alnukem

Thanks for having me. I am a Y-Body guy with LT-5's & LS Platforms. I basically did a "rescue" of a 96 Comp T/A (WS-6 LT-1 310 BHP), I am in the process of getting it running.....no spark from Opti. Running the numbers it turns out it is at the most, 1 of 4. Since the rarity of it, I want it to stay stock with the exception of gears.....got to have some giddyup! Now questions.

Are these 10 Bolt GM diffs?

Are gears somewhere around 4.30's available?

What would be a better choice with totally stock drivetrain, with the exception of gears, for purely street cruising, 4.10's, 4.30's, 4.56's?????

Thanks, Tim

shoebox

10 bolt with 7-5/8" ring gear.

The most popular swap gear for driveability with a six speed is the 4.10 ratio.

alnukem

Thanks Shoebox. This helps. Are there "steeper" durable gear sets out there?

shoebox

6 speeds are harder on gears than an auto and 10 bolts are not exactly known for their hardiness under extreme conditions. More teeth on the ring gear would probably bring down the durability a little.

Injuneer

Richmond and Motive both make 4.56's for the 7.5/7.625" 10-bolt. Yukon makes a 4.30:1 set.

As Rob points out, gonna be risky. I ran 3.73's when my car was still a T56. Wouldn't recommend them. I'd think 4.10 would be the upper limit for a street car. The stock 3.42's put you at 1,600RPM at 70MPH in 6th gear. The 4.56's would put you at 2,133RPM. 4.30's would be 2,012RPM at 70MPH.

If you did run the 1/4-mile, the 4.10's would allow you to trap at 105MPH in 4th gear without shifting into overdrive 5th, and the stock rev limiter, stock tire diameter. 4.56's would have you shifting into 5th at 95MPH to make it through the traps.

alnukem

Injuneer......why do you not recommend 3.73's....too little gear?

alnukem

Thanks guys, I appreciate your help. In reading on the forums, it seems people are worried about the durability of the 4.30 gear sets, alluding to puny gears without a lot of beef. Actually as far as cruising on interstates, I've run 3,000-3,200 RPM's for hours, I don't think it hurts the engine, just fuel economy.