Join Date: Sep 2005
Location: Spennymoor, County Durham, UK
Rear brake pads too thick to fit?
Hi guys. I'm changing the rear brake pads on my '99 LT for the first time and got real BMW ones from the local dealer, who has my reg. number, chassis number, etc., so they should be right. The pads I am taking off are right at (and perhaps slightly beyond) the wear limit.
So, I've taken the calliper off the rear drive unit and taken out the old pads. The pistons are not right back in their cylinders, but are sticking out by 1.5mm at most. When I put the new pads in, there is no gap whatsoever between them, which is going to make getting them onto the brake disk somewhat of a problem. I don't have BMW's special tool for resetting the pistons, but even if I did, I'd only gain two or three mm and that still isn't going to accommodate a 7mm+ disk.
When I get my digital callipers on the pads and measure their combined thickness, then measure between the ends of the cylinders I only get a difference of 4.5mm and my disk is 7mm+ thick. At least one of the pistons is so loose that I am sure it is back as far as it can go and it still protrudes from the cylinder by at least 0.5mm.
Has anyone had this sort of problem before? Am I being dumb or is it possible that the pads I've been given are wrong? Can you get thin pads and thick ones (or am I being thick?)? Does anyone have any idea how much pad material there should be on the pads? They have the same part number stamped into them, but perhaps that is for the pad back plate only. My new pads have a part number printed on them, but the same number is worn off my old pads so I can't compare that.
Anyone got any ideas?
2004 BMW K1200LT Blue (Derek)
1999 BMW K1200LT Champagne (George, ret'd to the seaside)
1976 Honda CB400F Maroon (The Beauty)