"The Beast" 85 Chevrolet Crew Cab Dually

[MrBeast]

Originally Posted by texanidiot25

With the D60, I've already got some good towing gears. With that 1st I should out right be able to pull a house or two in 1st gear.

When the short 1st isn't needed, their OK to launch in 2nd gear? Haven't driven a granny 1st gear trans before.

I do burnouts starting in 2nd gear all the time. from both a standing and rolling start.

The thing you have to realize is this, it all depends on gear ratio.

The 700R4 has a 3.06:1 first gear, 1.63:1 2nd, 1:1 3rd, and a .7:1 4th

The NV4500 has a 5.61:1 first, 3.04:1 second, 1.67:1 3rd, 1:1 4th, and finally a .73: 1 overdrive.

So in other words 2nd gear on a NV4500 is like being in first gear on the 700R4.

The hardest part about doing that swap is building the new cross member for your transmission.

Here is something else to consider, the tire size you want to run is going to dictate what rear end ratio you run as well. The Dana 60 is a great axle, but many of them came with 4.10 gears or even 4.56'es in some cases to help you lug a load.

If you run a 31.5" tall tire, (which is what most load range E's are) your engine will have to turn 2,235 RPM to go 70 MPH Where as if you run a 25" tall tire with 4.10's you are looking at 2,817 RPM to go the same 70 mph.

Now if you went with a 3.55 rear end ratio, and a 27.5" tall tire, you could then run 70 MPH @ 2,258 RPM. What is the difference? It is fuel mileage, the lower you can get your engine RPM's the better mileage you will get at least to a point.

And as per our conversation with your current tires being 31" tall, that means with your current 4.10 rear end you will pull 2,271 RPM @ 70 MPH

And just for giggles, with your current 4.10 and the 1:1 final drive ratio of the TH350 and a 30" tall tire, you have to turn 3,112 RPM to go 70 MPH!

So installing a NV4500 alone will get you a 841 RPM drop. In other words that is a 27% drop in engine rpm.

You decide to do the swap let me know, I know everything you need having done it myself a few times.