1028 highway ?

[islandguydon]

Yes, look at the trand pan, if it is 8" deep to the upper rim your good to go, I would ad an after market trans cooler anyway.

 

[wallew]

Ran my M1028A2 1500+ miles over 4 days...

http://www.steelsoldiers.com/cucv/37101-1800-miles-no-license-plates-half-pack-smokes.html

Sixty mph almost all the way back. Sixty five for several hours at a pop. But mpg was 15 at 60 mph and at 65 mph it dropped down to 10 mpg.

You can do the mph/rpm comparison for your tire/gear ratio set up here:
Gear Ratio Calculator

 

[krall]

oh I don't care about the people on the road, im more worried about blowing the truck or damaging it.

 

[krall]

wow that big of a drop at just 5 mph differences.

 

[wallew]

Yah, those 4.56's are steep gears.

YOU CAN do 70 but THAT is definitely pushing it past it's redline.

But I HAVE driven that truck long distances at 60 mph for long periods of time with no ill effects.

But that is that ONE truck. I did have the transfer case and both axles lube changed over to Royal Purple synthetic gear lube and the engine oil with Royal Purple as well before I did that drive when I had the tranny rebuilt in Scranton, PA. The tailshaft snapped off the tranny because a support arm was missing from the back of the tranny to the front of the transfer case. So all the weight of the NP205 transfer case rode directly on the rear of the tranny. It was NOT designed to do that.

So when the truck hit a deep pothole the tranny tailshaft absorbed the full weight of the NP205's movement up and down, but that movement cracked the case and spilled 6+ qts of tranny fluid on the highway. $2k+ later I had a newly rebuilt tranny.

 

[91W350]

If you only go 55 on the interstate your going to get the finger from alot of people when i was towing my m1009 back i was going 65 taking it easy and people were mean mugging me!!!!

Minimum Interstate speed is 40 in Kansas. Drive 45 to 50 all the time, very seldom 50, always over 45 on the Interstate. Never have been flipped off or mean mugged. I run the same in my deuce, about 45 or a little less. Made the 1400 mile round trip to get my deuce in Rapid City and never broke 50. I avoid I-80 in Nebraska as they fly up there.

Guess I spent too many years in slow vehicles. Older Jeeps with 5.38, 4.88 and 4.10 gears were not that fast either. My M715s were lucky to see 45 and they did have a transfer case that would get too hot to put your hand on the outside of the case in the summer.

My old 67 Chevy had 4.88s, it was no highway rocket either.

I would rather keep the oil and engine parts inside the block.

 

[ryan77]

The worst is when your trying to drive safe and a holes are passing you and cutting you off!!!!!

 

[ryan77]

Minimum Interstate speed is 40 in Kansas. Drive 45 to 50 all the time, very seldom 50, always over 45 on the Interstate. Never have been flipped off or mean mugged. I run the same in my deuce, about 45 or a little less. Made the 1400 mile round trip to get my deuce in Rapid City and never broke 50. I avoid I-80 in Nebraska as they fly up there.

Guess I spent too many years in slow vehicles. Older Jeeps with 5.38, 4.88 and 4.10 gears were not that fast either. My M715s were lucky to see 45 and they did have a transfer case that would get too hot to put your hand on the outside of the case in the summer.

My old 67 Chevy had 4.88s, it was no highway rocket either.

I would rather keep the oil and engine parts inside the block.

I would say Iowa is the worst ive seen and ive driven everywhere i work in Illinois, wisc and Indiana i drive in Chicago daily but Iowa on 80 is like the frigin Indy 500!!!

 

[krall]

70 and going into 495 twords baltimore and washington is like that as well. but they do it every day you just got to stay your speed and not change lanes, they will find a way around.

 

[TRG]

55 tops.. see the problem is the T case over heats and boils the fluid .

What about the guys that run an overdrive? I guess that slows the engine, trans and t case slowed down enough to safely ride at 70 mph.

