brianPA

I've had my 'vette for about 6 months and in the past few weeks I've noticed a new clunk in the front end when I let off the brakes at near-stop speeds. If I apply the brakes firmly and release quick (say at a stop sign) it clunks louder on release. I've already searched the forums for similar issues and seen a few suggestions (control arms, A-arms?, brake pads shifting, loose brake calipers/rotors) but none of the complaints quite match the clunk on brake release that I'm having.

Few more things:

- no noise when shifting or clutching (manual transmission)
- brakes work great at all speeds
- same clunk regardless of in-gear or neutral, clutch in our out
- only clunks at very low speeds
- I also get a bit of a clunk when hitting small potholes & other road defects, but unless this is a suspension issue I think it is unrelated

Does this ring a bell as something obvious that you've seen before? I'm going to check all the suggested places I'm just not very experienced.

themetalman03886

i had a similar problem to this except mine was when i hit the gas and the front end rose up a bit, it ended up my control arm pivot bolt was loose, I put a new nut on it and it fixed the problem. I had found that the PO did a lot of work to the car but forgot to tighten down a lot of the stuff he replaced, one of them being the straps for the drive shaft (yeah that wasn't a fun day.) Just go threw your suspension and inspect everything, look for something out of place or loose, shouldn't be too hard to find.

71scgc

I had a similar noise, although I wouldn't say it was a clunk so much as a click, and it too would happen on releasing the brakes at a slow speed. The only thing I could find that would have possibly caused it was the retaining pins for the brake pads. Check them and make sure the cotter pins are in place on the inboard side of the calipers. Then check to see if you can "duplicate" the sound. I didn't replace the pins, and the click continued, but I felt certain that was the cause. Things were together, and staying so, so I didn't worry much about it. I had no stopping or leaking issues, and didn't want to start any...
Hope this lengthy reply helps.
Carter

oldalaskaman

my noise is control arm bushings, replacing them today.

wombvette

Most likely his too.

C6DuffMan

I had a similar issues. One of the upper A-arm nuts came loose enough to let the alignment shims fall out. This left a huge gap which let the A-arm mounting bar move under braking. Good luck.

brianPA

Thanks for the responses, I will put it up on ramps again and check it out.

If the bushings need to be replaced, how big of a job is this if I pay somebody else? I assume this requires a lift (or jackstands) which I don't have myself. The guy I normally use is 2hrs away so I was hoping to queue up a few big jobs before I make the trip. I'm afraid of getting ripped off when finding a random mechanic locally.

toddalin

I had a similar issue with mine and it was really easy to fix. I would notice it most when applying the brakes at the bottom of the driveway.

The bolts that hold the "plate" that the caliper mounts too had backed out enough (or the metal plate had squeezed) that the plate could rock to the ends of its travel of the bolts in the holes. I could grab and rock the caliper and physically move this piece.

Tightening up the bolts took care of the problem but you have to remove the rotor/hub to get a wrench on the head to do it (which only requires removing the castle nut). Otherwise, the bolts will turn with the nuts and you won't get it tight.

Worked for me.

brianPA

Okay I've done some investigating. Before I even got to looking at the brakes I noticed that if I sit in the driveway, car running and turn the steering wheel all the way in each direction it clunks when I turn all the way to the left. I looked at what I believe are the upper control arms and I see that the passenger side has a 1/4" gap that the drivers side does not. Also, it has some kind of rigged-looking spacers on one bolt on the passenger side. Definitely looks wrong to me.

Any idea why this gap would exist, why spacers would be put there, and only on one side? I'm about to dig around the forum on control arm issues but here's some pictures:

Driver Side


Passenger Side


This clunk sounds the same as the one when letting of the brakes, which happens even when not turning, but I wonder if this is the root cause and the brake-release thing is just a result of weight shifting.

fanmanbd

you need to get some shims in there and get an alignment.

brianPA

Do you think the clunk sound is likely related to this or just a different problem?

my 76 ray

Yes, that is probably making the clunk. Your alignment shims have fallen out on the passenger side. The shims are put in to adjust the caster and camber.

JohnRR

Hey Brian,
It sure looks like your alignment shims fell out. That would explain the clunking when applying or releasing the brakes, and going over bumps. Get a four wheel alignment and make sure the nuts are Mother-Tite!

You should check all the other things suggested above because they could also need some attention.

John

lars

The shims have fallen out of your passenger side rear location, and this allows your entire upper a-arm to rotate and clunk every time you put some torque on the wheel (applying and releasing brakes). Take the car to an alignment shop and at least have the front end aligned to get the correct shims back in it. Judging from the surface corrosion on some of your parts, the shop will probably not be able to align the rear end, since the trailing arm bolts and shims will be frozen solid: just have them set the camber on the rear and leave the rear toe alone, but get that front end alignment taken care of.

Lars

brianPA

Thank you very much, I'll go get an front end alignment.

mrvette

Saves a lot of expense and agony IF you take some black RTV and put it over top of the shims and down the cross bar, chassis, points also, don't take a LOT, so that holds them in place so WHEN they come loose again, you don't lose them you just tighten down the bolt again....and use LOCKTITE RED on it.....

screwed loosely once, my fault, never again.....

lvmyvt76

I would think you need to have the front rebuilt, then have it aligned. If your bushing are original, they are dried out and need replaced. If they have been replaced sometime recently, then disregard my message.

OzBeast

Just thought I would drag this thread up and say, even four years old, it totally pointed me to right solution.

Clunking noise on my front left, exactly as described by the OP. Took it to the shop to put on a lift and they found most of the shims had fallen out of the front left (visible from the top of the engine bay, so I could have checked without going to the shop).

My mechanic has worked on Corvettes before, but not for a long time, he is going to do the alignment tomorrow as he thinks he has some shims left from working on the (garage) owner's C3 a few years ago.

Any tips? Anything I should remind him of before he starts work tomorrow?

Mountainoakie

That sounds like loose caliper mounting bolts.

OzBeast

It is definitely missing shims on the control arms, at least in my case and it seems was the same for the OP as well.