S197 Rotor Slop / Clunk

Solved a “clunk” issue with my 2007 GT vert. Maybe others can benefit.


I’m the original owner. Not a daily driver (only 91k miles). Always had a clunk sound when downshifting/ braking while making a turn. Ford dealer was useless in 2007 and I just put up with it, knowing I would upgrade the suspension over time.


All my drivetrain / suspension upgrades are complete (see below). Still had the same pesky clunk described above. I also noticed the sloppy rotors which others have mentioned in prior posts, so I thought I’d try to address the clunk by placing a nonmetal shim between the studs and the rotors. It seems to have worked. No more clunk (at least after several hard test drives)


I used 1/2 inch PTFE pipe from Ace Hardware. The pipe inside diameter was slightly less than 1/2 inch, so I used a 1/2 inch drill bit to slightly open the inside diameter. It fit snug on the stud. I then used my bench grinder to reduce the outside diameter of the PTFE pipe to fit snug in the rotors. I did not have to remove much. I then sliced off 1/4 inch shims of that pipe and gently tapped them in using a dull screwdriver and punch. I shaved off any excess with a knife so the wheel fit flush. The rotors are tight - no more slop. The clunk is gone, at least for now. I did this for front and rear rotors.


Upgrades over last four years: B326 with Paxton 2200, McLeod clutch and Magnum XL 6 speed, DSS shaft, 4:10 gears, Moser axles. Subframe braces. BMR rear upper and lower control arms and panhard bar, Steeda coil overs, adjustable end links, front lower control arms, FRPP sway bars, torque limiter, upgraded brakes and fore fuel system. Most was professionally installed, I did some of the weekend hobby mechanic stuff. I thought the suspension upgrades would eventually solve the clunk. Nope. I got the speed and torque -and all the fun that goes with - but still the clunk. So after spending the equivalent of a college education to get what I wanted, I did not want a “clunk”.

The rotors were actually slipping between the rim and axles/hubs? The clunk was the inside of the wheel stud bores impacting against the wheel studs? How frequently did you hear the clunk, only while shifting between forward and reverse?

Something just doesn't seem right. What rims do you have on there? Is the center bore the right size? In my 40 something years of driving and wrenching on cars I just don;t wee how this is possible without an ill fitting wheel or something along those lines. How about the factory washer installed on the rotors? Though I guess that would make the wheel sloppy and not the rotor. What about the wheel lugs. Do we have the right design for the wheels? One would think if the wheels are tight the rotor would be tight too.

It does seem weird, but it seems to have worked. My wheels were always tightened, and the clunk was with the factory wheels. The factory alignment spacer was removed with the new wheels about 20k miles ago.

The wheels are Vintage Wheels 407SSP with center bore at the stock 70.6mm. They were sold as a package deal for S197s.

The clunk happened during sharp changes in power, most notably when braking around a curve then let off brake and apply some power.


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These cars are notorious for clunking coming on and off the power. But usually it is the 2-piece drive shaft, differential or upper control arm. That bushing on the top of the diff went out on me and it took me forever to narrow down the clunk. Have you ever checked the driveshaft? With your car in neutral and the parking brake on, try to rotate the driveshaft back and forth. It should wiggle some but it should not be excessive.

I wonder if I inadvertently did something while inserting the “shims”? My initial thought was the rotors were moving slightly and clunking against the studs under those conditions. But now I’m doubting that after your input.

The diff and driveshaft parts were replaced with no noticeable changes. The brakes and rotors are newer and also did not make a change to the clunk.

These s197s seem to have lots of places for clunks. Either way, I’ll go with what I have and enjoy no clunk.


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I've been chasing clunks and rattles in the rear of this car it seems since day 1. I know it happened after messing with the rear suspension, but I can't get it to go away. Everything's poly bushings in the back. There is some backlash on the gear, but it's all stock. 1 piece driveshaft didn't cure it either.

I forget who posted it, but I've done a little measuring and they seem to be on to something. If you've replaced lower control arms, the aftermarket metal insert isn't as long as the stock metal insert in the front bushing. Last time I had my car in the air, I measured them both, and the Steeda front bushing insert was about 1/16" too short.
I was thinking about getting a rebuild kit from Steeda and inserting the stock inner metal sleeve onto the poly bushings. Just haven't gotten around to it.

OEM ford driveshaft bolts have a teflon-like wrapping like you describe.
I just turn my rotors against rotation before tightening the wheels. Even if I didnt, one good forward stop may produce one clunk. But I never noticed.

FrancoGT said:

I wonder if I inadvertently did something while inserting the “shims”? My initial thought was the rotors were moving slightly and clunking against the studs under those conditions. But now I’m doubting that after your input.

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Yeah, the only way for that to happen is if you have the wrong lug nuts. When you tighten them down the nut should center the stud thus the conical shape to them. The rim should not be able to shift on the studs unless they are loose or wrong.

Just to put a pin in this….. while installing the shims I noticed the plastic wheel well was flimsy. So I braced it to make it firm - not thinking this was anything but cosmetic. After this conversation about rotors, I removed the wheel well bracing and test drove. Low and behold, the loose plastic wheel well was causing the clunk I heard. I thought it was the shims.

Glad to hear you found the real cause.
If your rotors are moving so is the wheel and that is not safe.
The clamping force between the wheel/rotor/hub is what prevents movement, the studs are just there to provide the force needed with proper torque applied.

I'm not sure about pin drive wheels with spinners or center nuts, but you don't have those.

FrancoGT said:

Just to put a pin in this….. while installing the shims I noticed the plastic wheel well was flimsy. So I braced it to make it firm - not thinking this was anything but cosmetic. After this conversation about rotors, I removed the wheel well bracing and test drove. Low and behold, the loose plastic wheel well was causing the clunk I heard. I thought it was the shims.

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Might have to look into this. Are you talking about the lining inside the wheel well on the rear wheels?
I was thinking of removing and putting dynamat on the outside, heard it greatly reduces a lot of road noise.

pass1over said:

Might have to look into this. Are you talking about the lining inside the wheel well on the rear wheels?
I was thinking of removing and putting dynamat on the outside, heard it greatly reduces a lot of road noise.

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Thanks. Yes, it was actually the front wheel well lining. The factory has several push pin type connectors to hold the entire thing in place. I found mine had over an inch of play near the fender well. I am thinking that was enough to bang it against the fender. Might be worth checking out.


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