LS1 pwrd NOVA

iTrader: (1)

What do think is a better gear to put in the rear of this truck with a 4.8?
It has 3.23 per the rpo codes with g80 gov lok posi.
I don't pull much or often, use the truck more city but some freeway.
To me 3.23 gears a 4.8 engine isn't a good combo over all.
Also is this rear the same as all 1/2 ton trucks, an 8.5 or 8.6 they call it?
Reason is I have a set of used gm gears 3.73 we took out of an 03 escallade with a 10 bolt rear.
So the gear swap won't cost me much other than labor and a few other things.
Then I'll get it tuned.

3wide

I have a 07 NBS CCSB with the 4.8 and swapped from the 3.23 to 4.11 gears. With a 31" tire it gets better gas mileage than the 3.23 and I believe this motor does better with more gear than a 5.3 IMO

LS1 pwrd NOVA

iTrader: (1)

Have you hand calculated to see if it improved a few mpgs and is your speedometer calibrated correctly? I'm sure your speedo is calculated as that's a big step in gear ratios.
I have a 31-32" tall tire also.
Why did you go to 4.11s?
Any mpg on the freeway travel to see what it gets?

3wide

The 4.8 engine has a torque curve that favors 2k or greater so taking into account the weight of the truck and I like to cruise at 70mph, this keeps the engine in a sweet spot with out down shifting on every incline, I just see a unlock in the torque converter and the truck moves along without any strain.

I think everyone looks at the new 6&8 speeds transmissions and thinks wow it has a low first gear so every is fine but you still have 5,000lbs of truck that does not want to lug at 1500 rpm because of a 3.08 gear ratio. Also they do not look at the torque curve when they factor their trucks for towing.

My day job is manual trans & differentials and setting up for tracks (rules do apply what we can use)

LS1 pwrd NOVA

iTrader: (1)

I hate that down shifting crap when the cruise control is on going up a hill.
What do you mean about the tc unlocking vs downshifting?
What mpg you get on the freeway?

3wide

Trans in o/d and cruising at 70 or there about in now will just unlock the converter and drop a few hundred rpms versus downshifting to 3rd. Gas mileage is now at 19mpg vs 15 mpg before and that is hand calculated. Overall performance around town is much better and this is with a PCMofNC tune also.

madmann26

iTrader: (7)

If you're going to go through the trouble of changing gears, get out of the 3-series.

With a 4.8 and 6spd trans, you could go to a 4.11, 4.30 or 4.56 and you'd be better off all around and still see an increase in fuel economy.

Sure, you have the 3.73's and that saves some money but the difference from the 3.23's to the 3.73's is negligible at best.

With my 4spd and prior 5.3 with the Comp LSR 265 cam, I was getting about 16-17mpg while cruising.

After the gear swap, 20-21 all day, at the same speed. And this was tuned.

LS1 pwrd NOVA

iTrader: (1)

Madmann, I have a 4 spd 60e in this truck, not a 6 spd. So what you think gear wise to go with now, 4.11 still?

3wide, I get ya now, it'll unlocking the tc instead of downshifting.

Shoot now what gear set to get new? What gear set did you all buy?

Turbo09

Mine has 3.42's and a 31or 32" tire and a little more gear would be nice out of boost, 4.11 does seem like a big jump though. My plan is 3.73's when I switch to a 14 bolt SF.

Bluecollar Hotrods

iTrader: (18)

A good friend of mine has a 13' RCSB with the 4.8/65E/3.23 combo. It's a pig, the 3000 stall helped some. He's thinking 4.10s - I am trying to convince him to go with 4.56s. He's on a 32" tall tire, and will be installing a TSP Stg 3 cam soon. (216/220 .600" 110 LSA)

My 01' is a lighter truck, had 3.42s factory with the 4.8/60E. I swapped to 4.11s, it was much better. But still felt like it needed more gear. I am on a 31" tire BTW.