Hi Guys - I’ve finally got my project on the road and I’m having a blast with it but need some advice on how to choose the best gear ratio and wether or not I can build the 8.5” posi thats in the car to be strong enough. Some details: Car - 1985 Lesabre Coupe Engine - Buick 482 (Peak HP 582@5850, Peak TQ 582@4590 -from engine dyno) Trans - CK Perf 2004r Pro Street 2200-2500 12” lock up Rear - Stock 8.5” limited slip with 2.73s Tire 27”- 255/60/15 Cooper Cobras Goals - 95% Street use including some longer trips like Power tour/Buick Nats etc. When driving around with the 2.73s it clearly needs a bit more gear to find the sweet spots on the power band but also want to be able to cruise 70-80 mph without it screaming. I’m thinking anyware from 3.41-3.73 would be right but that only a guess. So my questions are: 1. Can the stock housing be built up to handle the power under street conditions? 2. What ratio would you recommend? Thanks in advance - Rich
Keep the 8.5 but upgrade the axles to Moser or somethign similar and a quality diff (Monzas or Brian Trick can tell you what theyre having good luck with thtese days and probably sell you the parts if not do the whole axle for you), and I'd think 3.42/3.55 would be the right gear for what youre doing.
The 8.5” can handle that no problem. Since you are running the 2004R,I would run a 3:42 or possibly 3:55. Drive it anywhere. Upgrade to 30-spline shafts and a good unit like a Tru Trac.
