How fast does a M1008 go?

[WARWAG]

There were a couple of OD units that were/are made. One is no longer in productinon and I can't remember the name to save my life, but it attached around the rear axle. A gear vendors OD would attach to the rear of the T-case w,hereas you still have the original slip yoke. There would also be additional wiring to the unit and there would be a controller for it. Just FYI that crazy aluminum thing is your transfer case.

U.S. Gear. They made a 20% and a 30% Overdrive unit. As you said no longer in production.

 

[SmokeyDod]

As said the trucks have 4:56 gear ratio. They have 41T on ring gear & 9T on pinion gear. On the outer edge of the ring gear there should be numbers stamped ( 41 - 9 ). As to one of these running stock tires 100 mph (that's gittin- her-done). You might want to look at the plastic speedometer gear that's inside the transmission where the speed-cable screws into the tranny. I think these are color coded to correspond to the gear ratio. Someone could have changed it & put wrong one in by error.

 

[soule64]

M1008A1 @ 70 mph and purrs like a kitten with the GV Overdrive.

 

[SmokeyDod]

That looks good. Could you give me an approx of what cost on it was? Also, what's ratio when it is in 1st gear and 4th gear? Did you notice any better fuel milage?
Thanks Smokey

 

[91W350]

I wont even take my 1009 over 65.

That is about where we consider top speed for our M1009s as well. I drove one home from Salt Lake City in two days at 60-65 mph, it was a nice trip, beautiful country out there! Glen

 

[allrevup]

I'm sorry but I'm a non believer. As far as I'm concerned any stock CUCV besides the m1009 could not reach that speed unless it was on a trailer, being pulled by something else.

I am with you!

I think my truck runs pretty well... No oil burning, nice idle and good MPG. The fastest, I have gone at sea level on a flat stretch of road with 37" tires, and verifyed by GPS was 83 MPH, she was still pulling and I may have gone a couple MPH faster but not much more before I back down, If stock an M1008 as stated before even with the governor turn up, will redline at around 3400 RPM and is numerically not possible acording to the gear calculation

 

[soule64]

That looks good. Could you give me an approx of what cost on it was? Also, what's ratio when it is in 1st gear and 4th gear? Did you notice any better fuel milage?
Thanks Smokey

Well, it's not cheap - $3k for the unit plus a new driveshaft. Final ratio in 3rdOD is 3:56 and I am running 33" tires. I haven't checked mileage, but it has to be better than stock. It's very easy to install - I did it by myself in an afternoon. Yeah, I know, the price sucks, but the truck is mint so I just bit the bullet.

 

[91W350]

I have read someplace that some of these military engines were set at 4400, which is outrageous if true. I can see where a non-mechanically inclined person would just keep the hammer down to see what it would run, regardless of the consequences, partially because they do not know or realize. I know I tried to hit the governor on my M1008 just to see what it sounded like and could not make myself do it. I think it was close to 80 mph, but I knew it was screaming and I really did not want a good look at the internals of my engine at 24,000 miles.

When I was a kid, the red line was wherever the valves starting floating, then back the tach off a couple of hundred rpm so the little Chevy did not sound too bad when shifting hard.... I got away with that hundreds of times in the days of 327s and 283s. That kind of thinking is not so good with a diesel, especially the 6.2.

 

[TRG]

Also, what's ratio when it is in 1st gear and 4th gear?

Chart here
Gear Vendors Under/Overdrive Chevrolet/GMC 4-Wheel Drive 3-Speed Automatic.

 

[M1008driver]

I will be getting a Gearvendor soon. It will let me keep my TH400 with several engines.

I made this vid for the doubters. In my defense I did have a 40 knot headwind. I know it is abusing the vehicle and I will not be going that fast again.

CUCV Speedo video by SunRiverMan - Photobucket

 

[idM1028]

Hmm. . . intresting. I don't know if its just my speedo, but my needle has a tendency to shake like a hula girl doll around the edges of the gauge. It doesn't like to steady out until about 15MPH on the low side and often starts shaking around when I'm topping the truck out on the high side (about 60 on the speedo, 55-57 according to the GPS) Yours doesn't seem to have that problem.

 

[YTS Deuce]

LOL, at your comment in the video.

The 6.2 CAN spin that fast, is it GOOD for it to spin that fast? Absolutely not. But for you guys saying it's just not possible, I'm sorry but you're wrong. I have personally witnessed cammed up turbo charged 6.2's spin well into the 4's. Sure, you're going to break something eventually, but that doesn't mean it can't do it if you're willing to pay the price.

