New gears anyone ?

[NYBRD]

Local shop offers a nice 3.73 package bundle , would only be doing this for some faster acceleration but not sure how bad it'll hurt me mpg wise when I'm on the highway going about 70. Im already on e85 so I go thru gas pretty quick as it is ha. Thoughts?

 

[tom3]

Not sure what you have now but a gear change can sure wake up a machine and with today's OD gearing not a big mpg hit in highway opertion.

 

[Marky Dissod]

Local shop offers a nice 3.73 package bundle, would only be doing this for some faster acceleration,
but not sure how bad it'll hurt me MpG-wise when I'm on the highway going about 70MpH.
I'm already on e85 so I go thru ethanol pretty quick as it is. Thoughts?

If your original gear is 3.08 (?), your MpGs MIGHT go down by 1 or 2MpG if you drive conservatively.
Then again, they might not; you'll spend more time in the higher gears, and there'll be less downshifts.

If you drive assertively, your MpGs may go down, but your SMILES per gallon will DEFINITELY go UP.

Either way, your transmission might even last longer -
unless you constantly drive like you stole it and ignore your ATF changes.

The harder your vehicle works / plays, the better 3.73 will suit it.

 

[Cut Wagon]

What about 4:10 like the Tundras? My 08 Tundra always was in right gear and it pulled great. Fun to drive around town too.

 

[Marky Dissod]

What about 4.10 (not 4:10, 4.10:1) ... ?
My 08' Tundra always was in right gear and it pulled great. Fun to drive around town too.

Don't know nothing about Tundras.

Had to research NYBRD's other posts to find that he originally has a 6L80 & 3.08.
6L80 & 3.08 was the most common, CAFE MpG-motivated powertrain package.
6L80s with a tow-pack got 3.42, which was still motivated by CAFE MpG.
6L90s - which were for 2500 & 3500 - got 3.73 or 4.10, because CAFE does not care about 2500 or 3500 vehicles.

If he is willing to risk a highway MpG or 2 or 3, 4.10 will be much more fun,
will improve city / metro / urban MpG & towing MpG.

 

[Doubeleive]

Local shop offers a nice 3.73 package bundle , would only be doing this for some faster acceleration but not sure how bad it'll hurt me mpg wise when I'm on the highway going about 70. Im already on e85 so I go thru gas pretty quick as it is ha. Thoughts?

View attachment 458143

I get about 10mpg, no matter what I drive 3.08, 3.42, 3.73
the difference being the 3.73 does more unintentional burnouts

 

[Cut Wagon]

If I’m going through the expense and trouble to swap gears, it’s 4.10 all day everyday.

 

[swathdiver]

Local shop offers a nice 3.73 package bundle , would only be doing this for some faster acceleration but not sure how bad it'll hurt me mpg wise when I'm on the highway going about 70. Im already on e85 so I go thru gas pretty quick as it is ha. Thoughts?

Go for it.

I did this to my 2009, 5.3/6L80/3.42 to 3.73 gears. Around town mileage improved slightly and no measurable loss on the highway yet. Definitely faster off the line and she puts down 8-10 more horsepower through the traps in the quarter mile at the drag strip.

Would 4.10s have delivered better performance, yep. I wanted an incremental improvement without too much of a hit in mpgs for when we were not towing.

 

[NYBRD]

Would 4.10 gears ruin any chances of road trips in the tahoe?

Go for it.

I did this to my 2009, 5.3/6L80/3.42 to 3.73 gears. Around town mileage improved slightly and no measurable loss on the highway yet. Definitely faster off the line and she puts down 8-10 more horsepower through the traps in the quarter mile at the drag strip.

Would 4.10s have delivered better performance, yep. I wanted an incremental improvement without too much of a hit in mpgs for when we were not towing.

 

[Cut Wagon]

How? In my opinion it makes road trips better, especially if towing anything or loaded down, or going to the mountains etc. 4.10 just makes everything better. The $500 extra a year in gas is worth every penny.

 

[CMoore711]

I get about 10mpg, no matter what I drive 3.08, 3.42, 3.73
the difference being the 3.73 does more unintentional burnouts

I’m so glad you posted this.

@Doubeleive is that with premium fuel or E85?

I too avg 10 mpg according to the DIC on my ‘13 Escalade AWD with 6.2 6l80 and 3.42 gears. That’s also with running pretty much 100% E85 fuel.

Sorry to get a bit off-topic in your gear swap thread @NYBRD.

 

[Doubeleive]

I’m so glad you posted this.

@Doubeleive is that with premium fuel or E85?

I too avg 10 mpg according to the DIC on my ‘13 Escalade AWD with 6.2 6l80 and 3.42 gears. That’s also with running pretty much 100% E85 fuel.

Sorry to get a bit off-topic in your gear swap thread @NYBRD.

same, with premium or e85. no change in mpg (for me). probably just the way I drive.
the only time I get "better" mpg is driving thru mountains, which makes no sense because I drive thru mountains like a crazy person
should have been born rich and been a rally racer that would be a dream come true, but it would be a hell of a way to die though.

 

[Marky Dissod]

Would 4.10 ruin any chances of road trips in the tahoe?

How? ... It makes road trips better, especially if towing anything or loaded down, or going to the mountains etc.
4.10 just makes everything better. The $500 extra a year in gas is worth every penny.

