C900 front calliper clonk

OK I have the classic clonk on my front callipers when I stop and reverse up and stop again. I know it's a "feature" of the C900 but it's getting worse.

What exactly is worn, and is it worth spending well over =A3100 to get it fixed. My specialists did the brakes for me recently as part of the MOT work, and the clonk was gone, but 3 months later it's gradually returned and is worse than ever.

Al

Reply to
Al
Loading thread data ...

The clonk is the pads shifting inside the caliper body. It is not a functional or safety problem. It is not worth worrying about. Next set of pads you get will probably have less slop in that dimension. If it really bothers you, you could fabricate some shims that you could fit over the ends of the pad carriers.

Reply to
Fred W

That's ok, it brings good luck.

The caliper is a sliding yoke design. The clunk is the outer bit (the yoke) pivoting and coming to rest.

£100 won't fix it, and it isn't worth fixing anyway.

There really is no fix. You can build up the yoke with a welder, and grind back to get a tight fit. But the clunk will be back within a couple of thousand miles.

Learn to love it.

Reply to
Grunff

add a fix to your list ... a piece of copper bend correctly and fitted between caliper and yoke. It does for a random narrowing of the gap and somewhat reduced the noise. Once the OP knows what it is he will not worry that much about it :-)

Charles

Reply to
Charles C.

If you take off one of the front wheels and look at the caliper, you'll see that there is a u-clamp holding a strangely-shaped spring against the backing plate of each of the brake pads and there is also a wire 'butterfly' spring as well. I've got a pic at this URL:

formatting link
which, if you look past all the cobwebs (!), shows the u-clamp, and the main spring. The 'butterfly' spring isn't really clear but it's there too.

Those components are designed to prevent or at least reduce that 'clonk' that you get. The kits to replace those components are low in price from places like Parts for Saabs, etc. and it's a very cheap way to help overcome the clonking. I've heard those parts called 'anti-rattle' components as well.

I've been told, but have not really proven, that if you replace the brake pads with new ones the clonking isn't as bad, but that's probably more related to overall wear of the brake caliper components and how well lubricated the sliding yoke of the caliper is.

Regards,

Craig.

Reply to
Craig's Saab C900 Site

The special Gleitmo grease that's recommended for use with the brake calipers on C900's is probably meant to prevent much of the clonking - but I have never found it for sale here in Australia. If there is meant to be a special grease just for use on sliding yokes, I'd be interested to know what brand(s) are available here and what the products themselves are called.

Craig.

Reply to
Craig's Saab C900 Site

Thanks for the re-assurance guys. I'm going to do my brake pads in June/July anyway as they wear out real fast. The front handbrake mech means they're real thin to start with unfortunately.

Cheers

Al

Reply to
Al

formatting link

The spring you ought to refer to ... is what in your photo is on the extreme right of the caliper and is shaped like a U. That fits (if I remember correctly) between yoke and caliper and stops the lateral movement. The clonk is mainly produced by vertical movement and the only correct way of reducing it is to rebuilt the missing metal.

I've heard those parts called 'anti-rattle' components as

A bit of both ... new pads might help, fitting new pads means lubricating everything etc.

Reply to
Charles C.

Not only the 900, my 96 has it too. Not much to worry about.

Reply to
MH

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.