|23/07/2003 16:52:05||Patrick||I've recently stripped down my front brakes of my 96 (1973) - changed pistons, seals, pads, discs and I now seem to have problems with the pads continually binding onto the discs. On jacking up the wheels both can be rotated by hand, with a small amount of rubbing heard from pads on discs. However, on the road the drag on the discs makes the entire brake assembly/wheel extremely hot. The pistons seem to move freely in the cylinders (when retracted by hand) and the pads easily fit in position in the calliper's. I can only assume that the pistons are not coming off sufficiently when I take my foot off the brake. Can anybody suggest where the problem lies? Thanks for your help. Patrick|
|23/07/2003 20:19:42||jake||hi patrick it could be the flexy pipes are collapsing inside and not letting the fluid return to the master cyl it happend to me and two new pipes were just the job all the best jake|
|24/07/2003 00:06:23||Alistair||That does sound the most likely cause if you have new pistons.|
|24/07/2003 13:27:56||steve h||How long have you run the new pads in for? I normally find it takes up to 100m of motoring before the noise, heat and (last time I did it) smoke stops. Unfortunately the last time I repalced pads was just before a family holiday so I didnt have time to run them in on short journeys round town first. All is fine now though. Dont worry, be happy. Even with new pistons and seals, although it shouldnt happen, Im sure mine still did this a bit when I replaced the whole lot.
Whose pistons did you use? My replacement ones have now pealed all their chrome and are very corroded. If your old ones are original, clean them and keep them (or sell them to me).
|24/07/2003 15:22:02||Senor Burt||Flexi pipes almost certainly as Jake says. This has happened to my 96. It is a fairly common thang.|
|25/07/2003 06:25:52||Tom||I've got this problem in my 99. You might have just saved me a few quid as I was all set to get the calipers rebuilt.|
|25/07/2003 12:16:32||simon||Dear Patrick,
As jake say's flexi's. I always change all of these when aquiring a 'new' car and replace them every 4-5 years thereafter as part of the brake system service. Buy overbraided hoses if possible :-)
|03/08/2003 21:04:44||Tom||I've just had all four flexi hoses replaced on my (1973) 99 and the problem was just as described. The old hoses had collapsed inside so badly that you could not blow through them at all. The car is now twice as fast and uses half as much fuel! :o)|
|04/08/2003 14:39:31||steve h||you lot are all so sure its flexis. Why didn't this happen before Patrick changed did the work? Why only now? Patrick, what did you do?|
|04/08/2003 19:17:11||ian||Assuming that the brakes have been thoroughly bled and that the lip of the outer seal hasn't got tucked in against the piston and that all the rubbing surfaces on the calipers have been eased and copper greased there's not much else to go wrong other than the flexis unless the pistons are wrongly dimensioned.
Patrick, are both wheels binding?
Steve H, who manufactured your dodgy pistons? It might be an idea if we all avoided them. Has anybody used stainless steel pistons?
|05/08/2003 13:56:08||steve h||Dont know as it was a long time ago. They came from highgates though. Stainless pistons would be great if anyone has a source.|
|06/08/2003 12:52:09||Richard||S/steel pistons are availible fron the saab klubben sweden.|
|07/08/2003 09:03:44||Patrick||Guys, I really appreciate your swift responses and apologies for not getting back to you sooner. With regards to the flexi hoses, and taking your advise I've changed just one side (near side) as a tea taster - however the problem still persists. The hose I removed did not appear to have any obstruction on blowing/sucking into the pipe! Coming to work today, the discs (on both sides) are so hot you can't leave your finger on them for more than a split second - even the wheel rims are hot! I feel that if I continue to run it as is, I will suffer from warped discs.
The pistons and seals (Lockheed) were from Highgate, however off hand I'm not sure of the pistons manufacturer - they are certainly the same dimensionally as the old corroded ones I removed. However I do feel Steve H has a point, why did this not happen prior to me starting the work? The reason I started the work in the first place was due to an MOT failure for off side disc binding - because the disc was warped. I've come to a dead end as where to go from here, only the master cylinder remains for me to strip down and maybe change the seals? I'd appreciate further suggestions.
|12/08/2003 13:48:56||steve h||If they are so cool you can actually touch them youre fine. Give it another 100 miles and all will be forgotten. As for warping the disks, im sure ive read a commentry of a rally where you could tell a 96 was coming by the orange glow of its brake disks. And as i said above, when I changed pads the other week and set of down the motorway, I smoked mine twice on the M40 but by the time I got to Hereford, all was fine.
And if it does go away, please let us know.
|12/08/2003 15:53:17||Senor Burt||If your discs are really hot, you would burn your finger badly the moment you touched them.
Change the other flexi hose anyway, so you know they are not causing a problem.
|12/08/2003 17:30:32||ian||Is excessive heat likely to bug*** the piston seals?|
|12/08/2003 18:56:46||Alistair||Just a thought here. Are the caliper pivots sticking at all? Does anyone know if this would prevent the pads from disengaging properly & hence the heat? What is weird is that you can turn the wheels OK by hand, there's obviously not much resistance. Getting a bit obscure here I know, but are your wheel bearings OK?|
|14/08/2003 13:46:49||Patrick||These discs are hot, damn hot and on a mile run down a relatively straight road I can assure you they are too hot to touch!
Now changed both flexi hoses and just recently stripped down and cleaned master cylinder. Could not remove second piston as I presume you need a special tool to extract it, however I retracted it with a screw driver and the thing seemed to pop back up with sufficient force. Unfortunately I didn't change any seals as couldn't get hold of any in time (the old ones seem in reasonable shape). As for the callipers sticking, I've greased the pivot pin and the sprung retainer at the top, however on one side the spring has rusted solid hence if anything, the pivot action is a bit sloppy.
Wheel bearings - I haven't looked at, but there does not seem to be excessive play when feeling for horizontal/vertical movement.