Clank

Gunner · #1 (**permalink**) 11-06-2009, 04:25 PM

I'm getting a pronounced "clank" when I go over speed bumps etc. I'd swear it's coming from the front, sounds like right front. I went over the whole front end and there are no loose bolts and no fitting that looks (at least superficially) like there's any excessive play. No signs of interference or inappropriate wear marks.

The guy who did the brake inspection said he thought the rear coilovers felt a little loose - I haven't thought so. I have the rears off now and a quick look shows no loose parts or worn fittings.

Could it be the front pads in these monstrous Sierras? They float loose in the caliper and are held by a single top pin; I could see a bump making them bang around against the caliper or rotor. That would explain why I only hear it sometimes - the times I have my foot off the brake. (Have not had the chance to test that idea.) I can't think of a way to clamp the pads down to see if that makes the clank go away - I'll live with it as long as I know what it is, but everything I can think of for testing interferes with proper brake operation, bad bad idea...

patrickt · #2 (**permalink**) 11-06-2009, 04:42 PM

Quote:

Originally Posted by Gunner

Could it be the front pads in these monstrous Sierras? They float loose in the caliper and are held by a single top pin; I could see a bump making them bang around against the caliper or rotor.

I would say "No." At the most they might squeal, or rattle all the time. I think it's something else.

EDIT -- You could test it out by going over the speed bump at the same speed, one time while "riding the brakes" the second time while not.

Sharroll Celby · #3 (**permalink**) 11-06-2009, 04:59 PM

Check the car front AND rear; it MAY be coming from the back.

Also, if you stand next to the car and bounce it up and down while pushing on any of the fenders, do you still hear the noise?

Gunner · #4 (**permalink**) 11-06-2009, 05:03 PM

Ack on the bumping-while-braking. I'll try that next time I'm out.

The fronts do clack and rattle a little if they haven't been applied for a while.

I've shaken the car pretty good (like shaking an anvil, if ya ast me) and don't hear anything. Ditto on shaking the wheels while up.

It's just a pronounced metal-on-metal clank, heard most when going over low-speed bumps. I think that if it was a worn fitting, shot rubber bushing, etc. I would be able to see some evidence of it. Strange.

patrickt · #5 (**permalink**) 11-06-2009, 05:13 PM

You can also jack the front up by putting your jack right behind the front wheel on the frame and while you're jacking it up listen for an unnatural sound as you're going up. Then let it drop down quickly (obviously you don't remove the wheel) and listen for a noise. Repeat on the other side, then do the same for the rear.

Gunner · #6 (**permalink**) 11-06-2009, 05:16 PM

Ah, good trick. I'll try that as soon as I get it back on the rears.

Blas · #7 (**permalink**) 11-06-2009, 05:29 PM

Check the caliper mounting brackets and the sway bars...

Gunner · #8 (**permalink**) 11-06-2009, 05:39 PM

Check and check. The car passed a thorough brake inspection just last week, as well, and the mechanic was both good enough and interested enough to tell me a number of points about the underside that indicated he was looking at everything. So he didn't see anything out of the ordinary, either... arrgh.

patrickt · #9 (**permalink**) 11-06-2009, 05:48 PM

And when you go over that speed bump, kill your engine so you're coasting over it -- it will be easier to identify the general location of the sound. While it's probably suspension related, don't completely discount the possibility of it being something else, like primaries/side pipes, loose fan assembly, the prop that holds your hood up, etc.