go rounding anything off. The other thing is that if you've already drained the sysytem then you might have caused yourself a problem in that you will have difficulty getting the pistons right out, unless you either know somebody with some special piston pliers thingymajigs. Link to comment Share on other sites More sharing options...
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