Gear ratio for M1008.

[FMJ]

Well guys I got my M1008 home yesterday. took it out on the road today and I thought it did not shift out of 2nd gear!!!???. 55mph and it does SCREAM!!! The people who specked these vehicles out for the US of A must have stock in GM, engine division, and the oil Cos. Way geared too lo, even for off road. Why such a Low gear ratio in M 1008 and Hi gears in M1009??? I am going to find a doner truck and change to 3:73. I had a 2500 6.2 in 84 and it was perfect gears for all around use. 25 -30 mpg. Next week I pick up my m1028.

Well......

The 1008's, and 1028"s were meant to tow trailers and and carry heavy loads, and since your looking at an engine that only makes 150hp/250lbft of torque.....it makes sense that they would gear it low....

Convoy speed is what, 45/50 mph?

 

[CCATLETT1984]

the 1008 is to move things, sometimes heavy stuff.

the 1009 is scouting and radio truck.

remember the military speed limit for a convoy is 35mph.

 

[AJMBLAZER]

All the M1008's were expected to do was tow a M101 trailer and haul some soldiers or supplies in the back at convoy speeds (35mph). M1028's could just tow and haul a bit more.

The M1009's were meant for actually moving folks around in "comfort" and command uses and such. So they needed more speed...not to mention in that time frame GM was putting those gears in a large percentage of the half ton trucks and K5's so I'm sure they got a discount.

 

[AJMBLAZER]

Oh yeah, anyone wanting to regear their trucks would do well to go over to www.ColoradoK5.com and talk to some of the guys there. I'd wager you could find someone who would not only swap you but do most of the work. 1 ton axles with 4.56's and a Detroit in the rear are rather desirable.

 

[csramsey640]

This is not a cheap swap!!!

1st of all, 4.56's in both a GM and a Dana uses a unique carrier, with a split at 4.11, so if you want 3.73's you must swap out the carrier as well. As mentioned, 3.73,4.11,4.56 are the best ratio's that will match, other than deeper. Gm went the 3.42 route, Dana, the 3.54 route.

So, you will need a dana 60 carrier of the same generation, 4.11 and better, and also a GM carrier of the same.

Id do the 700r4, but dont expect the same strength as the th400 in stock form. However, there are more aftermarket parts for a 700r4 than just about any other auto tranny

 

[hobie237]

Speaking of 700R4s, what bolt pattern does the 6.2 use to mount to the transmission? Is it the smallblock pattern? The 4cyl/V6 pattern? Big block pattern? I'm pretty sure there were a few differences in the bellhousings but I'm not all that familiar with them as I've only uninstalled, rebuilt and then reinstalled the 700R4, never have I swapped one where it wasn't previously.

 

[AJMBLAZER]

Standard GM, same as the traditional SBC and BBC.

 

[hobie237]

So the smallblock and big block use the same bolt pattern? Do you know if it's the same as the V6 bolt pattern?

 

[AJMBLAZER]

Depends on the V6. The 4.3L V6, the inline 6's, the SBC's, the BBC's all use the same pattern.

 

[hobie237]

It's the 2.8L V6 that I'm thinking of, there are lots of them in junkyards with 700R4s attached to them. I'm just not sure of the bolt pattern. Don't most of the 4.3L cars/trucks have the 4L60E?

 

[CCATLETT1984]

You do NOT want the 4L60E, you won't want to come up with a electronic controller for the transmission. Pre-93 should have the 700r4.

 

[hobie237]

I know that I don't want a 4L60E (or, for that matter, any "E" transmission), I'm just trying to find out whether the readily available 700R4s out of, say, 2.8V6 S-10s and Camaros will bolt up. I've got at least two sitting around, but they're a state away at the moment- just want to know if the bolt pattern lines up without having to get the transmission, crawl under the truck and start measuring.

 

[csramsey640]

Big Block, smallblock, diesel, gas Chevrolet GMC share the same bell. Buick,OLds, Pontiac and Cadillac have a different bell.

Im not sure but I thought that the diesel engine had a different stall converter, but i may be off. I know the 4.3 will swap, but i cant say on the 2.8

 

[hobie237]

Well, sometime when I get around to it, I'll see if the patterns are the same, and I'll be sure to get the info up here.

 

[11Echo]

The transmission for a 2.8, 3.1, and 3.4 V6's will NOT bolt up to a Chevy engine. There was a 3.3 Chevy 90 degree V6 that had the V8 pattern. I believe there are 3 GM tranny cases of this vintage. The Chevy pattern, the Buick/Cadillac/Olds/Pontiac pattern, and the dual pattern. These dual pattern cases had modified flange with extra bolt holes and is often called the GM case. I have a T350 out of an Olds that has a flange/bolt patterns that fits all GM blocks.

 

[AJMBLAZER]

What 11Echo said. Avoid the smaller V6's as their 700R4's have a different pattern. Those engines are called...60 degree I think?

Do a search and read Croatan Kid's 700R4 build up this summer. He gets into all the diesel specific parts he had to get for his 700R4.

 

[Croatan_Kid]

You rang?