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Resurfacing Rotors: on the car or off the car?

Joined
4 July 2004
Messages
1,189
Location
Augusta, GA
Hey guys,

I have heard that the nsx requires the rotors turned/resurfaced while they are still on the car?

Is this true?

if so, how does that compare do having them turned while off the car?

If the price is significent, do you get that much more value added for the money you spend vs just having them turned off the car?

thanks!

I am on a time constraint and trying to decide what to do. I currently have my car jacked up on jackstands and was going to remove rotors but trying to decide how should have them surfaced...

I have OEM 98'nsx rotors.
 
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Ah... I don't think that's even possible to do them on the car.

Why do you want them turned? It shortens the life of the rotor and if you don't have any vibrations from pad deposits then there is no reason to even do it. If you are changing to a different brand pad then just sand them a bit with 100 grit and/or brake cleaner and steel wool pads.

BTW: O'Rilleys Auto charges $14 a rotor to turn them and they did my slotted Racing Brake rotors. Carbotech recommended turning them before switching from Hawk pads. Didn't make a difference, the Carbotechs made bad pad deposits on the RB rotors anyway. They don't seem to play well with RB rotors for some reason.

For street use, you shouldn't get pad deposits as you're not getting them nearly as hot as I do with heavy track use.
 
Rotors can, indeed be turned on the car. I teach in a school that has an auto lab and they do it both ways. If the rotor is behind the hub necessitating the hub be removed to resurface the rotor off the car, an on-car system is used. Otherwise, a traditional off-car lathe is used.
Scoring in excess of about .06 inches, pulsating brakes, or extensive corossion are the only generally accepted reasons to turn rotors. It is not recommended to turn rotors when pads are changed.
 
Carrol Smith: THE MAN, no questions asked, sez: turn the rotors OR change the pads. Dont do both.
Lightguy: The humble follower sez; if you bring the rotors in for turning they will never magically meet factory specs. Please buy this (Chinese) rotor. IMO.
Unless you have warp (shimmy while braking) clean up the rotors with sand paper and put on new pads.
Lawyers; This is advice offered freely. Actual yes. Litigious no.
 
I'm so glad these corraborating testimonials on this. I have never subscribed to turning rotors; to me it simply takes away rotor life unnecessarily.

Whenever I've put on new pads I've only scuffed the rotors with sandpaper, and I've never had any problems with wear or performance (at least related to changing the pads).
 
I always measure my rotors when I replace the pads. If they meet factory specs I leave 'em alone. If they don't, they get turned. I assume the engineers have good reasons for publishing the specs they do. Most brake jobs I have to turn or replace the rotors.

On-car turning has a benefit over off-car turning if you dissect the numbers. The specification relates the bearing axis with the rotor face. However, there is tolerance at each interface between the bearing and the rotor face...from bearing to hub, hub to inboard rotor surface, inboard rotor surface to rotor face. Then there's the tolerance between the lathe axis and it's own interface. These little tolerances eat up the allowable total runout. A wee bit of rust anywhere in the mix can move you out of bed no matter how good the lathe is. When you turn rotors on the car, you eliminate most of the tolerances, and you can get much closer to "perfect" right off the bat. That said, I have always met factory specs by turning the rotors off the car, though I'm always closer to the limit than to nominal.
 
are the nsx rotors pressed on?

I took the calipers off and I can not get the rotors off. I also took the set screws off but the rotor will not break lose.
 
are the nsx rotors pressed on?

I took the calipers off and I can not get the rotors off. I also took the set screws off but the rotor will not break lose.

(assuming you have oem rotors), there is another hole on the center of the rotor that is threaded (by the screws you took off)... it's there to thread a bolt in and effectively "push" the rotor off if it's frozen on.
 
Why do you want them turned? It shortens the life of the rotor and if you don't have any vibrations from pad deposits then there is no reason to even do it. If you are changing to a different brand pad then just sand them a bit with 100 grit and/or brake cleaner and steel wool pads.

+1

If they need resurfacing I'd just get new ones.

Plus, isn't there going to be additional labor taking them on/off? Surely $14 couldn't be the actual price out the door...let's say 15 minutes of labor at each corner for r & r means another $20-30 and at $45 or so per corner I'd definitely purchase new ones for $80 each or however much they are.
 
