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      01-10-2011, 11:45 AM   #7
Mr. 5
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Drives: M3
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2007 e90 335i  [4.00]
Originally Posted by acnhdernegw View Post
NIce review as always Mr. 5!! You ever rememver to ask for me if the rotor fit 335xi with no prob ?
Sorry, but I guess it slipped my mind.
If the 335i rotor is the size as the 335xi rotor then I don't see an issue.

Originally Posted by 1QuikWS6 View Post
Have they ever done an FEA Analysis of the slotted areas with the integral thru holes to see anticipated stress and breaking point at the very thin web that is left?

I understand the concept and the reason for this design, but in the case of just slots alone - the slots may be 1/16" deep out of the total 1/4" thich rotor surface, or in the case of thru holes alone, you still have the total 1/4" thickness - weak point would be between the holes.

But with this design, you have the depth of the slots (which looks to be more than 1/16") and then they drill out the web thickness that is leftover even more with the thru holes - resulting in a very thin web that is actually left between the holes at the bottom of the slot.

These areas will be very prone to cracking in the thin web area between the thru holes in the slots. You may get away with it on street only brakes - but I wouldn't use them for continous hard track use without having the results of the FEA prove a safety factor of at least '4'

I also understand the concept behind the centrally located hat mounting tabs - so that you can switch the directional rotors side for side - but why would you want to?

Only reason I can think of is if say you had a damaged right rotor - you could swap over the left rotor and only need to buy (1) replacement rotor - but normal practice is to replace rotors in pairs...

Not tryin to bash their design - just throwin some observations out there.
I'll talk to them about the FEA analysis, but there hasn't been a cracking issue with this design, but for reference, this picture is after 6k miles of driving and a track day at Laguna Seca (which I believe is pretty hard on the brakes).

Also, you are somewhat correct with the center mounting. If you need to use them on either side then you can, but look at how the air can enter the inner diameter of the rotor. If the hat bolts to one side then usually the air flow (for cooling) can only enter from the inner side of the rotor.
Since RacingBrake mounts in the middle, the air entering the rotor can be drawn from the inner side or outer side.
e36 M3 Coupe, e36 325i Sedan
e90 335i--SOLD

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