A body rear disk questions--hat sizes?

[bart007]

Hi, I am in the process of adding rear disk to my 70 Tempest, all was going good and well within my abilities. Until I realized the 1987 Iroc rear disk hat inner demensions were smaller than the outer rear axle stud ring. The rear rotor measures 10.5" in total diameter, the inner is 5.75". The stud plate on the end of the Pontiac axle measures 6.25". As a result the Camaro hat will not fit over the Pontiac axle. Does anyone have any ideas as to a GM rotor that would be more in line with the Pontaic's outer axle diam. and remain no bigger than 10.5" total diam.? I would really like using this set up and would rather not make a stop by the machine shop to cut the axles.
All help will be much appreciated.
Thanks

[bart007]

Well, no interest in replying...off to the machine shop I go.

[72 GOAT]

I had the same issue with my C6 Z06 install on my 72 GTO, I had my local ,machine shop machine out the inside of the rotor and it fits fine.

[HarleyT]

I had my axles machined instead of the rotor hat. This way if I ever needed another one I could stop and pick it up from any parts store.

[Apogee]

Well, no interest in replying...off to the machine shop I go.

Most GM OE rear axles of that era equipped with drum brakes measured 6.15"-6.18" flange diameter and you've only got a 5x4.75 pattern, so your best bet is to just turn them down and be done with it IMO. I can think of plenty of rotors with larger hat areas, but none that are 10.5" diameter and you didn't specify the thickness or overall height either...

Tobin
KORE3

[PT Goat]

I had my axles machined instead of the rotor hat. This way if I ever needed another one I could stop and pick it up from any parts store.

Me too - the Baer serious street kit directions said machining of the axles was required.

[bart007]

I had my axles machined instead of the rotor hat. This way if I ever needed another one I could stop and pick it up from any parts store.

Exactly what I am doing, figuring easier to replace rotors in the future.

Thanks all, I was hoping there may have been a majic bean to cure my woes.