I am hoping the rotors are just slightly rusted on and that is why they will not budge. I will take a rubber malet to them tomorrow and hope they break free enough to come off.

yes they are oem rotors. calipers have been removed. the set screws have also been removed.

does the rear axel bolt also have to be removed in order for the rotor to break free?
 
+1

If they need resurfacing I'd just get new ones.

Plus, isn't there going to be additional labor taking them on/off? Surely $14 couldn't be the actual price out the door...let's say 15 minutes of labor at each corner for r & r means another $20-30 and at $45 or so per corner I'd definitely purchase new ones for $80 each or however much they are.

$14 you bring them in....
 
I am hoping the rotors are just slightly rusted on and that is why they will not budge. I will take a rubber malet to them tomorrow and hope they break free enough to come off.

yes they are oem rotors. calipers have been removed. the set screws have also been removed.

does the rear axel bolt also have to be removed in order for the rotor to break free?

There really isn't anything to this....

1. remove caliper
2. remove caliper bracket
3. remove the screw (if it's still on there)
4. pulls right off - if not give it a whack to break it free

No axel bolt, nothing additional.
 
ok....... New(different) pad material = new surface on the rotor. Pads bed themselves into the metal. Now if you change what pad material you use and do not get rid of the old pad material embedded into the rotor you will have problems. There will be inconsitant drag coefitiant spots all over and your brake pedal WILL pulse even though the rotors are true.

Also. as far as turning them on the car, I dont reccomend it at all!! The NSX has a LSD rear end and hooking up a high torque electric motor to just one wheel is/could be hard on the LSD.

So take em off and have them turned.... its an easy job, and a machine shop should not be more than 30 for a pair.
 
The two holes that are NOT counter sunk are threaded. You can stick bolts in there and alternatively torque them down until the rotor brakes free.

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Thanks for all the replies! Jim thanks for taking time to take a photo. I just matched the caliper bolts to a longer set and just torqured and turned the rotors until it popped, breaking free.

Thanks again.

Dropped rotors off at oreileys $28 for all four turned!
 
When I bought my car 2 years ago, it had a terrible vibration during braking, so I had the front rotors turned and put in new pads, stops perfectly now. I've turned rotors for many years on dozens of cars and never had a problem, just as long as they are within tolerance, after turning.. If they are too thin or have deep grooves, replace them.
 
My local Honda dealer & service just got some new machine. After talking to my mechanic he was telling me that does it right on the car... no more taking them off the car Honda Canada has been making the move to this new way. I will see if I can get more info on it in the next little while...
 
afaik in the old days dealers had to outsource rotor turning,so in the era of cost containment/ bottom line earnings dealers jumped at the chance to keep this lucrative service inhouse,and what better faster way than to lathe them without taking them off the car.The manufacturers of the lathes are the ones who made that reality.
 
FWIW, personally:

I wouldn't turn a cheap rotor or a slotted/x-drilled rotor. I would turn a Honda or Brembo "blank" though.

Cheapest to most expensive when changing pads:

-Take the rotors off and hook up a wire-wheel or sandpaper (100grit) to a drill and 'scuff' the rotors yourself -powertools =faster :)

-Take the rotors to a shop to have them turned (fairly inexpensive)

-Buy new rotors.


Billy
 
The two holes that are NOT counter sunk are threaded. You can stick bolts in there and alternatively torque them down until the rotor brakes free.

ARGH! I wish I'd known this. I must have hit those old rotors with a hammer 100 times before I got a bigger hammer and they finally broke free. ARGH!
 
I appreciate everyones help and replies.

So glad to finally have my brakes done! was one problem after another...

I installed Carbotech Panther Plus on oem rotors with SS lines and DOT synthetic brake oil and with speedbleeders.

Best tip when trying to remove rotors that are rusted on:

buy 2 bolts and nuts around 1.5 to 2 inches long that will fit in your braket holes. Tighten the bolt and allow the bolt thread to force the rotor off. Spin the rotor and torque then spin and torque til rotor breaks free

I broke my passanger rear stud so i had to reomove the rear hub in order to install a new thread. yes jim, PIT...with the right tools it is not hard.

Bedded the brakes and now letting them cool off...Going to wash the car tomorrow and go for a drive with some local buddies where I am visiting for Thanksgiving. Then 500 miles south back to FL with my 100lbs rottweiler, Bruschi as my co-pilot ; )
 
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