[b-man]

Originally Posted by DaleO

I'm not set on a 12 bolt. My only issue with it is when somebody would notice it they would then really expect me to be able to perform and I'm just not there. Not worthy. I really want to see what I an do and need drag radials to do that and am pretty sure I'd break the 10 bolt pretty quickly. Besides, I want a little steeper gears.

Thank you for your input. I've been looking at the Quick Performance site. The thing I need to study next is brake size, I have drums and they list 11" drums which I am not sure will fit 15 inch wheels. I suspect so because I think 11" drums were on the station wagons which likely had 15 inch wheels. The other issue I might have is with having larger brakes on the rear as I still have 9 1/2" drums up front. I think that is the size Pontiac used.

I’d opt for the 11” Ford drum brakes if you decide to the pull the trigger on a 9” rear, as I see it you’re overdue for a front brake upgrade. I ran the 11” rear drums on my ‘64 GTO bracket car equipped with a 9” and ‘69 GP spindles/11” discs up front, no problem with fitting those 11” drums inside a 15” wheel.

I was bracket racing launching off of a transbrake with slicks and it was nice to have a strong 9” under the car, however it wasn’t really a high strength unit and only had a stock cast iron housing, a Detroit Locker and shortened/resplined stock 31-spline axles. This was an old 1987 vintage Currie 9” that came in the car when I bought the car in 1989, built off of a salvage yard housing like most back in those days. It wasn’t that uncommon for my competitors to break their stock 12-bolts on the starting line which made me like the 9” even more.

For my street only ‘64 Tempest with the 430 hp LS3/4L70E I decided on the ‘71-‘72 Buick/Olds GM corporate 8.5” 10-bolt. My reasoning at the time was because those units are equipped with bolt in axles and tapered roller axle bearings to better handle cornering loads. Also the lower friction 8.5” gears as well as the lighter axle housing, for better suspension control since the axle housing is unsprung weight. I’m running fairly heavy 13.4” C6 Corvette rear disc brakes (and corresponding 14” front discs) so I thought compensating for that with a lighter rear axle assembly might be a good idea.

Maybe I’d have been better off with a new aftermarket 12-bolt but what’s done is done. I did upgrade the 8.5 with an Eaton posi and 30-spline Moser axles so I’m sure it’ll handle whatever I’m doing during spirited street driving and occasional canyon carving.