M1009 Highway speed

[Gspotorno]

I recently purchased a 1986 M1009 it has a 4 inch rough country lift and 37" good year wrangler military tires, i am very hesitant with it on the highway and am worried about driving it above 50 on the speedometer because the motor sounds like it is revving high, or what i think is high compared to my 1986 GMC Jimmy (fullsize) somebody please tell me whether or not it is okay to drive it much faster as i am getting sick of being passed by everyone on the road

 

[SRB1976]

I drive mine 70+ but mine is stock. Do you know your gear ratio? Stock is 3.08 I believe.

 

[porkysplace]

I drive mine 70+ but mine is stock. Do you know your gear ratio? Stock is 3.08 I believe.

From the
CUCV FAQ Article

The M1009 has Corporate 10 bolt axles front and rear with 3.08 gear ratio and a Gov-Lok in the rear. The front axle is open.

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The M1008 has a Dana 60 front axle open and Corporate 14 bolt rear axle with 4.56 gears, detroit locker. The M 1031 , M1028, M 1010 all share this gear ratio.

 

[OL AG '89]

google gear ratio / speed calculator... may even be one on the site somewhere.....
I have 33's stock rear and the TACH says right at 1800 at 60 - 62....... only question I have is the speedo accurate, but I can maintain in the right lane ......

 

[Bob H]

I recently purchased a 1986 M1009 it has a 4 inch rough country lift and 37" good year wrangler military tires, i am very hesitant with it on the highway and am worried about driving it above 50 on the speedometer because the motor sounds like it is revving high, or what i think is high compared to my 1986 GMC Jimmy (fullsize) somebody please tell me whether or not it is okay to drive it much faster as i am getting sick of being passed by everyone on the road

The 37" tires are 20% larger than stock, therefore your stock speedometer will be off by 20%.
At an indicated 50 mph you are traveling at 60mph
an indicated 25 mph would be 30 mph.

 

[midcounty]

I run my stock truck at 60mph every day, but I have the original 3.08 gears and original size tires. You need to verify your gear ratio before you can determine what speeds you can run. Then you need to check your speedo with a GPS. If you still have 3.08 gears you will be golden at 50 and more, but I can imagine it is a bit slow to get up to speed with those gears.

 

[forest522]

Last week I drove a 1985 M1009 all day on highway and on forest roads. Full of gear, high elevation and high temps. Went 60 to 65 most of the way there and back on the highway. Drove like a dream. Best to avoid anything over 70 for long periods of time. Just not worth the wear and tear.

 

[Gspotorno]

thanks and ya i have stock heavy half corporate 10s with the 308s, i just dont want to push the truck hard because it is my daily driver and i cant risk anything happening to it

 

[twomorestrokes]

Wow, with 3.08s and 37s it would seem that the engine would just about be at idle speed at 50 mph. Try driving an M1008 with 4.56s 50 mph and you will really appreciate what you have...

 

[chevyCUCV]

Wow, with 3.08s and 37s it would seem that the engine would just about be at idle speed at 50 mph. Try driving an M1008 with 4.56s 50 mph and you will really appreciate what you have...

This x a million

 

[twomorestrokes]

Welcome! ChevyCUCV, you've had your truck to 80 in stock form? I've never gone over 55 in mine for the most part. One time it was getting dark and my headlamps quit with a long ways to go. Got it up to 60 and i was not comfortable with it for that amount of time.

 

[midcounty]

thanks and ya i have stock heavy half corporate 10s with the 308s, i just dont want to push the truck hard because it is my daily driver and i cant risk anything happening to it

You should be turning 1500 rpm at 50mph. I run about 2500 rpm cruising my m1008. Engine should live a long life cruising under 2000 rpm.

 

[Mike68]

I drive mine at 65 mph alot. 70 some but not at long periods of time. I dont go over 70. Its my daily driver, it is all stock just as in the pic. So far knock on wood I have had great luck with it.

 

[GreggVA]

A couple of calculator links for you.. Someone will chime in as to the optimum RPM range for running the engine. I seem to remember that there is a sweet spot that people shoot for when changing gears.

Gear Ratio Speed Calculator

Gear Ratio Calculator