: Mysterious clunk



HUF
06-10-11, 04:39 PM
When I pass at low speed by a building or even curb I can clearly hear clunks in rapid succession definitely correlated with rotation of wheels. I cannot determine whether it is front wheel (wheels) or rear ones. If apply brakes slightly clunk goes away.

I assume it is on the passenger side, but who knows... Unfortunately, I rarely have passengers to ask them to pull down the window and identify the location of the clunk or clunks.

Today I jacked up the front right wheel and checked it for play. There was no play in 9 - 3 direction and less than 1/8" when I grabbed the wheel at 6-12 position. I also checked the lower ball stud and it was fine (the grease fitting was even with the surface of the stud).

I checked the caliper and it was not loose. The only thing I did not like was the outer pad - I could easily move it some 1/16" in vertical or horizontal directions. I do not think there were ever any antirattle shims installed. I can assume that loose pads can rattle if you hit a pothole, but I cannot see how it can make that annoying clunk-clunk-clunk noise on smooth pavement.

As far as I noticed the clunk is more pronounced when front wheels are not straight (on curves).

I have also jacked up the rear passenger wheel. It only had some 1/16" axial play - I could pull it out and push it in some 1/16" and it would clunk. Is it normal play? There was no play in vertical or horizontal directions whatsoever.

I am at a loss. The noise is very annoying.

Sorry for a long post. Any thoughts, gents?

jayoldschool
06-10-11, 08:42 PM
The clunk is likely the pad moving around in the caliper body. You can alleviate this by swedging the pad mounts properly. Have a look at the edge of the pad. See the little tabs that "lock" the pad to the caliper? Bend those so the pad can't slide around. Makes a big difference.

HUF
06-10-11, 08:48 PM
The clunk is likely the pad moving around in the caliper body. You can alleviate this by swedging the pad mounts properly. Have a look at the edge of the pad. See the little tabs that "lock" the pad to the caliper? Bend those so the pad can't slide around. Makes a big difference.
Thanks, Jay. I was wondering why would they make the pads so loose. Or they were supposed to be used with shims...
Anyway, that would explain a clunk when I hit a pothole. Still cannot understand where the over rotation-related clunk is coming from...
Could a failing differential make such a noise? Is that play in the rear wheel I have described normal?

durrk johnson
06-10-11, 11:58 PM
I have the same clunking sounding lik ethere is baggage flying around on my trunk or rear wheel well, i cant fins out whats causing this either! its only at low speeds or when im parking or coming into a parking lot!

HUF
06-11-11, 12:18 AM
Could that rear wheel 1/16" play (in-out) be caused with a bad wheel bearing?

HUF
06-13-11, 01:17 PM
UPDATE: The caliper bolt requires a 3/8" hex wrench which I did not have. Bending the tabs of the pad on the caliper did NOT look like a good idea to me, so will wait till I get a wrench.
Here is a video of the loose outer front brake pad.
http://www.youtube.com/watch?v=e8p4KbOHOAo

jayoldschool
06-13-11, 07:33 PM
Get a 3/8s or 1/2 drive hex socket. Those caliper bolts will come right out with a ratchet.

http://www.handymanlyness.com/archives/auto/repair/brakes/GM/96_Yukon_4x4/front/mxbrfy03a_brake_pads_96_Yukon.jpg

HUF
06-13-11, 07:37 PM
Thansk, Jay. I have shimmed the outer pad temporarily with a thick paper clip, and the clunks are reduced at least by 80%. So, you are the man! Pointed me in right direction. The pads have 1/4" of material left, so probably I will address the looseness issue when I install new pads in some 8- 10,000 miles.

Thanks again!

HUF
06-16-11, 10:42 PM
Found a 3/8" hex spacer with 1/4" internal thread at local Home Depot. Should work. :)

HUF
08-02-11, 09:17 PM
Found a 3/8" hex spacer with 1/4" internal thread at local Home Depot. Should work. :)
UPDATE: That thing did not work - too soft. Bought an L-shaped wrench instead.

HUF
08-02-11, 09:19 PM
UPDATE: A few hits with my favorite 25 oz hammer on the tabs on both driver and passenger side outer brake pad tabs, and the annoying clunk is gone! I have not removed the caliper and acted per FSM - hit them right on the axle. It looks like the pads get looser as they wear out. The Fleetwood rides and sounds like a Cadillac again. http://caddyinfo.ipbhost.com/public/style_emoticons/default/smile.gif Thanks for the advice!