Rear Rotors... Some new information for everyone

[JupiterBMW]

So, I recently purchased a full brake upgrade kit for my car. I chose the Turner cross drilled rotors as part of my kit. When the kit arrived, I was pleased to see that the rotors were StopTech SportStop rotors. The SportStop rotors are all created from Centric blanks which are direct OE replacement quality parts.

Well, much to my dismay, when I opened the box, I found that I had TWO left rear rotors. I figured it was a simple mixup and called TMS to verify and swap it out. They said that no, it was correct and that you use two left rotors on the rear. Now I was confused. The rotor not only had cross drill holes in it (granted, they're just for looks, but still!) but also, the cooling vanes in the center of the rotors were curved, further indicating a side specific rotor. I was very perplexed now, and somewhat upset at having 1 oddball rotor (it would look backwards compared to the other 3).

So, I called Turner again and asked them why this was the case. They said that all rotors for this car are like this. One part number for both rear rotors. They didn't have any definitive answers, but did say that ALL rotors would be this way. Hmm, ok...

So I called my local BMW dealer and spoke to my contact at the parts counter. I asked him to look and he confirmed that the OE replacement blank rotors showed only 1 part number for the rear. Same situation... He also said that the BMW Performance rotors are ALSO set up the same, only 1 rear part number. I confirmed that what he said was true, and mentioned how every car will have 1 rotor that is 'backwards'. He understood but couldn't make any speculations or guesses as to why.

Still unhappy, I called StopTech. The part number I received had an L on it, so clearly one must exist with an R instead... StopTech also informed me that there was only one part number for the rear rotors. I informed him of my concerns with the directional cooling vanes, and also the cross drill pattern... The long and short of his reply was that it came down to money. He said that ALL Centric rotors have to be made to OEM spec, and for whatever reason, BMW changed to only one part number for the rear rotors. He further explained that because of that, Centric also went to only one part number, to save on manufacturing costs. I understood this, but explained my concern with the cooling vanes and cross drilling and how one would be 'backwards'. He said "Yes, that's just how it is"...

The ironic part, I spoke with Charlie as he has this set of rotors from about a year and a half ago (he has them new in box as a spare set) and he has the correct rear rotor. So it does or at least did exist at one point. StopTech and Turner both said that there was no way to get that rotor anymore though.

So, basically, from what I have been told, if you order rotors for the rear of your car, plan to buy OEM blanks, or plan to have one with backwards holes...

The ironic part of all of this, on the StopTech website, if you choose to buy the PowerSlot slotted rotors, they show two part numbers for the rear, a left and a right.


Anyway, that's my story on rear rotors for our cars. They have directional cooling vanes, yet, you can only purchase one part number, which is left or right.

Feel free to post your questions in a reply or just gripe along with me... So frustrating.

[Hermes]

that sucks ridiculously... why would Centric make a directional vane in the rotors then not adjust it to straight vanes when they drop to 1 part number

An option that goes around this are the Performance rotors (albeit expensive). Rears have straight vanes and therefore are not directional (also the pattern of drilled holes makes it easier to not have an issue with how they look despite what side they are placed). Here are my rotors when I installed them

http://i29.photobucket.com/albums/c288/jhermes/zhp%20projects/DSC_1272.jpg

[UdubBadger]

^ seems like a better idea anyway

[wsmeyer]

That blows. The BMW Performance rear rotors are drilled like the Hawks above and are unidirectional. I've never looked but I assume the veins are straight.

*** never mind. In the little pic on my phone I didn't realize those are BMWP rotors.

[JupiterBMW]

^ seems like a better idea anyway

BMW Performance rotors? Yes, it does, but damn, they're pricey! I can't justify upwards of $1000 for brakes when all I do is cruise around town. Unless you're talking about Centric not changing to straight vane.... Then yes, I completely agree...

The funniest part is that the front rotors are straight vane... The rears are the ones with the directional vanes... That is completely ass backwards...



That blows. The BMW Performance rear rotors are drilled like the Hawks above and are unidirectional. I've never looked but I assume the veins are straight.

*** never mind. In the little pic on my phone I didn't realize those are BMWP rotors.

You mean to tell me on that massive Galaxy SIII screen, you couldn't see the pic well??? Geez, so much for that phone being awesome! :rofl

[wsmeyer]

You mean to tell me on that massive Galaxy SIII screen, you couldn't see the pic well??? Geez, so much for that phone being awesome! :rofl

Relax fan boy. I was initially looking at the little inline pic in the post. After I actually opened the pic I realized what they were.

That whole kit is the end result of decisions based on $$ and justifying them with the belief that their customers wouldn't notice. Will definitely make me think twice about buying anything with their name on it.

