A few 1 1/4 ton truck questions

[btrapr]

THIS ONE GOT AWAY____I am buying a 1986 1 1 /4 Ton military 4x4, "J" code 6.2, with 68K on the odometer...

I have a Few questions

Vehicle MODEL #-
Not sure what model this is 1028? 1031? This thing has a 45mph max painted on the glovebox...When drove it it was really wound up at 55mph....

***What gear ratios did these have...I would guess around a 4:56

Axle model-
What axles are they front/ear so I can price some 3:73's (if you think that will get me 70mph for freeway driving..or would i be better off with 3:42's because I want to leave the th400 trans in there! This thing shifts like its got a shift kit...WHAT gears should I be looking for???

Motor
Did all of these have the 20:1 compression pistons or the 23:1 as most 6.2's...I know there replacement pistons were the 20:1's. I am wondering because i have a complete 6.5 GM-8 turbo set-up I would like to put on it...and add an intercooler and high output water pump.

I also ran across three 6.2 J's that I had to buy...$300 and i could not walk away. I will be tearing one them down and doing some port/polish work on them and rebuild it to put in my 1990 Suburban that currently has a tired 6.2 with a Banks Sdiewinder trubo on it.



Thanks in advance

 

[Goose2448]

4.56 Rear and a dana 60 up fornt

I have a 4.10 in my civvy PU and a gas engine. Running 3 grand I can do about 45 or so. So my guess would be a 3.73. My sub has that set up and will run 100 untill the gov kicks in at 4 Grand, and will do about 80 at 3 Grand, agin with the gas engine. Thats up to you on the gear change. You could just put Bigger Tires on it.

Someone with more knowledge than me will chime in here soon.

Just my

 

[4bogginchevys]

Hey, gonna be a nice truck. It sounds like your gonna pump up the power with stuff you have laying around so I would bet if you keep stock tires and dont plan on towing around to many semi's you could go with 3.42's if thats what is availible. Better mileage than 3.73's if your running the interstate all the time. If you go with 285's (33's) than 3.73 is best in my opinion Good luck

 

[POOR WHITE BOY]

3.42 will be just fine - take a m1009 for a drive - they have 3.08 - this will give you somewhat of an idea of performance/economy change from 4.56

 

[btrapr]

WHAT MODEL is this thing?? 1 1 /4 ton?

what back axle is in it...front is a Dana 60....

also it has 225 tires on it now...ANY idea how it might do with 33"'s? need to be able to run at least 70mph...

thanks for the help...This truck ROCKS can not wait to do some tweaking...the Police Dept that had it painted it white...RATHER piss poorly as well....

**Need to find a source for some good old OLIVE DRAB epoxy paint like it had...

 

[319]

For the model, check the data plate on the drivers door jamb.
You can also, and everyone suggests this, download the technical manuals from the resource section. These will give you almost all the information you will ever need to know.

 

[91W350]

The rear is a 14 bolt GM with a Detroit Locker.

Your gear ratio will ultimately depend on your tire height. Jump on one of the online rpm; gear ratio; tire height calculators and target running 2000-2200 rpm at 70. Glen

 

[4x4 Forever]

This might help with your decision. Welcome to SS and good luck!

Gear Ratio Calculator

 

[91W350]

A much les complex one to use, remember that it is talking radius and not diameter. A M1009 with 3.08 gears at 2200 rpm on 31" (15.5") in this case, runs 65.9 pretty comfortably. You will pay stiffly in fuel mileage for speeds above that. 33" tires will give you 70 at 2200.


The rest of the trucks, 2200 rpm, a 4.56 gear and a 44" (22) for this calculator, will give you 63 mph.

Our transmission/cases are 1 to 1 Glen

Speed versus RPM calculator

 

[mtjbrown]

Not to hijack, but does anyone know the 4th gear ratio on 700 R4?



Never mind, I googled it and found 70:1 for 4th gear. Is 2200 the target rpm to shoot for??

 

[91W350]

.70 if I recall correctly....

 

[btrapr]

believe its a 1008 because the VIN starts with 1GCGD. . .
These did not come with a front locker from what I have read! What type would be best to install if i decide to?

This is a 1984 with 48K on the odometer, a perfect seat and floor mat, and NEW tires!
I felt and heard a rattle when I went over a speed bump that sounded like it was the front left axle area that needs inspecting and the brake pedal was a little soft...BUT good brakes_____
I need to get cooler fresh air into the air cleaner instead of that open snout on top of the engine!
I want to pull the front down far enough to check a minor wobble on the harmonic balancer...replace the GP's Wellman 070 and put some nozzles in it! It has a little rough spot at idle that I believe is injector related
The calculators were a GREAT help---THANKS
The downside my numbers would work the way I wanted them too! 33", 4:56 and 65mph clocked 3099 rpm's___________while it showed 2113 with an AOD .70
I have a 1991 Silverado 6.2 4x4...that I took out a th400 trans with adaptor output shaft...and stuck in a 700r4 with a beast sun gear shell, 9 clutch commercial pack OD, corvette servo kit, kevlar band, and a totally brazed sprague (My buddy brazed it) and rebuilt lock-up converter has around 1500 miles on it...
Really tempted to put the 400 back in the 1991 Silverado and get a different transfer case and run the 700 in it....OR just yank the motor and trans to use the serpentine belt set-up and tranny and scrap the truck____It is in need of paint and front end work anyways.
The 84 CUCV with a turbo and th700r4! I am going to pick up the truck on Thursday! A friend is going to let me tuck it in behind his warehouse.
AOD/ TH700r4 def sounds like the way to go! although I hate to give up the brute force low end this things has...BUT it should serve my needs more appropriately...If I can get the turbo set-up on there...it would be better.