Brake Pistons - To Grease or Not to Grease

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Brake Pistons - To Grease or Not to Grease

I'm currently rebuilding the brake calipers on my ZXR400-L4 after a complete strip and clean.  Having read the many and various posts on the subject from the helpful VD spannermen I think I've avoided the usual pitfalls.  One question remains - I'm going to need some lubrication on the pistons to get them back in the calipers past the seals.  Some people have suggested red rubber grease but I'm a little worried about contaminating the brake fluid and I am tending towards going for using fresh brake fluid as a lubricant only.  Am I going to manage to get the pistons in with this alone, and if not, and I do use red rubber grease, is the possible contamination of the brake fluid an issue with this substance or not?

Use brake fluid, it's fine as your lubricant and does the job, clean them off when they're all assembled then use your rubber grease as protection on the exposed bits.

Cheers Bez, that makes sense.  Will do.

Unless you're using the bike all year round, rubber grease isn't necessary. If you ARE, then it does help - my brake rebuilds have gone from every 3 months in winter to less than once per year

No, the ZXR isn't that keen on salt so I put it away for the winter.  It has never been used in winter and rarely in the rain yet there was a small amount of minor corrosion on the exposed parts of the pistons.  Nothing that's going to cause a problem when reassembled as it has cleaned off and those parts will be clear of the seals anyway.  For what it is going to cost to put the grease on I think I'll do a belt and braces job just to be sure.  I'm not dead keen on doing this job again any time soon if I can avoid it.  The bloke down the local bike spares shop has the little sachets of grease so it's no hardship getting hold of the stuff. I wish I'd known about this stuff years ago when I used a cheap bike for work.  The mess those calipers got into.....

Good call on the small sachets - much better for a home mechanic as you don't get thru' much so if you're using a big tub of it then it slowly gets contaminated over time...

Except that having told me he could get the sachets when I called in to get them I was told they can't get them!  Why do these people mess you around?  I could have bought red teflon grease, which seems to be the same thing under a different name, in a tube but at £8 with the amount of use I'd be giving it I reckoned it was more than I needed.  Ordered a 50mg tub off ebay which was only £4.99 with the postage and will last me a lifetime.I'll scoop what I need each time out with a clean knife to avoid contaminating the rest of the tub.  Should last me at least 50 years I reckon.

Teflon grease might not be the same at all - the "red rubber grease" should be Silicone Rubber, not teflon. Having said that PTFE's pretty inert stuff so it might be OK if it's definitely recommended for brakes...

Yes, that's what I was worried about too.  There was nothing on the tube to indicate it was for brakes.  The only thing about it the same was that it was red.  The person in the shop seemed a bit shirty about it when I pointed out it wasn't actually called 'red rubber grease' - I got the usual 'it's the same stuff' line which I'm afraid always makes me suspicious that I'm about to be fobbed off with some crap in the hope that I don't know what I'm doing.  So I left it.  When I Googled about a bit at home on 'red teflon gease' it does bring up some results suggesting it's for brake caliper work.  I dunno, I thought it was safer to leave it and get the stuff I knew was right. Anyone on here have any idea whether red teflon grease is as good as?  This is the stuff http://cgi.ebay.co.uk/Brake-Caliper-Teflon-Grease-Red-Rubber-Assembly-Grease_W0QQitemZ400063500644QQcmdZViewItem?rvr_id=187077891926&rvr_id=187077891926&cguid=8fae4b2112c0a0a9f4d56b35fde52d4a  Doesn't say anything on the tube about brakes.  To be honest it just looks to me like grease with Teflon added to reduce friction.  I have a suspicion that this will bugger seals up s good as copper slip.

Castrol red rubber grease can be used to lubricate brake pistons and seals when assembling. It is vegetable based and does not react with or harm rubber seals or brake fluid.

http://www.redrubbergrease.com/tips-how-to-brake-caliper-failure-repair-...

Silicone grease is ok too - keeps the water out.

Why lubricate brake pistons with brake fluid which as we all know absorbs water?

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