bmbutler

My setup (in sig) is complete, minus the pcm I'm waiting on from Allen.

Once I get the pcm in and its rolling, what gear ratio should I put in the rear-end to compliment the gear ratios of the new 4L80E transmission??

As of now, I have a 3.42 in the rear.
I do about as much highway driving as street driving.
Would 3.73 be okay, or would what I have now (3.42) be okay, or a 3.90, or what?

I heard the first gear is a BIAAA and doesn't shift till almost 60mph!
2nd Gear pulls very hard and is a lot shorter lived.
3rd & OD are the same ratio as 4L60.

L-EATER

iTrader: (2)

Well, I have only driven about 50 miles so (I have 3.73) I can't say for sure yet but I do know 3.42 will suck. If I had to change I would go with 4.10 but I do a lot of highway driving. If I were shooting for low et's I would go for 4.56. Just my opinion

bmbutler

I guess a 3.90 would be a good choice then? Right between 3.73 & 4.11.
I think that'll be the sweet spot to kinda keep highway driving mileage, yet good bottem-end as well.

HMMMMMMMM......with a 3.90, 2800 stall, I am just worried about traction.
I will have a posi, and a 12 inch wide tire (even though they're just Pirelli Scorpion Zero's), I wonder if I'll get a good bite on the street??

Maybe I should keep to the 3.73's?

BlownChevy

iTrader: (20)

Got 4:10's in mine and it seems to be ok....I will not now anything until I get to the dyno then the track. One thing is for sure, it feels good to be back in it after 2.5 months!!!

cstchevy

If I needed to switch gears I would go with the 4.10. I have the 3.73 and I can see where I could really use the 4.10 even just screwing around town.

Bonedog

I know that on the Avalanche the guys with the 3.73 are always talking about how they want the 4.10 gears. With our trucks gas milage diffrence is almost non existant. I have heard difrences of maybe 15-30 miles a tank between the 3.73 and 4.10. In my opinion go the 4.10 and have the bottom end with the driveability on the higway of the OD tranny with the passing power on the down shift of the 4.10.

BTW I have a 4.10 reared AV and my bro has the 3.73. So I am talking from experience. In the avalanche club it is always talked about and the consensus is 4.10.

Hope this helps

Bonedog

bmbutler

Just made the order for 4.10s!

They will be installed Monday PM

Allen's PCM should be delivered tomorrow if he comes through.

I cant freakin' wait!!

whitt1

I'm running 4.56s in my Tahoe,in my 96 Suburban I used 3.73s with a 454 the truck would not spin the tires from a stop.

GoatChs

iTrader: (7)

Don't you need Nelson to input your gear ratio for speedo calibration? Or do you have LS1Edit?

bmbutler

Allen was notified right after I made my appointment at the diff shop and he will be sending the pcm out with the 4.10s already programmed in it.
I am in Houston, he's in San Antonio, UPS Ground = Next Day Delivery.

Speedo and shifts will be screwed up on the way to the shop to get my gears I guess, but so what, its only 15 miles or so.