Hi guys. My friend lunched her 8.2 off the line at the track. It’s about 500 HP, 455 street strip runs low 12s. What are the advantages and disadvantages of going 12 bolt vs 8.5? I know either is up to the task but which is more cost effective and also leaving a bit of room in case she builds a better motor down the road?
Is this an A body? The 71-2 Buick/Olds 8.5 from the Skylark/Cutlass is bolt in axle. Chevy 12 bolt is C clip. The 8.5 has the same pinion diameter and support as a 12 bolt. You'll need a conversion U joint for the 12 bolt. I stepped up to 30 spline Moser axles and matching posi in my 71 8.5.
The chevy 12 volt has a upside down V like shape on the cover the ring gear splashes lube onto the cover the V shape acts like a oil diversion gutter that sends the oil into the axles, bearings....
For what 12 bolt cost i feel the 8.5 can be just as strong for less. The factory 12 case where pron to crack sometimes near the caps.......just thin on the casting......the aftermarket models are much better. I have an 8.5 in my car 30spline movers 4.30 gears, leaving off a transbrake run a best 660 time of 6.52 at 104........no issues so far. Hell I ran stk axles in the 10s.......not that I would tell anyone else too
The 8.5” 10-bolt is just as good or better than a 12-bolt Chevy. If both are in stock form,definitely the 8.5”. When both are built properly and with the right parts,they will handle whatever you can throw at it.
@sean Buick 76 i have a 12bolt in my garage that I’m planning to swap in over the winter. Have a 72 8.5 underneath right now w/ 2.56 gears. Not sure when I’ll get to it but would be willing to part with it when I do. Have a 2 series posi, ring gear spacer and a 3.73 gear set on the bench that could go along… and a TA cover.
Let me know if you need a hand. I would enjoy a trip across to you in order to ensure your gear mesh is correct.
That was only a CHEVY 8.2 rear... And an open too with how many miles????? Everyone always underestimates rear ends because they are the LAST thing anyone pays attention to. Engine big and bad...Trans rebuilt and high stall. Rear end .... 'oh well I do not here anything from it will just leave that along'...LOL. BOOM car is stuck - now you have to tow ...tow guy is a jerk ruins car.... YUCK Just make sure you build either correct you will be good.
