Rotors and brake job question

[kornphlake]

All those specs actually come from somewhere and are based on the engineering judgment and testing that OEM has.

I used to be a design engineer at a major jet engine manufacture. My company spent millions testing different oils, lubricants, etc. And testing proper servicing intervals and procedures. We also had material programs to bring new very specialized materials into existence, a new alloy program cost in the tens of millions. But a ton of our customers think they know better and use different oils and lubes and buy aftermarket parts made with inferior alloys.

The manual is generic because it does not need to change much model to model and testing is very expensive, especially if it gives you the same results you already had.

^this

It's not unheard of in heavy industrial equipment to use whatever lubricants or parts a salesperson recommends. We had a bearing vendor recommend we switch from a PFTE based grease that is required by the process to a hydrocarbon grease. Duh, a hydrocarbon grease will be better, but it would potentially contaminate the product that piece of equipment worked on. The recommendation was completely inappropriate, however the dept. manager who forwarded the report on was ready to place an order for hydrocarbon grease that day.

Occasionally you'll run across an OEM spec that calls out a cheap grade of lubricant as a cost saving measure, or when a parent or sister company manufactures the lube, but most often heavy industrial, including automotive, lube specs are not chosen on a whim.

 

[zerocool84]

Only one thing left to say...

If I were to buy a car and the manual said...

When the brake pads wear out and need to be changed the rotors should not be turned but replaced...

I`d say... "Must be like a Bic lighter when it runs out of gas throw that POS away...!" EOS (End Of Story)


I mean like damn even the little Kia Soul I bought for the wife doesnt say that in the manual...?
^

You don't need to turn the rotors on a basic pad change. Don't know why you keep saying that. Just because you do that doesn't mean everyone else should.

 

[exdeath]

Screw the dumbed down owners manual. What does the factory service manual list for acceptable rotor thickness? That's the one that's going to be based on a lab tested number for the weight of the car, heat build up of the brakes, etc.

If the OEM rotors are already minimum thickness to begin with, it doesn't matter if the owners manual says they can be turned or not, they are too thin.

Most high performance cars like the SRTs are going to say not to turn the rotors because they are a vented high performance brake rotor put on a fast car and they are subject to greater thermal abuse than standard passenger car brakes and require greater mass to dissipate heat. Not only does total thickness of the rotor matter, but also thickness from each side to the vanes.

 

[Howard]

I would say that it's not a bad idea to try to have the rotors examined every time. An honest shop wouldn't turn thin rotors anyway.

 

[RU482]

depends on what your time is worth.

Do you want to find out 6 months from now that you should have replaced your rotors?
Rotors are cheap compared to time x2

/EDIT: I'm used to GM vehicles that drive off the lot new with inferior rotors, FWIW

 

[Bartman39]

You don't need to turn the rotors on a basic pad change. Don't know why you keep saying that. Just because you do that doesn't mean everyone else should.

I can safely say you will never ever work on anything I own...

 

[kornphlake]

I can safely say you will never ever work on anything I own...

oh snap, he got pwned

I'll never work on anything you own either, regardless of what I consider a best practice, you couldn't afford my rates.

 

[geno]

You don't need to turn the rotors on a basic pad change.

More times than not, it's wise to at least resurface the rotors. Deposits from the last pads, glazing, etc will hurt the performance of the new pads. If your old rotors are free of any of that, then that's fine. But if there's any glazing / deposits / material / warpage, then resurfacing the rotors is the minimum you should do. If you want the brakes to work as well as they should, you shouldn't put new pads on old rotors that are worn / glazed. They should at the very least be resurfaced / turned so the pads can properly bed. If you don't bed the pads, you take a chance they won't bite as well as they should, increasing stopping distances.

 

[CraigRT]

Always new rotors and pads at the same time.

Never one or the other. Not in my garage.

 

[alkemyst]

really depends on the condition of the rotor. To many are turn happy on a perfectly servicable rotor.

If you have a ton of mileage and any kind of grooves then definitely turn or replace.

 

[Bartman39]

Then this is what they need... (cool tool I found and wish we had)

http://brakeview.com/


Also what "geno" said is what I`m talking about but in better terms and explanation... In addition to many times I`ve seen the pads wear the rotors in a cupped fashion across the width of the surface of the rotor so that they are not flat so the dont make good full contact with the new pad which of course is ground flat and square...