Who here would have rotors turned vs replacing them?

[DaCan23]

I personally would not do it, regardless of the reputation of the shop turning them.

[632 Regal]

no way, they are a replacement item.

[Blitzkrieg Bob]

BMW made them with a narrow tolerance with not much left for the machine shop to cut.

[Jeff N.]

.

I personally would not do it, regardless of the reputation of the shop turning them.

[ryan roopnarine]

on the bmw, id just mic them and put pads on them. if its my mother's ford taurus, which eats rotors and makes the car shake like a mofo if you don't, i definitely do. ill be the lone dissenter and say, despite the fact that they are at least 10 $ less than the bmw, yeah, ill turn em.

[Alexlind123]

I want to ressurect this thread. I have new front brake rotors, with no groovers or even a lip. However, when i spin them with the wheel off, they seem to grab on part of the rotor. So, with new pads and fresh and smooth rotors, would it be prudent to turn the rotors? My thrust arm bushings have been replaced as well. OH, and they shudder or pulse when stopping. The pulsing increases in frequency with vehicle speed upon brake application. If i pass a 40mph hay truck and then have to brake from high speed because a school zone is coming up, it is more of a vibration than pulsation.

[Blitzkrieg Bob]

Your rotors are warped or your pads are contaminated.

do not pass go.

go directly to a parts shop and pick up a new set.

[Qube]

I agree... the shop can't turn them cheap enough to warrant not buying new ones :| And those that do, you probably don't want them to do it!

[Alexlind123]

Actually i feel it in my seat.

[BillionPa]

get some cryogenically treated rotors, they are almost unwarpable, unless you really cant drive without the foot on the brake, and last at least twice as long as stock..... for twice the price of course!

[BigKriss]

I would get them turned, its common practice here.

[pundit]

Certain vehicles should never have their rotors machined.
These tend to be mainly European vehicles. Mercedes, BMW, Audi, Porsche etc.
The rotor material used in many of these vehicles tends to relatively 'soft' which while, wearing faster, enhances 'bite'.

Basically the disc pads and rotors are designed to be replaced as a set.
It's common for the rotors to be out of spec by the time the pads need replacing.
Rotors can be obtained relatively cheaply, often for little more than the cost of machining a worn set, (unless you take your car to a stealer with a sign on your forehead which reads "I'm here, rip me off!") and it's almost guaranteed machined rotors will suffer problems like warpage within a relativley short period after machining them and fitting new pads.

There's been a couple of instances in the past few months where I was glad of the braking performance of my E34.
I don't inteed to ever compromise the braking system just to save $50.00! ;)

[Paul in NZ]

yes even here in lil ol nz rotors are cheap,cheaper than pads

[nizmainiac]

its not something that i would risk doing , i got brand newies for £80

[Bill R.]

new rotor occasionaly you'll find that you need to do a cleanup cut on some cars. I usually get it done for free or for 5 bucks or less if a car needs it.

In your case however i would venture to guess that you didn't clean up the wheel hub when you put the new rotors on and there's rust and garbage behind the rotor causing it not to sit perfectly flat on the hub making it grab on part of the rotor as you spin it. Look at the photos of the hub here in this post (http://www.bimmer.info/forum/showthread.php?t=17346&highlight=brake+rotor+hub)

If there are any high spots or rust built up then it will cause the new rotor to have runout which will make it grab in one spot as you apply the brakes.
If you have cleaned the hub and rotor up and then torqued the wheels properly and it still does it then you have a runout problem and should put a dial indicator on the rotor to see how far out it is. To check this youll need to put all the wheel bolts in with some washers on them to pull the rotor down evenly before using a dial indicator on the rotor. If you just use the one screw that holds the rotor to the hub the rotor is typically cocked a little since its only pulling on one side with that screw.



I want to ressurect this thread. I have new front brake rotors, with no groovers or even a lip. However, when i spin them with the wheel off, they seem to grab on part of the rotor. So, with new pads and fresh and smooth rotors, would it be prudent to turn the rotors? My thrust arm bushings have been replaced as well. OH, and they shudder or pulse when stopping. The pulsing increases in frequency with vehicle speed upon brake application. If i pass a 40mph hay truck and then have to brake from high speed because a school zone is coming up, it is more of a vibration than pulsation.

[Alexlind123]

new rotor occasionaly you'll find that you need to do a cleanup cut on some cars. I usually get it done for free or for 5 bucks or less if a car needs it.

In your case however i would venture to guess that you didn't clean up the wheel hub when you put the new rotors on and there's rust and garbage behind the rotor causing it not to sit perfectly flat on the hub making it grab on part of the rotor as you spin it. Look at the photos of the hub here in this post (http://www.bimmer.info/forum/showthread.php?t=17346&highlight=brake+rotor+hub)

If there are any high spots or rust built up then it will cause the new rotor to have runout which will make it grab in one spot as you apply the brakes.
If you have cleaned the hub and rotor up and then torqued the wheels properly and it still does it then you have a runout problem and should put a dial indicator on the rotor to see how far out it is. To check this youll need to put all the wheel bolts in with some washers on them to pull the rotor down evenly before using a dial indicator on the rotor. If you just use the one screw that holds the rotor to the hub the rotor is typically cocked a little since its only pulling on one side with that screw.

Thanks, i will try that. The only reason i would consider getting them turned is that the pads are new and the rotors look pristine, with absolutely no lip or grooving. My mechanic says that its better to get good rotors turned than to buy new, cheap rotors. That may not apply to our cars, especially since the Opparts rotors seem to be good...