way up north

I had a 1996 5 speed that ran 70MPH at 2000 RPM. Then I got a 2007 6 speed with 3.73. It would run about 61 MPH at 2000 RPM. I've hated that for 4 years now. Thinking on a 2011, but when I ask a salesman how fast I will run at 2000RPM with 3.42 they mumble and look blank. Bet there are guys out there who can help me with this. Will appreciate it.

67guzzler

As for RPM's at speed, check this out:

I saw this chart below in another thread a while back:

G56 Manual w/0.74 final drive ratio in 6th gear, 265/70-17 tires, 654 revs per mile @ 70 mph:
3.42 axle -- 1931 rpm at 70 mph
3.73 axle -- 2106 rpm at 70 mph
4.10 axle -- 2321 rpm at 70 mph (combination NOT available -- just for comparison)

6-Speed Automatic w/0.63 final drive ratio in 6th gear, 265/70-17 tires, 654 revs per mile @ 70 mph:
3.42 axle -- 1644 rpm at 70 mph
3.73 axle -- 1793 rpm at 70 mph
4.10 axle -- 1976 rpm at 70 mph

* Early G56 manuals had a final drive ratio of .79. That really made things tough if you had a 3.73. You'd be turning 2200+ rpm @ 70 mph. Current G56 manuals have the .74 final drive ratio.

way up north

Super information. Thanks a heap.

67guzzler

No problem. I thought it was cool information too. I wished I'd seen that chart before I bought my 2005 with a G56 manual and the 3.73....

dhe9

patriotblu,

the 2011s are coming stock from the build with tires that measure 235/80R17E. how do you think the numbers will be with the G56 and 3.42 gears?

thanks,
david
san diego

67guzzler

I'd just get the diameter of tire #1 (the 235/80R17E (31.8")), compare it to that of tire #2 (the 265/70R17E (31.8" also)) and then figure out a % difference, if there is one.

Then multiply the % difference against the chart above.

In this case they're the same diameter so there is no difference.

I hope this helps!

AH64ID

Looking at your sig the main reason your 07 pulls that trailer like a kids toy is the fact that 2000 rpms is only 61mph. The G56 you have runs a .79OD, which is the same (or very close) final drive ratio your 96 would have been with 4.10's.

The gearing of 3.42's and a AE G56 will be 15% taller than your current setup, meaning at any given rpm in OD you will have 15% less tq to the ground, and since the 6.7 manuals have the same tq as the 5.9 manuals you may have a tougher time towing that 36' fiver, the VGT Turbo and 25 extra hp will make up some of that difference, but not all.

Just food for thought, while many people don't like the .79 OD in the 05.5-07 G56 its the reason they are so great at towing.

67guzzler

I towed 8k once in a while (boat) and I hated the .079 and 3.73. I would have loved the .74 and 3.42 or even a 3.23.

way up north

I've been looking at that chart and been going HMMMMMM??, ever since. I've been one of those guys that always bought standards convinced it would give me better MPG. But when I see 287 RPM less with an auto in the top gear, and with better automatics these days, I wonder if my belief is justified. What do you guys think??

AH64ID

Just noticed your in Florida.. I can see where you wouldn't like it, here in the inter-mountain West I sometime wish I had the .79 OD vs my .74.

67guzzler

Good point!

teamroper08

lol well at least yall arnt set up like me a 2002 5speed with 4.10's

teamroper08

lol well at least yall arnt set up like me a 2002 5speed with 4.10's 2400 at 70

AH64ID

The AD G56 with 3.73's is essentially the same as a NV4500 with 4.10's.

Your final drive is 2.993
G56 (.79) final drive is 2.947 (only 1% taller)