Top speed

[MarkM]

1991 M998 with the 6.5 and three speed. 24 bolt wheels with the Goodyear MTRS. I try to run between 60 and 62 and at that the motor is spinning fast.

Mark

 

[Milcommoguy]

1991 M998 with the 6.5 and three speed. 24 bolt wheels with the Goodyear MTRS. I try to run between 60 and 62 and at that the motor is spinning fast.

Mark

At some of the speeds i'm reading here... Those big fat tires must swell two to three inches round.

55 and stay alive for this old guy, CAMO

 

[Hammer]

While I prefer to cruise at slower speeds, both of my M1123s cruise nicely at 70 mph. Anything more than this is dependent on the grade of hill, head wind, etc.
Top speed, close to 95 mph on a decent downhill portion where I was REALLY trying to catch up to someone.
I have cruised in the 80 to 85 mph range though. On both my trucks. They felt great.
Btw, I have basically new tires that are either balanced really well or have Centramatics. So I don't feel like I was going to vibrate off the road (like all the ones I drove while in the army that I was scared to go over 55-60 mph! )

 

[TOBASH]

At some the speeds i'm reading here... Those big fat tires must swell two to three inches round.

55 and stay alive for this old guy, CAMO

With the advanced 1980’s aerodynamics, these vehicles are super stable at speed. Much improved over, say, a Model A or even an International.

The brick like shape is super advanced.

EDIT- Not sure I trust these much over 70

 

[Coug]

M1123 with BEOD and DRASH trailer.
Scaled at 13,500 lbs
Max speed on the level was 67 mph. Just not enough power to go any faster than that.

When no trailer and no BEOD she'll do 80+ on the flat, and 60ish on the uphills around here.

 

[Milcommoguy]

M1123 with BEOD and DRASH trailer.
Scaled at 13,500 lbs
Max speed on the level was 67 mph. Just not enough power to go any faster than that.

When no trailer and no BEOD she'll do 80+ on the flat, and 60ish on the uphills around here.

ME...Fast enough to leave the diesel smoke behind. Slow enough to smell the roses and catch a look at the girls. lol

Everybody else... go around, CAMO

 

[engele]

80mph 6,5turbo, 4 Speed, 3,08 diffs, 40“.

 

[Mogman]

80mph 6,5turbo, 4 Speed, 3,08 diffs, 40“.

I can't make it out what was the RPM?

 

[Hammer]

I can't make it out what was the RPM?

Looks like 3300 rpm.

 

[Action]

80mph 6,5turbo, 4 Speed, 3,08 diffs, 40“.

So how did you make your speedo compensate for the 40” tires?

 

[engele]

Was 3300. the factory speedo fits perfect with the 40‘ +- 3%. think they not adjust them for the Short 3.08 Diffs.

 

[Sjoconnor]

I'm a 55 guy in my M998. what amazes me is that people come up on you a$$ real fast. I actual installed amber strobes for any highway driving I do front and back. Hell, if the military has convoy lights, ill just take it up a notch. I did buy new BFG tires on 24 bolt rims which I've yet to mount so im curious to see if the ride improves.

Stephen

 

[Gamble]

I can't make it out what was the RPM?

What I'm amazed at is how quiet it is. Do you have white noise going in the background?

 

[dhaumann69166]

 

[T9000]

120 in the DuraVee (well that is as high as the GPS speedo indicates), 85 in the stock Detroit 6.2 with the 6L80 6 speed transmission also with a GPS speedo.

How big of an operation is to put the 6L80 in?

 

[T9000]

82mph on GPS, on flat freeway. Everything stock. 6.5TD, 37” tires on factory rims with runflats. The onboard speedometer maxes out at around 78mph on GPS.

 

[Mogman]

How big of an operation is to put the 6L80 in?

I have a thread on it in the HMMWV mods forum

 

[T9000]

Top Speed Military 2 seat, no cargo 1990 M998: possibly 85-95mph, speedometer needle was bottom center of the dial

Top Speed 2001 H1, 6.5 Turbo: 110 mph

So the H1 can get to 110mph because of the 2.56 differentials? vs 3.08 on mine? Otherwise it’s the same 4L80E transmission and 6.5TD engine, true?

EDIT: I don’t need to do 110mph, just 80-85mph, but below 3,000rpm. Around 2,500-2,700rpm, would be great!

 

[Mogman]

So the H1 can get to 110mph because of the 2.56 differentials? vs 3.08 on mine? Otherwise it’s the same 4L80E transmission and 6.5TD engine, true?

EDIT: I don’t need to do 110mph, just 80-85mph, but below 3,000rpm. Around 2,500-2,700rpm, would be great!

Possibly down hill?
My Detroit M998 turns 2300 at 75MPH with the 6L80 and its .67:1 2nd OD (5th is .85:1) and 2.56 gears so a little math,,,
With a 4L80 and its .75:1 OD would be 2575 RPM
Replace the 2.56 diffs with 3.08 diffs and still the 4L that would be about 3100 RPM so not going to get to 85 under 3K
Swap the transmission to a 6L with 3.08 gears and now your turning 2770 at 75 MPH, this would also give you more power to the wheels as the 6L is a 50 year newer design with less loss than the 4L.
The half shafts of course turn the same no matter what transmission and or diff is in front of them as long as the tire size stays the same.
And of course you have to have the power to push that brick though the air, in the Detroit weighing in at 7400LB and the added drag of the helmet top and that 6.2L is a little under powered
EDIT of course with the 308 gears you are going to be twisting those drive shafts and transfer case pretty darn fast!

 

[TOBASH]

So the H1 can get to 110mph because of the 2.56 differentials? vs 3.08 on mine? Otherwise it’s the same 4L80E transmission and 6.5TD engine, true?

EDIT: I don’t need to do 110mph, just 80-85mph, but below 3,000rpm. Around 2,500-2,700rpm, would be great!

80MPH is unsafe in these FMV’s. Not unless you perhaps have a RodHall modified unit