Turning Rotors?

[ShottsUZJ100]

When the front pads went out in my 2006 Rx8 I also had some warpage. At that time my mechanic didn't slap on the new Mazda rotors (we saved them for the next round of pads...now on). Instead he took his drill and used a filing attachments that evened them out. Worked amazing...shudder was gone until the pads went again...35K miles later! AND NO TO THE SKEPTICS...MY BRAKING PERFORMANCE WAS THE SAME.

got brakes?

Rx8 has the most amazing OEM brakes and they are non-Brembo!

 

[Tinkerer]

Gamble?

Significantly?

Millions of folks per day must just be nuts for turning their rotors. LOL!

I wonder where people get their data sometimes..."millions per day"? Hmmm...

"Significantly" in this case means "statistically significant", i.e. "indicating a correlation pattern with more than x% increased occurrence of subject output given subject input". In statistics, the x% is usually 5% to 20%.

For the rotor turning vs. new OEM rotors for brake jobs, the correlation I have seen is that more than 20% of turned rotors fail to deliver adequate perfomance (smooth powerful braking for expected number of miles), as opposed to 0% of OEM rotors.

How much more? More than 50% of turned rotors develop brake performance problems within expected life, more or less - in my experience.

Granted, I have not turned 100 series rotors for comparison, and I am not running a brake shop, so my own rotor turning experience is relatively limited and with other makes of vehicles. It is likely that Toyota's 100 series rotors fare better when turned than other, lesser-quality rotors. (GM, Ford, and Chrysler - are you listening?)

In any case: Turning rotors is problematic. Sometimes you get good results, sometimes not, and this is related to huge variation not only in starting condition of rotors but also turning equipment/condition/settings and technician skill in the service shop. Keep in mind: A single point lathe (without cooling fluid) chowing a rotor in Joe's Garage And Machine Shop will produce much different results than precision grinding using cooling fluid in a rotor factory with engineering staff and developed quality systems - and that's not even considering the typical poorly-maintained condition of the lathe and its tooling at Joe's. Its not just a matter of final surface roughness - there are heat and mechanical work aspects that can affect the metallurgical properties of the finished surface in ways that have a direct influence on rotor performance and life in service. Joe's Garage does not control the machining process for these details when turning rotors - heck, they don't even know about them most of the time.

So, anyway: There are lots of people who get good results with turned rotors, and even post about it in forums. But there are also lots of sour experiences with turned rotors.

I used to have lots of time to tinker with my vehicles and other fun stuff (hence my moniker in this forum), but I don't have much time for it anymore, so I choose to spend $600 on parts to assure a high-quality trouble-free brake job that will last as long as factory-new, instead of $300 (?) on a penny-pinching brake job with a high probability of requiring me to re-do it within its expected service life.

YMMV.

 

[OregonLC]

I can respect someone willing to pay for the value. No argument there.

However, I think in most cases you can get a better product for less cost if you do it yourself. Most shops will use cheap pads and (as mentioned above) do a poor job of turning the rotors. Others (like Les Schwab) will insist on all new parts (calipers, pads, rotors) and you'll end up paying for more than you need. I can't think of a brake job I've done that has gone over $100 per axle.

 

[spressomon]

Ok...so after almost 100k tough miles on my ART cryo'd rotors (Advanced Rotor Technology) they started to exhibit the "warped" rotor symptom a couple weeks ago and progressively got worse especially noticeable coming down the mountain passes.

I contacted ART about getting a quote for new ART rotors. Stephen Morgan from ART replied to my e-mail giving me instructions to try something first before buying new rotors from him/them!

His advice, given my rotors didn't appear worn at all, was to take 120 grit garnet paper "NOT sandpaper" (to keep the silicone used in most other types of abrasive pad material away from the friction surfaces...makes sense) and very thoroughly scuff both sides of each rotor. Apart of PM'ing my front hubs a couple days ago I did just that and also did a thorough cleaning and light scuff of the relatively new brake pads up front.

To my pleasant surprise the pulsating "warped rotor" symptom is gone. Drove it about 275 miles yesterday and the brakes seem like brand new!

So the garnet paper did abrade the deposited pad material without going to the expense and risk of having the rotors machined or "turned".

Stephen did recommend, if the pads were worn, going with brand new pads at the time of the scuffing procedure and then re-bedding the pads; however as I mentioned above I had recently replaced my front pads.

Anyway...its great to be able to report on a vendor's/supplier's/mfgr's excellent customer service. Even to the point the advice they offered cost them a new sale! My hat's off to Stephen and ART!!! I couldn't ask for better service than that!!!

