Need to replace front brake rotor on 1979 750f

Posted: Tue Feb 23, 2010 2:58 am

I have a 1979 750f with a dimple on the front rotor that causes some pulsing and needs to be replaced. Are the front discs compatible with all years of F bikes? Are there any other models with compatible discs that I should be looking for?

Posted: Tue Feb 23, 2010 4:12 am

I direct swapped the 1979 C rotors onto my 1982 F, the only difference was venting. I'd assume the same holds true for all cb rotors, hell maybe all the rotors honda made in that time frame are the same, my CX rotors appear to be the same diameter.

jaz

Posted: Tue Feb 23, 2010 6:55 am

Grebnaws wrote:

I have a 1979 750f with a dimple on the front rotor that causes some pulsing and needs to be replaced. Are the front discs compatible with all years of F bikes? Are there any other models with compatible discs that I should be looking for?

Are you sure there's a dimple? I thought that I had a warped set and took them to an old school mechanic/machinist to have them turned. He said, without even looking that they weren't warped, and that it was practically impossible to warp those type of disks (900F). It's a long story, but in the end, he was right. They weren't warped, the problem that was causing the pulsing was the paper 'gasket' between the wheel and rotor - it was ripped and part of it was missing which was causing a misalignment of the rotor.

Posted: Tue Feb 23, 2010 7:34 am

My 750f rotors were definitely warped, no doubt about it. dunno what the DPO did to warp them, but they were both warped severely. Of course, vegas temps are hot as fuck for 6 months out of the year, so warped rotors are pretty normal here.

jaz

Posted: Tue Feb 23, 2010 3:23 pm

I've got a set of drilled ft. rotors that I could let you have for a small fee...these are suppose to run cooler...if you're interested. Cool

Posted: Wed Feb 24, 2010 1:40 am

Yeah, I'm sure it isn't warped. There is a dime sized dimple that looks like it could have been caused by a heavy spot of rust or a casting flaw. The dimple looks just like unfinished cast iron. It is less than 1/16" deep but the previous owner warned me that it caused pulsing and I'm inclined to believe him. It would be a good case for turning but I don't know who would do it or what it could cost. I thought a replacement for the lowly 750f would easy to find and cheaper than machining.

Natscape, I'll send you a PM

Posted: Wed Feb 24, 2010 3:59 pm

Hey,

Why would an inverted (concave) dimple cause a pulse? Drilled rotors do not pulse. If you have access to a dial indicator, check run out. The paper gasket could do it. Good luck.

Grant.

CB1100F Joined: May 13, 2005 Posts: 3217 Location: NE OHIO

I have a set If your interested give me a PM.