Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.

New Posts Contact us

Just Commodores Forum Community

It takes just a moment to join our fantastic community

Register

Using Sandpaper to Roughen up Brake Rotors

ben315vz

Donating Member
Joined
May 11, 2011
Messages
1,466
Reaction score
22
Points
38
Age
32
Location
Tamborine Mountain, QLD
Members Ride
'05 Holden VZ Calais V8
A while ago in another thread (can't remember which one), I got flamed because I said that sometimes I roughen up brake rotors with sandpaper instead of machining them.

I just found post on another forum that I found quite interesting. Please read it, and discuss.

Resurfacing Brake Rotors

Since I am constantly reading posts where this question is asked I thought I would make a post devoted to it.

DO NOT resurface brake rotors just because you are replacing the pads. There is absolutely no reason. You shorten the rotor life, make it thinner so it does not hand the heat as well and spend money you should not be spending.
Almost every auto manufacturer has now come out and confimed that all of thier dealers should not be resurfacing rotors when brakes are done. It is only done to make money for the dealer.

Reasons for a rotor to be resurfaced.
1. Parallelism. The rotor is not true as it relates to the hub when it is on the vehicle. This is why they all recommend on car resurfacing.
2. Rotor scoring due to poor pad formulation, etc. Even then, GM's recommendation is to check the depth with a penny and if you can still see the top of Lincolns head then they are okay (believe it or not!)


If you would like to remove old pad transfer material from a rotor surface then you can use a 120 grit sandpaper to scuff up the surface. Excess pad transfer buildup can be removed without resurfacing. Many times it can be done by rebedding the pads. Roll-loc discs is also an option to clean up the surface of a rotor for pad transfer but even then I would go with a red (aluminum) disk, browns are just a bit to heavy.

I can honestly say that in the last 15 years I have never resurfaced a rotor on any of my 7 or so cars from all different manufacturers. Reason? Wheels should always be torqued with a torque wrench with no exceptions. I worked in a dealership for years and NO I didn't use one on customer cars because A) thatisn't the fast way when your flat rate B) If they start to pulsate I can just cut or replace them later (not my money but I make money doing it)
That is just the way it is. Don't think for a second that wheels get properly torqued at a dealership. Torque sticks only worked in a controlled situation in which the impact gun only puts out 250 ft lbs of torque. I've seen sticks broken by Impact guns because they are capable of a lot more then 250!

If you must have the wheels removed by a delaer or anyshop for that matter, request they use a torque wrench to reinstall the lugs and then when you get home, loosen all the lugs and retorque anyway.
 

383 hatch

Well-Known Member
Joined
Jun 14, 2005
Messages
3,922
Reaction score
67
Points
48
Age
41
Location
Cowes, Phillip Island
Members Ride
VG Ute 5.0,Torana hatch 383,WB Ute 5.0,VR stato5.0
At work, we never, ever machine rotors. We do 1 of 2 things. If the rotors are not pulsating, grooved/scored or undersized, we just put pads in and leave it at that. If the rotors are stuffed, we just whack new ones on. It seriously isn't worth machining rotors these days (that's also because we are an hour away from the nearest place that can machine rotors which means too much down time). Having said all that, we've never used sandpaper on rotors, because there is no need.
 

showbags

SENIOR EL'BAGO
Joined
Dec 7, 2009
Messages
1,898
Reaction score
32
Points
48
Location
geelong
Members Ride
VT Calais, BMW 135 m sport
^^^^ + 1. For the price you can buy rotors for now, why bother machining. Throw those mother f#%\ers in the bin and put new ones on.
 

ben315vz

Donating Member
Joined
May 11, 2011
Messages
1,466
Reaction score
22
Points
38
Age
32
Location
Tamborine Mountain, QLD
Members Ride
'05 Holden VZ Calais V8
Where I work, I have no choice. I have to do what I am told, so if the boss says to machine the rotors, they have to be machined. If he wants me to just roughen them up with sandpaper, then thats what has to be done.

They get good prices on rotors from Repco anyway, I would rather pay the extra to get new rotors.
 

Darren_L

Well-Known Member
Joined
May 2, 2009
Messages
1,872
Reaction score
73
Points
48
Location
Toowoomba, Qld
Members Ride
VH SS
the only time you need to machine rotors is when they have excess lateral runout or there is excess surface wear/lips on the edges etc.

Otherwise, if the rotors are in good condition and you are just carrying out a routine pad change, nothing wrong at all with just roughing up the rotor surface with some sandpaper to aid brake pad bed-in.
 
Last edited:

1SIKR8

New Member
Joined
Feb 26, 2010
Messages
453
Reaction score
3
Points
0
Location
Tamworth NSW
Members Ride
VK -Project-, VX R8 Clubsport
^^^^ + 1. For the price you can buy rotors for now, why bother machining. Throw those mother f#%\ers in the bin and put new ones on.



try pricing rotors on the HSV's with the premium brake upgrade, not cheap even if going aftermarket

deafinatly a good read scvs6
 

showbags

SENIOR EL'BAGO
Joined
Dec 7, 2009
Messages
1,898
Reaction score
32
Points
48
Location
geelong
Members Ride
VT Calais, BMW 135 m sport
Yeh, that's a different story of course. I was really referring to the likes of DR40's & 41's.
 

ben315vz

Donating Member
Joined
May 11, 2011
Messages
1,466
Reaction score
22
Points
38
Age
32
Location
Tamborine Mountain, QLD
Members Ride
'05 Holden VZ Calais V8
try pricing rotors on the HSV's with the premium brake upgrade, not cheap even if going aftermarket

deafinatly a good read scvs6

There is a 2007 FPV BF MKII GT that comes in to work all the time for servicing, we have already had to replace the brake pads twice and the rotors were so worn out that they had to be replaced as well. You could tell because the slots were almost gone. We ended up buying aftermarket drilled and slotted rotors and brake pads (both times) but they were still expensive.

There is also a customer that owns a FPV BF Force 8, I have never worked on that car myself but I am pretty sure that the brakes and rotors have been replaced a couple of times (at least once). Genuine was too expensive.
 

ben315vz

Donating Member
Joined
May 11, 2011
Messages
1,466
Reaction score
22
Points
38
Age
32
Location
Tamborine Mountain, QLD
Members Ride
'05 Holden VZ Calais V8
Top