do you turn your rotors on a lathe?

So I just had my leaf springs replaced under recall and want to know how you all treat your rotors
because the dealership told me they "inspected" the truck during the recall
and determined that the "transmission fluid needs changing"
even though I literally just did that. Awesome.

But one thing they mentioned was that the pads are at 60% life.
Good to know, because the steering wheel shakes like hell under braking. Which tells me the rotors might be warped. Or have uneven pad buildup. Whatever thing causes that.

Apparently, the Toyota dealership has two on-car brake lathes. Meaning not bench lathes that grind down a rotor itself, but mobile ones that attach onto a car.
I heard the bad things about most lathes, is they're not good quality enough to get precise cuts. That they cut off way too much.

So with German cars, they say not cut the discs on a lathe. Because the disc has an imprint on it that says Minimum and Maximum thickness. And apparently a lathe would cut too much metal off, and make it below the minimum they require.

Is it that way with Toyota? Do you all spend the extra money for new rotors every brake job, or find a place to cut them? It sounds like a difference of $100 per brake job vs $300+. Very noticeable.

One time I walked past a Japanese auto repair shop and noticed they had a lathe in use in the back.
Though I heard it's become a "dying art" and is not used a lot at auto part shops like O'Reilly's/Autozone, or they discontinued offering the service.

 

As long as the rotor is greater than the minimum required thickness when the turning is done I would reuse the rotor.

 

In before "Rotors don't warp"

Toyota trucks are famous for under-engineering rotors. Tunrdas murder rotors and most have steering shake.

Most are not warped. Hot spots, pad embedding and uneven rotor wear are the cause in Toyota land for steering shake. For the most part you can usually see when a rotor is pooched and can't be cut.

I machine almost 90% of Toyota truck rotors on the vehicle. This ensures proper runout and the best cut. Some shops have banned cutting truck rotors on a stand-alone lathe because of the inaccuracies.

Trade secret. Don't hold your brakes hard after a panic stop, or long highway braking. Put the truck in neutral or keep crawling in drive to keep the pads from embedding into the rotor.

 

There was some article from a brake company or something,
that said brake warpage is a myth, and that what truly happens is "DTV" or disc thickness variation, which is from a pad depositing a layer of transfer material onto one spot. That every time the brake skips over that spot, it ends up resulting in a vibration.
Hence possibly the need for turning, to cut that part off and make it fresh again.

Very easy for me to put the truck in neutral. It's stick-shift so it basically has to do that anyway, whenever it stops. Bought it like that already shaking from the previous owner.

I guess one side is the extra downtime of having to walk to a shop carrying used brake discs, and asking them to turn them, while the truck is taken apart outside on jack stands.

The trick when stopping in stick-shift is to let it roll back, to flex on all of the automatic drivers that your vehicle is stick, a rare value-holding theft-preventing reliable and controllable transmission choice that requires more skill and is easier to work on. And get close enough to their bumper that they start honking out of fear.

 

Where do the inaccuracies come from turning a rotor on a lathe?
Aside from operators being slobs, i don't see how pulling a rotor and putting it on a lathe rather than turning it on the vehicle could be worse.
Seems to me that turned it on the vehicle would be worse, having to take wheel bearings and steering angles into consideration when setting up.

 

They don't warp, as said. They do pulse from improper bedding or bad material transfer.

A good machinist (not AutoBone catalog jockeys) can turn a rotor just fine. You mic the deepest grove bottom, which is your 'target', and if that measurment exceeds the minimum thickness, they can be safely turned.

The 'turn rotor on vehicle' lathe is very nice. It works well for vehicles like Hondas where rotor removal is not a simple process.

Around here turning a rotor is up to $20 or so, if you pull them and take them in. So you have to compare that cost to the cost of just swapping on a new quality rotor.

Your price comparison indicates you are not DIY. Correct?

 

The 2015 I just bought a few weeks ago had poor rotors and pads. I’m not sure how they got that way. The truck only had 20k miles on it when I got it.

I had the rotors and pads replaced for $300 when I upgraded the front shocks. Braking vibration is gone.

 

I use to turn my rotors until the local shop closed. It is a dying art.

 

So this is primarily a heat issue? The pads get hot during a hard stop or long braking, then deposit material on the rotor during a long stop?

 

I went with full replacement. Rear seal went out and junked rear putting more strain on front and it pulled when braking. Had to drive like that until I could round everything together. I didn’t want to haul and drop off crap in my wife’s new ride so I replaced everything. I couldn’t get the hoses off yet. Need some quality metric wrenches not the crappy ones.

 

Why not replace the rotors? They aren’t very expensive at napa or online.

 

am DIY
haven't looked into pricing on pads vs rotors, which brands to get, etc.
I just know from experience with German cars, the addition of rotors increases cost significantly
the brands they seem to prefer, including Zimmerman zinc-coated rotors, can get pricey
and that is for the part alone

supposedly caliper piston seals wear out over time.
IDK if there's a way to diagnose it, such as seeing if MPG has dropped if the brake drags, and monitoring temperature readings on it when coasting with brakes off.

 

Read the posts above about uneven pad material transfer. It can happen with only one mile on the odometer.

@TacoTuesday1 , pull your rotors, lightly sand both sides with a fine paper. Reinstall with new pads, properly bed the brakes and your vibes should be gone.

For all-
https://m.youtube.com/watch?v=Zawfu9xTkag

 

I've had more problems with leaky slave cylinders and such on manual transmissions. I've had way better luck with autos, there more fuel efficient and durable. As far as cutting the rotors I prefer the on car lathe. Does a much better job than a bench style.

 

On the bench lathe it's really important to set up the lathe with the proper adapters plus the rubber band which helps with vibration. On the car lathes bolt to your hub and turn the rotor in the exact same position so there a lot more accurate.

 

I’ve turned thousands of rotors. No problem

 

Again why not just replace them and be done? You taking them off to scuff them with sand paper and all that shit if I’m going threw all that trouble I’d just replace them while there off.

 

If you’re going the budget route, PepBoys will cut 6-lug taco rotors off the truck. I paid $30 for both just yesterday.

 

I knew from the service history on my truck that the previous owner and dealer had already attempted correction. One of the service history records indicated they had already turned the rotors, and whatever else not in the record.

So I choose replacement when I had the suspension and alignment done. Working great now. But, this thread has been very educational so I thank yall for the info.