new rotors - turn or not? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mole2000 · 10-05-2008, 10:33 AM

I'm in the middle of a frt disc brake conv on my 70 c10. I have brand new rotors. Should I have them turned before install? The surface appears smooth and non-directional already.

Thanks.

Cyclone44 · 10-05-2008, 10:43 AM

No if they are new they should be good to go......

Sinister · 10-05-2008, 11:19 AM

pumpkin · 10-05-2008, 11:35 AM

I am a mechanic and work in a shop, we machine all new rotors. For us its just not worth the hastle of redoing the job when the rotors are not true. I have found about a 30% fail rate on new rotors, as far as having too much runout. I have also found about 2% being too bad to even bother machining. When I do brakes at home, I just take my chances.

mbgmike · 10-05-2008, 11:37 AM

Turning your new rotors off the car/truck really IMO is not really needed unless you bought some really inexpensive ones. If you are looking for the maximum performance,Yes i would turn them installed on the vehicle. Thats the best way and most manufacturers are doing it now

mbgmike · 10-05-2008, 11:42 AM

Quote:

Originally Posted by pumpkin

When I do brakes at home, I just take my chances.

I do the same thing. I just slap them on and when they go bad, do it again

**jerry moss** · 10-05-2008, 11:44 AM

definitly have them turned. i also work in a shop and it's cheap insurance to turn them before installing them. normally they are pretty close to being true and a couple thousandths will true them. a lot depends on where they were purchased--if they are cheap rotors and/or were not stacked properly in the warehouse they can be off quite a bit.

Lugnut64052 · 10-05-2008, 11:54 AM

Quote:

Originally Posted by Cyclone44

No if they are new they should be good to go......

mbgmike · 10-05-2008, 12:05 PM

Quote:

Originally Posted by jerry moss

definitly have them turned. i also work in a shop and it's cheap insurance to turn them before installing them. normally they are pretty close to being true and a couple thousandths will true them. a lot depends on where they were purchased--if they are cheap rotors and/or were not stacked properly in the warehouse they can be off quite a bit.

Yeah we only charge $8.00 per rotor to our customers but I am too lazy to do my own.

70GMCer · 10-05-2008, 12:10 PM

I guess it's 50/50 on the subject. I have always just put them on. Never a problem. I do, however clean them with brake clean before final assembly. JMO

BLACK AND BLUE 67-72 · 10-05-2008, 01:07 PM

1pc. rotor like yours just put it on and run it, 2pc. like a 4x4 that is seperate from the hub then those need to be turned!!!!!

Fastfun · 10-05-2008, 01:45 PM

I always check the run out first if they are off then I have them turned.

Lugnut64052 · 10-05-2008, 08:09 PM

Quote:

Originally Posted by 70GMCer

I do, however clean them with brake clean before final assembly. JMO

Good point. They have a preservative film on them so they won't rust while sitting on the shelf. You can just slap 'em on and run 'em, but they'll stink the first time or two you hit the brakes while the preservative is burning off. After that they're fine.

10-05-2008, 10:33 AM	#1
mole2000 Registered User Join Date: Aug 2008 Location: Austin, Texas Posts: 78	new rotors - turn or not? I'm in the middle of a frt disc brake conv on my 70 c10. I have brand new rotors. Should I have them turned before install? The surface appears smooth and non-directional already. Thanks.

10-05-2008, 10:43 AM	#2
Cyclone44 Step Brother Join Date: Sep 2007 Location: K-town Posts: 4,029	Re: new rotors - turn or not? No if they are new they should be good to go......

10-05-2008, 11:19 AM	#3
Sinister Between Trucks... Join Date: Mar 2002 Location: Los Angeles, CA. Posts: 3,830	Re: new rotors - turn or not? __________________ Beat it to fit, Paint it to match...

10-05-2008, 11:35 AM	#4
pumpkin Registered User Join Date: Apr 2006 Location: East Sooke B.C. Canada Posts: 543	Re: new rotors - turn or not? I am a mechanic and work in a shop, we machine all new rotors. For us its just not worth the hastle of redoing the job when the rotors are not true. I have found about a 30% fail rate on new rotors, as far as having too much runout. I have also found about 2% being too bad to even bother machining. When I do brakes at home, I just take my chances.

10-05-2008, 11:37 AM	#5
mbgmike Registered User Join Date: Aug 2005 Location: Pasadena,Tx /Pto Pta DR Posts: 5,415	Re: new rotors - turn or not? Turning your new rotors off the car/truck really IMO is not really needed unless you bought some really inexpensive ones. If you are looking for the maximum performance,Yes i would turn them installed on the vehicle. Thats the best way and most manufacturers are doing it now

10-05-2008, 11:44 AM	#7
jerry moss Born Psycho Join Date: Feb 2001 Location: brentwood,cal,usa Posts: 4,852	Re: new rotors - turn or not? definitly have them turned. i also work in a shop and it's cheap insurance to turn them before installing them. normally they are pretty close to being true and a couple thousandths will true them. a lot depends on where they were purchased--if they are cheap rotors and/or were not stacked properly in the warehouse they can be off quite a bit. __________________ jerry moss 72 cheyenne super K20- tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,tow hooks,bumper guards,toolbox,aux. fuel tank,posi front and rear,plus other goodies!!! SOLD 69 suburban K20-tilt,tach,vacuum,speedwarning,buckets,shoulder belts,am/fm,4 inch all spring lift,4 speed, 14 bolt full floater, dana 44 HD,warn winch,posi front and rear,tow hooks,plus other goodies. 73/80 chevy/gmc K20 SB400,turbo 400,205,tilt,a-c,gas hog. 77 K/5 cheyenne blazer-daily driver/beater. SON HAS IT NOW BRENTWOOD,CALIFORNIA

10-05-2008, 12:10 PM	#10
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: new rotors - turn or not? I guess it's 50/50 on the subject. I have always just put them on. Never a problem. I do, however clean them with brake clean before final assembly. JMO __________________ 1997 GMC Sierra Ext 1965 Mustang

10-05-2008, 01:07 PM	#11
BLACK AND BLUE 67-72 Firefighter Join Date: Feb 2001 Location: Yellville, Ar, USA Posts: 1,943	Re: new rotors - turn or not? 1pc. rotor like yours just put it on and run it, 2pc. like a 4x4 that is seperate from the hub then those need to be turned!!!!! __________________ '72 Chevy SWB 350 Auto '67 GMC LWB 350 4 speed '70 Chevy 4x4 Stepside 350 Auto Yellville, Ar. USA

10-05-2008, 01:45 PM	#12
Fastfun Registered User Join Date: Jun 2005 Location: Scottsdale, AZ Posts: 615	Re: new rotors - turn or not? I always check the run out first if they are off then I have them turned.



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