clunk when braking

Post by **Petros** » Wed Feb 28, 2007 7:25 pm

When I am putting on the brakes when tranisioning from my driveway to the street (when the suspenion is under compression) I sometimes get a single "clunk" on the left side in front (it sounds like it is coming low in the front, like in the suspension). And then when I accelerate it will "clunk" only once again.

It feels like something is slipping back, and the forth "clunk-clunk" when I brake, and then accelerate, but I can not find it. I have had the whole front strut out, inspected all the bushings, even added a rubber spacer behind the swaybar/drag strut bush to tighten up that connection in the lower arm. All the rubber looks good, the brake caliper bolts are tight. ball joint is tight, steering and rod ends are good. I checked the cross member bolts, engine mounts, and everything else I could find down there, but still could not find the what is clunking.

Any ideas?

I thought maybe the subframe could be cracked and flexing, but I can not see anything wrong with it. When I brake the wheel has backward pressure on it (and the engine mounts forward pressure), and when I accelerate the front wheel has forward pressure. It would seem to come from somthing that is not quite tight and shifting back and fourth. But I can not find it.

Post by **ARCHINSTL** » Wed Feb 28, 2007 9:27 pm

I'm certain you checked these, but maybe I misread the post:
1. Lower control arm bolts/bushings at subframe;
2. Inner tierod ball-and-sockets (mine rattled when they did the driveway/street transition);
3. Steering rack mounting bushings (my d/s looked like rubber mush);
4. The two "mystery rods" (at least to the FSM) which attach diagonally from the front Xmember __to the chassis (one of mine was loose-tightened them, but did not notice any +/- difference);
5. The two mountings for the swaybar to the Xmember;
6. The 4 big bolts which hold the Xmember to the subframe (farfetched, I know);
7. The transmission mount at the rear (really farfetched, but hey...).

Since you did not mention it, I presume you can "feel" nothing in the steering when this occurs?
Tom M.

Post by **Petros** » Thu Mar 01, 2007 12:08 pm

No I do not feel anything through the steering wheel, and little if anything through the floor of the car.

I have inspected everything on the underside of the car and the struts, all the rubber looks good, I see no damaged parts. I have put a big breaker bar wrench to the cross member bolts, the engine mounts, the diagonal brace "mystry bars" , to the lower control arms, the two bolts that hold the bottom of the strut to the ball joint. I have put a large pry bar on the lower arm, the sway bar, the streering linkage, and the strut assembly to see if I can get any movement or duplicate the sound with the car on a jack. All without any luck.

The only thing I am not confident of is the frame (no way to really test this), or the big rubber mount and bearing at the top of the strut. Though these do not look bad, and the clunk is coming from lower on the suspension. Could a worn CV joint cause a single clunk? [not in my experiance]

I will ckeck the steering rack mounts, though it would seem i would get a clunk when I trun the streering wheel back and fourth, not accerate or brake. When I had the front end aligned when I had the struts replaced last year they did inspect everything, if there was a sloppy rack they would not have done the alignment until I paid them to replace the rack (I know these guys too well).

Post by **ARCHINSTL** » Thu Mar 01, 2007 4:18 pm

I did not mention the strut mounts, as I presumed that you checked these when the strut was out, per the first post. There was a thread back in '05 about this; a member was driving and noticed a clunk (as I recall the scenario), and found that the mount had collapsed entirely. There are some dramatic photos. Mind, this was a complete failure.
Other than cost, why didn't you replace the mounts when the struts were replaced?
It would seem that you have covered the usual suspects ? ? ?
Please keep us posted; what happens to some of us will (probably) happen to many of us.
Tom M.

Post by **Petros** » Thu Mar 01, 2007 8:00 pm

I presume you mean the upper strut mounts, these looked fine and yes cost (why replace perfectly good parts?). I even applied a pry bar to the top of the struts after it was all assembled, but could not duplicate the sound. Both I and the shop that replaced the struts and did the alignment inspected everything, I looked everything over in their shop. I am sure the shop would be happy to find something else to sell me, but they found nothing (there were some other rubber parts they replaced, bump-stop, boots, etc.). I had it all appart a few months later when I replaced the trans, and took out the struts to look them over again since it was up on jacks anyway. Still found nothing that would cause it.

I can ignor the clunk, it does not happen very often. I want to know what is causing it just in case it is something that could be dangerous or is about to fail. Not likely whatever it is could become danerous, but I WANT TO KNOW THE CAUSE. Even if I choose not to fix it. I can not feel completely safe unless I know the cause.

I am thinking the "Click and Clack" method [of Car Talk Radio fame] might be the only way to find it. Have someone lay accross the hood with their head hanging down under the car, and they hold on while someone drives the car in a way to cause the noise. Not recommeded.

Still looking for ideas.

Will keep you posted if I find anything.

Jts · Post by **Jts** » Fri Mar 02, 2007 3:49 am

is it possible its your brake pads being moved around inside the calipers? If the anti rattle clips are gone they can click as they move back and forth.

