Can slotted rotors be cut/turned/machined?

[rxrep]

Just wondering. Anything special needed to know... if it is possible?

[Papachristou]

it was my understanding that they cant be machined down because the lathe will bump into the slot or hole...

[Gallep]

it was my understanding that they cant be machined down because the lathe will bump into the slot or hole...

I concur.

[Matt@JHM]

it was my understanding that they cant be machined down because the lathe will bump into the slot or hole...

Lathes have no problem with interrupted cuts. It should be fine.

[Gallep]

I would just replace them regardless. Considering what rotors do for you'd I'd always go new.

[Papachristou]

LEE has stoptecs though... probably not as cheap

[F16HTON]

FWIW my Alcon rotors are $395 each to replace and I go through a set every year.

[Gallep]

FWIW my Alcon rotors are $395 each to replace and I go through a set every year.

Holy shit, that's a ECS Stage II BBK every year. My Jewish Balla ways can't hang with that.

[dougyfresh]

Lathes have no problem with interrupted cuts. It should be fine.

Coming from a Machinist himself. Case closed.

[absolutegtr]

The lathe cuts at a fixed step. It should be fine.

[Papachristou]

maybe its because i live on the arkansas/tennessee border... they dont know about our fancy slotted and drilled rotors, the shop said "I aint never seen no brakes likes them! i dont think we can grind on those!"

just joking, i would never let anything of these shops touch my car!

[F16HTON]

Holy shit, that's a ECS Stage II BBK every year. My Jewish Balla ways can't hang with that.

That is just the rotors, you also need to factor in the pads too, when it is all said and done, it is a $850 trip to Napa to see the guys at STaSIS (they are all terrific though)

The rotors are cheap in comparison to the stops at Union Square (Macy*s, Nordstrom, Cartier, Chanel, Hermes, Saks) for shopping with Tracee afterwards.

[pondside36]

A good machinest should hav no issues with turning down slotted rotors.. is it a good option not sure..

[rxrep]

It's not on the Audi. The wifey's DD has slotted, and if they were not slotted.... I'd for sure get them cut (some glazing and aone small line of pitting). But they are fairly new and I don't want to replace just yet. Putting new pads on and I figured I'd get them done while I'm at it if it is possible.

I didn't say it was for the audi in my initial post so I could get answers before mods moved it to "General Auto" purgatory where no one would answer it.
Local tire place said no problem, but I wanted to make sure because I've never heard of it being done before.

[04QuattroTurbo]

I wouldn't turn my stock ones, nonetheless a drilled and slotted one. A shop charges me on average $40 a rotor to turn, I think someone here said that the stock Audi are $55 a piece...for $15, why not. On my Toyota Tacoma, the front rotors were $86 for the set, at $40 a rotor to turn, it simply did not make sense. With that truck, they turned it twice since, everytime I would brake and car would pulse and vibrate hard, indicating a warped rotor, it easily went away when I replaced the rotors with new ones.

[CyberPMG]

Most shops that offer rotor turning service will use a bench grinder. Problem with that is that they cannot guarantee a level surface and consistent thickness around the entire rotor. That's why turned rotors can feel like they are warped (they are - from the bench grinder).

The only type of rotor turning I've been told that is good is to have the rotors turns while they remain on the car. They must use a different type of grinder that can provide consistent results. Problem is that almost nobody has the ability to do this. That's why it would be better to simply replace the rotors when the time comes.

I was looking at this for my Stoptech kit this spring (had some heat cracks). Decided to replace the rotor rings instead. Found a great price on replacement rotor rings for BBKs (Stoptech, Brembo, etc.) over at www.racingbrake.com.

[dirtybrd]

I've cut mine before, so I know it can be done.

[04QuattroTurbo]

I've cut mine before, so I know it can be done.

But is it worth it? What is the savings v. a new one?

[dirtybrd]

Well it depends on the cost of a new one and how much material has to be removed off your used one to make them flat again.

[04QuattroTurbo]

Well it depends on the cost of a new one and how much material has to be removed off your used one to make them flat again.

Like I said, from what another member here has said, it costs $55 a rotor for a new one. Wheel Works in Northern California charges $40 a rotor to turn.

[A4TL]

lol some a-hole superman impacted the brakes on my car (PO) so i had to turn them 3 times to get them straight. sand down the ebc green junk and they went from warped to fine for a year. got tired of the squeal and moved to b7 A4 calipers and new solid rotors/pads all around. no more school bus and great stopping power.

but the old ones were slotted and warped pretty bad. they came clean. dunno why people think its smart to use an impact gun on our cars.

[04QuattroTurbo]

lol some a-hole superman impacted the brakes on my car (PO) so i had to turn them 3 times to get them straight. sand down the ebc green junk and they went from warped to fine for a year. got tired of the squeal and moved to b7 A4 calipers and new solid rotors/pads all around. no more school bus and great stopping power.

but the old ones were slotted and warped pretty bad. they came clean. dunno why people think its smart to use an impact gun on our cars.

Good to know, since I am a avid Les Schwab customer and they always use an impact wrench...

[brewmastr]

well you can cut drilled/slotted rotors no problem, but you say this is for the wifeys car, what kind of car are we talking about here, benz and bmw usually by the time your first brake job comes the rotors are below minimum or right at minimum thickness, i would say 95% of the brake jobs i do on benz's i sell rotors, so check into what the spec on the rotor is and measure it, depending on the car you may have to buy new rotors any how.

