Please help…rear suspension clunk in 07 Mazda6

Hi all, I desperately need help. Have an 07 Mazda6 with 110k miles. It developed a clunk in the right rear suspension about 6 months ago. Constant clunk at low speeds, whether small bumps, snow-covered roads, etc. Been to five different mechanics with no luck.

So far, the rear shocks have been replaced; made no difference. Stabilizer bar and end links were removed from car and driven carefully around the parking lot; no difference. New control arm lateral links installed; no difference. Top shock mount plate is tight, and rear coil springs removed and inspected during that process; no difference. No brake pad retaining pins are missing.

When I sit in the back of the car with the seats down, the sound seems to come from the top of the shock mounting area, but perhaps the noise is just traveling up through that area of the car.

Could it be a bad lower control arm bushing? Each mechanic checks them with a bar and reports little play. But I don’t know where to go next. Please advise – thanks!

(Car drives fine, but the noise is maddening.)

Has anyone checked the spare tire well in the trunk and the jack location (if elsewhere) to see if that is loose and clunking around?

Another thing that can get overlooked because people get so focused on suspension items is loose bits of the exhaust system.

Yes, I should have mentioned that I’ve removed the spare tire, jack, and every loose item in the trunk. Thanks for the suggestion though…

Also, I should add that no one can reproduce the noise without the car driving down the road, whether the car is lifted or not.

Slowly around the parking lot says something about the conditions required that might help isolate… is it only on turns or if straight too? Snow covered, so does it NEED a bump to make the noise or is it more like something is binding?

I once had a suspension noise that was really tough to find. I made a small wooden step to drive over so that the suspension would get a shock coming down off of it and I could stand right next to the car as someone else drove it off the step. Eventually, I had to kneel down next to it and watch the process and viola! it was then obvious what was making the noise. The key is to find a way to isolate it and piecing together all the information you have should help to identify a way to reproduce it in a way that lets you observe and identify the cause…

Thanks for the suggestion. By “slowly around the parking lot,” I meant that the mechanic didn’t want to take it out on the road at a fair amount of speed without the stabilizer bar installed. I only notice the noise below 45 mph, but that might be because of road noise above that speed. The noise is constant, whether driving straight or around corners.

No one has been able to reproduce the noise in the shop or driveway using blocks of wood, etc. The really frustrating part is that two different mechanics used chassis ears (microphones) and still couldn’t pinpoint the noise.

Thanks again for the reply though…

OK, that helps narrow it down. The noise is constantly occurring; is it related to the speed of the vehicle? Does it still happen when coasting or only when power is applied?

I had one of these clunks and, after extensive searching, I found a golf ball had fallen into a pocket between the floor of the trunk and the rear fender. I couldn’t see it, but I could feel it with a thin stick. Just a thought.

I assume the rear shocks were replaced as part of the search? Who replaced them? As I understand it, that upper shock mount is a complete bear in terms of access and since you hear it there, it wouldn’t surprise me if it was up there and things didn’t go well on the shock install. Of course, it is implausible if the noise was identical before and after. I am also still wondering about the exhaust…

Thanks again for the replies. The speed of the vehicle does not change the clunking sound – whether accelerating or coasting. Also, applying the breaks does not change the sound either.

The rear shocks were replaced by trained mechanics at a military auto shop. Afterwards, the guy admitted that he had never changed shocks on a Mazda6 and grumbled about the difficulty. But a mechanic at a Mazda dealership drop the newly-installed shocks, checked the mounting plate, tightened everything down well, etc., and that made no difference. Several of the mechanics also checked the exhaust system, heat shield, etc. One even pulled the gas pump to see if there was a loose baffle banging around in the tank, but he couldn’t find anything.

Several of the mechanics also checked the rear fender wells to make sure something like a golf ball hadn’t fallen down there. No luck.

The car drives fine. I can’t keep dropping money trying to solve this noise. I should have followed the first mechanic’s advice and turned up the radio. Thanks again for your inputs.

But returning to the original question, could a bad control arm bushing make a clunking noise, even though the bushings don’t seem to have much play in them?