Post by **ARCHINSTL** » Sun Mar 11, 2007 1:07 pm

Anything new on the mystery clunk?
Tom M.

Post by **Petros** » Wed Mar 14, 2007 7:35 pm

I still have not found the cause, though I have been listening more to see if I can find a pattern. THis is what I noticed:

Seems to only happen when it is cold, within the first 1/4 mile of driving when starting it from cold. I can not make it happen after been driving several miles or more. Even so it does not happen every stop and start.

It can happen on both the right or left side (both sound like they are low on the car), though left side is more pronouced.

Have not localized the sourse, and could not make it do it noticably when I nudge the front tire back and forth when parked.

I do not think it is something loose in brakes (though it is possible) because I would not think that it would clunk back at acceleration. Brakes sourse would clunk when apply brakes, and then clunk when let off brakes (or when backing up) I would think. because it happens with brakes and then acceleration, I tend to think it is from suspension or frame.

shogun · Post by **shogun** » Thu Mar 15, 2007 6:49 pm

have you checked the sway bar bolts, sometimes the nut breaks off and it seems to be tight, but the whole thing moves, it also gives a slopy feeling in steering

takza · Post by **takza** » Fri Mar 16, 2007 4:40 am

My vote is for the swaybar end bushings. Bet if you'd replace or shim these...the noise MIGHT go away?

Post by **Petros** » Mon Mar 19, 2007 9:59 pm

I did check all the sway bar bolts, and applied a large pry bar to all the parts to see if I get any movement or clunks. I also shimmed the left sway bar bush with a 1/4 in think rubber washer, which had no noticable effect (the left side was more noticable).

I am almost thinking now it might be movement at the top of the strut towers, after careful listening it is possible it coming from higher on the strut than I first thought. The big rubber upper strut mounts are in good shape, what I am not sure about is the bearing at the top of the strut.

I know a had a bad pair, the suspension shop wanted over $100 each to replace them when I was getting new strut inserts, I told them no thanks. (I bet I can get them from Autozone or NAPA for $30). But a number of month latter I had to remove the struts (when I did a trans swap, old one died), and rented some spring compressor and swapped out another used pair I had from my parts car. But there was no noticable change in the clunking. It is possible the other pair were just as bad as the old ones I swapped out, but is seems unlikely.

Is it possible that these upper strut bearings could cause a noticable clunk when they are worn?

takza · Post by **takza** » Tue Mar 20, 2007 4:48 am

Petros wrote:Is it possible that these upper strut bearings could cause a noticable clunk when they are worn?

I've heard of these failing or getting loose...but since they almost always have a load on them...they would be difficult to diagnose...something like a ball joint?

Any econobox FWD car is going to be a little noisy in the front...I've always noticed this with Toyotas. It's nothing loose...just the noise transmitting thru the frame? I notice this espec when cold.

Can't say in your case...but if I can find no looseness I usually say good enough.

There are (4) tie rod ends..plus the sleeves that hold the rack on each end...plus the rubber surrounds that hold the rack housing....ball joints...inner control arm...etc...etc....

keith · Post by **keith** » Tue Mar 20, 2007 5:09 am

If the bearing was bad enough to cause a clunk, it wouldn't just do it one or two times. Any you won't get new upper mounting blocks for $30. I paid over $130/pr at O'Reilly's. They cost more than the strut cartridges.

If this clunk started right after the strut cartridges were first installed, I guess that the spring is not located properly in one of the seats, more likely the top seat, but it could be the bottom. Its very difficult to get the spring and upper spring cap lined up correctly while tightening the nut that holds it all together. See my post on Struts and you can see that my first attempt was not successful. Typically an out of position spring cause a single clunk on sudden changes in speed. They don't rattle like an upper bearing might.

Post by **Petros** » Tue Mar 20, 2007 7:08 pm

It occured to be it could be the spring install. It did it before the strut install, and after, and after I and reinstalled them as well. Though it is possible it was never in correctly. If that all it is I will not worry about because nothing will come of it.

I am just concerned something important will come loose when I am driving it.

hberdan · Post by **hberdan** » Wed Apr 25, 2007 4:01 pm

I've been having that same clunk lately. Same randomness to it as well. Had my mechanic look at it, the same mechanic that helped install the struts last year. He thought it might be caused by a loosened strut. We tightened the top nut on the left strut, the side where the sound seems to be coming from. FWIW, the nut did need tightnening, but just a bit.
The sound, however, has not gone away. Since we didn't realign the strut spring when the nut was tightened, I'm going back to him and we are going to recheck the spring alignment. If it's out of position I think it would explain the random noise.
I would think bad ball joint wouldn't be so random, and I do notice the noise more at low speed on bumpy roads.
We've had a really snowy winter, and the roads are in bad shape everywhere, lots of potholes showing up, I know I've hit a few! Could 'splain the loosened suspension. I think I'll check the rear shocks too.
He also mentioned the possibility of loose front brake pads, like the spring was off/loose, but he said in either instance, misaligned strut spring or loose brake pads, their is no reason not to continue to drive.