Nilfisken Posted May 21, 2012 Share Posted May 21, 2012 Hi,just started a rebuild of a pair of used calipers acquired via eBay. Today I removed the pistons with some compressed air and they all got out fairly easy. The brake fluid looked pretty sad but the bores appear to be in good condition. The pistons had only minimal corrosion on the part that is in contact with the piston bore but will be replaced anyway. I'm planning to polish up the bore with some emery cloth, repaint the calipers with Eastwood Brake Gray and then install a set of stainless pistons and a new set of seals and dust caps. What is the best way to ensure the interior of the calipers is clean, would it be sufficient to blast them out with compressed air? It is not to tricky to get sludges out of the piston bores itself but since I don't plan to separate the caliper halves I need to find a good way of cleaning the channels inside. Pictures will follow as the rebuild goes along. Any hints and suggestion very welcome!Cheers,Oskar Link to comment Share on other sites More sharing options...
Gene Thomas Posted May 21, 2012 Share Posted May 21, 2012 Im struggling to remove the pistons on mine. I don't have the luxury of compressed air. Any ideas? Link to comment Share on other sites More sharing options...
uksnatcher Posted May 21, 2012 Share Posted May 21, 2012 I would use wet and dry rather than emery tape, emery tape a bit harsh in the cylinder walls. And dont be afraid of splitting the calipers, there is an 'o'ring in the middle that you should really replace on a caliper refurb anyway mate.If you dont have compressed air Gene, use a grease gun on the bleed nipple and block the brake pipe inlet hole with a bolt, loosen the nipple and a few good pumps of grease will pop the cylinders out, use a j clamp on the first one that moves forcing the other one to move then use pipe grips/vise grips to work them out, you will need to split the calipers too to get out all the grease but the 'o' ring will need replacing probably too. Link to comment Share on other sites More sharing options...
thescrapman Posted May 21, 2012 Share Posted May 21, 2012 GeneYou could connect the caliper directly to the master cyl using one of the flexipipes and then try pumping the pistons out with the brake pedal.CheersColin Link to comment Share on other sites More sharing options...
Gene Thomas Posted May 21, 2012 Share Posted May 21, 2012 Thanks Colin. Your tip worked like a charm! Link to comment Share on other sites More sharing options...
Nilfisken Posted May 21, 2012 Author Share Posted May 21, 2012 I had really hoped to avoid splitting the calipers, I thought the bolts holding the two sides together were rather special and not reusable and I cant find a source for either the bolts or new inner seals. Also all manuals I have access too specifically point out NOT to split them. I have just finished wire brushing the calipers (mostly removing brake dust actually, no old paint and only a few rust specks) and apart from a bit of crud at the very bottom of the calipers the bores look to be in very good shape.Any more opinions on splitting or not? If so, were do I get the new hardware to get them back properly?Cheers! Link to comment Share on other sites More sharing options...
timraven Posted May 21, 2012 Share Posted May 21, 2012 When I rebuilt mine I didn't split them, just used compressed air, and bled them through on the car (obviously) have been fine for the past year, around 10000 miles... Link to comment Share on other sites More sharing options...
Clive Posted May 22, 2012 Share Posted May 22, 2012 I bought a kit to space my callipers from Canleys. It came with new (longer) bolts and seals, so the bolts/seals are available. Not sure what spec the bolts were, but I didn't notice anything about them, so I suspect they are just high tensile?Canleys should have the stuff you need, and no doubt many other place too. However, I have overhauled several sets of callipers in my time, and the spacing episode was the first time I had split them.I have found compressed air only works if the pistons can move OK anyway, connecting to a master cylinder is rather more effective. Link to comment Share on other sites More sharing options...
Nilfisken Posted May 22, 2012 Author Share Posted May 22, 2012 Just ordered the seals, bolts are not available but seals cost a pound each and has the part number cs1.Cheers! Link to comment Share on other sites More sharing options...
