Gear swap from 3.42’s to 3.73’s worth it?

[DoubleDingo]

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[Marky Dissod]

Placing the shifter in '3', '2',or '1' burns up overrun clutches over time (less so driven gently, but still).
Since 1993, the 4L60E will last longer between rebuilds if the pcm is tuned to use the gears you want when you want them used, and avoid the gears you want when you want them avoided, than to use the shifter to do that.
Mechanical manuals have even less in common with electronically commanded automatics (4L60E) than mechanically commanded automatics (700R4/4L60h).

GM started using of 3.42 & 3.23 in the early noughties due to inherently unrealistic CAFE MpG testing.
In the real world, 3.23, 3.42, and 3.73 get similar highway MpGs, but the lesser-geared get worse city MpGs,
have weaker tow/haul ratings, and are more susceptible to shorter-lived 4L60Es.

No it is not, not compared to a Tahoe or Suburban with 3.73 or 4.10, it ain't, it can't be.
You don't see anything wrong with 3.42 because you lack enough experience with 3.73 or 4.10.
Drag race a Suburban with a 5.3L & 4.10, you won't be able to unsee what you've been missing.
Drive the 3.73 or 4.10 suv around in the city long enough to see the real-world city MpG, you'll be a convert.

You know who else thinks 4L60E's 1st gear is insufficient? GM Powertrain.
4L60E: . . . . . . . 3.06 . . . . . . . . . . 1.63 . . . . . . . . . . . . 1.000 . . . . . . . 0.70 (4.43 Spread)
6L90E: . . . . 4.03 . . . . 2.36 . . . . . . . . . 1.53 . . . . 1.15 . . . . . . . 0.85 . . . . . 0.67 (6.01 Spread)
8L90E: ... 4.56 ... 2.97 .... 2.08 .... 1.69 . . . . . . . 1.27 ... 1.000 ... 0.85 . . . . . . . 0.65 (7.01 Spread)
10L80: ... 4.69 ... 2.99 ... 2.15 ... 1.77 ... 1.52 ... 1.28 ... 1.000 ... 0.85 ... 0.69 ... 0.64 (7.32 Spread)
8L90 & 10L80 2nd gear is basically 4L60E's 1st gear. GM was looking to improve city MpG.
Everyone who drives their 10L80 in 9th to avoid Cylinder Confusion is basically using 4L60E's 4th.

Not roasting you, roasting what you wrote. Get tuned, you won't regret it.
Get 3.73 (4.10 might be excessive, for YOU ... maybe), you won't regret it.

 

[West 1]

In my Tahoe with the 4.10 gears, it was a 2002, I was hit by another driver that chose to RUN after the hit. With the 4.10 gears I had to jump on it, swerve around a second car the same driver had hit and go after him. The Tahoe was no race horse for sure but it sure surprised the guy who thought he could run away and escape. I caught him in no time and stayed on him till Police joined me and pulled him over, little more involved than that but that truck would scoot when floored. It was fun and got good MPG as long as you did not go too fast on the HWY. I thought the truck would get better MPG with a 3.42, I swapped one in and drove it for a couple months. MPG, no change, truck felt like it lost 50 HP. I swapped the 4.10 back in and kept them till I sold that rig in 2014.

 

[DoubleDingo]

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[swathdiver]

Not inexperienced in low gears, just prefer gears that allow highway cruising at a better rpm. If I want 3.73 I use my Cherokee. The Cherokee came with 3.55, I added taller tires, gear swap. But, need 4.10, 81 C20, 4.57, 65 C20. Thank you for all the info, it's good to learn/know more stuff. I guess I'll learn the hard way on using gears in the Tahoe instead of tuning gears. Don't have the time or the equipment to tune.

You are experiencing her as she was designed. She's plenty capable as is and delivers good performance. She'd be a little more spritely around town with little change in highway mileage.

If you keep the Tahoe long enough and overhauling the axles becomes necessary, you could revisit that question again.

 

[Marky Dissod]

You are experiencing her as she was designed. She's plenty capable as is and delivers good performance.
She'd be a little more spritely around town with little change in highway mileage.

If you keep the Tahoe long enough and overhauling the axles becomes necessary, you could revisit that question again.

@DoubleDingo,
You're experiencing her as her design was poorly altered by GM to satisfy a CAFE MpG target that is irrelevant to how these vehicles are actually used in the real world.
She's capable as is of delivering a standard of performance that only exists because GM lowered the bar.
She'd be more sprightly around town with little change in highway mileage,
specifically because when 3.42 must downshift to 3rd or 2nd on the highway, the suv with 4.10 stays in 4th or maybe downshifts to 3rd.
Whatever 4.10 'wastes' in highway MpG (very little for someone like you), pays off in 4L60E durability and longevity.

If you keep the Tahoe long enough that overhauling the axles becomes an option, you should revisit that question again ...
but you likely will not because you own multiple vehicles ...
Neither of those C20s have a 700R4, right? You only own one vehicle with either a 700R4 or a 4L60E?

 

[DoubleDingo]

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[DoubleDingo]

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[DoubleDingo]

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[Marky Dissod]

Revisiting the various transmission ratios. In order to achieve 6, 8, 10 forward gears, they have to have deeper take-off gears, because you can't have too much overdrive;
if you reduce RpM too much you can keep the vehicle rolling.

