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 crazy. 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!

[Dr. evil]

i belive you are right o n turning the rotors as long as they have enough metal.

you should check the rotos with a dial indicator to see if they really are warped. in some cases the ABS makes it feel warped

[Bill R.]

run cooler or dissipate heat better. The factory vanes internally in the rotor have the greatest effect on cooling.
The minimum thickness of the 540 rotor on the front is 26.4 mm and the maximum you are allowed to machine off of a new rotor is .8 mm or 31 thousands total. Not much. If its very warped it won't clean up.



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!

[derick]

I don't think that cross drilling and sloting has anything to do with cooling the brakes. in fact if you want that use an M5 retrofit and the ducts direct air at the hat of the rotor. Cooling the disc apparently does nothing.

what the drilling and sloting is for is to make better pad contact. During hard braking a gass is formed and causes the pad to "float" on the rotor instead of making full contact. the drilling and sloting make a way for this gase to escape and hence better pad contact.

[joshua43214]

I don't know what horror stories you have heard abuot e34 brakes warping, its no worse than any other car. I use nothing but OE rotors and make frequent hard stops from over 100mph when I turn the music up too high. Have yet to have a brake fade or fail, I get 2 sets of pads per rotor and don't turn them between pad replacement. I let them cool off before I park the car though. As stated above, most of the cooling comes from the vents, adding holes to the rotor won't substitute for proper care of the brakes. Keep you left foot off the pedal, let the rotors cool down after hard driving, make sure the calipers move with thumb pressure and you wil be fie.

The brake system on the e34 was one of the selling points of the car originaly, it has a tremendously short braking distance. Every time I drive my mothers '03 300M, it feels like it has no brakes at all by comparison.

Cross drilled rotors give you bragging rights and not much else, modern pad material doesn't gas as much so the whole idea of better gassing is really only a track issue.

[Qube]

Really then? I have Zimmer and PBR Ceramics... now that they are COMPLETELY worn in, I love them!

[uscharalph]

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.
I went with Bremo rotors. A pair at a time. Cross drilled seemed like overkill. You go through pads quicker.

[sKilled]

I think the dust issue is because of the soft pads which is a good thing (better braking and less disc wear) - I have stink normal discs but a huge layer of dust on my wheels. When I repair my front end (still a little pissed at myself) I will waterblast that crap off as I think it is messing with the balance of my tyres. Unless you are racing, go with stock, they were chosen by BMW as they work best.

[genphreak]

I think the dust issue is because of the soft pads which is a good thing (better braking and less disc wear) - I have stink normal discs but a huge layer of dust on my wheels. When I repair my front end (still a little pissed at myself) I will waterblast that crap off as I think it is messing with the balance of my tyres. Unless you are racing, go with stock, they were chosen by BMW as they work best.I don't like cross-drilled either, they don't allow pads to last and you can't machine them.

Porsche may do it, but check the prices of their services- I suspect they would be tempted to be replacing rotors and pads together every 40,000km.

Hmmm $25 each for the Opparts front rotors eh?

Does anyone know what a pair of 540 rotors are worth for the rear?

BMA quoted me rears (34 21 1 165 265) for $49 each last time... which makes them twice as much for half the metal!

Is this true? Thanks, Nick

[tasman]

Has anyone used the Power Slot rotors. I have read a lot of good comments on them. Right now http://www.thepartsbin.com/ has them for $98 and free shipping. The grooves are supposed to keep gases from building up between pads and rotor surface. As a side note, most mechanics do not turn rotors anymore. Quality rotor are so inexpensive and the problems are so numerous when turning, that it does not make it worth while. The few that do turn, only turn while mounted on vehicle, as most believe this is best way.

TasMan

[tim]

Here's what I paid at BMA (FWIW)

4 Opparts rotors, Mintex pads, 2 sensors, anti squeal = $260 (includes bimmer.info group discount)

Shipping was free.

-tim

[tasman]

Here's what I paid at BMA (FWIW)

4 Opparts rotors, Mintex pads, 2 sensors, anti squeal = $260 (includes bimmer.info group discount)

Shipping was free.

-tim

How much of a discount do they give and how do you get it??

Thanks
TasMan

[genphreak]

Here's what I paid at BMA (FWIW)

4 Opparts rotors, Mintex pads, 2 sensors, anti squeal = $260 (includes bimmer.info group discount)

Shipping was free.

-timDamn cheap. I don't suppose you have any idea what the shipping weight of all that was? :) Nick

[Anthony (M5 in Calgary)]

I don't like cross-drilled either, they don't allow pads to last and you can't machine them.

Porsche may do it, but check the prices of their services- I suspect they would be tempted to be replacing rotors and pads together every 40,000km.



