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3.42 gears?

THEFERMANATOR

THEFERMANATOR

FRANKENBURBAN
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Has anybody here ran a DURAMAX ALLISON 5 speed with 3.42 gears? If so how did it perform? My 95 SUB that I'm transplanting an 01 DMAX/ALLY into has 4.10's with 245/75/16 tires now, and I know this is too low for the DMAX with what I plan on doing. I only plan on towing 10-11K pounds tops with this rig. I know a gear swap is in my future with this set-up, and figured instead of 3.73's why not 3.42's.
 
IF you are keepign 245 (30.5")s or even 265s(31.5) 3.42 probly wont be bad... pulling less then 12k i woudl go 3.42s

3.42 245 @65 puts you 1700-1800rpm
3.73 is ~150rpm more at same speed
4.10 is 2100 @ 65

just my .02 :smile5:
 
I plan on keeping the 245's as my brakes work better with them(the early brakes weren't the best), plus my other half demands the truck stay as low as possible as she is vertically challenged. Milage will be a big concern as I plan on taking a trip this summer once the transplant is complete. The bulk of my towing will be around 7-8K with the ocasional 10-11K maybe a 12K pound load once in a blue moon. Figured the DMAX could handle 3.42's with ease, although I know this won't help with the turbo lag(I'm hoping EFILIVE will take care of that).
 
THEFERMANATOR said:
Has anybody here ran a DURAMAX ALLISON 5 speed with 3.42 gears? If so how did it perform? My 95 SUB that I'm transplanting an 01 DMAX/ALLY into has 4.10's with 245/75/16 tires now, and I know this is too low for the DMAX with what I plan on doing. I only plan on towing 10-11K pounds tops with this rig. I know a gear swap is in my future with this set-up, and figured instead of 3.73's why not 3.42's.
Click to expand...

From the factory, I believe the lowest gear ratio you could get with a Duramax engine is 3.73.
 
I have an 01 DURAMAX/ALLISON that I am putting into a 95 K2500 SUBURBAN that has a 14 bolt 10.5" full floater. The DURAMAX came stock with 3.73's, but my 6.5 SUBURBAN had 4.10's in it. I know I don't need 4.10's for what I will be doing, and I think the 3.42's will be a better match than the 3.73's as I don't need to be able to tow 12-14K on a regular basis.
 
THEFERMANATOR said:
I have an 01 DURAMAX/ALLISON that I am putting into a 95 K2500 SUBURBAN that has a 14 bolt 10.5" full floater. The DURAMAX came stock with 3.73's, but my 6.5 SUBURBAN had 4.10's in it. I know I don't need 4.10's for what I will be doing, and I think the 3.42's will be a better match than the 3.73's as I don't need to be able to tow 12-14K on a regular basis.
Click to expand...

Gotcha, the 3.42 will behaive much like the 3.73s. Like someone previously said, the rpms wont be off much compared to the 3.73 gears.

Sorry about the confusion, I though you where asking about stock Duramax trucks with 3.42 gears. My mistake.
 
Engine RPM vs Vehicle Speed vs Axle Ratio

This chart should help you decide what's best for your intended application.

Engine RPM vs Vehicle Speed vs Axle Ratio
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    Engine Speed vs Vehicle Speed vs Axle Ratio.jpg
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Looks like the 3.42's will work. I know 3.73's were stock with 245'75'16's on the 2500HD's, but I'm more so after milage than being able to pull 14K. Now I have to decide if I want to go to the hassle of swapping over the BCM and cluster to make the TOW/HAUL button work.
 
THEFERMANATOR said:
Looks like the 3.42's will work. I know 3.73's were stock with 245'75'16's on the 2500HD's, but I'm more so after milage than being able to pull 14K. Now I have to decide if I want to go to the hassle of swapping over the BCM and cluster to make the TOW/HAUL button work.
Click to expand...
Keep in mind that unless you reprogram the TCM, your transmission shift points are going to move UP.
 
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