smurray

Hi, Im starting to dig into the possibility of building a small to midsized truck (something under 4000lbs) with an LS motor like the 5.3 or 6.0. Id like to maby eventually make as much as 450ish hp/ft-lbs, but more realistically ill probably be somewhere in the mid 300rwhp range. Im a sucker for manuals, so ive been doing some reading on the NV4500. It seems to be the best fit for me, it would hold my power and could easily be converted from 2wd to 4wd depending on what i decide to do. However, Ive driven a dodge with an NV3500 and that thing felt MISERABLE. Does the NV4500 have a better feel to it?

Are there any other transmissions that would fit my needs well? The truck will be used as a truck, towing and hauling so i need a decently low first gear, but i also definetly want an OD as the truck will do a whole lot of highway cruising as well. I cant really find a transmission that has an OD as high as i want with a first gear as low as i want. I wish I could find something with the 4500s 5.7:1 to first and a T-56s .50 OD

InchUp

iTrader: (2)

What you could do instead is go with that T56 6-speed and gear the axles down low, taking advantage of that double overdrive feature. That way gears 1-5 feel like the NV4500 but you still get the double overdrive 6th which now becomes your cruising gear.

Say for example the ZO6 and various heavy bodied Pontiacs, that come with the steep geared T56 6-speed.

First: 2.966 x 4.56 = 13.525
Second: 2.066 x x 4.56 = 9.421
Third: 1.426 x x 4.56 = 6.503
Fourth: 1.000 x x 4.56 = 4.560
Fifth: 0.710 x x 4.56 = 3.238
Sixth: 0.562 x x 4.56 = 2.563
Reverse: 3.276 x x 4.56 = 14.938


Compared to the NV4500 5-speed in trucks.
First: 5.610 x 3.73 = 20.925
Second: 3.04 x 3.73 = 11.339
Third: 1.666 x 3.73 = 6.192
Fourth: 1.00 x 3.73 = 3.730
Fifth: 0.750 x 3.73 = 2.798
Reverse: 5.04 x 3.73 = 18.799

Check out the two red 1st gear ratios after being multiplied by the rear end ratios. See the difference? The NV4500 still has that monster 1st gear but now the gap has been narrowed compared to the T56 1st gear with the same 3.73's (11.063), yet keep in mind that this truck you say will be 2 tons...which shouldn't be towing any more than 3 tons of trailer weight to begin with. The NV4500 is found in 2500HD trucks and 3500's which double the weight of your proposed 4000lbs, especially their towing ability. I do not see the lack of 1st gear multiplication being that crucial in such a light truck. You're talking about a 2wd regular cab short box or a small 4wd S10/Sonoma.

What you did mention is that the truck will see a lot of highway use, which is where the T56 comes in handy, even geared with 4.56's. The difference between the T56 6th gear with 4.56's and the NV4500 5th gear with 3.73's will be a drop in highway rpms by 9% so instead of cruising along at 2000rpms you're sitting nice at +/-1850rpms.

Bottom line, the difference here is the use of that 1st gear difference. If you absolutely needed more torque than what the T56 can offer in 1st gear, drop it into 4LO and make that 13.525 become 36.788:1. The helpful 2.72 4LO gear of most GM New Process transfer cases is why I geared my truck with 4.30's in the axles instead of 4.88's like everyone else. I figured if I absolutely need more power than what my motor, 3.06 tranny first gear and 4.30 rear end gears can provide, I have the granny 4LO I can put it in to almost triple my power.

StrokerAce03

iTrader: (7)

Basically the T56 is a more performance oriented transmission; the NV4500 is a truck transmission meant for strength and pulling, not play. Since you're building a lightweight truck I'm guessing you want both so go t56 and lower gears.


It'll be a blast

smurray

OK so i guess ive found all of my options then.

What are the weights of the two transmissions?
Also, where can i find good prices on both?

InchUp

iTrader: (2)

The NV4500 weighs in around 215lbs. The T56 out of the Z06 and various heavy body Pontiacs (GTO comes to mind) weighs in around 120lbs. You can definitely see the brute strength differences of the two transmissions, though the T56 has been better tested against enormous power houses for motors. Take the Corvette and Viper as two examples.

Local classifieds and car-part.com would be my two places to check first.

smurray

thanks a lot for the responses, ill take a look around and see what i come up with. I guess if theyre priced similarly ill go with the T-56.