Rotors Moving/Clunking
 

OK so I know that the rotors are moving. I can see it when I spin the front wheel in one direction and someone in the car hits the brakes. The rotor turns and clunks against the wheel studs. The size of the stud and the size of the holes in the rotors are different enough that there is some play in them. I am using Powerstop rotors and had a pair of rotors that did the same thing before these. It is not a good sound and only does it when I change the travel direction from forward to reverse and reverse to forward. The rotors only move once but I still don’t like the fact that it happens at all. The car has 36,000 miles on it.

Has anyone had this same issue? How did you fix it?

are your lug nuts torqued to 100ft-lbs. The wheels are really the only thing that holds the rotor against the hub.

I’ve torqued them to 100ft/lbs, 125 ft/lbs and 140ft/lbs with the same results.

My car does this too. I was thinking it was the retainer clips on the calipers not holding the brake pads still. I have aftermarket pads on the car now. My stock pads don't make the noise, but I don't like the way they feel (clamping force) when I step on the pedal, so I run the aftermarket pads and just live with it. However, they didn't make noise when they were new. But I don't remember when and at what point of wear they started moving in the calipers. At least, thats what I think is going on...

Well I know for a fact that the rotor is moving. I took the wheel off, torqued the lugs to 100ft-lbs, spun the hub and had someone hit the brakes. You can see the rotor turning. There must be a 1/16" or so of play in the rotor holes for the wheel studs and the rotor just moves.

What should I do here, anyone?

All rotors come like that. ive never seen a rotor not come with slightly bigger holes like your explaining. Dont know what to do as i never had a rotor move before like that.

Right!...I'm hoping that this won't damage the wheel studs or cause something to break. I know how brakes work and know that the calipers and pads are not to blame here and that in the end the car stops but WTF.

Does anyone think this will cause the studs any undue stress? I'll have a machine shop make me something that will fill the gap in the rotor holes if it will reduce any safety issues. Slowing that car down is pretty important seeing as I drive it like I stole it.

I'm thinking that maybe all our cars do it and we just don't notice it. I mean, you have OEM style rotors and your wheels are torqued to 100ft-lbs.

Good point. I guess I'll just keep my eyes (and ears) on this one. Still annoying though. :bang:

Weld them in place. They won't move then.

:jest:

unless your studs are worn, or the stud holes in your rotors are elongated from them previously not being torqued right, or the lugs are not torqued correct, i do not know how they would otherwise be moving back and forth........hmm

The holes in the rotors, for the studs, as several folks have already noticed, are a bit oversized. Mine are also. You torque the wheels studs to 100 ft/lbs, but look at it this way....the brakes have to generate a LOT more than 100 ft lbs of torque, to stop a 3500 pound car. Therefore, the rotors are going to "move around" a little.



And yes, I've wondered about that a few times myself......

I still think the pads have something to do with this. I changed from stock to aftermarket pads and my stock pads didn't make any noise. At one point I changed the rattle/retainer clips and the noise (aftermarket pads) stopped for awhile, but returned shortly after. Pads are just 'along for the ride' inside the caliper untill you press the brake pedal, clamping down on the rotor, making them move in the caliper even if it's just a little bit of movement. The rotor is clamped between the wheel and hub. If you torque each lugnut to 100 ft/Ibs, that's 500 ft/Ibs on one wheel, no? That's quite a bit of force to overcome. I'm pretty sure I'm not pressing down on the brake pedal that hard (to make the rotor move) to stop from backing out of my driveway or coming to a stop from 15 mph at the end of my street. I brought this subject up on Frrax a few years ago and the few who answered didn't think it was the rotor moving. Just my experience...

The rotor hat is crushed between the wheel and the wheel hub. It is the lug nuts and wheel studs that clamp everything together.

The wheel, brake rotor hat and hub become one solid assembly when correctly put together.

If you're tightening the lug nuts properly (as it appears you are) you need to look elsewhere as to why the rotor hat isn't being clamped properly.

What lug nuts are you using?

With the exception of brand everything is stock. Original stock lug nuts, original stock wheel studs, original stock wheels. The clips are stock and lock the pads in place. I really don't think they are a problem at all since I can't see or hear them moving when I "test" it all out.

I think leadfoot4 and others are right. I'm not doing anything wrong. I am just hearing it louder than others do. Which is surprising because the car has no mufflers and is undoubtedly the loudest car in town in the exhaust department.

I guess I am just being too anal but this is my only "toy" car afterall.

Hi I was wondering if anyone ever figured out why this was happening. I am having the same problem with the rotor moving when going from reverse to drive and visa versa. And for those of you saying that it can't be the rotor it is. I marked the rotor and my rim put it in drive and moved a lil bit and hit the brake, heard the clunk and then checked my marks and they were not lined up. I've called the technical support and they basically said that it's impossible and that there was something in the way. I've checked 3 times myself and even had a mechanic look at it and it's still happening, even when I over torque the lug nuts. I can't figure it out so if anyone has an answer please let me know. The only thing I can think of is to return the rotors and get a different set. Thanks.

Welcome to LS1tech!

It looks like you've actually searched and found info about your exact problem-bravo!

Can you take a picture of the mark on the rotor before & after it moves?

You'll need to put the pictures on a website like photobucket then add the links to them using the yellow photo box above here.

Brake Rotors Clunking
 

I have this problem and I know what it is!!! ..I replaced my Rotors with some aftermarket ones and when I did this is when it started.
They don't fit perfectly and as a result you have all those close tolerance areas were they should be touching but don't .
Now if you have the factory ones and they are doing it...I would suggest you pull them off and clean and lube (WD-40) the areas on the hub and rim.
This was a problem in the old days with drum brakes and they sold these little thin metal "Keepers" that you could slide down on the threads of the wheel stud and would keep pressure on the drum...I'm going to see if I can find some and try them on my Rotors.
That's it guys!!!...Good luck

these are the fix
 

You misunderstand torque vs clamping force
 

Torque on a nut is just the amount of torque to tighten the nut.
Clamping force can be determined from the fastener properties and base material properties, but it's significantly higher than the fastener torque.
One equation to use is T = KDP, where T = tightening torque, lb-in.; K = torque-friction coefficient; D = nominal bolt diameter, in.; and P = bolt clamping load developed by tightening.
So, P=T/KD. If the coefficient of friction is .5 and the diameter is .468, the clamping force at 100ft-lb of torque is 427 lbs.
I have a similar issue on a vehicle.
the lug studs are 12mm (.468) and the rotor lug holes are .55 (14mm).
Whenever I change direction or even release the brakes or engage them, I hear a pop. And it's scary as hell sometimes.