I am slapping a Wilwood disc big brake kit onto a Moser 12 bolt with 33 spline axles. I am having issues with the rotor hats not fitting flush against the axle face due to slightly thicker/beveled wheel stud ends. This causes the calipers to be out of line as they cannot be properly centered. The wheel studs are 1/2 inch diameter but appear to be slightly thicker at the top. Using the supplied spacer shims that go between the caliper and bracket is not applicable in this case as they are used to decrease the gap that I am missing at the moment. Please see the pictures as they tell the story.

Anyone run into this issue? Should I slightly enlarge (drill) the stud holes in the rotor hats? Or is there another way to properly seat the rotor hat onto the wheel stud? Thank you in advance...


http://www.mattlekawa.com/pictures/camaro/thickerWheelStudEnds.jpg

http://www.mattlekawa.com/pictures/camaro/rotorHatNotFlushWithAxle.jpg

http://www.mattlekawa.com/pictures/camaro/uncenteredRotor1.jpg

http://www.mattlekawa.com/pictures/camaro/uncenteredRotor2.jpg

Yep.the stud seems to be THE issue ...I would drill em....cool car Hope mines as nice when its done....chek it out....


http://s452.photobucket.com/albums/qq247/vette468guy/?start=80:hurray:

DRill em.

DRill em.

Hey Jim,
Based on previous conversations with you I know you have a similar rear (and front) Wilwood brake setup on your car. Did you have to drill your hats to fit the studs?

They must be enlarged....been there done that.

Hey Jim,
Based on previous conversations with you I know you have a similar rear (and front) Wilwood brake setup on your car. Did you have to drill your hats to fit the studs?

Jim, I think I answered my own question as I just found your thread regarding rear brake assembly you did on your car. You had some 'similar' issues but yours were on the 'other side' as you had to shim pretty thick to compensate. I haven’t gotten to the shim part yet and hopefully I won't have to cross the same bridge once my rotor hats seat themselves correctly.

http://www.camaros.net/forums/showthread.php?t=100665&highlight=rotor+hats

i think that i'd be calling Moser and asking if they could send out some studs that don't have the shoulder on them instead of drilling the rotor hat.

Just measured and the stud shoulders are 17/32 while the threaded portion of the stud and rotor hat holes are 1/2. Hmm...so I am hearing drill vs. no drill and get the right studs...decisions, decisions, decisions... It's not going to be a quick fix either way as I don't think I am going to be able to find a 17/32 bit anywhere in this tree hugger town.

17/32 drill bit is next to impossible to find. None of the auto parts, Sears, HomeDepot, Lowes, etc carry this size. I will have to order on-line. I'll call around some machine shops tomorrow and see what they have.

Would drilling out to 9/16 be taking a chance?

1/32" sounds like just enough clearance to me
I would go with the 9/16" hole
But thats just me...

my logic for getting different studs goes like this: someday, you (or the next guy that owns the car if you ever sell it) might need a new rotor for whatever reason.
you get the new rotor and go to put it on, and only then do you remember how you had to modify the original part and that you can't remember where you put that stupid bit that you only ever used to drill the rotors in the first place.
new studs seems like the most logical fix- but it would be more logical for the makers of the axle to put in studs that don't have an extended shoulder like that when they first make them.

my logic for getting different studs goes like this: someday, you (or the next guy that owns the car if you ever sell it) might need a new rotor for whatever reason.
you get the new rotor and go to put it on, and only then do you remember how you had to modify the original part and that you can't remember where you put that stupid bit that you only ever used to drill the rotors in the first place.
new studs seems like the most logical fix- but it would be more logical for the makers of the axle to put in studs that don't have an extended shoulder like that when they first make them.

I hear ya. I'll call Moser tomorrow and see what they say. Just having to disassemble, break the thread locker on the nuts, pull the axles out, press studs out, press studs in and reassemble seems like a lot of work when there is acceptable alternate solution used by many before. Also, Wilwood's instructions do mention having to enlarge the stud openings due to thicker than 1/2 inch studs on some applications.

I used a die grinder until I had just enough clearance for a snug fit.

A touch with a die grinder is perfect. Moser does not have a smaller shank stud.

I called Moser today and they told me that when they install Wilwood hats they use a 35/64 bit to enlarge the hole to make up for the stud sleeve. I'll give it a touch of die grinder like Frank said and should be good to go. Thanks everyone...

The die grinder I had wasn't big enough so the 35/64 drill bit got here today. Drilled the holes and the hats fit perfectly now. No shims needed on one side while 1 upper 1 lower shim needed on the other side. Good to go!