Routine Rotor Turning???
Team Owner
Joined: Jun 2005
Posts: 46,295
Likes: 2,596
From: Northern, VA
St. Jude Donor '15
"In honor of jpee"
I don't know if that's a requirement but the surface can be checked before it is "required to be turned." It doesn't hurt, except your wallet.
Some rotors are in such good shape that a very light sanding done in the proper manner is all that's required. On other cars, incl. Z51, it can be that you need to replace the rotors when you change brake pads. But that differs from driver to driver and car to car. It's not a given, to my knowledge.
Some rotors are in such good shape that a very light sanding done in the proper manner is all that's required. On other cars, incl. Z51, it can be that you need to replace the rotors when you change brake pads. But that differs from driver to driver and car to car. It's not a given, to my knowledge.
Safety Car
Joined: Dec 2005
Posts: 4,157
Likes: 37
From: North Carolina
St. Jude Donor '07-'08-'09-'11-'12
BS - GM does not "specify" it for a pad change, actually the opposite. Many of the OEMs have issued bulletins in the last few years providing guidelines for brake rotor servicing and they've indicated that brake rotors should not be resurfaced during routine brake pad replacement. Even so, it is an easy revenue generator for the service dept. Ive seen "resurfacing" fees that are as much as cost of new rotors, and it's all labor profit.
Resurfacing the rotor unnecessarily removes material and makes the rotor thinner, lessening its ability to absorb and dissipate heat and shortening the rotor's usable lifespan. Improper machining also can create problems that did not exist before. For instance, if a non-integral rotor is not setup properly on a bench lathe, an excessive lateral runout condition that did not previously exist can be created when it is reinstalled on the hub. Improper resurfacing also can create a friction surface that is too rough, causing brake noise, premature pad wear and a hard pedal condition.
Here's a link to some interesting reading reading about brake pads, rotors, etc -
http://www.stoptech.com/tech_info/wp_bedintheory.shtml
http://www.stoptech.com/tech_info/wp...rakedisk.shtml
Resurfacing the rotor unnecessarily removes material and makes the rotor thinner, lessening its ability to absorb and dissipate heat and shortening the rotor's usable lifespan. Improper machining also can create problems that did not exist before. For instance, if a non-integral rotor is not setup properly on a bench lathe, an excessive lateral runout condition that did not previously exist can be created when it is reinstalled on the hub. Improper resurfacing also can create a friction surface that is too rough, causing brake noise, premature pad wear and a hard pedal condition.
Here's a link to some interesting reading reading about brake pads, rotors, etc -
http://www.stoptech.com/tech_info/wp_bedintheory.shtml
http://www.stoptech.com/tech_info/wp...rakedisk.shtml
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
http://www.tciprecision.com/products.../blanchard.php
Look at the finish of a brand new rotor and then look at one that's been turned. You'll see the swirl marks from the blanchard grinding process on the surface of the new rotor and a very smooth finish. The turned rotor will have a rough spiral finish from the tool bit depending on the feed rate of the machine...ie how much of a hurry the mechanic is in.
Team Owner
Joined: Feb 2000
Posts: 45,043
Likes: 892
From: Texas
CI 1-4-5-8-9-10 Vet
St. Jude Donor '03 thru '10, '17
It's BS. GM says don't turn the rotors unless it fails to meet the criteria for runout and grooves. I don't know what the criteria is for the C6, but I can tell you GM does not advocate turning rotors just for the sake of turning them. The final finish left on a brand new rotor can't be duplicated in the Chevrolet dealerships' shop...unless they can blanchard grind them, and I doubt they have that machine.
http://www.tciprecision.com/products.../blanchard.php
Look at the finish of a brand new rotor and then look at one that's been turned. You'll see the swirl marks from the blanchard grinding process on the surface of the new rotor and a very smooth finish. The turned rotor will have a rough spiral finish from the tool bit depending on the feed rate of the machine...ie how much of a hurry the mechanic is in.
http://www.tciprecision.com/products.../blanchard.php
Look at the finish of a brand new rotor and then look at one that's been turned. You'll see the swirl marks from the blanchard grinding process on the surface of the new rotor and a very smooth finish. The turned rotor will have a rough spiral finish from the tool bit depending on the feed rate of the machine...ie how much of a hurry the mechanic is in.
Le Mans Master
Joined: Jul 2005
Posts: 5,328
Likes: 405
The service manual has a procedure to get the surface finish of a turned rotor close to a new rotor that requires more work after it's turned on the lathe. There are also RPM/feed rates when turning a rotor specified in the manual.
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Safety Car
Joined: Jun 2004
Posts: 3,563
Likes: 2
From: Dallas Tx
Tell them to read the service manual page titled:
Brake Rotor Surface and Wear Inspection
That page tells when a rotor is to be turned. It lists all the reasons for turning a rotor. Pad replacement is not one of them. If there is nothing wrong with the rotors, they are not to be turned. I've done countless brake jobs without turning the rotors when there was nothing wrong with the rotors.
A burnishing procedure does need to be done immediately after installing new pads.
The service manual instructs burnishing new pads into the rotors by driving 30 mph and doing 10 to 20 stops using moderate to firm pressure. Allow cooling time between stops.
To me 20 seems a bit excessive, so I generally to 10 firm stops from 30 to 0, with a couple minutes of cool down driving between stops. That will burnish in the pads nicely and they will match the rotors. I've done that tons of times and my brake jobs turn out great.
Brake Rotor Surface and Wear Inspection
That page tells when a rotor is to be turned. It lists all the reasons for turning a rotor. Pad replacement is not one of them. If there is nothing wrong with the rotors, they are not to be turned. I've done countless brake jobs without turning the rotors when there was nothing wrong with the rotors.
A burnishing procedure does need to be done immediately after installing new pads.
The service manual instructs burnishing new pads into the rotors by driving 30 mph and doing 10 to 20 stops using moderate to firm pressure. Allow cooling time between stops.
To me 20 seems a bit excessive, so I generally to 10 firm stops from 30 to 0, with a couple minutes of cool down driving between stops. That will burnish in the pads nicely and they will match the rotors. I've done that tons of times and my brake jobs turn out great.