toms rear disc stud fit issue

[bobscott]

So the rotors in the toms kit are not fitting over the wheel studs. The rotors have a half inch hole. The studs mic out around 0.605 to 0.610 at the base. Anyone else run into this issue? What did you do? I am thinking of drilling the rotor out to 39/64. Any issue doing this with a hand held drill? The rotors have a recess on the front side around 0.610". Wonder if this is there as a pilot to make this easier if needed.

 

[Apogee]

If the rotor is hub-centric on the axle register, then the wheel stud hole diameter in the rotors doesn't matter, you can make them any size you like. If you're relying on the wheel studs to center the rotor in a lug-centric fashion, then you want things as snug as is reasonable from an assembly perspective. Ideally though, you would make the rotors hub-centric or run a hub-centric ring on the register, then it won't matter what you do with the holes.

FWIW, the stock studs are 1/2", so is it the knurl sticking through the axle flange that you're running? If so, then you might be able to just countersink the backside of the rotors to clear the bulge depending on how far it protrudes from the flange.

Tobin

 

[garberz]

The rotors wont be easy to drill or even make a countersink. That's some hard steel.

Mark

 

[TwoDalesDad]

If you want to do any cutting on the rotors...I would take them to a friend....or a shop....A hand dril will hurt your wrist.....the steel the rotors are made from.....are harder than any drill bits you would own.....

 

[bobscott]

Thanks guys, it is the knurl of the stud that is the problem. The front side of the rotors has a countersink that is the right diameter. I wonder if this was a mix up where the countersink got put on the wrong side? Probably not though, as if I put the rotors on backwards the countersink isn't deep enough for the rotor to flush up.

I dropped the rotors and one of the the old drums off at a machine shop this morning. I realized that the hole in the center wouldn't register with the axle, so the studs are the only alignment. Once I saw this I knew using a hand drill was out. Also I was worried any drill press in my price range would have too much run out to get these right. Either way the $50 it is going to cost is worth the reduced aggrevation anyhow.

 

[jhill52]

Call Toms and ask them. They may have a solution.

 

[Apogee]

Why does everyone think rotors would be hard to drill? Assuming a uni-cast rotor design, they're cast iron? If anything, the only thing that can make them difficult to drill is that they're so soft and cut so easily that the drill bit can grab hard when it breaks through. Even if the disc kit uses rotors with a composite steel hat/cast disc design, the hats are still only mild steel. Maybe I'm missing something or others are thinking about modifying the axle flanges...those are a bit harder to drill.

If you're going to pay a machine shop to do it, I would just have them punch the stud holes out to 5/8 (.625") diameter and then machine a stainless ring for the axle register so that the rotors are hub-centric. For future rotors, you can hand drill the rotors and not negatively impact the axial runnout of the rotor.

 

[bobscott]

I like the idea of the ring for the register. I will have this done.