M1008 with 700r4 swap.. MPG and top speed?

[pa.rich]

Oh yes, forgot to say I have a 87 K30. 1 ton dually dump.

 

[bshupe]

Will the 205 t-case with PTO output work in this swap? Does the T-case from the TH350 have the same specs as the stock one and just a different input shaft?

 

[wayne pick]

the 700r4 will have 16 bolts on the pan, Hotrodders.com has a great thread on identifing the 700r4.

 

[wayne pick]

Was the suburban diesel? There was two 700r4's, gas and diesel. I know this as my rebuilder asked me that very question before tearing into mine. U will need a diesel 700 and a no more than a 1600 stall DIESEL converter to do the swap right. U can also put a diesel valve body in a gas 700 if it is a gas 700.

 

[Iceman3005]

A NP205 that came off a turbo 350 will work with the 700r4, must do 2 of 3 things first though. First will need a 2 inch spacer, here is two places that have them, Offroad Design - Fullsize Chevy GM 4x4 Suspensions, Parts and Performance and A & Reds . Then one of these 2 things will work, will either need to grind off about 1 inch of tail shaft or tear transmission down and get a shorter tail shaft, I just grind them down unless the trans needs a rebuild. Yes an NP205 with PTO will work with the 700r4. As far as a diesel or gas 700r4, there exactly the same except for the governor and the tv cable spring. I am using a 700r4 out off a s-10 blazer and didn't change the governor or tv cable spring, seems to work pretty good. If shifts feel delayed or not firm, then just change governor and tv cable spring, both or really easy to change, governor is at back of trans, just pry off round cover on the left side of trans pull out governor put new one in. The tv cable spring is under pan, just remove pan, then remove tv cable spring assembly replace with new one and reinstall.

 

[sarge62]

Diesel Economics and Fuel Mileage, TheDieselPage.com

Found this link while I was trying to figure the best rpm for the best mpg. Being that the 6.5l and the 6.2l are close I assumed that the recommended rpm would be close. My m1008 has 37" Hummer tires and rims. They measured 36.4" I think. I used the gear calculator to determine that 50 mph is about 1860 rpm.
In August, I drove my M1008 from DE to CA(2700 miles) with my Subaru, Goldwing, and fourwheeler on the trailer. Went out on I70 and then I40 through Flagstaff and the Needles. The rig weighed 13,600 lbs. I drove at 60-85 mph depending on how I was feeling and 20 mph climbing some hills in 1st gear (the Needles). The best mpg I got was 10.5 and the worst was 9.5. Thought I was doing well and that the 6.2 was very consistent only differing 1 mpg with all the varying speeds and terrains.
In February, on the return trip I found these calculations and decided to drive at 50 mph (2700 miles) for a target 1900 rpm. I was a long trip but with the same load I got 13-14.5 mpg!
I would like to swap the 700r4 in my truck as well but got other more important things at the moment, but when I do, this will give me an idea of the target rpm/mph to shoot for.

 

[1ton cucv k5 turbo]

So, Im assuming doing the 700 swap, and using 4.56 gears and 37" would be my best bet to have highway gears... my only issue is that i have a 203/205 doubler the front of the 203 was redrilled to accept my orignial 208 mount.

 

[islandguydon]

Good thread, I run 37" tires. I was looking into a highway gear myself. I have the standard package but looking for a highway gear for even better mileage. Whats the general opinion on what gear to run..?

 

[Iceman3005]

you could use an np203 from a turbo 350 will require minor modification's, just like using an np205 from a turbo 350.

 

[maxpanic]

Is there any difference between putting the 4.56 axles from an M1008 onto a 6.2 diesel suburban that already has a 700r4 transmission versus putting the 700R4 into a m1008? I would like to know what a safe speed is for the over drive on a stock civilian suburban if I put the 4.56 m1008 axles on it and use the stock 235x85r16 tires. Can anyone answer that? or better yet tell me where/how to use a gear ratio calculator?

 

[1StumpJumper]

Google grimjeeper gear ratio calculator.

Presuming your "safe" refers to engine speed, shooting for....

@55 mph w th400 and 4.56 gears, the rpms are about 2800

@55 mph w 700r4 and 4.56 gears, the rpms are about 1850 in either vehicle.

@55 mph stock m1009 runs about 1900 rpm I believe.

The difference is, what vehicle do you want to keep vs kill.

 

[1ton cucv k5 turbo]

1 stumpjumper

What size tires did you calulate with those numbers? As I'm running the TM400 4.56 gears and 37" on my M1009

 

[1StumpJumper]

1TON

That was with 235/85r16 listed in post#70, and 31" tires for the M1009

@55 I believe it would put yours about 2400 rpm.

 

[wallew]

I believe THIS is the link you are looking for

Gear Ratio Calculator

 

[1ton cucv k5 turbo]

cool link... Thanks....

 

[WARWAG]

Thanks for the info MB4wd. I've looked at some of the treads on here about the Gear Vendors, and went to their site. It sounds like a great option. In overdrive it changes your axle ratio from 4.56 to 3.56. The problem with it is, the $2995 price.. I'm on a tight budget, I still want to do a 6.5 turbo install, and a new paint job by spring.

The price and it wont allow you to run OD in 4wd too turned me off of it.

 

[WARWAG]

just finished mine, trans was free, spent 300 on torque converter, 60 on flex plate, 100 on tq lockup kit, 25 on bracket and tv rod, 16 on tv cable and 200 on transfer case w/adapter total=686. I'm getting 20-21 with an average speed of 55-60, at 55 i'm at 1900 rpm's, 70 is 2500 rpm's.

What size tires (??")

 

[Iceman3005]

what size tires (??")

235/85/16

 

[1ton cucv k5 turbo]

im liking the specs given..


700r4 , 203/205 TC.. ( keyed in manual specs for high, low, and double low) 4.56 gears , on 37"

Shows i will be at 2028 RPM at 70MPH...


I'm so going to start sourcing parts now to do swap this fall...

 

[Iceman3005]

im liking the specs given..


700r4 , 203/205 TC.. ( keyed in manual specs for high, low, and double low) 4.56 gears , on 37"

Shows i will be at 2028 RPM at 70MPH...


I'm so going to start sourcing parts now to do swap this fall...

That will be a sweet setup, exactly what I am going to do.