turning rotors

[dirtynails]

so I took my rotors to my local Checker to have them turned and they are saying I need to have them mounted on the hub because the can't hook up the centering disks. The grease would have to be wiped out of the hub and bearings and seal removed so they can access the races.

Is this right?

 

[oneofthefewbmx]

they are idiots ....take that **** to oriely's for 7 dollars

 

[dremu]

Some say it's better that way -- makes the new surfaces absolutely perpendicular to the hub's turning axis.

OTOH, I've seen lots of folks do just the rotors without hubs.

-- A

 

[oneofthefewbmx]

daniel has turned i dont know how many rotors in the 3 years he was a manager at oriely's and has never needed a hub....(i know you guys are thinking "auto-parts ppl are all idiots", but this is my best friend that works on my rig and he is the only one there that knows his **** back to front..he is the exception to the auto-part-idot-rule )

 

[4X4HIGH]

The proper way is to have the rotor mounted to the hub. There are two reasons why a rotor is being machined. First you need to eliminate any runout in the rotor (parallelism between both sides of the rotor) which is what causes the pedal to pulsate and secondly the rotor surface needs to be perpendicular to the hub centerline. If you machine the rotor without the hub and then press the rotor on the hub you are fighting two different elements at the same time. The pressing of the studs is enough to distort the rotor (which was just machined true to the spindle on the brake lathe) and also the center is no longer going to be true once it is pressed to the hub.

You can take or leave my advice but i've been doing this for 21 years now.

 

[oneofthefewbmx]

The proper way is to have the rotor mounted to the hub. There are two reasons why a rotor is being machined. First you need to eliminate any runout in the rotor (parallelism between both sides of the rotor) which is what causes the pedal to pulsate and secondly the rotor surface needs to be perpendicular to the hub centerline. If you machine the rotor without the hub and then press the rotor on the hub you are fighting two different elements at the same time. The pressing of the studs is enough to distort the rotor (which was just machined true to the spindle on the brake lathe) and also the center is no longer going to be true once it is pressed to the hub.

You can take or leave my advice but i've been doing this for 21 years now.

...i have now been told

 

[Thunder]

The proper way is to have the rotor mounted to the hub. There are two reasons why a rotor is being machined. First you need to eliminate any runout in the rotor (parallelism between both sides of the rotor) which is what causes the pedal to pulsate and secondly the rotor surface needs to be perpendicular to the hub centerline. If you machine the rotor without the hub and then press the rotor on the hub you are fighting two different elements at the same time. The pressing of the studs is enough to distort the rotor (which was just machined true to the spindle on the brake lathe) and also the center is no longer going to be true once it is pressed to the hub.

You can take or leave my advice but i've been doing this for 21 years now.

X2 to Properly do a good brake job the rotor should be turned on the hub, torqued equally, and throughrouly cleaned out.

And I have been doing this stuff off and on for 30 some odd years. But dont let me tell ya what to do

 

[rdn2blazer]

The proper way is to have the rotor mounted to the hub. There are two reasons why a rotor is being machined. First you need to eliminate any runout in the rotor (parallelism between both sides of the rotor) which is what causes the pedal to pulsate and secondly the rotor surface needs to be perpendicular to the hub centerline. If you machine the rotor without the hub and then press the rotor on the hub you are fighting two different elements at the same time. The pressing of the studs is enough to distort the rotor (which was just machined true to the spindle on the brake lathe) and also the center is no longer going to be true once it is pressed to the hub.

You can take or leave my advice but i've been doing this for 21 years now.

Yes its the BEST WAY, But turning a rotor with it off should be good if done properly. I doubt when they manufacture a new rotor they take the time to mount every new rotor to a hub then turn it. Car rotors dont come on a hub, you just take the rotor off, turn it, put it back on.

 

[4X4HIGH]

Most cars are lug centric not hub centric. If a rotor bolts or presses to a hub then it should be machined that way. Also even if you had a hub for machining purposes and pressed it together for machining and then pressed it back apart and put it onto a different hub it will not be true to that hub.

 

[rdn2blazer]

Most cars are lug centric not hub centric. If a rotor bolts or presses to a hub then it should be machined that way. Also even if you had a hub for machining purposes and pressed it together for machining and then pressed it back apart and put it onto a different hub it will not be true to that hub.

DOH! I completely forgot about Hub vs lug centric, I have herd these terms and descriptions before. I know about the pressing aspect, from one hub to another even if exactly the same dimension, you will get runout, thats common in machining. It, in many cases its very little runout.