Barke Rotor Size Discrepency

[SchnellBMW]

Hi everyone! I have a strange issue.

I inherited my mom's 2003 530i with sport package. She only put 44k miles and according to her, my sister, and my knowledge, the brake rotors were never replaced. A few weeks after I began driving the car, the brake light came on. The mechanic that has been working on the car and my sister's other two BMW's told me it was time for new pads and rotors.

When he ordered the rotors, he got some from his parts guy that were 328 mm in width. He called and said they wouldn't fit in the calipers properly and said he was just going to size match them to what was on the car (supposedly from the factory) which was 324 mm. He did the brake job and the vehicle braked fine.

Fast forward a month later and I had to get the vehicle inspected for a salvaged title in California, (my mom had an accident and they took her license away), and they said the rotors on there were too small and should be the 328 mm rotors! Now my mechanic is saying the only way to get the larger rotors on there is to replace the calipers.

The inspection shop showed me a printed copy of the disc diameters. But ECS Tuning website is showing the size to be 324 mm. HELP! Thanks and have a good weekend everyone!



-Eugene

[CSMBlack-540i]

They should be 324mm (324X30)

http://www.realoem.com/bmw/enUS/show...diagId=34_1123

but why would 4mm difference in sizing affect inspection. People customize their cars all the time. 4mm larger is even better. Do they actually measure calipers during a Cali inspection?

[SchnellBMW]

That's the issue apparently. The spec sheet says 328 mm but my mechanic says he can only fit 324mm. I guess they do measure brakes for Cali inspection.

- - - Updated - - -

This is what the guy from the inspection shop showed me.

20190517_121044.jpg20190517_121054.jpg

[CSMBlack-540i]

I would dispute that info that inspection shop has since even Brembo has 324mm as the specs: (realoem and brembo info match so Inspection station data if incorrect)

https://www.bremboparts.com/america/...0i-base/006154

[Jaaap]

This is what the guy from the inspection shop showed me.

20190517_121044.jpg20190517_121054.jpg

That's about rotor thickness.
Your mixing thickness and diameter in your question.
The diameter is 324mm == 12,756"
The minimal thickness is 28.4 mm == 1.118"

I guess your rotors are too thin because your mechanic turned the rotors?
Strange move from the mechanic.

[CSMBlack-540i]

That makes more sense:
https://www.bimmerforums.com/forum/s...-and-measuring

and explained here about 1.6mm wear level

https://www.bimmerfest.com/forums/sh...15&postcount=6

[SchnellBMW]

I'll ask him about it. I don't know what to do. If that's the case, I'll need new rotors again? This is getting to be a pain in the arse!

[CSMBlack-540i]

44k miles on the OEM sounds about right. You never mentioned the mileage on the new rotors though. Anything over 25K miles depending on driving styles is possible. Could also be a sign of pads binding too.

[Jaaap]

I'll ask him about it. I don't know what to do. If that's the case, I'll need new rotors again? This is getting to be a pain in the arse!

I wouldn't go back to that same guy unless he promises to make it right, without turning the rotors.
Maybe he couldn't push the pistons back far enough, maybe the wrong (thicker) pads were ordered?