[brewmastr]

Most shops that offer rotor turning service will use a bench grinder. Problem with that is that they cannot guarantee a level surface and consistent thickness around the entire rotor. That's why turned rotors can feel like they are warped (they are - from the bench grinder).

The only type of rotor turning I've been told that is good is to have the rotors turns while they remain on the car. They must use a different type of grinder that can provide consistent results. Problem is that almost nobody has the ability to do this. That's why it would be better to simply replace the rotors when the time comes.

what in the hell r u talkin about lol, a complete retard can cut rotors perfect on a bench lathe, and almost every shop ive ever worked at has an on-car lathe. and the way a lathe is setup you tell it how much to cut, so how is it an unconsitant thickness if you take .004 off each side of the rotor. thats pretty consistant if you ask me.

[CyberPMG]

^^^It's based on a conversation I had with Stoptech tech support several months ago....

Machining the rotors is good way to clean them up, but not necessary if you are not experiencing a pedal pulsation or if there is not severe grooving in the part. If they must me machined, I recommend that an On-car lathe be used, as most bench lathes will cause more problems than they solve.

[dougyfresh]

/\
I've personally turned many rotors on a bench lathe. I learned in high school. It is super easy and accurate for daily driving usage. In fact, I had my S4 rotors turned on a bench lathe and they are perfect. I've heated them up quite good with some spirited driving and the pedal feel is fine.

Sometimes you have to read in-between the sales pitches when talking to vendors. Whether the individual is a 'technician' or not. I prefer facts over wordy sales pitches.

[pondside36]

lol some a-hole superman impacted the brakes on my car (PO) so i had to turn them 3 times to get them straight. sand down the ebc green junk and they went from warped to fine for a year. got tired of the squeal and moved to b7 A4 calipers and new solid rotors/pads all around. no more school bus and great stopping power.

but the old ones were slotted and warped pretty bad. they came clean. dunno why people think its smart to use an impact gun on our cars.

I don't get this post.. our rotors aren't bolted on, sandwiched between hub and wheel, and even if you used an impact gun to put the calipers on it wouldn't effect the rotors... Also how in the world would you get an impact wrench in there to bolt the calipers on

To keep with the thread, bench grinding rotors.... um yeah that would be a bad idea.

[UGwagen]

here is something you have to consider whether they are OE applications or aftermarket big brakes:

On OE, since the rotors these days are spec'd so thin when new, the difference between new & needs replacement is only 2-3mm total, including both sides of the rotor (depending on front, 3 or rear, 2).

Aftermarket big brakes, you have a similar issue. You may have enough that you think you can turn the rotors, but depending on the total runout before, the amount you need the shave off, can put you into the "needs replacement" requirement.

food for thought

[dirtybrd]

I've used both types of lathes and if done properly both will have great results. Yes most OE German car rotors will be under spec at the first brake job, or at least after they're machined so replacement is needed. OE rotors are very soft to help keep noise to a minimum. When cutting a rotor, usually only a few thousandths on an inch are needed for them to be true again. As for using an impact on wheels, it can cause a warping issue if the person using the impact doesn't have a good feel for their tools due to uneven torque being applied the the rotor hat. I personally use a 3/8 air and sometimes an electric impact on customer and my own wheels. I have developed a good feel for my gun and have never had an issue.

[smarrick]

I've used both types of lathes and if done properly both will have great results. Yes most OE German car rotors will be under spec at the first brake job, or at least after they're machined so replacement is needed. OE rotors are very soft to help keep noise to a minimum. When cutting a rotor, usually only a few thousandths on an inch are needed for them to be true again. As for using an impact on wheels, it can cause a warping issue if the person using the impact doesn't have a good feel for their tools due to uneven torque being applied the the rotor hat. I personally use a 3/8 air and sometimes an electric impact on customer and my own wheels. I have developed a good feel for my gun and have never had an issue.

Same here.

I think there is some confusion here know one actually uses a BENCH GRINDER
for brake rotors. BENCH LATHE like some said is correct. So ya I would never let anyone grind rotors they get machined or cut precisley.

I think you just heard them wrong. Or maybe you went to the shade tree mech a nic.

Ya there is no problem turning slotted or drilled rotors. I've done it before no prob.

Yes they are probably to thin to turn though.

[A4TL]

i (215lbs) could not stand on a 3foot breaker bar to get the lugs off. took a fat dude :) (j/k i am fat). seriously the kid was a bit heavier than me. i was pissed.

the pattern was bizzarre after the first grind. it was a half moon pattern. the other rotor was a more traditional warp cut.

i've never seen any decent wheel shop nor VAG mechanic use anything but a torque wrench (~89ft/lb) on my car. heck i even got that level of service on my old camaro (LS1) they even knew not to lift it on their pseudo-lifts after looking under the car to spot aftermarket headers (too low).

If you really know your impact gun you could get a good estimate on the wft/lb but undertorquing = lose your wheel. So yeah i'm sure some of you are badass but the $10/hour kids/folks that work at most shops probably don't even know how to set the impact up to come anywhere near 89ft/lb or perhaps they just don't care.

what i was taught was to torque to 89ft/lb (or somewhere around there) then after a few days re-torque. never had any issues since then.

only reason i turned the rotors was because i wanted to ensure it wasn't a suspension component really. i'm suprised the wheel bearings didn't take a punishment. or perhaps they did :)