Saturday, November 18, 2006 - 08:04 pm, by: Juan Landauro(Enigma)
When I took the brake pads from the front calliper I noted that the mark left by the calliper piston on the pad shim was 2/3 of a circle and the other 1/3 of the circle just fades away. It appears that the piston pressure when the brake pedal is depressed doesn’t catch the whole of the brake shim, perhaps because the brake pad or the calliper assembly are not parallel anymore. What could cause this behaviour? What should I do in order to put it right? Shouldn’t I bother about it?
Monday, November 20, 2006 - 07:45 pm, by: Juan Landauro(Enigma)
Hi Mark:
I am a bit confused I though the piston push the internal brake shoes and the floating system calliper react by pulling in the outside brake pad by operating the sliding pins.
Monday, November 20, 2006 - 08:51 pm, by: Mark Paddick(Sparks)
That's right, and when the slides or pistons get worn the slide is no longer square to the disc and this results in uneven pressures on the pads and hence the shims have uneven wear marks on them.
Without a doubt, sliding calipers are THE worst feature of the Soarer. Such a nice well-designed car with cheap-arsed brakes. Great when new but as any old Valiant owner will tell you they are the absolute pits when older.
Monday, December 11, 2006 - 12:32 pm, by: Mark Paddick(Sparks)
Yes, with callipers using sliding pins like these. Also actual flex of the caliper housing and distortion of the piston/bore but that only happens with very large brake applications and should not be happening on the street even with 15yo totally stuffed calipers, serious Race cars only and I do mean serious. Formula one cars have this problem especially as the pads wear and pistons have lnger travel. It is possible that badly built or designed calipers could do it badly but not out of Japan and not in the last 30 years or so with metallurgy that was available then and has only improved since. The Japs are up there with if not THE best in that field. The 4 pot design of Supra and Celsior later calipers gets away from pin flex and wear and clearance problems completely. I cannot believe they used the sliding design on a prestige car like a Soarer when 4 pot technology costs not that much more in the factory and they used it elsewhere. It's one of the anomalies in design of an otherwise excellent car. There are a few. Nothings' perfect in all respects. And easily fixed.
I don't compare 40 series Soarers to Valiants except in looks They got 4 spot brakes and bloody good ones, but look like an AP5 on steroids. Matters not at all after you drive one; it looks great no matter what!