3.08 or 3.31 with 4L65?

[CaliWagon83]

Thanks vanrah. Actually, the Moser 12-bolt is slightly cheaper than the 9-inch, and from what I've read, it has a little less mechanical drag than the 9-inch. If I was doing a massive 1,000-hp monster, I'd get a 9-inch, no question, but for the amount of power a stock LS3 puts out, I think a 12-bolt will be plenty strong. Basically, the ratio choices with the Moser 12-bolt start at 3.08, which seems slightly on the tall side (but probably OK) and the next step is 3.31. I'd probably do a 3.15 or 3.23 if they were an option, but I think 3.31 should be close to the "sweet spot" for what my needs are.

 

[TURNA]

One good thing about the Moser 12 bolt is they put the bolt in axles on it

 

[455'ed80Regal]

My vote is for 3.31 gears.

 

[TURNA]

3:73!!!!!!!!!!!!!!!

 

[roger1]

With the driving you want to do on the highway, I say the 3.08 hands down.
I have a 4L60E and a 3.42 in my El Camino. Ratios in the transmission are the same in a 4L65 and my tires are pretty close to yours.
I think it's revving too high to feel real comfortable cruising at 75 to 80 mph. Not too bad at 70 though.
Back in the day, we were all used to engines revving high at 75 & 80 but today, we are spoiled by the newer cars we use for our daily drivers.
If I had it to do over, I would have gone with a 3.08 in my Elky.

A 3.08 is still great off-the-line with a 3.06 first gear and an automatic transmission. You will still be able to smoke 'em if you want to with that LS3.

 

[CaliWagon83]

Thanks for your perspective roger1. Seems like the immediate reaction by most is “shorter is better.” Sure, if your main goal is quarter-mile and stoplight drags.

But with the amount of power the LS3 has relative to the weight of the vehicle, I think 3.08 will work fine.

For perspective, I was looking at some of the Corvette gear ratios with models equipped with the 4L60, and they were 2.73 standard, and 3.15 for the “performance” ratio. I know my wagon will be a little heavier than a C6, but surprisingly, not by that much.

 

[Turbolq4]

My sedan has 2.73 ratio in a ferd 8.8. I also have 245/45 17s all the way around. My 80e has a shorter overdrive than a 65e has. I'm a fan of leveraging torque with longer gears (numerically lower) than most. The 5.3 is whirring along at 2200 at 85+ with the converter locked. Torque is a non issue even locked down at those speeds it's easy to pick up speed. Don't let the big block crowd scare you into thinking to your engine is peaky, it isn't. It will eat most anything you come across regardless of engine speed. I personally would get the 3.08 gearset but would also look into a performance converter so it's still lively around town. Lockup is a must. Circle D worked great for me but there are many options.

That car will be vicious, to hell with the doubters.

 

[fleming442]

Was researching your situation, and bumped into this.

 

[CaliWagon83]

Was researching your situation, and bumped into this.

Yeah. The LSA...Potentially an option if I can pull together the scratch. Realistically, I think the LS3 will be more than enough for my needs.

Interesting you guys bring up the issue of torque. I know on the LM7 I have in my Avalanche, on paper, the torque peak is 330 lb-ft at 4,000 rpm, but I also read somewhere else that it’s making 300 lb-ft at just 1,700 rpm. I imagine it’s a similar situation with the LS3...Plenty of torque “under the curve” that just happens to “peak” higher.

 

[roger1]

LS3 torque curve