[UdubBadger]

That doesn't seem right... I have stoptechs and all of mine are directional


- Goin' H.A.M. Mobile

[Hermes]

ZHP is at the dealer right now (driving a loaner '09 335i!), I will double check my rotors when I get the car back

[cakM3]

Yeah, I was in "text" discussions with Jon yesterday when Jon told me about this issue. I was shocked and, to tell you the truth, alittle upset by this stupid decision. Since I already have a set of BMW Performance rotors installed all around when they do go bad if I can't source a new rear set , I have an additional front set stored as spares, then I might as well install my spare Turner cross-drilled rotors....

At first it may seem ridiculous to have spares laying around but now after learning about this issue....I think it may be a good idea...

[JupiterBMW]

That doesn't seem right... I have stoptechs and all of mine are directional


- Goin' H.A.M. Mobile

Yes the correct rears used to be available, that's how Charlie has the correct part numbers too. This was something that had changed in the last year or so which is why if you order now, this is what you get.


Sent from my hybrid iPhone 4/4S... :shifty

[cakM3]

Funny....and sad how changes are made to important parts like directional rotors w/o anyone knowing until it's too late....:facepalm

[JupiterBMW]

Agreed Charlie...

Seth/JP & others... Would definitely like to have you all double check and post your findings here. I'd be curious to see if anyone is still selling any sort of correct, directional rear rotors...

[wsmeyer]

The straight ones in the front would bother me more than the reversed one in the rear. Sure it's more efficient to move air outward but I'd bet it still moves more air than the straight one's.

If you had an infrared temp gun you could measure the temp difference of the two rears after a couple hard stops. Would be interesting to know for sure.

William.

[JupiterBMW]

The straight ones in the front would bother me more than the reversed one in the rear. Sure it's more efficient to move air outward but I'd bet it still moves more air than the straight one's.

If you had an infrared temp gun you could measure the temp difference of the two rears after a couple hard stops. Would be interesting to know for sure.

William.

Yeah... I have an IR gun on the ship that we use frequently... I'll have to see if I can locate one of these here at home to do some tests. I too would be very curious. I have had cars in the past with straight vanes up front, has never been an issue before, but would be good to see what vanes/directions provide what sort of temperature dissipation... With all of the flat/straight roads here in Florida, it'd be the perfect place for these kinds of tests...

[328ioc]

Yeah... I have an IR gun on the ship that we use frequently... I'll have to see if I can locate one of these here at home to do some tests. I too would be very curious. I have had cars in the past with straight vanes up front, has never been an issue before, but would be good to see what vanes/directions provide what sort of temperature dissipation... With all of the flat/straight roads here in Florida, it'd be the perfect place for these kinds of tests...

Damn thats all so crazy.......

Also sounds like you need to find an IR gun drive an hour to my house then we can check them.

Sent from my DROID RAZR using Tapatalk 2

[JupiterBMW]

Damn thats all so crazy.......

Also sounds like you need to find an IR gun drive an hour to my house then we can check them.

Sent from my DROID RAZR using Tapatalk 2

No, you need to drive to MY house, then we can check your stock brakes for a baseline. :biggrin

[Hermes]

I just called Tom and left a message, I think he still might have his old spare set of Performance rotors from before he sold his ZHP that we can check... will edit this later

[terraphantm]

I really don't think the 330 ever came with directional rotors. The brakes on my ZHP (which were original when I bought the car) had straight vanes all around. I don't doubt the stoptechs were once directional... sounds like they started producing only lefts to save money.

GM does the same thing on the corvettes. They come factory with two left rotors. Can someone post a picture of *factory* directional rear rotors?

[Jesse M]

Same here.. Ordered the Turner kit and received two rear of the same spec.. Called and got the same story you did. I don't care. I don't track my car enough to even bitch about it. If that's the way it is then that's the way it is. I'm very happy with the performance thus far though, considering the majority of heavy braking is front bias anyway.

Sent from my Samsung Galaxy S3

[JupiterBMW]

Terra... I don't have them or any photos, but my rear rotors had directional cooling vanes (and they were side specific, and correct for that matter, one left and one right...)

Jesse... Yeah man, I'm not concerned with the braking of it as I probably won't ever track my car, it just bugs me to see the backwards holes on one side...

[terraphantm]

Terra... I don't have them or any photos, but my rear rotors had directional cooling vanes (and they were side specific, and correct for that matter, one left and one right...)

Jesse... Yeah man, I'm not concerned with the braking of it as I probably won't ever track my car, it just bugs me to see the backwards holes on one side...

If you didn't throw them away yet, can you get the part numbers? (Should be stamped somewhere on the rotors themselves) -- I've been digging through old versions of the ETK (as far back as Feb 2004) and cannot find any that have L/R specific rotors (front or rear) for the 330.

I'm sure your rotors were directional, but I'm really doubting that's factory. No one else seems to have observed such a setup on these cars

[JupiterBMW]

Sorry man, I tossed them already. Besides they were rusted as hell and I couldn't make out any part numbers anywhere. I looked a little when I removed them.


Sent from my hybrid iPhone 4/4S... :shifty