250 Rear caliper piston boot

Discussion in 'Suspension, Brakes, Wheels & Tyres section' started by jack250, May 15, 2018.

  1. Alright chaps. Can this be replaced without removing the brake line and full piston? Cheers
  2. -Jamie-

    -Jamie- RSM Moderator

    Possibly but it will be a pain to get it to seat properly in the caliper I'd of thought, I done my spare calipers a while back and they were fiddly enough off the car
  3. Cheers Jamie. I've never removed brake lines before and bled the brakes so wanted to avoid if poss. When you say it was a pain to get it to seat properly, are you referring to the boot sitting properly on the piston before pressing back in? I was hoping to remove the caliper and apply the brakes gently so the piston came out and pull the new boot over... No that simple I take it?
  4. Yer it is, what you saying is correct, push piston out, lubricate whole piston with that castrol red grease that is brake fluid friendly, slide boot over inner edge of piston and tuck outer edge into caliper groove, then wind piston into caliper as boot slides easy along piston, when piston fully in the boot will slip into its own groove in piston, job done
    jack250 likes this.
  5. Spot on bobsan! Nice one mate
  6. Just to be clear... Does the piston have to be fully out to do this? Also, when you say inner edge, are you talking about the end of the piston that is inserted to the caliper first? Then as you push the piston back in, the boot slides over the piston and into correct position?
  7. Yes youve got it, and piston out completly, give good clean and lubricate, pour out the horrble fluid that remains in caliper, then streach boot over what is effectivly the worng end of piston that has internal thread (not the end that meets the brake pad) and offer the piston up to the thread, seat the outer edge of boot into its correct groove just inside caliper, now can start to wind the lubricated piston into caliper without tearing the boot which dosent rotate with piston as it slides toward its own groove at Other end piston. At end of everything the boot outer edge should be in caliper groove and inner edge in piston groove
    jack250 likes this.
  8. That’s made it very clear. Nice one. Will the brakes need bleeding after and topped up with fluid?
  9. Sure will, and all time you're faffing with boot seal fluid will slowly be filling up the empty caliper , if got brake hose clam you can pinch the short section of hose that links swinging arm and chassis, save tossing away the good fluid that fills the caliper, another little trick is streach cling film over the reservoir and screw the cap back on.
    jack250 likes this.
  10. Yep I know the section you mean. I'll get what I need for the job and give it a go. Will report back once complete. Thanks again for the advise mate.
  11. While caliper is off should realy lube the slider shafts as well with correct grease, that and getting the piston proper clean the seal replaced and boot correctly placed could be looking at 10 years trouble free brake issues
    jack250 likes this.
  12. Yeah I’m going to do the works whilst it’s all off. I won’t be able to clamp the line as they’re braided so might give the cling film trick a shot.
    It’s the first time I’ve done this so going to take my time. Always avoided doing brake fluid so I think the time has finally come
  13. Good for you, this is quite fiddly jod, if using cling film fill reservoir to top get much air out to create best vacuum effect
  14. You sure the rears are braded ? Not everyone fits them just the fronts, good luck
  15. Yeah pretty sure they are. The hose is mega stiff and the section that you were on about clamping is mega stiff also where as standard this bit is soft I think.

    I have a plan, going to use the cling film method but I've ordered some rubber hose to fit over the end of the brake line. I'm going to push the caliper out using the braking force then un-do the brake line, put the rubber hose over the bolt and clamp this hose. Should work? How much fluid roughly will be lost? I'm going to do a thread on the fix once I've sorted it also
  16. If taking the brake pipe off caliper can just pop the bleed valve dust cover over end to stop fluid leak. Also be mindful when undoing the union that dont twist the pipe itself
    jack250 likes this.
  17. Boxed this off yesterday. Cheers for the advise @bobsan itbwas a big help!

    Stripped the fronts too to clean them up and the pad guides were absolutely covered in rock hard brake dust and shit so cleaned them with sandpaper and re greased everything. All works great now
  18. Just one thing bothering me. I bled the brakes at least 6-8 times doing the two man method. Around 200mltrs came out but I’ve not had to refill the reservoir? Is this an issue?

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