 

[Barrman]

Over drive will only slow down the engine and the front part of the transmission. The t-case, drive shafts and axles are still spinning the same speed. Only taller tires or different gears will slow the t-case down. Besides running a slower speed of course.

This is the first I have ever heard about the NP208 having a cooling problem. However, my M715 with the NP200 was born with an over heating t-case. Most of us with those trucks have learned to stay slow, go fast in burst and carry an infrared thermometer to check case temps at stops.

Non synthetic oil should stay below 210°-220°. Synthetic can live at 250°. When the tcase case temps get above 260°. The driver can smell it while going down the road.

Just like with anything else mechanical. Do preventive maintenance, seek out advice, listen to the advice and check to verify everything is working right. Adjust you speed for the situation and all will be good. Trying to make a part do something it wasn't designed for will normally cause that part to fail.

When it comes to diesel engines and fuel economy. RPM is the big killer. 1800-2400 rpm seems to be the "happy spot" for the 6.2 Get above or below that and effeciency goes away. 2000-2200 is where they seem to be real happy. The 6BT engines seem to drop off above 2400 rpm about the same way. 6.0 Ford PS engines seem to do ok until 2300 rpm and a Multifuel looses it above 2400 rpm. I have never spent enough time behind a Duramax to know, but I would imagine it is about the same as the other V8 diesels. Just like the I6 diesels seem to live in the same range.

Don't forget that diesel combustion is not fast like in a gasoline engine. It takes a longer time to develop. The faster the engine is turning, the less push the piston gets which means more fuel is needed to do the same thing.

 

[chupa]

Drive my M1028 to work everyday. 31 miles both ways. Just at 55 mph though.

 

[GATVILLE]

Drive my M1028 to work everyday. 31 miles both ways. Just at 55 mph though.

Same here, i run to work in it, 30 miles each way at 65-70. Ive put a solid 1000 miles on it like this so far with no problems.

 

[WARWAG]

When im on the highway for the 5 mile run to town I go 40 to 45 unless I see someone coming up behind me. I then kick her up to 55 max and get as far over as possible to let them know they can and should pass. Most people up here are pretty much slow going....... anyway so its no big deal for most. I would NEVER run this engine with these Low gears over 55 unless I had 37" tires. Change out your Tcase and other fluids more often if your running on the highway allot. I will be changing mine out to Valvaline synthetic ATF since it was on sale at my local NAPA store. I will eventually switch everything over to AmsOil synthetics. The transmission will also get the same fluid as the T-case for now. There may be some confusion in this thread regarding the Transmission and T-case oil. They DO NOT share the same oil pan and do not have there own cooler (Tcase that is). The transmission oil is completely seperate from the T-case oil. They just both take the same type of fluid. Thats it. Hope this helps.

 

[WARWAG]

Same here, i run to work in it, 30 miles each way at 65-70. Ive put a solid 1000 miles on it like this so far with no problems.

Are you running the stock size tires? If so then your engine will grenade soon.

 

[WARWAG]

With stock size tires your engine is turning 3512 rpms at 70 mph. That is basically running the engine right at red line. Diesel dont do well running at or near red line. This engines sweet spot is between 2000 to 2200 rpm. This is where you will see you best economy and longevity.

 

[91W350]

I am with WW on this one, that is way too hard to be running. You will be looking for a 6.2 one of these days. This is a case where it is not the junk 6.2's fault when she blows. I am not sure you could run a 6bt that hard and expect long life. A small block Chevy the 6.2 is not......

 

[atankersdad]

I run mine at 55-60. Let the speed demons get mad at me... No faster. I think I will change fluids this weekend and go with AmsOil.

 

[DrJekl]

I picked up a used gear vendors unit for mine. The 50 mph on the road is slow going, sick of the a55holes flipping me off, and the engine is loud (running a K&N filter so the manifold noise is up there). We'll see how she runs in a few weeks.

 

[chupa]

70mph?!! Dang. That's about what I put so far, 1000 miles. Starting to see some small fluid leaks though. I heard where when it stops leaking that's when you worry.