interested in any input on the swap ,

i have 4:10 gears and definately want to swap to the 3:42 gears
i have a 04.5 4x4 nv5600 6 speed

do i need the spacer for the front gear or not i have read both
please tell me where have you gotten your gears from .
thanks, joel

 

left you a PM

 

w/ the nv5600 id do 3.73s, but randys has them

 

the spacer depends on if you buy actual dodge 9.25 aam gears, or aftermarket gm 9.25 gears.

assuming stock 30" tall tires, a set of 3.42's will drop you to 1600 rpm @ 60 mph, 1875rpm@70

rpm of course will be lower with taller tires.

imho : unless you travel unloaded @75+ mph ALOT it'd be a waste of time and money. $1k+ to drop 300 rpm...

what exactly are you TRYING to acomplish.. ? mayby we can point you in a better direction..

 

A drop from 4.10s to 3.42s should be more than 300rpm @ 80ish mph. My reason for doubting, and please correct me if Im wrong, but back in my drag racing days, every step up in gear was approx. 200 rpm at the stripe. (100-105mph). We would commonly go from 2.73s to 3.73s and gain almost 1000rpm at the end of the 1/4.
So from a 3.42 (we used 3.55s) to 3.73 to 3.90 to 4.10s should be around 600rpm at 100mph, and .80 (80mph) would be in the 480-500rpm range. Again, if Im wrong, please show me where.

That IMO could be worth the swap if you plan on keeping the truck for a long time. Im also sure that drastic of a drop would make the truck feel quite sluggish, when compared to the 4.10s. Again, IMO.

 

@80: 2575 w/ 4.10's, 2340 w/ 3.73, 2145 w/ 3.42

the math is easy, or just go to http://www.ringpinion.com/Calc_RPM.aspx use the aod results.

 

So my rule of thumb wasnt far off.

 

Man, I can't stand my 3.73's with 35, feels like the truck lugs too much. I'm going with 37s, so I'll be upping to 4.10s soon.

 

I'm running 37" now with 3.73/G56 combo. The 37" dropped my RPM from 2,100 to 1,800 RPM @ 65 MPH. Works for me as I never tow.

 

It might be a good idea to decide on what tire you want before you consider the gear swap. If you want to stay with the 265s the higher gears make sense. But if you go to 285/75 for instance you will be way high geared with 3.42s. I have the 48RE (.69 OD), 3.73 gears and 285/75s and I run 1500RPM at 60. It's as high as I will ever go because it struggles a bit when towing.


John

 

I think its more important to decide how heavy is your load when you tow. I only tow maybe 7,000#, and anly once a month or so, so that low gear wouldnt be bad for my application.