Sorry, after re-reading twin turbo’s original question, yes it does need a bump to produce the clunking sound. If I’m driving on smooth pavement it drives and sounds like a brand new car.

Technically I don’t think they are control arms back there, but links instead. It doesn’t matter much since there are bushings than can make noise. Others here have more experience than I, but anytime I’ve ever had a control arm bushing causing a problem it has been obvious. If you look at the things, the rubber would have to be completely gone to rattle - squeaks are another story. If they’ve been inspected I think that having them replaced would be one more thing that doesn’t fix it.

What kind of wheels are on this thing? If they are steel with covers I assume its been driven without the wheel covers.

Yes. But the most common source is the bushings that hold the sway bar to the unibody.

Try this. Pick up some ramps at the local store. Back the vehicle up onto the ramps, shut the engine down and put the parking brake on, chock the wheels, slide under the vehicle (I use a sheet of corrugated cardboard to lie on), and try vigorously shaking the sway bar and other parts with your hand. Don’t worry, you cannot hurt the suspension doing this. My guess is that you’ll hear the thunking. Do this with the engine cold so you can shake the exhaust too and not worry about burning yourself. If you can’t find the thunk, try the front end too. Sound waves can move throughout structures.

Post back with the results.

Cigroller: all of the mechanics tell me the bushings look good and don’t have too much play when they pry on them. The rubber is definitely not missing on any of the bushings. And the rims are stock alloys.

Mountainbike: One of the mechanics completely removed the sway bar and end links from the car and drove it around the parking lot; clunking remained the same. The exhaust has been checked multiple times as well. I haven’t checked the front end yet because the noise seems so isolated to the right rear. When I remove the seats and have my wife drive, I can hold my ear against the metal on the inside of the car directly above the top of the shocks/coil spring and it’s coming from down there somewhere. Very frustrated…almost at wits’ end.

Thanks for the suggestions though…

I’m thinking you might want to visit some Mazda forums to see if any other 6 owners have similar issues.

My golf ball story was actually a Miata. The ball was in the pocket in front of the rear wheel on the right side. I have no idea how it got there, but it made me crazy until I found it, and then getting it out was another challenge. I thought about injecting that insulation foam you use around windows in a house into the area. A person with a long skinny arm got it for me.

Does it happen when the car is moving but not running (coasting with the engine off)? Will it clunk once if you let it roll in neutral, engine off, and stop hard at just a slow roll? Try that with you standing outside near the rear wheel while someone else does the stopping. Try it forward and backwards. I’m thinking with the engine off you eliminate the exhaust issues, and eliminate a lot of other sounds.

I did a quick look at YouTube and found a couple of references to suspension noises on Mazda6, and it seems like it could be a bushing, as you think.

Cigroller: I have read some of the Mazda6 forums. Almost all of the suspension clunking issues were solved by replacing the shocks, end links, or tightening the mounting plate. In theory, I’ve ruled all three of these options out. A couple of people have mentioned the control arm bushings, but apparently you can’t replace just the bushings; you have to replace the control arm which comes with new bushings. This may be my last attempt. I’ve sunk over $800 trying to get rid of this noise, which I know is irrational.

Wentwest: I’ll double check the rear wheel pockets again, though the noise sounds more ‘metallic.’ That’s an interesting point about checking the car while moving but with the engine off. I think that is one thing we haven’t tried yet. It definitely makes noise coasting with the car in neutral, whether moving forward or backwards. I’ll give it a try with the engine off.

I’ll probably press ahead with replacing the lower control arm ($170 installed). I didn’t know a bad control arm bushing could sound like a loose, clunking shock, but someone said it can (much like a loose stabilizer bar with bad end links).

Thanks again for the inputs…

Don’t those lower rear control arms have a ball joint on them? A worn ball joint with any amount of slop at all can make a thunk noise on any kind of bump.

Ok4450: The reason I’ve been to five mechanics is because I don’t know cars very well myself. I’ll have to check on the ball joint theory. None of the mechanics has brought this possibility up, so I guess I assumed it wasn’t an issue. Thanks for the input.