1st, remember that 4.10 with the 6L90 is EXACTLY what GM did for 2500s & 3500s, so if you're afraid of doing something that is not 'GM OE', open your mind.
2nd, please feel free to indulge us - WHY do you think it would RUIN road trips?
As already stated, city MpG and towing MpG will improve. Highway MpG may improve IFF you drive more conservatively - that's a distinct possibility;
engine will need less help maintaining a given road speed, transmission won't need to downshift as often (so it may last longer too).

Y'all need to let go of your fear of more axle gear!
GM undergeared every V8 vehicle they ever sold since CAFE MpG target scores became a thing in the early 70s.
In the real world, the only mod that puts more power down thru the tires AND can improve MpG, is an axle gear upgrade.
If it costs a few highway MpG (and it might not), the tradeoff is your transmission appreciates the extra help.

 

[swathdiver]

Would 4.10 gears ruin any chances of road trips in the tahoe?

Not at all. That doesn't mean she'll get the same mileage as 3.08s though. My truck with 3.42s gets better gas mileage at 77 mph than at 71-73 mph. With the 3.73 gears, she's now spinning at about the same rpms at 71-73 mph as she was with the 3.42s at 77. Have not driven enough on the highway to measure it properly yet. Short term runs suggest there is no difference in mpgs.

 

[NYBRD]

If your original gear is 3.08 (?), your MpGs MIGHT go down by 1 or 2MpG if you drive conservatively.
Then again, they might not; you'll spend more time in the higher gears, and there'll be less downshifts.

If you drive assertively, your MpGs may go down, but your SMILES per gallon will DEFINITELY go UP.

Either way, your transmission might even last longer -
unless you constantly drive like you stole it and ignore your ATF changes.

The harder your vehicle works / plays, the better 3.73 will suit it.

Referring to gear ratio someone on the site told me I had 3.08 rear gear but I was just doing some googling and looks like I have 3.42 gears from my rpo code GMU . So if I do have 3.42 im starting to lean towards some 4.10 gears and now they have 4th of July sale on the gears

 

[Marky Dissod]

... looks like I have 3.42 from my rpo code GMU ...

GMU is a color code for metallic pepperdust. Whatever that pic is, it doesn't have any gear code.

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You've 3.08 - GU4 (not 3.42).

Upgrade to 3.73 if you're shy, 4.10 if you're feeling froggy.

 

[NYBRD]

GMU is a color code for metallic pepperdust. Whatever that pic is, it doesn't have any gear code.

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Free GM VIN Decoder - Do a VIN lookup to acquire specific car information. Ordering exact-fit parts has never been this smooth and hassle-free on GMPartsGiant!

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You've 3.08 - GU4 (not 3.42).

Upgrade to 3.73 if you're shy, 4.10 if you're feeling froggy.

Ohhh google chatgpt has failed me ! Hahaha thanks appreciate it !

 

[strutaeng]

My 06 Suburban 2500 LQ4 has 4.10 gears. I really like them, even though it's kinda of a heavy vehicle. I drive it all over the place, city or highway. No issues. I run LT265/75/16 tires. Hardly ever downshifts since the engine is usually on the slightly higher RPMs where it's making more power.

My 99 Silverado 5.3 ECSB has 3.42. I bought an axle to swap and regeared the axle to 4.10. I think 3.73 would have been a good all-around ratio since the 1500s are lighter weight trucks...but 4.10 should be slightly better for towing.

What tires are you running? Spicer has a handy online calculator to determine engine rpm based on transmission ratios, axle gear ratio and tire size. The LS engines are very happy on the 2500+ RPM and they make plenty of power above that, so slightly higher RPMs is no issue.

 

[NYBRD]

My 06 Suburban 2500 LQ4 has 4.10 gears. I really like them, even though it's kinda of a heavy vehicle. I drive it all over the place, city or highway. No issues. I run LT265/75/16 tires. Hardly ever downshifts since the engine is usually on the slightly higher RPMs where it's making more power.

My 99 Silverado 5.3 ECSB has 3.42. I bought an axle to swap and regeared the axle to 4.10. I think 3.73 would have been a good all-around ratio since the 1500s are lighter weight trucks...but 4.10 should be slightly better for towing.

What tires are you running? Spicer has a handy online calculator to determine engine rpm based on transmission ratios, axle gear ratio and tire size. The LS engines are very happy on the 2500+ RPM and they make plenty of power above that, so slightly higher RPMs is no issue.

I run 285/45/22
Local shop has either 3.73 or 4.10 4wd kit for about 1000, and another 950 in labor to get it done for me. Im just wondering is the 2k worth it in acceleration and will it give me a little smile everything I romp on this thing lol I drive about 25 min every night around 1am to work so roads are always empty and im always out there having a good time. Id hate to spend the 2k and feel like it wasn't worth it

 

[OBSandaNNBS]

I run 285/45/22
Local shop has either 3.73 or 4.10 4wd kit for about 1000, and another 950 in labor to get it done for me. Im just wondering is the 2k worth it in acceleration and will it give me a little smile everything I romp on this thing lol I drive about 25 min every night around 1am to work so roads are always empty and im always out there having a good time. Id hate to spend the 2k and feel like it wasn't worth it

What I'm hearing is you'll probably regret not doing it sooner.