mcolectd

Ok, took about a 7 hour road trip this weekend down to Port Aransas, and I have to say this is the first time I really missed my automatic. And its not because of the shifting, its because running 80mph, I'm at around 2400 rpm. Not only does the sound of my exhaust get annoying running down the road with the rpms that high, but the fuel mileage was crap, and its got to be harder on my truck running that hard. I even slowed down to 70 or so to try to get better mileage, and I'm still running 2100 rpms and its still crap. I calculated about 16mpg for the trip which is terrible compared to the 21+ I could get at 75mph+ in my 05, which could cruise 90mph easy and barely be at 2000rpms. So, my question is, is there a higher 6th gear for these trannys, or do I just have to either deal with it, or change the gears in the rearend. I love my new truck other than this, which makes me really miss my 05 even more than I already did

kjmoore

Check these guys out. http://www.gearvendors.com/

cbrahs

put taller tires on. that will help a bit.

mcolectd

I've got 35s. Can't go higher than that without a lift, and don't want a lift cause i've gotta pull a gooseneck

mcolectd

That looks really cool, but dang its expensive. For the price of that and a performance clutch I can almost swap in a full billet auto. Thank you for that though, i'll definately look into it

cincydiesel

Gearvendors is the way tho go. I believe cummins forum has a gearvendor splitter for a g56 in their classified section. Might want to check it out

mcolectd

Ya I will for sure. Thank you. What about puttn higher gears in the rearend? I heard the new 08s have 3:42s to make up for the lower overdrive. I was thinking about just finding a wrecked 08+ at a junk yard and just swapping out rearends

cbrahs

if we were closer, i would be interested in trading 4.10's for my 3.73's. that would help ya a bit.

mcolectd

Cincydiesel, is this in the 3rd gen classified section? I can't find it

mcolectd

I'm pretty sure I have 3.73s, the 6th gear is just that low. I don't even wanna know what itd be like with 4:10s

matego

2100@70MPH would be 3.73's. I would think your best route would be a gear swap. I am pretty sure Yukon makes 3.42's for it. I believe you will have difficulty finding the 08 axles and if you do they will be crazy expensive. Gears front and rear installed should be under 1k.

cincydiesel

Give me a feew minutes and I will check for myself. Its been awhile (month) since I've been on there

mcolectd

Thats what I was thinking. That gear vendors thing looks like it works really good, but its so expensive. If I had the money to spare, gear vendors would be the way to go, but I think just changing the gears would be best for now. How much would changing to 3.42s drop my rpms?

matego

At 70 you should be around 1800 RPM. http://www.corral.net/tech/gearcalc.html
G56 ratios are:
1st - 6.29
2nd- 3.48
3rd - 2.10
4th - 1.38
5th - 1.00
6th - 0.79
Rev - 6.29

homewrecker

This chart should help some.It is shown in 1:1 direct drive(5th gear) for rpm's

http://www.4lo.com/calc/geartable.htm