Trying to figure out why my rear rotor is running so hot after changing the rear stock wheel to a custom rim. Mounted a new tire on the new rim. Changed to brake pads and went for a ride. The rear rotor was very hot. Im wondering if the old rotor is warped or if the new pads are dragging on the old rotor and are trying to seat in. I brought the bike back home and put it up the the lift. The rear wheel turns freely and when I apply the back brake the tire stops. When the brake pedal is released the wheel will turn freely again.
Do you think the callipers are sticking?
How do I check to see if the rotor is warped?
Any suggestions
Thanks in advance
Scot

 

If you used it at all it will be hot for a while. Friction is what makes it work so it has to get hot. If it is not dragging while turning it I would guess it is normal. After use mine is too hot to touch for quite a while.

 

............. seizing up completely notwithstanding, friction would rapidly wear down the pad to allow pad/disc clearance. If you jack the back and manually spin the rear wheel you can confirm correct operation - there will always be some light drag. Discs get extremely hot - wouldn't advise the touch test!

 

Are the spacers on the correct side?

 

I would think that if the wheel turns freely like you say,it's just normal.

The best way to check for rotor runout is to use a dial indicator.
If its really bad, you can see it while turning the wheel by hand and the pedal may pulse when applied.

 

Thanks for the replies. It just seems weird because the front two rotors are no way near as hot. I can touch them and there is a BIG difference in temperature. I am worried that the temp on the rear rotor may cause wheel bearing breakdown or failure.

 

Rear rotor does not get as much cooling air as the front wheel rotors do.

 

Also depends on your braking habbits.

 

If it works as you say, that is, no drag brake off, brake on, then no drag brake off again--- ride it. A warped rotor usually will give you 'as you spin' drag - loose- drag and also it can give you a pulsating pedal. If you still think there is a dragging type problem, go ride a bit with no rear brake then check it again. To be safe, spit on your finger and touch it quick. If it is only warm ( from normal pad contact) you should be good to go. If not, further diagnosing is in order. If you wish, I can elaborate further, but I'm thinking you'll be fine.

 

Disconnect the pedal. If it is cooler than before, you are dragging the brake without knowing it.