Nilfisken Posted May 24, 2012 Author Share Posted May 24, 2012 OK, calipers are now split, bolts looked in perfect shape so should be reused. Have anyone here tried to use a drill driven honing tool to clean up the bore in the calipers? Example of toll I'm referring to: http://www.ebay.co.uk/itm/Draper-Brake-Cylinder-Hone-Small-Bore-Honing-25mm-57mm-56244-/140758623342?pt=UK_Hand_Tools_Equipment&hash=item20c5de246e#ht_500wt_1180 Link to comment Share on other sites More sharing options...
Nilfisken Posted May 24, 2012 Author Share Posted May 24, 2012 After a bit of reading I think honing might be unnecessary since the sealing surface is the piston itself meaning the bore surface should not be the critical point. I probably just use some very fine sandpaper instead to remove some light corrosion and make sure to get the groove where the seal goes extra clean to ensure a good tight seal against the pistons. Link to comment Share on other sites More sharing options...
junkuser Posted May 24, 2012 Share Posted May 24, 2012 It is really only the groove for the seal that it critical.This must be thoroughly cleaned.Shaping bits of metal to scrape into the square corners of the bottom of the groove I found effective. Link to comment Share on other sites More sharing options...
Nilfisken Posted May 25, 2012 Author Share Posted May 25, 2012 I'm thinking about using a small rotating brush on a dremel, worried scraping might damage anything? Link to comment Share on other sites More sharing options...
junkuser Posted May 25, 2012 Share Posted May 25, 2012 Doubt that the brush on Dremel will clean out the sort of gunk that was in mine.Mild steel unlikely to damage the cast iron of the caliper but you could use brass if worried.Just see how you go. Link to comment Share on other sites More sharing options...
Nilfisken Posted May 25, 2012 Author Share Posted May 25, 2012 I wil report back with pictures :) Link to comment Share on other sites More sharing options...
markcro Posted May 25, 2012 Share Posted May 25, 2012 5848 wrote:Im struggling to remove the pistons on mine. I don't have the luxury of compressed air. Any ideas?I rebuilt mine last month. To get the pistons out of mine I firstly extended the pistons out as far as possible while on the car by pressing the brake pedal. I then removed the caliper from it's bracket and wrapped it in cloth and pressed the brake pedal again which will cause one piston to pop out (as well as a lot of fluid!).I then disconnected the brake lines and put the caliper in a vise. With the piston to be removed facing the ground, I used a large flat head screw driver and a mallet to rap around the lip in the piston until it came out. Link to comment Share on other sites More sharing options...
Nilfisken Posted May 26, 2012 Author Share Posted May 26, 2012 Some pictures of the progress :)Calipers split, came apart easy and the bolts looked good.Messy bores filled with dirty brake-fluid. Pistons came out using compressed air and a bit of hammer and chisel.Calipers masked after having been cleaned out using a rotating brush from brass wire on a Dremel. Some pitting in the bores but in general fairly good condition and the groove for the seal cleaned up very well. The internal channels were cleaned using the type of pipe cleaners that are used for tobacco pipes and a lot of brake-fluid followed by even more compressed air.Time to paint! Prior to painting and masking the caliper halves were all cleaned up using liberal amount of brake cleaner followed by a blast of compressed airLast look of the original cast iron...Now covered in Eastwood Brake Gray, were easy to apply and hopefully good lasting quality!All left now is to install the new seals and pistons, unfortunately I was asleep this morning when the delivery of brake grease arrived asking for a signature and now I wont be able to get my hand on it before Monday :( Link to comment Share on other sites More sharing options...
Nilfisken Posted May 26, 2012 Author Share Posted May 26, 2012 Found some Lookhead Rubber Grease in my landlords garage so now it's all finished except torquing up the caliper bolts.Piston greased up and ready to go into the borePushed in a bit by handAnd then with some wood to even out the pressureFinished! Except the final torque of the bolts holding it all together. Link to comment Share on other sites More sharing options...
.thumb.jpeg.b15b81ef10abeea1c3039ae03c4a9f3a.jpeg)
Recommended Posts
Archived
This topic is now archived and is closed to further replies.