Rotor replacement

[tim]

I have the zimmerman x drilled rotors on my e39 540it. They have about 40k mi now, and I suspect my front right has developed a warp (usual symptoms felt during high speed braking, offramps, etc). Control arms etc. check out ok. Lip is there, but not excessive. Wear seems pretty even on all four. I've never been that happy about these rotors though, and I want to go back to oem.

Here's the question: I'm going oem on the replacements- do need to do all four? Is it safe to have oem on the front and cross drilled on the back at the same time. The Ned Flanders in me says do all four, but the Homer Simpson is trying to save some beer money.

[Bill R.]

*bling bling* crossdrilled rotors but in this case the backs are very unlikely to develop any problems. I would just change out the fronts if thats where the warp/distortion/hotspot is.

I have the zimmerman x drilled rotors on my e39 540it. They have about 40k mi now, and I suspect my front right has developed a warp (usual symptoms felt during high speed braking, offramps, etc). Control arms etc. check out ok. Lip is there, but not excessive. Wear seems pretty even on all four. I've never been that happy about these rotors though, and I want to go back to oem.

Here's the question: I'm going oem on the replacements- do need to do all four? Is it safe to have oem on the front and cross drilled on the back at the same time. The Ned Flanders in me says do all four, but the Homer Simpson is trying to save some beer money.

[yaofeng]

Ned Flanders will never be welcome in my house. Homer, however, can come any time he wants. But he has to bring his own beer. That's how cheap I am.

Do the front and see what happens.

[mholbrook]

I agree, just do the fronts. I think you will be fine.

[tim]

thanks guys,

I'll save some Duff for ya'

-tim

[632 Regal]

BMA has Opparts rotors for like 25 bux, seem okay so far.

[tim]

I talked to Yves and went with the opparts. He said they were pretty good and they haven't had bad reports. Tough to beat the price. I went with the mintex pads. Fingers crossed.

[Gearhead]

I have the zimmerman x drilled rotors on my e39 540it. They have about 40k mi now, and I suspect my front right has developed a warp (usual symptoms felt during high speed braking, offramps, etc). Control arms etc. check out ok. Lip is there, but not excessive. Wear seems pretty even on all four. I've never been that happy about these rotors though, and I want to go back to oem.

Here's the question: I'm going oem on the replacements- do need to do all four? Is it safe to have oem on the front and cross drilled on the back at the same time. The Ned Flanders in me says do all four, but the Homer Simpson is trying to save some beer money.

Hey Tim, quick question about your experience w/the Zimmerman's. I just installed a pair on the rear of my 540ia (the were terribly warped) and with the next paycheck, was planning on matching the front with the same (also warped). Why is it you were never happy about these rotors?

Now, I'm not going this route for the "bling" factor as I stil have the stock wheels. I legitimately was looking for a rotor that dissapates heat better than just vented (or slotted for that matter). I realize the x-drilling is to prevent brake fade, but additional heat dissapation is also a benefit. Living in Florida, all it takes is a good downpour and some hot brakes to wind up with warped rotors. Although this hasn't yet happened to any of my other cars here, I keep hearing horror stories about these E34 rotors that warp if you just look at them wrong.

One more while I'm on a roll...

What about just having them turned/resurfaced? I heard something about how the front rotors on our E34's cannot be turned as there's not enough "meat" on them to do so? I chalked this up as a shop trying to sell me rotors, but is there any truth to this?

[tim]

The cross drills were the previous owner's choice. They're nice, and if I lived in the mountains or tracked my car, I could live with them. Mine were too grabby and squeaked with the jurid pads like . Very dusty too. Mine developed a pulsing, that very slowly turned into a noticeable warp on my right front. Perhaps the lugs were torqued incorrectly. My car is tough on tires too, so maybe that could contribute. I'll get them rebalanced after I do the brakes.

With my wheels (the '99 stock "sport wagon" multispoke alloys), the bling factor is not there anyway, since you can't really see the rotors that well. I don't really care about bling but if I did I'd go for the four piston caliper setup which looks pretty badazz on an open wheel design like the M-Parallels.

The oem rotors, and anybody who makes them out of good metal to the oem spec like ate, balo, etc, are plenty good for street use. As far as your heat is concerned, I lived in dallas texas for years and had several BMW's there and never once did I have a problem with stock rotors. Bill R is out in AZ (where it's also hot) and a combo he likes is the oem (balo or whatever) and the Raybestos QS (or Akebono ceramic) pad.

Hope it helps,

tim

[Gearhead]

Thanks Tim, that does help. However some of the issues you had (noise and dust specifically) sound like they're related to the pads and not necessarily the rotor.

The only problem I had so far with the rear rotors is that the hole for the 5.5mm keep screw didn't line up with the hub. Not sure just how ctitical that is being that most cars don't even have keepers for the rotors (and the ones that do are for assembly line purposes), so I'm doing without. So far, no problem.

Now back to the question of "can we turn the front rotors?" Can anyone clearly tell me whether the fronts are "one and done" on these cars. I would think that so long as you mic them and there's enough thickness left, you could resurface, regardless of Zimmerman x-drilled or oem replacement. Anyone know differently?

Thanks!