Resurfacing Brake Rotors

[Garak]

Originally Posted By: KrisZ
That's a big generalization. Car lathes may be more idiot proof and easier to set up, but there is absolutely nothing wrong with resurfacing the rotors off the car, but it is up to the operator to do the job right or botch it up.

It is a big generalization, but some rotor manufacturers are no longer providing warranty on their rotors unless any machining is done right on the vehicle. I suspect that is to address exactly what you're mentioning - people using equipment they have no idea how to handle.

 

[camrydriver111]

Originally Posted By: Rolla07
I would have Toyota resurface them here but I wouldnt bother with aftermarket resurfacing. I recently replaced some jobber rotors with some wagners for about 60$ each. I get the impression OEM is better than most aftermarket parts but if the runout is off that much something aint right. You would figure they would measure the runout after doing the work...


Wagners are massively overpriced in Canada. They sell them for $60 CAD while the same rotor is like $19 USD on Rockauto.

I think Qualis rotors (AKA Centric) are a better buy and the price is closer to the USD price.

I've bought Wagners a few years ago and still feel ripped off.

 

[JustinH]

I throw rotors into my recycling pile and buy new every time I do pads.

Would never service a used rotor on a passenger car.

If you get into high dollar truck rotors then it may be worth it to take them to the machine shop, but not my 25 dollar aftermarket rotors for my Toyota's.

I do agree with measuring runout out of the box with a new rotor. More than once I have had unusable rotors new out of the box from China.

 

[punisher]

This comes up every so often, and the answer is the same.

Runout by itself does not cause problems with pulsation or pedal feel. The problems occur when you have a rotor that has either pad deposits on it (from melting the pad during an overheat event), or when the rotor surfaces are not parallel.

Many shops throw rotors on a lathe, machine them, then throw them back on the vehicle, and never have a problem. Just turning them removes pad deposits, as well as machines both surfaces parallel, with no real consideration of runout. Biggest problem with excessive runout is excessive wear of parts the pads slide/bear upon during braking. Machining rotors thinner does have a negative impact on life...if the customer is prone to overheating the rotor the first place. Less mass in the rotor=quicker heat build up=more potential problems.

Sometimes a machined OEM rotor is superior to a cheap replacement Chinesium rotor.

 

[nthach]

Originally Posted By: Garak

It is a big generalization, but some rotor manufacturers are no longer providing warranty on their rotors unless any machining is done right on the vehicle. I suspect that is to address exactly what you're mentioning - people using equipment they have no idea how to handle.

The OEMs either call for rotor replacement(BMW and Mercedes) or for the rotor to be machined with an on-car lathe(Honda and Toyota). Problem is, most dealership techs don't use an on-car lathe, it takes a little time to set them up, it's easier for a flat-rate tech to slip the rotor off the hub and chuck it onto an off-car lathe which may not be maintained per manufacturer specs.

I had a local tire shop turn some rotors for me, and I also installed new pads. Later on, a shimmy developed. These were OEM Toyota rotors. I now have Dura coated ones installed, but Dura has come under fire for "lightweight" rotors.

 

[JustinH]

I have not seen a non-china brake rotor in quite some time.

 

[stephen9666]

Originally Posted By: punisher
This comes up every so often, and the answer is the same.

Runout by itself does not cause problems with pulsation or pedal feel. The problems occur when you have a rotor that has either pad deposits on it (from melting the pad during an overheat event), or when the rotor surfaces are not parallel.



You're partially right.

excessive runout in the rotor causes it to wear unevenly over time, leading to thickness variation (the lack of parallel you're referencing) and pedal pulsation.

 

[demarpaint]

Originally Posted By: Yup
My brakes lasted about 110k miles. I bought new rotors. Guy doing work said they could be resurfaced. The price difference was about $30 more for new. Every 100k miles, it won't keep food off the table. And, like is being shown, you never know who is working the lathe.


That's exactly why I pitch them and start with new. But in the case of the OP, the customer is always right.

