Digsy Posted September 18, 2004 Share Posted September 18, 2004 I started refurbishing my spare set of J-spec brake calipers today and have hit a bit of a snag. Does anyone know if you can get the pistons out of the caliper using normal workshop tools? The service manual I have says you need to plumb compressed air into the brake line union and literally blow them out. Cheers. Link to comment Share on other sites More sharing options...
Digsy Posted September 18, 2004 Author Share Posted September 18, 2004 Ok, update: You can get at the back of one of the pistons through the banjo bolt hole and apply pressure directly using a drift to press the piston out. You cannot get at the other one, but you can make a judgement about the state of the piston / bore by the condition of the one you can take out. A bit of a leap of faith, but the best you can do without the "proper" tools. The rear you can do in the same way, but there is only the one piston to take out so you can do a complete dissassembly. Link to comment Share on other sites More sharing options...
Gordon F Posted September 18, 2004 Share Posted September 18, 2004 Compressed air is the most popular way of removing them. It's good to cut some wood to fit inside the caliper to stop the pistons when they come out. Also, keep your fingers out of the way There are also piston pliers, which are basically a large pair of long nosed pliers with the serrations on the outside, so you can grip the inside of the piston and pull it out. I have some somewhere if you get stuck. Link to comment Share on other sites More sharing options...
Chris Wilson Posted September 18, 2004 Share Posted September 18, 2004 Demon Teeks sell caliper piston tools. Ali circles with a split in the OD connected to handles. Hard to describe, but in their catalogue. You can get enough pressure from a foot pump, depressed by hand, unless the caliper is well buggered, should you want to use air, but don't have access to a compressor. Rather than a drift a long, correctly threaded bolt, down the pipe nion hole, will often push them out without the impact of a drift. Heating the caliper body with a blowlamp, then freeze spraying the inside of the piston with a plumbers pipe freezing aerosol will help recalcitrant ones. Link to comment Share on other sites More sharing options...
Digsy Posted September 18, 2004 Author Share Posted September 18, 2004 Cheers, guys Gordon: I wouldn't say no to borrowing that caliper tool, if you can dig it out. Would be good to do a proper job now that I've got this far. Link to comment Share on other sites More sharing options...
Scarface GTti Posted September 19, 2004 Share Posted September 19, 2004 I normally use compressed air to blow pistons out but i have been known to use a grease gun. To clean the pistons, stick them in a lathe and the best stuff to use is Micromesh. So long as the pistons aren`t corroded they`ll come up like brand new this way. Minimal effort as well. Link to comment Share on other sites More sharing options...
Digsy Posted September 19, 2004 Author Share Posted September 19, 2004 Originally posted by Scarface GTti I normally use compressed air to blow pistons out but i have been known to use a grease gun. To clean the pistons, stick them in a lathe and the best stuff to use is Micromesh. So long as the pistons aren`t corroded they`ll come up like brand new this way. Minimal effort as well. Whats Mircomesh? is it some kind of proprietary name for an abrasive like Scotchbrite? Link to comment Share on other sites More sharing options...
Chris Wilson Posted September 19, 2004 Share Posted September 19, 2004 Very similar to Scotchbrite pads, yes. Link to comment Share on other sites More sharing options...
dangerous brain Posted September 19, 2004 Share Posted September 19, 2004 Micromesh also make fine abrasive papers, Well I say papers its actually a woven material on a roll. I know that they go all the way up to 12000 grit because I have some 12000 grit. Link to comment Share on other sites More sharing options...
Terminator Posted September 19, 2004 Share Posted September 19, 2004 Originally posted by dangerous brain Micromesh also make fine abrasive papers, Well I say papers its actually a woven material on a roll. I know that they go all the way up to 12000 grit because I have some 12000 grit. Can you PM details of supplier. Link to comment Share on other sites More sharing options...
Scarface GTti Posted September 19, 2004 Share Posted September 19, 2004 Yes, it`s sandpaper but so fine it feels like cloth. Excellent for polishing items but very expensive. Link to comment Share on other sites More sharing options...
dangerous brain Posted September 19, 2004 Share Posted September 19, 2004 Originally posted by Terminator Can you PM details of supplier. Erm the RAF bought mine lol where they got it from I really don't know. We used it for polishing compressor blades on gas turbines and the special plastic polishing kit that they do for blending out scratches on canopies. Could try google-ing it and find it like that. It is apparently exceedingly expensive though:music: Link to comment Share on other sites More sharing options...
Scarface GTti Posted September 19, 2004 Share Posted September 19, 2004 Mine is "borrowed" from work also. It`s hard to get hold off even from there as it is so expensive. Link to comment Share on other sites More sharing options...
Digsy Posted September 19, 2004 Author Share Posted September 19, 2004 So what grit paper would you say it's roughly equivalent to? There is a car body refinishers' supplier in Norwich that I can go to for this kind of stuff. Link to comment Share on other sites More sharing options...
dangerous brain Posted September 19, 2004 Share Posted September 19, 2004 Originally posted by Darren Blake So what grit paper would you say it's roughly equivalent to? There is a car body refinishers' supplier in Norwich that I can go to for this kind of stuff. Its equivalent to 12,000 grit If you want some 800 which should be good enough for what you need PM me your address and I will post you some. Link to comment Share on other sites More sharing options...
Digsy Posted September 19, 2004 Author Share Posted September 19, 2004 I have some 1500 grit paper in the garage, so I'll probably use that with some lubricant (no giggling at the back please). Cheers for the offer though Link to comment Share on other sites More sharing options...
dangerous brain Posted September 19, 2004 Share Posted September 19, 2004 OK no worries mate I have some 1200 as well. The good thing about micromesh is that it doesn't rip like emery papers do and is washable so can be re-used almost indefinitely so it makes its initial expense back over time. Link to comment Share on other sites More sharing options...
Digsy Posted September 23, 2004 Author Share Posted September 23, 2004 I was making a list of parts that I need to buy last night using my EPC, but the diagrams leave a bit to be desired. Has anyone bought the piston seal kit for the J-spec brakes? Can anyone tell me whether it includes the small rubber bushes that go around the tips of the troublesome sliding pins? Link to comment Share on other sites More sharing options...
Justin Posted September 24, 2004 Share Posted September 24, 2004 I had the smae problem with the second piston. I used my halfords (cigarette lighter electric type pump) with one of its adapters to pump air into the chamber. You need to hold the adapter in tight to stop air getting out. The piston came out at speed and nearly snapped my fingers off but it worked a treat. Link to comment Share on other sites More sharing options...
Chris Wilson Posted September 24, 2004 Share Posted September 24, 2004 I now keep remanufactured (in germany) front and rear calipers on the shelf. the UK remade ones don't appear to have the correct piston sizes, probably off a Lexus, although the mountings are the same. It's hardly worth the hassle of rebuilding when you buy ones that are totally indistinguishable from new for little money. If you strip them and find the bores are corroded or marked, you are stuffed! they usually are! Link to comment Share on other sites More sharing options...
Digsy Posted September 25, 2004 Author Share Posted September 25, 2004 The fronts are fine (the housing is aluminium, so they aren't corroded. No marking either. The rears, which look like a cast iron parent bore, are dull, but not corroded or marked as far as I can see. I'll give it a go. About time I did some proper "Fred Dibnah" style engineering, really! Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now