That's why the final gears of the 4L60E, 6L80, 8L90, & 10L80 are pretty damn close.
What I was trying to point out was that GM hobbled a bunch of vehicles in '05 & '06 with 3.42 & even 3.23, 3.42 being far less available from 99-04,
& 3.23 being unavailable from 99-04. In other words the nearest equivalent to your vehicle in '04 most likely got 3.73; you'd barely notice any MpG penalty if at all,
but your 4L60E would last longer between rebuilds.

GM's correction for this was more forward gears with more assertive gearing in future transmissions.
Far and away the most common axle gear with 8L90 & 10L80 is 3.23 ... even with that assertive 4.56 or 4.69 1st gear, and a 2nd gear that is basically 4L60E's 1st.

Gearing is fun. Keeping the engine in its happy spot is the goal of gears.

More gearing is more funner, keeps driver in his happy spot, reduces the number of unnecessary shifts (shifts less often = lasts longer between rebuilds),
and would likely cost you little to no MpG penalty.

If you find me a set of 4.10, I'll send you my 3.73

 

[homesick]

I owned a Tahoe, 5.3L with 4.10 gears and liked it a lot, the only time I did not like those gears was on a long highway trip we did every year. 780 miles one way, across Nevada and north to Salmon Idaho area. In Nevada it is flat and straight, I wanted to go 85 but the 4.10's wanted me to stay closer to 80. Beyond that mpg really dropped. We also had a Denali with the 6.0L and 3.42 gears, it was great on that trip, 85-90 across Nevada was easy. I hated the 3.42 gears below 70 mph in that truck with 4L60 tranny.

Next Yukon had 5.3L with 4L60 and 3.73 gears, a nice mix, good on highway, much better than 3.42 around town. Now I have a 08 Denali with the 6.2L and 6L80 tranny with 3.42. Even on the highway I would like it to have maybe a 3.73 gear set.

In the mountains and towing the 4.11 were perfect so it depends on what you are looking for. 3.73 is a good compromise. Maybe test drive rigs that have the gears you are considering before spending money?

Both of my [4 speed] Camaros, and 3 of my 4X4 Blazer/Tahoe trucks came with 3.73 axles. I agree that it's a great all-around ratio.

joe

 

[DoubleDingo]

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[DoubleDingo]

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[Marky Dissod]

'Harm' is a relative term. Anything worse than 'good' is relatively 'bad', 'good' is 'bad' when compared vs 'better' ...
The 4L60E is an electronically commanded transmission, it can be programmed/tuned to do what you do with the shifter in '3', EXCEPT
WITHOUT using the overrun clutches, in 'D' - you just edit the 3Up4 and 4Dn3 shifts in 'Normal mode / D mode to avoid 4th.

You canNOT avoid using the overrun clutches by using the shifter, because using the shifter in any position besides 'D' engages overrun clutches -
you can however tune the pcm to do what you do and get better MpG than you do using the shifter, by having the pcm tuned.

Which leads to my next point: You're avoiding lugging the engine by using '3', because GM dun wrote the 3Up4 & 4Dn3 shifts wrong,
or at least very suboptimally for most of your situations ... and using '3' is 'not as good for 4L60E longevity as tuning the pcm to avoid 4th as you do otherwise,
because you're using up the overrun clutches, and you don't need to.

My Police Pursuit Vehicle-Interceptor Vehicle concept involves a 6.0L with 243/799 heads - still haven't yet decided which GM OE cam yet - and 4.10 axle gears.
Won't need one mortgage, just a lil patience and about $3,000. For $8500 all in I get the Tahoe that I want ...
Mind, I - after research, see the Impala SS Forum - installed selected limo & V4P tow pack parts on his mid-90s LT1 Caprices to make them quicker than 9C1s.
They also got better MpGs than the 9C1s I previously owned, which came with 3.08, AFTER I installed 3.42 and tuned them.
When I go to BK, they give me my burger my way, no questions asked, or they've got PROBLEMS. GM gets away with this horseschidt daily.
Feel free to make excuses for them, but don't rope me into it. (Porsche overcharges, but GM will not give anyone a Tahoe with a 6.0L! What's up with that?)
Still making mistakes and learning from them; Bilstein 4600s are too genteel ...

Everyone decides what to do with their I.T.E.M.S. (Info Time Energy Materials Space) to their 'taste'.
When my power windows quit, I may very well replace them with window roller-uppers, just 'cause that's how I prefer them from experience.
And I ALWAYS select police pursuit-rated semi-metallic brake pads. Need? no, but glad I informed myself thoroughly enough to know what I really want,
instead of giving GM so much deference a priori - don't forget my 2010 Suburban front brake kit.

Already explained how GM made a mistake (in my experienced opinion) making 3.42 more available in '05 & '06 (& 3.23 available at all in '05 & '06).
3.73 & 4.10 are simply better choices in the real world over 3.42 (except maybe when the earth is flat?).

I will give my 3.73s (front & rear) to anyone who wants to give me 4.10s ...

 

[DoubleDingo]

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[Marky Dissod]

3.73 was also a GM OE option available for '00-'06 Tahoes; nothing wrong with increasing your tow rating and improving your 4L60E's durability & longevity -
unless you ...
A pcm tune, suited to your taste, which should not cost you more than about $250, would help your 4L60E almost as good as 3.73,
and would make you wonder why GM was holding out on you in terms of the engine as well, plus improve the engine's durability & longevity -
unless you ...

Anyone who tries to help should be helping to be helpful; no thanks needed & you're welcome.