 

[philipp10]

I find this an interesting discussion. Having driven since 1977, I NEVER replaced a rotor on any car I owned until last year with my 2008 RAV4. They were rusted so bad that they swelled on the outer edge and ate up my pads. It's always been my policy that I would prefer to surface a good OEM rotor over replacing such rotor with some pile of junk $30 special probably made in China. Secondly, unless I am feeling pulsations before the brake job, I don't see a reason to resurface a rotor. No pulsations means no run out so why turn a rotor. Hence I seldom resurface either. Ironically with my RAV4 that I replaced the rotors...they are pulsating now. IMO, OEM rotors are superior and are better as resurfaced than to pick up some aftermanrket cheapo everytime a brake jod is done. Finally, I have never replaced a caliper nor do I ever bleed my brakes......

 

[buck91]

Either you turn your cars in after the lease or you simply don't care about brake feel and performance!

YMMV.

 

[philipp10]

well the average car has plenty of reserve brake capacity so I an in-sure what you mean. Would my brakes lock up if I could turn off the ABS? Yes. So what more braking do I need? And no, I keep my cars till about 175k miles.

 

[MONKEYMAN]

Thanks Critic for the info. If you recall I was getting pulsation due to excessive runnout corrected by a shim on passenger hub. I have a pair of Napa's Premium rotors that I was considering having turned at O'Reilly's. These rotors were one set pre-shim and had terrible pulsation. So would a shim and measuring runnout when installing be sufficient? I will need a shim no matter what rotor I use since my hub is a little off. It seems like a waste to just pitch those rotors. Not many miles on them.

 

[2002 Maxima SE]

Do rotors need to be resurfaced if reused? I recall reading an article that if the material seated into the rotor is the same as what the replacement pad contains (lets say semi-metallic) then there should be no issues reusing the rotor as is.

On my 2000 Ford Taurus, I replaced the pads, but not the rotors and have experience no change in braking performance or noise (30k miles).

On my other cars, I've replaced the rotors when replacing the pads.

 

[The Critic]

Originally Posted By: zzyzzx
OK, so you get the resurfaced rotors back out of spec, and the reason why you didn't ask them to resurface them again to something within specs is?


That was actually their 3rd try.

Originally Posted By: Chris142
If there is any corrosion on the rotors they wont cut straight unless you clean it off before mounting them. Or someone bent the Arbor with a huge drum.


Very true. You need to clean the back of the rotor hat before machining a rotor.

Originally Posted By: KrisZ
Originally Posted By: The Critic
So, if you really want to resurface your rotors in the field, the best approach is to use an on car lathe.


That's a big generalization. Car lathes may be more idiot proof and easier to set up, but there is absolutely nothing wrong with resurfacing the rotors off the car, but it is up to the operator to do the job right or botch it up. Car lathe is no different, the operator must know what they're doing, excessive runout is excessive runout, no matter what type of lathe was used.
You know, the same goes for mechanics, there are plenty of hacks out there, should we start proclaiming that everybody DIY?

Actually that is not entirely true. Assuming that the operator cleans the rust from the back of the rotor and the hub flange, on car lathes are always better because the rotors get machined on the same plane that it rotates. Any runout that the hub has, gets machined into the rotor so the entirely hub/rotor assembly is "true."

 

[zzyzzx]

Originally Posted By: The Critic
Originally Posted By: zzyzzx
OK, so you get the resurfaced rotors back out of spec, and the reason why you didn't ask them to resurface them again to something within specs is?


That was actually their 3rd try.

Then they should give you your money back and use it to offset part of the cost of new rotors.

 

[The Critic]

Originally Posted By: zzyzzx
Originally Posted By: The Critic
Originally Posted By: zzyzzx
OK, so you get the resurfaced rotors back out of spec, and the reason why you didn't ask them to resurface them again to something within specs is?


That was actually their 3rd try.

Then they should give you your money back and use it to offset part of the cost of new rotors.


We did advise the store manager of the runout issues, and he said that he will have their Ammco rep come out and inspect the lathe.

 

[Boss302fan]

If my rotors look good, I just clean them up and put on new pads...

 

[zzyzzx]

Originally Posted By: Boss302fan
If my rotors look good, I just clean them up and put on new pads...


Exactly what I do. At > 235K miles, I still have the original rotors on my 1995 Escort.

 

[KitaCam]

New Akebono high performance pads I installed on the Kitacamry @ 137k miles actually smoothed out the rotors, eliminating a few minor scratches/grooves....the rotors are smoother now than when I got the car @ 97k miles.

 

[KrisZ]

You guys in the warm climates can do all sorts of things with rotors. In the rust belt, after about 4-5 winters the rotors usually have so much rust that it only makes sense to scrap them.