Top speed

[T9000]

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!

As another option, it looks like 42” tires will increase the speed from 70mph to almost 80mph vs the 37”tires at the same rpm and I get 70mph around 2700rpm.

 

[Retiredwarhorses]

I’ve owned more H1’s and Hmmwv’s than a small Army, doing over 80mph in this brick is IMO, stupid.
I’ve had Dmax equipped trucks as well, the issue is the overall design of the vehicle…I’ve never exceeded 70mph in my H1, even than it was like re-rentering earth’s atmosphere.

 

[T9000]

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

I looked at its construction and understand what you mean, the frame is buried in on the inside and the only piece of steel that would keep the sides from coming in is the beam behind the front seats (which everyone seems to want to remove . There is very little steel around the cabin in general, which is not a good thing, like you say.
How about the H1, is it more steel reinforced? Maybe the doors since they are enclosed? Any additional steel in front and rear passenger areas? Just curious

EDIT: I am thinking to use the armor attachment areas to add steel which would transfer the energy to the frame. 3/8” steel plate weighs about 15 lbs/sqft.
Same for the doors. That would encapsulate the cabin underneath and the sides. I didn’t check the factory top I think it’s 1/4”.

EDIT 2: I just checked, the top is about 5/16”, varies between 0.3”and 0.315”

 

[T9000]

I’ve owned more H1’s and Hmmwv’s than a small Army, doing over 80mph in this brick is IMO, stupid.
I’ve had Dmax equipped trucks as well, the issue is the overall design of the vehicle…I’ve never exceeded 70mph in my H1, even than it was like re-rentering earth’s atmosphere.

70mph or 80mph it’s bad in this truck if God forbid something happens, even 60mph, so yes I am with you and thinking how to solve some of it, maybe by using the armor supports and connect the plates to the frame, I saw underneath there are several places where the frame has locations to attach heavy plates.

 

[dmetalmiki]

Considering the top speeds that are quoted here, this is probably just a nice story:

In the early 90s, I talked to an FAC of the 1st Armoured Div, at that time stationed in Germany. You know in Germany, at that time, we still had that "unlimited speed" on our Autobahns, so traffic was flowing much faster than the average HMMWV would go.

When asked how his Humvee coped in german traffic, he said it made about 60 mph, so about 95 kilometers per hour, which is about the average speed for trucks overhere, so he could survive on the right lane of the Autobahn. BUT, he said, their military police HMMWVs had their "governors removed", so they would be doing 140 kph (which would be almost 90 mph) !

At that time, I was willing to believe, but when I hear the noise today coming from my Humvee at 55 mph, I´m pretty sure that 90 mph are a tale.....

However, and that´s a fact, at that time, I drove an old french car that was just able to barely do 110 kph (70 mph) indicated, and while at top speed, I once was easily overtaken on the Autobahn by a two-door Humvee, which must have been doing 120 kph (about 75 mph) - indicated, however.

HUMPH!..c'ept the speedo in that little car was about 15MPH fast!.
And most set some KMs per Fast indicated by law.

 

[fr8242]

70 is easy in the 4speed truck, I own 4 of them...do you want to go that fast in this truck? No....not really, they are all over the road. This truck is very happy at 60-65mph all day. I drive them daily....

I am really glad that you brought that up. My m1097r1 starts to get "bouncey" 65+

 

[TOBASH]

I am really glad that you brought that up. My m1097r1 starts to get "bouncey" 65+

Get her aligned and check the shocks and ball joints and tie rod ends. 65 and I’m still good in my M1025 and my 1995 Hummer

 

[Mogman]

I am really glad that you brought that up. My m1097r1 starts to get "bouncey" 65+

Could it be your tires are 15-20 years old?

 

[MarkM]

I have the three speed tranny along with the 6.5 and I keep her a 62mph max. Goid enough for me


Mark

 

[frauhansen]

This is ridiculous, stupid and unreasonable... I'm in!


roughly estimated, just under 80mph.
RPM at 3500 with new tires in stock dimension, 6.5 non turbo.

But you ca feel that the engine dont want to spin so high!

 

[TOBASH]

This is ridiculous, stupid and unreasonable... I'm in!
View attachment 909431

roughly estimated, just under 80mph.
RPM at 3500 with new tires in stock dimension, 6.5 non turbo.

But you ca feel that the engine dont want to spin so high!

Yikes!!!

 

[H1JAX]

What would happen if you kept it at a 70 mph for a long time ? Think it will blow the motor ?

 

[Mogman]

What would happen if you kept it at a 70 mph for a long time ? Think it will blow the motor ?

Welcome to the SS forums!
A little more info is needed like just what are you talking about

 

[H1JAX]

Welcome to the SS forums!
A little more info is needed like just what are you talking about

People are saying max speed is between 70 and 80. I have a 2012 M1114 6.5 4speed. What I’m asking is has anyone had an issue with keeping the speed at a constant 70 mph Without having any issues ?

 

[Mogman]

People are saying max speed is between 70 and 80. I have a 2012 M1114 6.5 4speed. What I’m asking is has anyone had an issue with keeping the speed at a constant 70 mph Without having any issues ?

That is helpful, there are two different transmissions and three different gear ratios available in the HMMWV, I will let others comment on your request.
You have a 4 speed and 3.07 gears

 

[Retiredwarhorses]

People are saying max speed is between 70 and 80. I have a 2012 M1114 6.5 4speed. What I’m asking is has anyone had an issue with keeping the speed at a constant 70 mph Without having any issues ?

2012 is the reset date, they didn’t make m1114’s in 2012, its probably a late 90’s-2004.
doing 80mph is for a fool…don’t care which model you have…but hey, Darwinism is alive and well.

 

[TOBASH]

I believe there was a Rod Hall modification that did close to 100

I am almost certain Mogman created a DuraVee that hit 100 and tore out all the CV joint boots doing it.

 

[Coug]

People are saying max speed is between 70 and 80. I have a 2012 M1114 6.5 4speed. What I’m asking is has anyone had an issue with keeping the speed at a constant 70 mph Without having any issues ?

6.5 turbo and 4 speed will run the same RPMs at 70 as the old 6.2 3 speeds did at 55, their max top sustained speed. There should be no issues with doing 70 in it until it's time to stop again for fuel.
6.5 non turbo 4 speed will do about 78 at the same RPMs.

I've hit over 70 a few times in my M1123 (non turbo 4 speed) and that's about the max I ever want to go, but did take it up to 80 once and it was running out of power at that speed.

I won't make any guarantees since everyone's trucks are in different shape, but as long as the cooling system is working properly and fluid levels are all good you should be okay

 

[H1JAX]

2012 is the reset date, they didn’t make m1114’s in 2012, its probably a late 90’s-2004.
doing 80mph is for a fool…don’t care which model you have…but hey, Darwinism is alive and well.

Thank you for this info. When you say reset date, what exactly does this mean? And also, how would I be able to tell what year it is when I bought it the title shows 2012.

 

[Gcelevator]

I daily drive or almost daily drive my M1123 highway speeds around 70MPH and the engine does not scream (don't have a tach) I have reached around 82 and did not want to keep going as it felt very unsafe and unstable.
6.5 turbo on 40's.