Turning Rotors: a case study...

what does measuring disk thickness tell you about how accurately the disk was kept axial with the bearing?

If this were the only factor in the performance of brakes than I would be concerned. But by just removing the tire and rotor you can effect the bearing to rotor play if a small piece of dirt were to fall between them. In fact, how do you know your "new Honda replacement rotor is true to your old wheel bearing?. We do have a 5000$ on car lathe, that is suppose to be "the most accurate way to turn the brakes" but it broke again. (600$ was the last repair bill) and having a brother-in law that is a machinist, we can see no great advantage to turning it on the car of off, as long as the turn job is true.

Wear of the rotor and warpage (runout) are the two biggest factors of a brake job.

Personally I have had very poor results in dealing with warped rotors through turning them. On my '03 Accord the rotors warped enough to cause brake shudder. Turning them helped for about 50 miles, when they warped again. New Brembo rotors cured the problem completely. 20,000 miles later the brakes are still working perfectly.

John

"John Horner" wrote

warped rotors

enough to

miles, when they

completely. 20,000

Where did you buy these? How much did they cost? They're not OEM, right?

I'm confused. You just told us that you took 0.004" of material off the rotor, but your initial and final thicknesses only vary by 0.001"?

anyway I installed new front rotors on my taurus today, turning the old ones was $20 ea, new ones was $27...guess I could've saved $14........ Oh well, maybe next time..

A couple years ago my brother asked me to fix his brakes, said they just quit workin'. The rotors were wore down through the vents, mustaben steel on steel for at least 10,000 miles..... wonder if they were past the minimum thickness....

ok, so now let's /cut/ a disk with a piece of dirt under the rotor. now we have a disk that is perfectly planar with respect to the dirt, not the mounting. and that causes brake judder.

well, i've never had a problem with a new disk. i've had repeated problems with skimmed disks. you figure it out. labor and a $5k machine to futz about with a part that can be replaced with a flawless new disk for $50-$60 in about 10 minutes? forget it.

no kidding.

summitsportcompact.com has great prices on brembo disks. quality is very good.

my experience exactly. thank you.

One of the online parts sources, though I forget which one. It was probably one of: rockauto.com, alleurasianautoparts.com or discountautoparts.com.

Personally I trust professional level aftermarket brands, but stay away from the no name and "value" brands of auto parts.

No need to go with OEM for these. I hated the rotors which came on the car, so why give Honda more of my money?

John

Not worth the $14 "savings" IMO.

John

"John Horner" wrote

one. It was

or

but stay away

which came on the

Sounds good; appreciate the info.

You may have had problems, and in a perfect world everyone would replace parts with new when worn with high quality stuff, but many want it done cheap.

Anyway my point was to show how little metal comes off during a lathe job.

Seen that before; and had customers drive out of the store like that too!

As for the Taurus, You did just fine Ford Taurus factory rotors were crap. Wouldn't hold a clean cut for 2 months. Almost all Taurus brake jobs would have pulsation when they came in and most cutting would help, but on a few they would come back. we learned new rotors were the only real solution. Even on My and my Mom's Taurus.

Because the rotor wasn't true-- the outside edge was thinner than the inside edge, so only 001 was removed from the outside.

i have two points:

1. it ain't cheap enough to be worth bothering with [unless it's a disk that requires complete disassembly of the hub] AND

1. the results frequently aren't good enough to be worth the trouble. in fact it often /causes/ problems.

i'd much rather live with a slightly scored disk than one that's been machined wrong and is now ruined.

there's laws about letting a vehicle leave the shop in that condition, regardless of how it drove in. you need to check into them.

but that's the point guy!!! you get /trained/ to skim disks as the "solution", but [and here's the point that i find fascinating] your experience contradicts what you were told! but you still /repeat/ what you were told! can you tell what's wrong with this picture?

I don't think this issue can be resolved into a single best course of action. In another recent thread the subject of professional standards vs DIY standards came up, and I think that applies here. A DIYer who routinely leaves untouched disks that look good and have performed well is frugal and smart. A shop that routinely leaves untouched any disk is being sloppy.

Jim, I gather you and I are on the same page on the DIY way of doing it. If the disks are serviceable as-is there is no point in doing anything to them except a quick wash with brake cleaner when we get our mitts off them. If they need more, replacement is the way to go. If we had free access to a lathe we might do the same as Stephen does - clean the surface up. Or maybe not.

Mike

"jim>> Anyway my point was to show how little metal comes off during a lathe job.

My point is different; We do it for free with a brake job It takes about 10 minutes to do total

We have never had an issue with machining them wrong. Its to simple. But and idiot could play with the settings on the lath and screw it up... Perhaps the people who turned your rotors in the past were idiots?

I agree with pressed on rotors... What a wonderful idea someone had...

Take care,