tow rating - '90 2500 Suburban

[Keith Seymore]

@Keith Seymore - There's a wealth of info in those docs you linked to. Thank you again!

For posterity, looks like my tow capacity is 7,000Lbs, with 3.73 gears. 4.10 would give 7,500.

Interestingly, the R2500 w/4.10 & tow package can tow 9,500! I'm kinda surprised 4x4 decreases capacity that much.

Thanks all!

Yes there is; you are welcome.

If you look closely you'll see it's not so much the 4x4 that is knocking the rating down but the available gear ratios.

The gear ratios available with the 4x4 version are a little more conservative because you can use the 4L feature of the T case to double the ratios.

With the 2wd variant you can't do that, so steeper (higher numerical) ratios are offered.

K

 

[Keith Seymore]

who knows what else they figure in.

(I do).



It's pretty much what you would expect, in terms of evaluating braking and ride and handling.

The only part that is perhaps not obvious now is the final check: you had to be able to launch up the 16% grade at the Milford Proving Ground from a standing stop, at GCW.

There were a few vehicles that got knocked back because they couldn't pass that portion of the development.

K

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[GTX63]

Install a transmission cooler #1. Unless you are towing a push mower on a 4'x6' trailer, you will need a transmission cooler regardless of engine/transmission/gear ratio.
I have towed 8k before without issue. As with late model trucks, make sure the trailer is evenly loaded and you have a functioning trailer brake controller.

 

[skipdup]

Yes there is; you are welcome.

If you look closely you'll see it's not so much the 4x4 that is knocking the rating down but the available gear ratios.

The gear ratios available with the 4x4 version are a little more conservative because you can use the 4L feature of the T case to double the ratios.

With the 2wd variant you can't do that, so steeper (higher numerical) ratios are offered.

K

Very interesting. Makes sense. Thanks again!!

 

[SirRobyn0]

(I do).



It's pretty much what you would expect, in terms of evaluating braking and ride and handling.

The only part that is perhaps not obvious now is the final check: you had to be able to launch up the 16% grade at the Milford Proving Ground from a standing stop, at GCW.

There were a few vehicles that got knocked back because they couldn't pass that portion of the development.

K

You must be registered for see images attach

In the back of my head when I was writing that, I hoped you'd have something to say about it. Thank for that info. I'm curious what you mean by "launch" Was there a particular speed you guys looked for going up the hill, or was it stopping and ability to get the load going again?

 

[Keith Seymore]

Stopping on the hill and the ability to get it going again.

K

 

[Bextreme04]

Stopping on the hill and the ability to get it going again.

K

That was one of the evaluation tests when the M-ATV was going through evaluation testing to be the replacement for the HMMWV in Iraq and Afghanistan. When it got selected and we were doing the driver training for the military, every driving course got a 60% slope hill(~31 degree) put on it. The M-ATV, at 27,500lbs curb weight, would go from a dead stop on the slope and accelerate through 25mph up the hill like it was nothing. It was wild. You felt like it was going to flip over on it's back it was so steep.
https://oshkoshdefense.com/vehicles/mine-resistant-ambush-protected-mrap/m-atv/

Cat C-7 engine, Allison SP3500 6-speed automatic, oshkosh designed and manufactured transfer case and 4 wheel independent suspension that had more than 19" of travel on each corner. It would ride like a cadillac at 40mph across the desert and 75mph on the freeway like it was nothing. All of the seats were suspended and dampened fabric to prevent blast waves from transferring through a hard seat and snapping your spine, so it made for an extra soft ride when driving around normally.

 

[Keith Seymore]

a dead stop on the slope and accelerate through 25mph up the hill like it was nothing. It was wild. You felt like it was going to flip over on it's back it was so steep.

We had a white race truck (85 C10 stepper with an aluminum 454) that was running 10.70's.

We used to take it out to the grade and do launches; it was like being in a rocket ship.

K