Discs Hitting Carriers

#1

I was making good progress with the suspension and brakes until I got to this. I’ve got the rear of the car jacked up and was replacing the rear discs, which are OEM-spec by Brembo, and they went on just fine. But when I put the caliper carrier back on, the disc was hitting the far side of the carrier (or the side of the carrier closest to the center of the car). Not just really close, but completely mashed up against it. I tried the other side and the same deal.

I took them both off and tried again. Tried the driver’s side first and it didn’t rub this time (why it fit now and not before, I don’t know, there isn’t really much to do in the way of adjustment. The little 5mm allen screw was tightened both times, so the disc was all the way on there). Still, it wasn’t centered in the notch of the carrier, there was much less room on the far side. Enough to put a few sheets of paper between the disc and the carrier, but the close side had far more space. I tried the passenger disc a second time, but it hit the carrier the same as the first time.

I measured the thickness of the new and old rotors, as well as the hat, and they’re all the same. The old discs were probably on the car for some time and were pretty worn, so I’m thinking that’s the reason they weren’t rubbing on the carriers when I bought the car, if something is indeed out of whack. Not really sure what to do now. If anyone’s got any suggestions, it sure would help. If I can get out there and take a picture or two, I’ll post them up.

#2

I can’t think of a way that you could have put the carrier on wrong. Which makes me think that you don’t have the correct rotors.

#3

does sound like the carrier is on cockeyed though…
bruce

#4

The carrier is the same part # left-to-right but if the car was apart for awhile, and the carriers were separated from the calipers you might have found an ingeniously wrong orientation. Make sure that the carrier and the caliper fit properly together then reattach the carrier to the car.

#5

Well I went back out and tried a few things. First I swapped the carriers and put them on that way, even though they should be the same. It didn’t really change anything. The pass. side still hit and the driver’s side wasn’t really centered in the notch very much. So I took off the new rotor and put the old one back on along with what was originally the driver’s side carrier.

Well guess what - it was centered, at least in the bottom notch. A little pushing on the top of the rotor and then tightening the upper bolt got it somewhere closer to being in the center of that top notch, although not quite. Still, it was closer than with the new rotor. I checked it at the lip, where it isn’t worn down. Same carrier, different rotor, two different results. That makes me think there’s something off with the rotor. I called the shop last week to make sure I got the right discs. The part number was correct.

#6

FWIW,
Had the same problem with some fancy aftermarket rotors. Got cheap Advance rotors and they fit fine. A careful comparison showed that the aftermarket rotors were not the same “height”.

#7

Fred42 wrote:

Awww SNAP! Gasman has someone new to accuse of cheating! :laugh:

I never woulda guessed, Pshrink… :wink:

Steve D.

#8

Fred - just so we know what brand to look for to spot the cheaters. Please tell Steve what brand they were and where you got them…:dry:

#9

Jimmy -

You know it’s M3 pads and rotors FTW. Plus I am working on a reflash of the ABS computer to help me with standing start launch control. Linux is fun.

Steve D.

#10

Run the Bosch Motorsport ABS, its like 6 grand, but what is money when it comes to plastic trophies.

The rule is gray here since it was technically homologated with the E30 DTM cars so you can call it a ‘factory’ part.

I even have an ‘authentic’ German repair manual that illustrates the factory process for installation.

#11

Went back out again. Measured everything about the two rotors. Laid them on a flat, level surface and placed a level across the two, so they’re the same thickness in both the rotor and the hat. For the heck of it, I tried Fred’s idea and picked up a single rotor at Advance. 38 bucks for one cheap Chinese-made rotor, whereas I got both Brembos for 50-something, but it was all the stores around me had in stock.

Stuck it on there along with the carrier and the rotor was centered bout as good as possible in the top notch. It was close to center in the bottom notch. I’m going to take the Brembos back to the shop and see about getting a German OEM replacement. Maybe I’ll have better luck with that? The Chinese rotors were a total pain to put on and take off, and they’re more expensive than the German/Italian stuff.

One thing that has me wondering about the carrier is this - at no time was any rotor really centered in the bottom notch, even though there is space on both sides of the Chinese one. Maybe twice as much space on the close side as there is on the far side. Should it really be in the very center of both notches? The consensus is the garage is 1 for yes and 1 for no. Does that sound fishy?

#12

is the mating surface that the rotor is up against clean? I don’t recall having any issues with putting on new rotors on any of my e30’s
bruce

#13

leggwork wrote:

[quote]is the mating surface that the rotor is up against clean? I don’t recall having any issues with putting on new rotors on any of my e30’s
bruce[/quote]

Yeah, I gave the new rotors a good shot of brake cleaner and a wipe down soon as I got em.

#14

Alright, Brembos are coming off and going back to exchange them for new Balos. Let’s hope these turn out better.

#15

IndyJim wrote:

I don’t remember the brand but there was a picture of a cute blonde on the box. Does that help? :silly:

#16

Alright, the Brembos went back and the Balos came in. They went on fine - no problems. Calipers, brake lines and the whole thing went on both sides without rubbing on the carrier. Of course, the car has exchanged one wacktastically hilarious problem for another, but I’ll save that gem for another time.

#17

Glad you got it fixed. FWIW, next time I pull my rear rotors I’ll make careful measurements of both that set (that fits) and the fancy set (that doesn’t) and post 'em.
–Fred