Suburban towing a Suburban

[Marky Dissod]

You don't get to have your cake and eat it, too.

Depends on which cake you want.

Changing ratios is always a give & take.

No it isn't, not always. Don't worry, I'm about to explain it.

Yes, 3.73 would be better for towing. 4.10 would be better still.

Glad we agree on that.
GM does too, by the way, but GM saved 4.10 with 6L80 for the heavier-duty stuff where HIGHWAY MpG was of less importance than durability & tow rating.

But 3.73 will yield LOWER MpG when not towing. Again, that was the whole point of 3.08 - better mileage to help with CAFE.

Although absolutely true for highway MpG, especially if one prefers to drive OVER 65MpH, it turns out to be patently false for stop'n'go traffic.
CAFE's MpG tests feature anachronistically sparse traffic, featherfooted accelerations, and Nixon-inspired top speeds.
Ever bother to study the gear spreads for the 4L60, 6L80, 8L90, & 10L80?
Their final gears are 0.7, 0.67, 0.65, & 0.64. 4L60E has 1 overdrive gears, 6L80 & 8L90 have 2, & 10L80 has 3.
Their 1st gears are 3.06, 4.03, 4.56, & 4.7. 4L60E has 2 underdrive gears, 6L80E has 4, 8L90 has 6, & 10L80 has 7.
More gear(s) is (are) improving stop'n'go MpG, towing performance, towing MpG, and durability / longevity.

Gentle drivers who don't speed on the highway will not lose much MpG. If anything, they'll drive even more gently!
Leadfoots will gain SMILES per gallon, plus durability if not longevity.

Any MpG sacrifice will not be as bad as feared, especially for gentler drivers.
Small price to pay for better city MpG, better towing MpG, & better longevity / durability.
Fu'h CAFE.

4.10 with 4L60. 3.73 with 6L80.

 

[mikez71]

So you're saying 3.42's with a 10L80 be about perfect?
I need to do this fuel saver mod because I do all city driving, terrible mpg. (Tell your wife! it's true!)

I'll be so happy if I ever get out of 3.08 land...

 

[Marky Dissod]

So ... 3.42 with 10L80 would be about perfect?

10L80 has so much / many forward gear(s), in THIS case, 3.42 might cross diminishing returns?
In the specific case of the 10L80, my guess is, it'd need BIGG tires for 3.42 to improve much of anything,
because it has 7 underdriven gears to use to maximize stop'n'go & towing MpG.

4L60 needs a custom rebuild for serious work and play.
With 4.10, the 4L60E works and plays better, and will last longer between rebuilds.

6L80E's weaknesses are hinted at by how GM programmed it for use with the 6.6L LGH DuraMax.
With 3.73, the 6L80E works and plays better, and will last longer ...

3.73 wouldn't help the 8L90 as much as the 6L80E, but it'd only hurt highway MpG a lil bit, if anything at all.
If anything, it'd be able to spend more time in 6th & 7th on the highway.

 

[Pyramid_Head]

Although we all agree on f'uh CAFE (statistics back it up), I'm totally up for 3.73 gears. I mean, I live in 3000ft elevation and I just average 12mpg wussy peddling everywhere (I baby my torque converter). I've also installed a new oem water pump, replaced all coolant, new air filter, new spark plugs and wires (all oem), reinstalled my oil catch can, installed new front disc brakes and pads, rebuilt the whole front and rear suspension 2yrs ago with oem parts, and I recently did 3 fill and drains, installed a new oil strainer, also replaced rear-end oil.... I mean, I did a lot on this truck, and I'm loving it!! It presently has 127k miles on it. I also have the range dod disabler.

 

[R467X]

I third and fourth the rent a uhaul and let them deal with the wear and tear.

If you want a suburban tow rig, look at eBay listings. There are Duramax swapped suburbans that go on sale from time to time. Those things are suburban tow monsters.

 

[Marky Dissod]

Although we all agree on f'uh CAFE (statistics back it up), I'm totally up for 3.73.
I mean, I live in 3000ft elevation and I just average 12MpG wussy peddling everywhere (I baby my torque converter).

It's a safe bet that the CAFE MpG 'road tests' do not include steep hills.
Those who only drive on flat plains seem to tolerate the axle gears CAFE forced GM to give them.
6L80E + 3.08 + long steep hill ... the greater the elevation change, the better off with 3.73.

I don't disagree with using a different dedicated tow rig, but
If you want to turn YOURS into a tow rig, more axle gear can't hurt.

 

[K2 Kaiju]

I also say tow the burb with the Uhaul, and you pull the CRV or another trailer with his belongings. I have never used one, but could one use a tow bar for the burb? I know the stock tow limit on my 18 burb was only 6k...

 

[B-train]

The way I see your post title.......LOL

nothing more to add that hasn't been mentioned.

 

[Pyramid_Head]

2500s have leaf springs. Since you have highway gears, leave her in 4th for the run and use Tow/Haul of course. Use a trailer with a weight distribution hitch and anti-sway or a U-Haul with its surge brakes. Pick your favorite trailer brake controller if you're not using a U-Haul with the surge brakes. Change your transmission fluid now if it has more than 30K miles on it or change it when you get back.

Oh... I see... well, I added some type of spring 2 yrs ago that lifted up the suburban about 2-3 inches. Here is the link to my thread install from almost 2yrs ago.

Help with reviving suspension

Hello everyone. I'm an owner of a 2011 Suburban LT with 115k miles, plain jane suspension. I've been buying suspension parts lately to replace shocks, and i can't decide whether to go with KYB from Rockauto, or the more expensive brand Bilsteins 4600's. My truck is usually a family hauler, and...

www.tahoeyukonforum.com

 

[Pyramid_Head]

I also say tow the burb with the Uhaul, and you pull the CRV or another trailer with his belongings. I have never used one, but could one use a tow bar for the burb? I know the stock tow limit on my 18 burb was only 6k...

Very true. I'll relay the plan to my brother. Thanks again everyone for your input.