It's no different than back when I was hot rodding Cummins powered Dodges. At about 55-60 psi of turbo pressure, you'd start blowing head gaskets, the answer? O-ring the heads. Then you're good to the north side of 70 psi, still not enough? Weld the head to the block, then she'll handle over 100psi. YES, I said 100 psi of turbo pressure being forced out of compound twins into a 5.9L Cummins. Not many people would believe that either...

At any rate, glad you love the truck, I've listened to my share of V-8 diesels and I can tell you just by the sound in the video with about 90% certainty that you are spinning 4k or better. I'm almost positive you have stock 4.56 gears.

Cheers!

 

[YTS Deuce]

Hmm. . . intresting. I don't know if its just my speedo, but my needle has a tendency to shake like a hula girl doll around the edges of the gauge. It doesn't like to steady out until about 15MPH on the low side and often starts shaking around when I'm topping the truck out on the high side (about 60 on the speedo, 55-57 according to the GPS) Yours doesn't seem to have that problem.

His is one of smoothest 1008's I've seen. Sometimes they just build em right. Not too mention the documentation in the truck shows it was very well maintained.

 

[YTS Deuce]

Speaking of overdrive units, one advantage to the US Gear unit over Gearvendors is the fact that it mounts Between the tranny and transfer case, that means it works in 4wd as well. It also is a motor driven electrically shifted unit, so you can leave it in overdrive the entire time. The Gearvendors works off of oil pressure to shift similar to an automatic transmission. It needs to be spinning in order to shift and therefore goes out of overdrive every time you slow down or stop.

I had a US gear unit in a pickup in the 90's, I was very pleased with it. If you're looking for one I can put you in contact with a friend of mine in Kalispell, he might be able to still find ya one. I think I paid around $2200 for mine installed with the necessary driveshaft work. That was 14yrs ago though.

 

[M1008driver]

Interesting. Let me check locally and I may be giving you a call. Thanks and thanks for selling me a great truck! Sorry I abused it but something was sticking in my craw.

 

[91W350]

That is a strong running 6.2 to drag that truck up there like that. I was just waiting for the big bang.... I know they can spin up there pretty hard, never saw a M1008 at 85 before.... I guess I am gutless. She was a screaming though! Glen

 

[allrevup]

OK, I am not an expert but this is the bases for my skeptisimm

A CUCV Pickup that weight arounf 5900lbs. with the aerodynimics of the side of a barn and possible with a shelter (as per avatar), N/A 6.2 J code about 135-155hp 240-260 lbs. tq. with a lets say 3400 RPM govern or less, 4.56:1 gears, and a tough power zapping 3 speeds GM TH400, NP 208 in 1:1 4x2 high (or worse yet a gear to gear NP205), 235/85/16 A/T tread for the lowest rolling resistance, 31.75" tires the talest tire that size I found in the internet=

3 speed auto = 4212 RPM @ 85 MPH
AOD (.30 reduction) = 2871
3 speeds manual = 4102
5 speeds W.25 O/D =3281

well beyond the know capabilities of stock N/A 6.2 diesel 1982-1992
I think I am looking at a very optimistic speedomeer or at one lucky guy with ONE of a kind 6.2L.

 

[91W350]

Speed versus RPM calculator

plug in 4400 rpm
1.1
4.56
15.5 loaded radius... 31 inch diameter

and get 89 mph

4000 would be 80 and that is screaming for a 6.2

 

[Gunfreak25]

This is an old, but great thread. Anything over 3600rpm is pushing it, nevermind 4000+. But these will go much, much higher.

6.2 Diesel tractor that turns 5500rpm.
[media]http://www.youtube.com/watch?v=5PUwHt7SqVA[/media]
The Diesel Page, Readers Rigs

Or the legendary Bill Heath who made a 580hp and 780ft lb 6.2 diesel that turned 4700rpm.
He dropped it in a 76 GMC, unfortunately it made enough power to pop a ring gear and it skyrocketed to 8400rpm before letting go. Rumor has it the bottom end was fine but the top end was practically missing in action. Lots of discussion on him over at "other" boards.

The fact is the 6.2 is an oversquare diesel and can safely turn 3000-3600rpm providing the harmonic balancer is in good shape and the engine has no serious ailments. My 6.2 powered M211 with a Th400 and 6.17 gears will make 3200RPM at 55mph. Although it will rarely see these speeds, I have no problems turning those RPM's with fear of something breaking. Sure, mileage will drop over 2000rpm. But mileage wasn't the topic at hand with this thread. Detroit/GM poured lots of money into research and development on these "new" engines, there's a reason for the recommended factory redline of 3600rpm. FWIW, the HMMWV manual shows 4000rpm max on an "unloaded" engine.

 

[Thunder Dog]

I have easily done 80 MPH or more in my m1009. Speedometer needle is steady (no bouncing) at about 55 its actually doing 60 according to GPS. On long trips I run it between 60 and 70.