My M5 got new OE (not OEM, OE) brakes and rotors all around at 103,000km in October 2000 and they now have 162,000km. The pads still have about 30% remaining thickness but the front rotors are worn slightly below minimum thickness. I'll be replacing rotors and pads together. Considering how much dust these pads make it is surprising they lasted so long.

This wear pattern is consistent with all BMWs I've owned over the years regardless of what pads I used. Tried skimming warped rotors on the '88 325iS and they warped again in about 5,000km.

I'd say don't bother turning BMW rotors, full stop.;)

[Beemr750]

Six years ago I replaced my brakes with Jurid pads and Ate rotors.This year after 63k miles my front ones alerted me to be worn.Besides dust I had the best of service with the combination.
After shopping around for dust free GOOD pads, decided to get QS type. Stupid me let the sales person talk me in to also get Raybestos discs.The price was about $40 a piece.Well after 3k my frt brakes started give me pulsating signals at high speed braking.Not much later I took them and had them turned at a friends garage.It did not take much to smooth it out. Now 1500 miles later the same **** is coming on.

I was looking for ATE's to no avail in the internet,They all claim to be out of stock.But I found Balos for $42 a piece and no freight.
I like the QS pads so far, also will use them on the rear; when they're gone, with Balos.Since Balos are OEM I expect to be OK for years to come without much dust.

[tim]

How much of a discount do they give and how do you get it??

Thanks
TasMan


You just have to say you are a bimmer.info member. When you call the first time and open an account just tell them (and I recommend calling, since Yves and Patrick are very smart and can often help you in making a choice or avoiding a mistake).

The discount in this case was about 20 bucks ~ 7.5%. It varies as I don't think all parts qualify. I'm not really sure what the exact deal is, but between not having to pay sales tax, and free shipping over $50, it's a pretty good deal anyway.

[BillionPa]

I will be replacing my rotors in about 2 weeks with "frozen" powerslot rotors.

Powerslot used Balo front and Brembo rear disks, then they are balanced and slotted, cadmium plated, and shipped to Diversified Cryo where they are cryo treated at -300F and then heat cycled.

They are supposed to be the best rotors for the dollar and last about 3 times longer than stock OE rotors.

I will report on their awesomeness after I break the pads in.

[tim]

IMHO,

For street use, "spirited" or otherwise, the single most important factor affecting rotor longevity is proper torque on the wheel lugs.

I think that's what brought about the demise of my Zimms. I took off the snows about 2 months ago, and although I usually retorque them after my tire guy, I forgot this time. Didn't take long. My tire guy is not a bad wrench, but his impact wrench get's plenty of use and it's just not BMW reliable. Do whatchagottado- but make sure those lugs are true to torque before you spend big money on any brake components.

On that last part, orient the wrench so you are pulling up, not pushing down. Make sure the car can't roll at all. My breaker bar has a socket head on both sides, so you can do it no matter which side you're on. I get a better sense of torque when pulling versus pushing.

Another, less obvious issue in rotor wear and diagnosis of "wobbles", is the wear pattern that BMW's make on tires and the effect it has on wheel balance. There's no avoiding it, and don't rotate them, but the outside fronts and the inside backs obviously wear very quickly ('specially on a 540:D ). Not the end of the world, but people often forget- if it was last balanced when it was new, and there's clearly alot of rubber now gone, what are the chances it's still balanced? Slim I'd say.

I'll post some pix of the new stuff and my R&R when it gets here. I should be recovered from sanding and painting the bottom of my boat by then. Right now I'm doing beer therapy, and the wife has promised a "JFK back treatment".

I can barely lift my arms right now.

[tasman]

You just have to say you are a bimmer.info member. When you call the first time and open an account just tell them (and I recommend calling, since Yves and Patrick are very smart and can often help you in making a choice or avoiding a mistake).

The discount in this case was about 20 bucks ~ 7.5%. It varies as I don't think all parts qualify. I'm not really sure what the exact deal is, but between not having to pay sales tax, and free shipping over $50, it's a pretty good deal anyway.

Thanks:D

[joshua43214]

I don't have an impact wrench. It's tough to find a 1/2" drive socket torque wrench that'll do 200+ ft/lbs, but it you top out all five in the star pattern on the typical beam wrench at 150lbs, and take it another couple degrees with a breaker bar you'll be in the ball park. Most importantly, they'll all be about even. On that last part, orient the wrench so you are pulling up, not pushing down. Make sure the car can't roll at all. My breaker bar has a socket head on both sides, so you can do it no matter which side you're on. I get a better sense of torque when pulling versus pushing.



I had to read this 2 times before it sunk in.

Ummmmm dude, I hate to break it to you, but, you need to put the beer down.

the old spec for wheel torque was 72 foot pounds, a service bulitin was released raising that to 87 foot pounds.

I'd be getting the torque wrench out again if I where you.

[BillionPa]

monkey wrench for monkeys, got it!

[BillionPa]

Anyone using wheelmates and know if you need to torque the lugnuts tighter?

