M1009 to M1008 differential gear ratio swap

[powerwagonwc12]

I would be happy if I could swap carriers and gears in both axles for less than $800. And I work in a heavy truck shop for a living. I considered the 700R4 also, and it is indeed the easiest and cheapest way to go. It drops your cruise RPM down low enough at 60, that the motor is not struggling. I do have some reservations about it though, it needs to be built by a reputable builder, for heavy duty service. The 700R4 was intended for lighter vehicles, but with careful planning it can survive.

For my own vehicles I install manual transmissions in everything. Everything I own is a 5-speed.

Either transmission swap can easily be over $2000, with me doing all my own work. So in terms of fuel saved, it takes the entire lifetime of the vehicle for it to pay for itself.

If I was swapping just the gears/carriers, I would keep the stock trans and go with 3.73 gears, with 33-inch tires. It'll get you close enough to what you want, around 2500 RPM at 60.

Thank you so much.

 

[LT67]

Does 4:10 have the means to achive a comfortable 70 MPH for this application?

With a 37in tall tire yes. Anything smaller may be stretching it...

 

[nyoffroad]

Thanks for bringing this topic up, Is the 700r4 durable enough for this application? I mean verified miles/ years of service? Thanks.

For me , Yes. In the early years 700R4 had a bad rap for being weak and burning clutches. But that was back then and this is now. I've done the swap a couple times and never looked back! On my one truck I plowed not only my driveway but also my (private)street and a parking lot that was big enough to park a couple tractor trailers in and still turn one of them around in. With that being said I did have the trans rebuilt before installing it and did not specify any performance parts. I'm not hard on equipment (no hole shots or burnouts) but do take care of things. I sold that truck (with 700r4) after years of use and still see it now and then, I put about 45,000 miles on that tranny.
If I was to buy another CUCV a 700R4 or 4l80 would be the first thing done.

 

[powerwagonwc12]

For me , Yes. In the early years 700R4 had a bad rap for being weak and burning clutches. But that was back then and this is now. I've done the swap a couple times and never looked back! On my one truck I plowed not only my driveway but also my (private)street and a parking lot that was big enough to park a couple tractor trailers in and still turn one of them around in. With that being said I did have the trans rebuilt before installing it and did not specify any performance parts. I'm not hard on equipment (no hole shots or burnouts) but do take care of things. I sold that truck (with 700r4) after years of use and still see it now and then, I put about 45,000 miles on that tranny.
If I was to buy another CUCV a 700R4 or 4l80 would be the first thing done.

Which would be your first choice R4 or 4l80?

 

[powerwagonwc12]

With a 37in tall tire yes. Anything smaller may be stretching it...

Thank you.

 

[powerwagonwc12]

I would be happy if I could swap carriers and gears in both axles for less than $800. And I work in a heavy truck shop for a living. I considered the 700R4 also, and it is indeed the easiest and cheapest way to go. It drops your cruise RPM down low enough at 60, that the motor is not struggling. I do have some reservations about it though, it needs to be built by a reputable builder, for heavy duty service. The 700R4 was intended for lighter vehicles, but with careful planning it can survive.

For my own vehicles I install manual transmissions in everything. Everything I own is a 5-speed.

Either transmission swap can easily be over $2000, with me doing all my own work. So in terms of fuel saved, it takes the entire lifetime of the vehicle for it to pay for itself.

If I was swapping just the gears/carriers, I would keep the stock trans and go with 3.73 gears, with 33-inch tires. It'll get you close enough to what you want, around 2500 RPM at 60.

Thank you.

 

[nyoffroad]

Which would be your first choice R4 or 4l80?

700R4, for simplicity's sake and it's what I know. I believe the 4L60 and 80 series needs a computer to shift, IIRC the computer is available as a stand alone unit but why put any computer on a mechanical engine? Remember K.I.S.S? Keep It Simple Silly?

 

[powerwagonwc12]

I would be happy if I could swap carriers and gears in both axles for less than $800. And I work in a heavy truck shop for a living. I considered the 700R4 also, and it is indeed the easiest and cheapest way to go. It drops your cruise RPM down low enough at 60, that the motor is not struggling. I do have some reservations about it though, it needs to be built by a reputable builder, for heavy duty service. The 700R4 was intended for lighter vehicles, but with careful planning it can survive.
For my own vehicles I install manual transmissions in everything. Everything I own is a 5-speed.
Either transmission swap can easily be over $2000, with me doing all my own work. So in terms of fuel saved, it takes the entire lifetime of the vehicle for it to pay for itself.
If I was swapping just the gears/carriers, I would keep the stock trans and go with 3.73 gears, with 33-inch tires. It'll get you close enough to what you want, around 2500 RPM at 60.

 

[patracy]

With a 37in tall tire yes. Anything smaller may be stretching it...

I have 37's with 4.56's. 60-65 is about all I want to drive it at. I'm sure 4.10's would bump it up to 65-70. But I'm going to eventually swap in a 4l80e I have sitting. Not really to gain more top end speed. But to lower engine cruising RPMs and help fuel economy. I'd probably drive my CUCV a lot more if I wasn't running 2750rpm everywhere...