Need opinions: 3.42 vs 3.73 GR

[bobsburban]

FWIW, I'm pulling a 17' Winnebago that weighs about 4500 lbs loaded on 3.42s with a 6L80 and 5.3. With my 275/65-18s (32.1" diameter), the effective gear ratio is 3.40. I'm also looking at some Cooper Rugged Trek tires and they're 32.6", which bites into the gearing even more. So I'm not crazy about it and am thinking about 3.73s as it's still a daily driver. 4.10s might be a bit much to my way of thinking but I'm open to thoughts.

Just got back from a 3000 mile trip up and down the east coast and Allegheny Mountains and spent well over 50% of the time in 3rd and 4th, twisting the engine between 3500 and 5000. Guess I'm glad it's a Corvette block at heart...

 

[Marky Dissod]

... pulling a 17' Winnebago ... about 4500lb loaded on 3.42 with 6L80E & 5.3L.
With 275/65R18 (32.1" diameter), effective gear ratio is 3.40.
... also looking at Cooper Rugged Trek tires, 32.6", which bites into gearing even more. So I'm not crazy about it, thinking 3.73.

Stop thinking about 3.73, just do it already.
GM already did - if only for some 6L80E pickups with their version of HD towing.
Not like you'd be in uncharted waters.

 

[bobsburban]

True this...

 

[Dustin Jackson]

My opinion is to go with the 3.73. I wouldn’t worry about using a 10 bolt rear end I can’t recall seeing anyone having a diff failure in these

 

[buckwild27]

I can honestly say you'll be happier pulling that land Yacht with 3.73 gears. That's what I run in my trucks.

 

[intheburbs]

I've always been of the opinion that if you're going to go through the effort and expense of regearing, do a "double jump." Either 3.08 to 3.73 or 3.42 to 4.10.

My Suburban 2500 has the 6-speed and 3.73s, and has a tune. While my Denali is 1000 lbs lighter and has 50 more hp, the 3.42 gears prevent it from walking away from my Suburban in a drag race.

And with 3.73s, engine is at 2250 at 80 mph, compared to 2000 at 80 with 3.42s.

If it was me, I'd regear to 3.73.

 

[Marky Dissod]

For 4L60E, 4.10 with 31.6" tall tires seems (to me) to be ideal.
For 6L80E, 3.73 with 31.6" ...

Should be blatantly obvious that GM undergeared nearly all these vehicles to improve MpGs for tests that have no realistic bearing on today's driving conditions.
Nearly every vehicle (not just GMs) would have more axle gear if the test results were determined by giving the cars to metro / urban cabdrivers for a month and tracking their MpGs - which is never as good as what's on the Monroney.

As a leadfoot forever stuck in rehab, I get the double-jump idea, but that's mostly from the context of my arse.
Driving conditions (and wheel / tire height & weight) are what ACTUALLY have more bearing on things like MpG.

 

[blackelky]

How much are regearing costing in your areas? I'm looking to go 3.73s myself. 3.08s are killing me.

 

[buckwild27]

I tow a 7500lb camper with the 3.42 and the 6L80, and am completely happy. I run at 65 mph in 4th most of the time when towing because Nick Transmissions says that's the strongest path through that transmission. I'm turning about 2800 RPM with rarely ever a downshift needed, unless on a steep incline. If I had 3.73's I'd be over 3000 in 4th, with zero practical benefit for power. This is with a modified 6.2L though, so perhaps with the 5.3 that extra 200 rpm would be beneficial.

If you had 3.73's you could leave it in 6th gear.

 

[intheburbs]

If you had 3.73's you could leave it in 6th gear.

No, he couldn't. My Suburban can't even stay in 6th pulling a 3,500-lb 6x12 enclosed trailer. Even if it could, I'd still tow in 5th with 6th locked out. No reason to overstress the transmission.