New rotors wobble inside pad bracket

[Sh1n0b1]

Hi, I have put new front rotors on my car for the first time.

They are OEM replacements and fit just fine. I have placed back on the caliper holder which the pads sit in. On both the nearside and offside the rotors have a slight wobble to them when spun by hand to the point where one rubs on the inside of the bracket.

I then put a couple of lug nuts back in to further hold the rotor in place but still the same problem, I then put the whole wheel back on and gave it a good shake to check the hub was OK which it was. Even with the wheel on and the nuts torqued the rotor still rubbed on the bracket.

Should I assume once I put the pads in and press the pedal a few times and the wheel is back on the ground things will align up properly or should I maybe use a washer to space the rotor more central inside the bracket?

I checked the rotors are the same thickness as the old ones, I torqued the bracket bolts to spec. Its my first time changing brakes so not sure if I have missed something or if this is normal?

Any help would be much appreciated, I can't let the Mrs say "I told you so"

Oh the car is a Mercedes C220 Model C204 Year 2013

[ReverendCounter]

Are the new discs actually flat or could they be slightly warped? Can't see that being the issue but lets start with the basics.

[ReverendCounter]

Sh1n0b1 said:

Should I assume once I put the pads in and press the pedal a few times

You should definitely assemble everything the way it is supposed to be - ie, with pads in place.

Sh1n0b1 said:

should I maybe use a washer to space the rotor more central inside the bracket?

You should definitely NOT do this.

[Sh1n0b1]

Thanks for the quick reply. Yeh at first I thought maybe the rotors were warped but I placed them both on a flat marble surface and they were flush. I then also put one of the old ones back on and it had a similar wobble.

Oh I also cleaned all the crud off of the hub too to make sure it sat flush.

Ok good to know washers are a bad idea, I did think that as I assume everything is meant to fit as it is. I will try putting the pads in too and everything assembled and see how it is. I was just worried to drive it and end up ruining my new rotors?


I also wasn't sure, once the caliper piston is pushed back, the new pads are in place and the caliper bolted back on.
Should I loosen the brake fluid reservoir lid slightly and pump the brakes?

[brman]

if the disc will not run true with a couple of wheel nuts on then something is wrong. I would not expect it to improve just because you put the pads in.

Most likely cause is some dirt or rust behind the discs.

[RobXjcoupe]

If the mounting hub wasn’t clean you may have mounted the new clean rotors on the dirt which would give the wobble and rub on the caliper brackets. Best take all apart and make sure all mounting faces are free from dirt and corrosion before rebuilding the components again

[brman]

ReverendCounter said:

Sh1n0b1 said:

Should I assume once I put the pads in and press the pedal a few times

You should definitely assemble everything the way it is supposed to be - ie, with pads in place.

Assuming it is a normal brake setup with a rigid disc and floating caliper and a fixed carrier I would say that is wrong. The disc should run true without any pads.

OP you said putting the old discs back on and they had the same problem. Assuming they did not rub before you touched them then you have obviously done something wrong. You just need to work out what it is

edit: OP can you post a link to the discs/caliipers you have? Because if they are floating discs then RC might have a point

[ReverendCounter]

Sh1n0b1 said:

Thanks for the quick reply. Yeh at first I thought maybe the rotors were warped but I placed them both on a flat marble surface and they were flush. I then also put one of the old ones back on and it had a similar wobble.

You would have detected vibration when braking. It might be a bit early to call, so a second opinion is required - but I'm leaning toward a diagnosis of wind up (lockdown getting to you?!).

Edited by ReverendCounter on Sunday 29th March 19:03

[Sh1n0b1]

brman said:

Assuming it is a normal brake setup with a rigid disc and floating caliper and a fixed carrier I would say that is wrong. The disc should run true without any pads.

OP you said putting the old discs back on and they had the same problem. Assuming they did not rub before you touched them then you have obviously done something wrong. You just need to work out what it is

Haha yes I have no doubt its my fault somehow and I have missed something. It all seems so simple, there are two bolts to torque for the bracket and its on, it doesn't move and it doesn't adjust.

I cleaned the hub with an attachment on a power drill and some brake clean, the thing looks shiney new!

The wobble on both sides is significant, by looking down from the top i would say 3-4mm side to side, so all the way from one side of the bracket to the other basically.

Not sure what else to try? Is there a better way to check if the rotor is warped? I laid them on my marble kitchen surfaces as I figured that was the flattest surface I had.

