Resurfacing Brake Rotors

[The Critic]

Earlier today, we had a customer who insisted that we resurface his original brake rotors instead of installing premium aftermarket replacements. Since we do not own a brake kathe, we sent the rotors to another shop to have the resurfacing work done.

Upon getting the rotors back, we washed the rotors with soap/water (to prevent metal shavings from embedding into the new pads) and re-installed them onto the vehicle. As always, we checked the rotor runout after cleaning the hub flange very well. Now keep in mind that this particular vehicle's manufacturer specifies a maximum allowed runout value 0.014"...

https://flic.kr/p/GtUqdU

In the video, you can see that the rotor has 0.009" of runout!!

When customers insist, we have their rotors resurfaced on a bench lathe. Most of the time (regardless of who does the resurfacing), the rotors come back with at least 0.005" of runout. The only way to make them usable is to use runout correction shims. Most vehicle manufacturers allow no more than 0.002" of runout.

In comparison, when using new premium rotors, we almost never have an issue with getting runout readings of 0.002" or less; usually 0.001" is no problem.

People always say that resurfacing rotors causes them to "warp faster," but the real issue is that most operators of brake lathes are unable to resurface rotors correctly. As a result, the freshly resurfaced rotors have a ton of runout (sometimes more than before they were resurfaced) and this quickly turns into disc thickness variation...which causes a pedal pulsation complaint after a few thousand miles. So, if you really want to resurface your rotors in the field, the best approach is to use an on car lathe.

 

[Kuato]

Not getting your point here....the .009 is less than the maximum .014 so there should be no issue.

 

[The Critic]

Sorry, I missed a 0.

The vehicle's spec was 0.0014." The resurfaced rotors measured 0.009."

 

[Tomioka]

I had no issues with the same front brake rotors resurfaced 3 times by the same old dude at the mom and pop auto parts store.

Not trying to be cheap but I spent a pretty penny when I bought these rotors almost 10 years ago trying to solve the infamous "brake warpage" issues that plagued the 1st gen Toyota Tundras. Along with the updated calipers I had no issues with 100,000mi of stop and go driving and carrying heavy loads. The Wagner TQ pads now have 50% life from when I took the pics. Next brake job I'll be replacing the whole brake system with new rotors, rebuilt calipers and OEM pads and shims. I might be able to budget in one of those runout gauges for a fully complete brake job.

 

[dlundblad]

So basically you checked the rotor for 360* flatness.

The spec is .0014 (1 thousandth and 4 tenths), but the measurement is .009 (9 thousandths)?

This will cause some major vibrations IMO.

 

[RamFan]

Just out of curiosity but how much does resurfacing typically cost? When a good, new rotor can be as little as $20-30 I can't imagine that you'd actually be saving much by just resurfacing.

By good rotor, I mean a standard daily driver rotor, not a high performance rotor.

 

[buck91]

I have had minimal to no luck with rotor resurfacing as I've stated many times before. That said, I haven't owned too many vehicles that I can find $20-$30 quality rotors for; at least not easily.

 

[WillsYoda]

Originally Posted By: buck91
I have had minimal to no luck with rotor resurfacing as I've stated many times before. That said, I haven't owned too many vehicles that I can find $20-$30 quality rotors for; at least not easily.


I own pretty standard toyotas, so decent rotors can be pretty cheap. I change mine out every 50k-60k or so.

I've been running the cheap centric rotors (around 25 bucks) on my cars and they seem fine.

 

[The_Eric]

Critic- my findings mirror yours, which is why I simply do not bother with re-surfacing them anymore. In fact the last time I had some surfaced, the old boy (notorious cheap skate) insisted that it would be fine after hearing my concerns. Well it wasn't his car, it was his granddaughter's- a 2006-8 Nissan Altima. Yeah, they shook straight out of the shop- he didn't care. It was after that I decided that re-surfacing was no longer going to be an option.



Originally Posted By: RamFan
Just out of curiosity but how much does resurfacing typically cost? When a good, new rotor can be as little as $20-30 I can't imagine that you'd actually be saving much by just resurfacing.

By good rotor, I mean a standard daily driver rotor, not a high performance rotor.



The actual resurface job is going to be less, but the extra parts & labor involved with getting rid of the excess run-out will add additional cost to the job. Also keep in mind that if you're going to a shop, you pretty much won't find a $20-$30 rotor. There will be a mark up. I think the smallest rotors might be in the mid $30 range at my shop, but they are always a premium part. I generally have 3 choices and have found the middle line gives me the low run-out I want, but without the increased price of the added black corrosion protection. (They are basically Raybestos rotors). Costs typically average $40-$60/rotor. 3/4 ton and up trucks can get pretty spendy.

edit: I mention this because Critic is doing this for a customer, so there will likely be consideration for time and parts spent trying to correct the excess run-out and a mark up on said parts.

 

[Falken]

I don't bother spending the money on resurfacing, I just get new mid range quality rotors and bolt them on.

Especially that I live in the rust belt.

 

[goodtimes]

The problem would be the operator of the brake lathe. I guess it always was a problem as they invented on the car brake lathes to machine rotors exactly as installed on the car. All the rotors seem to be made in China. I saw what were called high carbon rotors and wonder if that is something worthwhile.

 

[Bgallagher]

Originally Posted By: Kibitoshin
I had no issues with the same front brake rotors resurfaced 3 times by the same old dude at the mom and pop auto parts store.

Not trying to be cheap but I spent a pretty penny when I bought these rotors almost 10 years ago trying to solve the infamous "brake warpage" issues that plagued the 1st gen Toyota Tundras. Along with the updated calipers I had no issues with 100,000mi of stop and go driving and carrying heavy loads. The Wagner TQ pads now have 50% life from when I took the pics. Next brake job I'll be replacing the whole brake system with new rotors, rebuilt calipers and OEM pads and shims. I might be able to budget in one of those runout gauges for a fully complete brake job.


That's because the "old dude" knew what he was doing. He was working when resurfacing rotors were common practice. Rotors now a days are not made the way they were before. They are better off junking when you replace the pads. You might be able to get another run out of a pair of rotors by resurfacing them. I have seen expensive rotors [censored] out and cheap rotors last forever and everything in between.

 

[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?

 

[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.

 

[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.

 

[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?

 

[bdcardinal]

Generally there isn't a lot of "meat" on the rotors to make multiple passes.

I personally don't resurface rotors on my personal cars. I buy new OEM rotors and put them on when I replace pads.

 

[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...

 

[Nick1994]

I'd rather buy new cheap rotors than have mine resurfaced. Who knows if the person doing the resurfacing knows what they're doing.

 

[SteveSRT8]

Originally Posted By: Nick1994
I'd rather buy new cheap rotors than have mine resurfaced. Who knows if the person doing the resurfacing knows what they're doing.


Right on the money!

I only have my rotors ground at our family's third gen machine shop. My BIL is a fanatical machinist and makes them better than new.

I would never take them to some auto parts store to be ground for exactly the reason stated above...