Dan

 

[OregonLC]

Dan, that parallels other stuff I've seen posted regarding the 'myth of warped rotors'. Seems like it's more often a result of uneven pad material deposited on the rotors. Interesting comment about the garnet paper - where did you end up getting it? Is it readily available? As for the sanding, could you use something like a palm or 1/2-sheet sander to do the work? And suggestion on the direction to abrade? Radially or circumferentially?

Good stuff, thanks for posting. BTW, do you have a website set up for your spressoFab items?

 

[spressomon]

Garnet paper from the hardware store; old school sand paper; wood block and carpet tape. I tried to find non-coated or garnet sand paper for my Festool sander but all I could find was aluminum oxide, etc. Me thinks that would be fine if you thoroughly wash it down when done with good brake cleaner; I use a non-aerosol commercial brake cleaner as it doesn't have the carrier/propellent and works better than any $3 can stuff.

I don't think the pattern matters as you're just removing the pad material and the 120 grit garnet isn't abrasive enough to really cut into the rotor metal.

Not yet.

 

[super90]

Ok...so after almost 100k tough miles on my ART cryo'd rotors (Advanced Rotor Technology) they started to exhibit the "warped" rotor symptom a couple weeks ago and progressively got worse especially noticeable coming down the mountain passes.

I contacted ART about getting a quote for new ART rotors. Stephen Morgan from ART replied to my e-mail giving me instructions to try something first before buying new rotors from him/them!

His advice, given my rotors didn't appear worn at all, was to take 120 grit garnet paper "NOT sandpaper" (to keep the silicone used in most other types of abrasive pad material away from the friction surfaces...makes sense) and very thoroughly scuff both sides of each rotor. Apart of PM'ing my front hubs a couple days ago I did just that and also did a thorough cleaning and light scuff of the relatively new brake pads up front.

To my pleasant surprise the pulsating "warped rotor" symptom is gone. Drove it about 275 miles yesterday and the brakes seem like brand new!

So the garnet paper did abrade the deposited pad material without going to the expense and risk of having the rotors machined or "turned".

Stephen did recommend, if the pads were worn, going with brand new pads at the time of the scuffing procedure and then re-bedding the pads; however as I mentioned above I had recently replaced my front pads.

Anyway...its great to be able to report on a vendor's/supplier's/mfgr's excellent customer service. Even to the point the advice they offered cost them a new sale! My hat's off to Stephen and ART!!! I couldn't ask for better service than that!!!

Dan

I just did this as an experiment. I scuffed the rotors with 120 grit garnet paper and I replaced the pads with new Akebono ProAct pads. It was interesting to see the amount of what appeared to be the old pad material coming off the rotors as I used the garnet paper. In my initial test drive, the pulsation is gone. I figured for $55 it was worth a shot. As a side note, I had very good experience with Akebono's on my 80 series, and wanted to try them on the 100.

I will report again with longer term results.

 

[scottm]

I have pads waiting to go on my LC and 4R, will try sanding the rotors. The 4R has some pulsing that doesn't seem to be warpage: no pedal or steering wheel feedback. I'm not sure why aluminum oxide would be a problem. I've had problems with silica at the shop, well aware of that, but no problems with aluminum oxide. But I'll locate garnet paper.

 

[OregonLC]

I have pads waiting to go on my LC and 4R, will try sanding the rotors. The 4R has some pulsing that doesn't seem to be warpage: no pedal or steering wheel feedback. I'm not sure why aluminum oxide would be a problem. I've had problems with silica at the shop, well aware of that, but no problems with aluminum oxide. But I'll locate garnet paper.

don't think the prob is with the aluminum oxide, but in the silicone binders on 'standard' sandpaper. if i understand it correctly, the silicone leaves a low-friction coating on the rotor = bad.

 

[spressomon]

That's how it was 'splained to me. But you would think a good wash with brake cleaner would remove any binder/silicone.

 

[haryv]

Rotors with lots of metal left just do not warp. There is a reason. Are you ridding on the brakes going down a hill ? I pulse my brakes and give them a opportunity to cool off. Do you drive though deep puddles just before using your brakes? Water that splashes on a hot rotor will warp them all the time. Are these cheap Chinese rotors vs Rayspestos rotors? if so, that is why they warp..not enough metal to act as a heat sink.

Best of luck.

 

[scottm]

That's how it was 'splained to me. But you would think a good wash with brake cleaner would remove any binder/silicone.

We tried washing with laquer thinner then alcohol, and with soap and water, didn't get rid of the silicone from sandblasting. Sandpaper might not embed material like sandblasting, but it sounds like it does from this thread.

What about using ScotchBrite pads? I have plenty of pads, and disks I can use with a die-grinder to speed this up.