What is the OD ratio on the 06 vs 07?
What rpms are you guys seeing on the 07 6sp, 3.73, 265 tires at 75, 80, 85mph?

Sorry, just bought the truck, didn't get over 65mph test drive, wife is bringing it up from Denver today (It's her new truck anyway. I think I win for best Mother's day gift!

 

Wow sure wish I got in the high teens and 20's like you guys.

My 05 G56 is great... definitely a bit short in the top gear but it works so very well in everything else that I don't complain much.

I went to Reno and back this weekend... on the way there, I ran 70-75 and averaged 15.3 mpg. On the way back, I ran 62-65 and got 18.2 mpg.

That's with Smarty on #1 (Revo). I can't run anything higher until I finish breaking in my new clutch...

Rob

 

05-06 G56 is .79 OD (Same rpms in 6th with 3.73's as a NV5600 with 4.10's)
07+ G56 is .74
NV5600 is .73

I have a NV5600 and dad has a 06 G56, the mileage difference cruising is negligible... He does much better towing heavy weight thru the mountians in 6th... Makes me want to add an overdrive, GV or US (.78 or .80)...


I still think the manual tranny is better for every appication but city driving... You have more gears, and more gears where you need them... especially if you tow/drive in the mountains... Even a 6 speed manual is much better than a 5 speed manual for mountain towing... True I would like a lower OD every now and then, but 3rd and 4th are used much more than a lower 6th would be... Look at it this way, (tq converter aside) from 1600-2500 rpms with 3rd and 4th in a 6 speed man gets you 19-44 mph, good power and not screaming the revs... a 5 speed (3rd gear) gets you 23-37, a 48RE gets you 27-42, and the 68RFE gets you 21-43 (better)

As you can see the 6 speed manual has the best range of speed in that gear area and rpm area (data is 3.73 and 265/70/17's).... \

I say go manual... best ratios and you dont have to worry about heat.

 

Agree, I wouldn't have anything but the manual for towing, but for purely fuel economy and ease of city driving the auto may be better. That being said, I've been happy with my G-56. Really works good with the exhaust brake and for when I tow in the mountains....

 

What about the gearing of the '07s do you think is better?

I have an '07 with 3.73s and at 65 I'm turning 2100 rpm. Thats with a 150 rpm reduction when I went to taller tires.

2250 with stock tires sucks.

 

You have an early 07, somewhere near the 07.5 mark the G56 got a .74 OD vs your .79...

 

You should have lower RPMs than that with the 07 G-56 gearing, unless they didn't switch the gearing until the 07.5 year? .79 for the 06 G-56, .74 for the 07. 2250 RPMs at 65 MPH seems high, what is 2000 RPM for you?

 

2000 rpm is right at 60 mph.

 

I see, it was the 07.5 that they made the change.

 

Well close, as there are some 5.9's with the .74...

 

i tow heavy and like the .79 g56 best , i have a hard time understanding why anyone with a Cummings would want a piece of weak expensive junk auto behind it.

 

Another "cummings" reference. The auto can be made to handle some serious power, depending on how deep your pockets are. I think the guys with the new 6 speed auto are fairly pleased, but time will tell.

 

I pull a lot hevier then most The gearing of the G56 is geat if you live where the speed limit is 55. But time is money and when I am hauling I needed something that can move down the road. I am tagged for 42K and am usually loaded around 39K I went to the 22.5's for the gearing change and that is the best thing I have ever done. Nothing like 80 at 2100RPM
When it comes to auto vrs manual the new 6 speed I don't here much for complaints. But if you are one to tow heavy, past the factory ratings I would stick with a manual.

 

I would say manual. I love my 05 g56, very strong and I get very good fuel mileage. I have not been able to drive the new 68RFE, but I have heard it is awesome and I am sure Dodge is really getting better with Auto tranny's.

 

Well, I lucked out w/the .74 gearing. Took the truck for my first drive last night. Stock 265 tires. At 75mph, I'm at about 2250 rpms, at 80mph, 2350-2400rpms. Not bad. 285's will bring that down nicely!