New rotors wobble inside pad bracket
Discussion
Sh1n0b1 said:
Ok thanks I will give them an extra good scrub tomorrow see how it goes
Whilst the hub needs better cleaning, that looking the pictures we have, is not the cause of your problem. Manufacturer specification for disc run out is usually approximately 0.10-0.20mm. Significantly smaller than the 3–4mm run out you have got.Your looking for a fundamental issue with the parts not a cleanliness issue. The poster above might be on to something, have a look at the inside diameter of the top hat part of the new disc, paying particular attention to the radius in the corner and compare that to the hub.
I reckon the discs you have been supplier are not correct.
Sh1n0b1 said:
Ok thanks I will give them an extra good scrub tomorrow see how it goes
If that corriosion on the face of the hub is what it looks like scrubbing will do no good, it will need chipping up back to the level of the hub face. You need there to be nothing proud of the original level of the hub face.Don't 'open' the hub, there's nothing to see there that cause the issue you're having.
Refitting the old disks could well exhibit the same issue unless you're putting them back on in the exact same alignment they came off.
Have you got the grub screw still in 1 piece that holds the disk against the hub whilst refitting the brake carrier? Quite often goes missing/gets drilled out due to corriding into hub.
Megaflow said:
Ah, missed that bit. In case case it is something the OP is doing, because the old discs weren’t 3-4mm out before he took them off.
I think what others are pointing out is this: 
(cropped from the last picture the OP posted of the hub. I missed it to start with as it looks just like tarnishing when viewed normal size.
Unless my eyes deceive me that is a big lump of rust still on the hub face and would definitely cause severe runout problems. As someone pointed out, if the old disc was removed an then put back on in a different orientation then it too would now wobble like mad. (especially as the hub has now been partially cleaned up)
OP: This is the stuff you need to look at. the face of the hub needs to be absolutely flat all over. Small rust pits are ok (but don't sand too much away!) but any lumps are not.
I think you are actually over thinking it all.
With just the disc mounting screw in the disc rarely sits perfectly as it is a single fixing in one place.
Your wheel bolts are tapered & likely will bottom out before they are fully home in the hub.
Put it all back together & see how it fits then.
With just the disc mounting screw in the disc rarely sits perfectly as it is a single fixing in one place.
Your wheel bolts are tapered & likely will bottom out before they are fully home in the hub.
Put it all back together & see how it fits then.
brman said:
Megaflow said:
Ah, missed that bit. In case case it is something the OP is doing, because the old discs weren’t 3-4mm out before he took them off.
I think what others are pointing out is this: (cropped from the last picture the OP posted of the hub. I missed it to start with as it looks just like tarnishing when viewed normal size.
Unless my eyes deceive me that is a big lump of rust still on the hub face and would definitely cause severe runout problems. As someone pointed out, if the old disc was removed an then put back on in a different orientation then it too would now wobble like mad. (especially as the hub has now been partially cleaned up)
OP: This is the stuff you need to look at. the face of the hub needs to be absolutely flat all over. Small rust pits are ok (but don't sand too much away!) but any lumps are not.
E-bmw said:
I think you are actually over thinking it all.
With just the disc mounting screw in the disc rarely sits perfectly as it is a single fixing in one place.
Your wheel bolts are tapered & likely will bottom out before they are fully home in the hub.
Put it all back together & see how it fits then.
As I said on Sunday...With just the disc mounting screw in the disc rarely sits perfectly as it is a single fixing in one place.
Your wheel bolts are tapered & likely will bottom out before they are fully home in the hub.
Put it all back together & see how it fits then.
ReverendCounter said:
OP hasn't posted since 8pm last night - can someone pop round and check under the car - I've got a bad feeling (kidding obvs) 
Hahah thanks!Cheers for all the reply's everyone. I haven't had a touch on it today, I'm waiting on some new wire drill bit attachments to come tomorrow. I will clean the hub again, put it all together and see how it goes.
I aligned the new discs to the old ones and measured them, I also checked the part numbers online again. I am 90% certain they are the right rotors. They seem identical to the old ones.
In the mean time I decided to take the calipers off, clean them up and paint them like all the cool kids do. Only grey though, more to rejuvenate them.
You can check whether the disc will be pulled flat when the wheel is tightened on without putting the wheel on. Use some large(r) bolts as spacers pushed down loose over the studs and tighten up the brake disc using the wheel nuts to press against the large bolt spacers. I hope that makes sense.
You can then spin the wheel and see if the disc has been pulled 'true' with all the wheel nuts tightened up.
Again, from your last message, wire drill bit attachments are unlikely to help you get those lumps of stuck corrosion off your hub face to make it flat. Use a sharp chisel with hammer and knock them off flat back to the hub face. You'll be there all day trying to get those lumps down flat with a wire attachment.
You can then spin the wheel and see if the disc has been pulled 'true' with all the wheel nuts tightened up.
Again, from your last message, wire drill bit attachments are unlikely to help you get those lumps of stuck corrosion off your hub face to make it flat. Use a sharp chisel with hammer and knock them off flat back to the hub face. You'll be there all day trying to get those lumps down flat with a wire attachment.
Wheel bolts on their own will not be tightening the disc to the hub. The retaining screw will not tighten the disc to the hub on its own.
Put the whole lot together and torque the wheel nuts correctly.
Drive the car. If there is something wrong, you will feel it as soon as you touch the brakes, if not before.
When you tighten the wheel up properly, this "wobble" will vanish in all likelihood (as long as the mounting faces are reasonably clean).
Put the whole lot together and torque the wheel nuts correctly.
Drive the car. If there is something wrong, you will feel it as soon as you touch the brakes, if not before.
When you tighten the wheel up properly, this "wobble" will vanish in all likelihood (as long as the mounting faces are reasonably clean).
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