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

[mark 5.45]

Hello all, I've been looking into doing a 700r4 swap in my 84 M1008, it still has the stock TH400, 16" tires and 4.56 gears. I was wondering what kind of MPG's any of you were getting running the 700r4? And how much your top speed increased with the overdrive? Thanks in advance for any help, and thanks for a great site!

 

[moose]

Hi there Mark. I have a 700r4 built by Art Carr in my 66 Chevelle, different set-up but some info may be valuable. The gearing in the 700s can be changed to suit your needs and desires. They can also be upgraded to improve reliability under high hp and torque. Mine has been handling 800 hp for a few years now and has not had any problems, I know those power numbers are well below the 6.2's output but i just wanted to show that they can be built up. Also the final drive ration is usually not that big of an overdrive ratio, but this too can be changed to suit your needs. It is sort of a balancing act between top speed and the amount of power needed to push the truck in that lower gear ratio. just some stuff to think about.

 

[WARWAG]

This is the exact swap I will be doing on my M1028. Its the only thing that really makes sense to get low RPMs at highway speeds. There is a member here who builds automatics for a living who knows his stuff. He is also a retired vet. He is also in your neck of the woods I believe. Since Ive been getting a bunch of replies on another thread about auctions and avertising I will PM you his name. Not sure if I can post it here? Anyway drop him a PM.

 

[mark 5.45]

Thanks for the info Moose, and thanks for the PM Warwag, I'll contact him. The 700r4 swap is my winter project for "old green" my M1008. I mostly only drive it around the house on the weekends. But I know I would drive it more if I could run it at 70 mph or so, and take it on the highway. I hate the 60 mph screaming RPM's from the motor, and the big rigs trying to run you over in the slow lane..lol I've looked into a gear swap with 3.73 or 4.10's, but it cost so much being a full floating rear end. And I really don't want to give up the 4.56 gears. MPG wise, if i could get 16 to 18 MPG I would be very happy with that.. Thanks again, Mark

 

[MB4wd]

What about possibly fitting a grear vendors selectable O.D. unit? Has anyone done such swap?

 

[southdave]

I h ave done this in my 1009, there is more to than direct swap.... do a search for laundry list of crap you will need....

 

[mark 5.45]

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.

 

[kope]

I have an 86 chevy suburban 1/2 ton 4x4 with a 6.2. It has a 700r and 3.73s with 31x10.5x15. At 70mph it is turning about 2000rpm.

A while back the tranny took a crap and I had to have it rebuilt (I was active duty army and had no time to rebuild it myself). The nice thing about the 700r is that there are quite a few aftermarket upgrades (as stated earlier in the post) that can pretty much make them bullet proof.

I have a 1008 that I to would like to improve highway performace so right now I am planning a 700r swap and possibly a gear change (4.10 maybe but that is still up in the air).

I'm in the midwest right now and its starting to get colder so it will probably have to wait till spring but that gives me time to collect some parts.

If you do make the change let us know how it turns out.

 

[Croatan_Kid]

I ran one in my M1008 for a while with some 11.00R-16 Michelins. I kinda wish I only had 35s, it would have been matched a little better and had more power. Stay 35s and down and you'll be fine. It was a lot more fun to drive since I could go the speed limit, mileage wasnt really affected.

You can do a search and I've got a lot of info on doing this swap, costs, and parts you'll need.

 

[combatmech]

Check out monster trasmissions Mark. Unless you want a zero time transmission, there are good rebuilts out there.

 

[12vctd]

with a 235 tire you looking at 2333 rpms at 65mph with 31 inch tire your looking at 2249 rpms at 65 mph with a 33 inch tire your looking at 2113 rpms at 65 mph. With 33's you will be doing 2600 rpms at 80 mph which is alot less than a m1009 would do with the 3.08's and th400. Or About 52 mph with 33's and the 4.56 gears and th400 in your truck right now. So MPG wise well I would think you would pick up a decent amount, for highway driving. The lower first gear in the 700r4 would make the truck better offroad as well as towing. Just make sure you have a very good build unit and TV cables are the death of a 700r4.

 

[mark 5.45]

Thanks for all the info guys.. I talked to a shop today about a 700r4 build, should know a price tomorrow. Thanks for the RPM and TV info 12vctd . I've had trouble with TV cables in the past on mustangs with AOD trans. I just want to drive my M1008, like my M1009. Being able to run down the highway at 70- 75 mph. My M1009 is in pieces at this time.. I always have 2 or 3 projects going at once..lol I have a set of new 36" goodyears, and a set of Hummwv 2pc wheel that I had back spaced for the M1008. But I don't think Im going with them now. My plan for now, is to run a 33"- 35" AT or MT tire on the stock wheels, with a 4" lift, front springs, rear shackle flip from ORD. So, with the tires and the 700r4. I think, I'll be good on getting The RPM's down enough to run on the highway. Now, I just wish I could get 20 mpg like my M1009... Thanks again, Mark

 

[eric_banks32]

Finding the TV bracket has been the downfall to my 700r4 swap. I'm debating on making my own. I've also considered a 4l80 w/manual valve body.

 

[bronconut]

my friend did this exact swap with the monster trans, the trans -t-cases are the same length, but you will need a t-case from a 700 or th350 as your 400 tcase wont work. you will also need a flex plate for the 6.2 with 700. for the tv bracket, he made his own. its veary simple swap. he can now run 70 and is getting 18mpg

 

[tamecrow]

I just bought a completely rotted out '85 Blazer with a perfect 6.2 diesel, 700R4 and a 208 transfer case, for the parts to do the 700R4 swap. Blazer performs well on and off road, so should be a straight forward swap. I was going to buy just the transmission and transfer case, but when the guy said a $100 for the whole truck, I bought it right there. I figured I'd get the stuff I need to get the torque converter to automatically lockup as well from the Blazer.

 

[Recovry4x4]

I just bought a completely rotted out '85 Blazer with a perfect 6.2 diesel, 700R4 and a 208 transfer case, for the parts to do the 700R4 swap. Blazer performs well on and off road, so should be a straight forward swap. I was going to buy just the transmission and transfer case, but when the guy said a $100 for the whole truck, I bought it right there. I figured I'd get the stuff I need to get the torque converter to automatically lockup as well from the Blazer.

Fill out the police report yet? $100 is theft!

 

[WARWAG]

Some people have all the luck! Did that include the pink? lol. Great find.

 

[mark 5.45]

$100.. Awesome find tamecrow.. I've been looking today, trying to find the same thing. Rusted-rotted out blazer, truck..ect.. with a 6.2-700r4 setup. No luck yet.. ****, I didn't think it would be that hard to find a TV cable bracket..lol I sent out some emails, and put a wanted post on CL, so I still have my fingers crossed. Does anybody have one, they can take a picture of? I'm not 100% sure what I'm looking for?.. Bronconut, how did your friend make his bracket? did he fab one of a gasser bracket? Thanks, Mark

 

[12vctd]

NP with the info, I seem to be on my gear ratio caculator daily anyways. I love the idea your kicking around, I personally if I ever get a m1008 will be using a nv4500 but to each thier own.

 

[mtjbrown]

Just got my truck running tonite after a 700 swap. Westech on here helped me out with the bracket, still had to modify to hook up the cable, not hard at all. I haven't tested yet because my procurement officer didn't have any coolant in stock for the new radiator that went in at the same time. oh well, I will pick up some coolant at work tomorrow and finish up. I'll post up after with results, keep your fingers crossed.