[tim]

Err, brain fart there. Thanks for pointing that out. Post edited. It's amazing how much sense things make in the morning when sober.

-tim




I had to read this 2 times before it sunk in.

Ummmmm dude, I hate to break it to you, but, you need to put the beer down.

the old spec for wheel torque was 72 foot pounds, a service bulitin was released raising that to 87 foot pounds.

I'd be getting the torque wrench out again if I where you.

[Gearhead]

Well this is good to know....headed outside w/my torque wrench right now to get them up to 87.

Thanks!!

[Gearhead]

Okay, so I just installed the thrust are bushings (Polyurethane) and all 4 rotors. Wow...it's a different car. Before I was almost afraid to step on the brakes as I thought I would loose a filling or two. Now she stops smooth and fast!! I'm loving it.

Now I'm so pissed off at the old front rotors that I want to take them to the range and "x-drill" them with my .40 calibre. I can't believe they were that badly warped. I have no idea what brand they were as the PO had them installed with the last Brake job, but I hope these Zimmerman's do better.

[DallasBill]

Just thought I'd resurrect this thread to give an update. I was just talking to BMA to get a better feel on the Opparts discs. Apparently they are from China and BMA was guaranteed they were made with quality steel. They have sold a lot of them, going back a year now. So that means there's got to be 10-20k miles on some of them out there. They haven't had a single complaint or return.

When you consider that they are 1/2 the price of the other OEMs, how can you go wrong?

[94_e34_525i]

There made in CHINA! thats whats wrong, I am sorry nothing but German parts goes on my car, even American parts make me feel uncomfortable. I dont care if its 27 per rotor I'd rather spend 70 a pair on ebay and get Brembo discs. The funny thing is that I was on the forum trying to figure out if the opparts were indeed from China!

[Toomas]

There made in CHINA! thats whats wrong, I am sorry nothing but German parts goes on my car, even American parts make me feel uncomfortable. I dont care if its 27 per rotor I'd rather spend 70 a pair on ebay and get Brembo discs. The funny thing is that I was on the forum trying to figure out if the opparts were indeed from China!


Isnt Brembo "Made in Italy"?

[genphreak]

Isnt Brembo "Made in Italy"?Chinese tooling for mass production of disc rotors is probably German. VW setup the auto industry there with old tooling from Germany. The tooling making those discs is probably as good as any, if not newer too.

The spin people put on this is enormous.

The truth is the machines are not operated by Germans and a good operator can work the machine to get the right tolerances and keep desired output consistent. Anyone else cannot extract this even if given 10 years to work out the nuances of the machine.

I think I'll avoid Chinese parts for my BMW always.

And before anyones says Balo/Brembo, yes I would even have trouble buying Italian parts... though probably unfairly. :) Nick

[Bill R.]

rotors made in italy , china, spain, poland, mexico or brazil
Check here (http://www.brembo.com/ENG/AboutBrembo/InvestorRelationsFinancialInfo/LetterfromtheChairman/shareholdersnewsletter2.htm)






There made in CHINA! thats whats wrong, I am sorry nothing but German parts goes on my car, even American parts make me feel uncomfortable. I dont care if its 27 per rotor I'd rather spend 70 a pair on ebay and get Brembo discs. The funny thing is that I was on the forum trying to figure out if the opparts were indeed from China!

[nuclearfusion]

This is why I use exclusively Balo brake discs. No question where they are from (Germany) and to go along with this they are usually a few $ less expensive than Brembo.

Enjoy!

Fusion

[shuriken]

The only thing i'd question about Chinese discs is the metal quality. It's not gonna be German or British. The tooling I don't see as an issue. It's the metal that grips with the pads. Stainless Steel was a big favourite on motorcycles up to the mid 80's coz it didn't rust and lasted. But with the advent of the new breed of sports bikes the discs now have more iron in them, get a bit of surface rust but boy do they grip. 0-100mph and back to a stand still in 10 seconds is what your looking at on most big bikes now. Crossed drilled and groved discs are to get rid of gas build up and to also cean the pad surface. Pad wear is slightly higher as a by product but thats coz the disc is abrasive on the pad from the holes or grooves. ATE, Brmbo, EBC are al good disc makers and you should notice a difference with any of them. Bottom line is how hard do you brake, and how often?
BMW say their discs are a consumable item and two sets of pads to every disc replacement, because they use a 'soft' metal which is quite grippy.
Also replace discs on the same axle, same as pads. Cures any uneven grip and pulling on the steering. Different discs at the rear is no problem. Personaly i'd have cross drilled or grooved, ie ATE at the front if I was going that route, far bigger breaking forces on the front wheels. Same as on the bike, i very rarely use the back brake, but thats a different issue.If you want to stop fast also use good tyres, unbelievable the difference good rubber makes, after all, it's the tyres that stick to the road.