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gnhovis
08-06-2006, 07:54 PM
I set out this weekend to replace the rotors and brake pads on the E30 convertible. The rear end didn't present any challenges (other than the sheer amount of corrosion I had to clean up), but not so when I got to the front. Once I got the corrosion scraped off and I could see the rotor retaining screw and I could see it was stripped. Not having a better plan, I decided to drill off the head so at least I could get the rotor off. I finished the pad install, and put on the new rotor with about 1/8th an inch of the old screw still sticking out of the hub. The stub didn't hold the rotor, but at least it stopped it from spinning when I pressed the rotor against the hub. Same thing happened on the other side.

So here's my question: Does the retaining screw matter? Can I live without it or am I better off drilling out the rest of the screw and retapping it?

BahnBaum
08-06-2006, 08:08 PM
I don't think there's any need to fix it from a safety standpoint. It's really only there to avoid the hassle of lining up the rotor with the hub when mounting wheels.

Alex

SharkD
08-06-2006, 08:13 PM
The rotor retaining screw definitely matters (it prevents the rotor from slipping while you are replacing the wheel -- if the rotor isn't seated properly, it could lead to a bearing failure from the wobble), and should be replaced every time you remove/replace rotors.

I would strongly suggest going to Sears and getting a set of drill-out stripped head remover bits, that way you don't have to destroy the threads in your wheel hub.

When tightening the new screw -- like the bleed screw on the calipers, it only needs to go finger tight + ¼-½ turn.

John in VA
08-06-2006, 08:36 PM
A dab of anti-seize on the new screw will help, too.

hoyabmw
08-06-2006, 10:12 PM
The rotor retaining screw definitely matters (it prevents the rotor from slipping while you are replacing the wheel -- if the rotor isn't seated properly, it could lead to a bearing failure from the wobble), and should be replaced every time you remove/replace rotors.

I would strongly suggest going to Sears and getting a set of drill-out stripped head remover bits, that way you don't have to destroy the threads in your wheel hub.

When tightening the new screw -- like the bleed screw on the calipers, it only needs to go finger tight + ¼-½ turn.

Actually, as Alex said, it really doesn't do anything but hold the rotor in place when changing the wheels. If you run wheel studs (you are running them on the race car, aren't you?) they're useless. Torquing the wheels evenly is all that matters for both the rotors and the wheel bearings.

If you do use them, use anti sieze on the threads to prevent their getting stuck, and only put them in finger tight--NEVER use tools to tighten them down.

I pitched mine about the time I put in the studs. I was running without them for a while before that, because I forgot to order new ones. Never had a wheel bearing or rotor failure related to that. Just make sure you properly torque the wheels.

Kevin
'90 325i

Nick325xiT 5spd
08-06-2006, 10:32 PM
Mine are gone on the race car. Why add an additional and unnecessary point of failure?

SharkD
08-07-2006, 10:39 AM
Since gnhovis's E30 is a convertible, it's pretty unlikely that the car is racing, so I presumed that he's (she's?) using lug bolts, rather than studs. I was answering his street car question, rather than addressing racing practices.

I kept the screws --they're the originals from when I bought the car -- because it makes life that much easier to keep the rotors true when you're rushing to swap your practice tires for qualifying rubber when time is tight between sessions.

gnhovis
08-07-2006, 11:18 AM
Thanks for all of your replies. Definately not a race car. Hopefully wheel changes will be infrequent, so I'll probably leave it as it is for now. I was concerned that there was some other safety issue I was missing.

1996 328ti
08-07-2006, 12:18 PM
Thanks for all of your replies. Definately not a race car. Hopefully wheel changes will be infrequent, so I'll probably leave it as it is for now. I was concerned that there was some other safety issue I was missing.Only safety issue is it falling on your toes.

hoyabmw
08-07-2006, 02:05 PM
Since gnhovis's E30 is a convertible, it's pretty unlikely that the car is racing, so I presumed that he's (she's?) using lug bolts, rather than studs. I was answering his street car question, rather than addressing racing practices.

I kept the screws --they're the originals from when I bought the car -- because it makes life that much easier to keep the rotors true when you're rushing to swap your practice tires for qualifying rubber when time is tight between sessions.

I knew his was a street car. The stud question was actually aimed at you, but hard to pull out in the quote. I have never had any problem with the rotors moving when the wheels are off. To each his own with a racecar, but gnhovis's problem shouldn't hurt anything.

The next time the wheel bearings need replacement, you'll have a fresh shot at it. If you're not changing the wheels very often, I wouldn't worry about it, and you should have a tool in the trunk toolkit to help line up the wheels anyway, which becomes much more useful when the rotor locating screw is missing.

Kevin