Tomorrow in daylight I will try putting one of the old rotors back on again on each side this time and see if the problem remains to try and eliminate the rotors as the problem.

Appreciate all the quick responses guys

[Chris32345]

Remove the DISC and rotate hub with a stationary object axle stand or something at the side to check for any runout on the hub if that's fine the problem is with your discs or fitting

[brman]

Sh1n0b1 said:

Haha yes I have no doubt its my fault somehow and I have missed something. It all seems so simple, there are two bolts to torque for the bracket and its on, it doesn't move and it doesn't adjust.

I cleaned the hub with an attachment on a power drill and some brake clean, the thing looks shiney new!

The wobble on both sides is significant, by looking down from the top i would say 3-4mm side to side, so all the way from one side of the bracket to the other basically.

Not sure what else to try? Is there a better way to check if the rotor is warped? I laid them on my marble kitchen surfaces as I figured that was the flattest surface I had.

Tomorrow in daylight I will try putting one of the old rotors back on again on each side this time and see if the problem remains to try and eliminate the rotors as the problem.

Appreciate all the quick responses guys

If it is that bad then I would remove the disc and check the hub itself. See if you can set up some sort of pointer (eg off the caliper carrier or upright) so you can see if the hub is wobbling when it turns. Unless something weird is going on it will be straight, but worth checking.
Assuming that is ok, try putting the disc on back to front (without the caliper carrier). That way you can look at the disc to hub faces and see if they are contacting all the way round. Odds are they are not and that will point to what is stopping them coming to gether properly.

[Sh1n0b1]

Caliper


Old and New pads



Discs I bought
https://www.ambush.parts/20742

Pads
https://www.ambush.parts/pp637

[brman]

Looks a normal setup to me so go back to basics. It is very unlikely 4 discs are all warped. It is also pretty unlikely you have damaged the hub unless you really went over the top cleaning any rust off.

I suspect that if you go back and check everything again you will find what it is.

[autohead]

Have you checked the correct discs have been supplied?

[Jakg]

Chris32345 said:

Remove the DISC and rotate hub with a stationary object axle stand or something at the side to check for any runout on the hub if that's fine the problem is with your discs or fitting

I would imagine without some proper tools it's very difficult to see a small amount of runout at the hub - and it'll only take a small amount on the hub to cause something much more visible on the edge of the disc.

It's much more likely to be an installation problem, though - something on the hub (or disc) face, or the flange.

[Pothole]

Put it all back together and drive it. It'll either be perfectly fine or you'll find out what's wrong. I'm betting on the former.

[ReverendCounter]

Have you aligned the retaining screw in the disc with the hole its supposed to screw into in the hub?

[Piersman2]

Are you sure you've got all the hub face flatted off? That photo seems to show some kind of corrosion on the hub surface that could potentially be stopping the new discs sitting flush to the hub face.

Not sure how it could have got there mind, unless it's corrosion left over from the old discs when they were taken of. Knock it off with a chisel if it is as sanding with a dremel will just smooth it off, not get rid of it.

Make sure that hub face does not have anything preventing the new disc sitting absolutely flush, even a small lump of any kind on the hub surface would prevent the disc sitting flush. A small mis-level on the hub would easily give a few mm mis-alignment at the edge of the discs.

[Sh1n0b1]

Thanks for all the responses everyone. I am tempted to just put it back together and see how it is, but also worried I will score my new rotors and screw them up?

Here is where I am at.

1. New rotors are 100% Flat
2. Old rotors have large lips and grooves worn into them. see pics. Bear in mind they have sat out in the rain for a while.
3. Despite the state of the old rotors the car seemed fine before disassembly, no shaking or noise. Unless I was just oblivious as it happened over time.
4. Hub seems true to the eye and I tried spinning it slowly holding a tape measure to it and it seems the same distance from the guard all 360
5. Hub has no apparent wobble or noise to it when spun or with the wheel attached
6. Hub does look a bit worse for wear but I have cleaned that thing pretty well with an electric drill attachment, sanded and wet and dry paper.
7. Old rotors wobble just the same as the new ones, with guide screw and a few lug nuts in.

Is it normal for old rotors to have grooves in like this? What could I try next to try and solve the problem? Open the hub?








I also noticed the inside of the wheel seems to have a groove worn into it?




Really starting to regret giving this a go!

[brman]

Piersman2 is right, even in that last picture you posted there are lumps of rust on the face of the hub. That needs cleaning off before before you do anything else as it is guaranteed to cause run-out on the discs.