rockytopper

I am about to install a posi unit in my bop 8.2 10 bolt. The current gear ratio in the open unit is 3.08. I would like to purchase the eaton posi but the smallest gear it will support is a 3.36. I can purchase a augburn unit that will allow me to keep the 3.08 ratio. It is also the most economic way because it is about 150$ cheaper and I don't have to buy gears. I have heard it is not as good as the eaton unit. I have run a best of 14.015 at 101 mph with the current ratio and open rear. My times are hurt by the fact I cannot launch hard or even mildly without smoking the tire. I am quit certain that even if it was a posi it would still smoke both tires if you tried to launch it with instant WOT or just under that. I really like the highway driving with the 3.08 ratio. I'm running a 26.62 tall tire and it turns 1900 at 70 mph. I have no plans to put slicks or drag radials on the car so basically I'm thinking the shorter 3.36 gears will just make my traction issues worse and hurt me on the highway for mpg. I plan to run Bfg 9.64 wide Ta on the rear. The engine is a stock 2002 LS1. The factory camaro A4 cars had 2.73 or 3.23. I have read that there wasn't to much performance difference in them. What are your toughts on going with the 3.36 gears on street tires. Will it be to much gear or not. The car weighs about 3400, 3750 with me in it.
Thanks in advance.

V8Rumble

iTrader: (9)

Honestly, I don't think it'll hurt you much at all (if any). Using this calculator (& substituting a 700R4 trans instead of the 4L60E that isn't an option) it shows you running 62 mph @ 1700 RPMs with a 3.08 gearset. Swapping to the 3.36 gears changes the speed to 57 mph. And it's just about a sure bet that you'd be into the 13s (I know that's not super-important to ya, but it IS nice to be able to say...).

Also - 75 mph in 4th gear is still only about 2200 rpms, roughly where it is with my car when it was bone-stock! (And LS engines don't seem to mind revving a little bit...)

I'd say that the benefits would outweigh the slight rise in RPMs, but I don't know how you would weight the different factors.

bczee

iTrader: (12)

I wouldn't go more than 3.42 or 3.55's.

I have 4.11's and 275's street tires and I can't come off of the line without smoking them either and that is from a idle and then rolling into the throttle.

LS-1<>57

iTrader: (3)

Ya just need bigger more manly tires .......lol..!!!! I put M/T 30x12.5x15 street radials on mine with the 4.11 rear and hang on for a great launch... I have 355 hp at the rear tires to make me happy. I'm at about 2200 rpm's @ 70 mph What could be better than huge, manly tires on the back..??? LOL that's MHO.

Later DK

Stu Cool

iTrader: (13)

My Stude is similar weight to yours. I have 3.80 gears with 28 inch tire. 2100 RPM at 65 mph. Get 26-27 mpg on the highway. Traction is an issue for sure. I have run 13.68 on a cold track, rolling into the throttle. I also have a 2800 stall converter. The car is a real neck snapper from 15-35 mph roll. I am quite happy with my set up and hope to try it again at the track under better conditions. I think low 13s are definitely possible.

Pat

Oscar Will

My heavy old '35 sedan really likes the 3.70 gearset that I run. I experimented with a set of 3.25 gears but took them out and threw them away after a couple thousand miles. I have 28.5" rear tires and run a Detroit Tru-Track and the car hooks up pretty well. The performance and fuel economy suffered with the 3.25 gears and I actually HATED driving the car......it just was NOT "happy". I don't have a tach in the car but my "seat-of-the-pants" dyno told me all I needed to know.

bczee

iTrader: (12)

Ok.. I'll add my stats...:

with the 4.11's and a T56 .50 6th gear.. at 65mph, I am turning 1750 rpm's wtih the 275x40x18 tires.
I get 23+mpg's on the highway
Will run 13.8 @ 102 in the 1/4 on a hot 85* night