Rear axle ratio, need some advice. - Chevrolet Forum - Chevy Enthusiasts Forums

Rear axle ratio, need some advice.

Old  January 23rd, 2008, 6:33 PM
Rear axle ratio, need some advice.

I'm a newbie to this forum and am looking at purchasing a 2008 Tahoe most likely with a Z71 trim. I realize the truck comes with 3 different axle ratios to choose from. The particular vehicle I'm interested in on the local dealer lot has a 3.42 rear axle ratio. I've read and been told conflicting information regarding the pros/cons of each one. I think 3.73 is the most popular and the 4.10 comes more on the 4wd models.

My situation/need is this. The only towing I will be doing is pulling a 20 foot skeeter fish/ski boat on a dual axle trailer. Minimal if any off-road use. I live in Texas so the only inclement weather would be the random once a year ice storm and rainy weather.

Should I avoid the 3.42 ratio and find one that hasa 3.73?

Or should I opt for a 4wd model?

I'd appreciate any advice.

Old  January 23rd, 2008, 6:49 PM
RE: Rear axle ratio, need some advice.

My personal opinion is this;
The actual physical and operational difference between these ratios is slight (+ or - one tooth on the pinion gear) , most people can get out of a Tahoe with a 4.10's and get right in another with a 3.42 and not be able to tell the difference, now if you were pulling a more substantial trailer then I would recommend the 4.10 without hesitation.

If you drove the Z71 2WD Tahoe with 3.42 gears and you liked it then I would look no further, on the other hand you may want to take a different Tahoe with the 3.73 and see if you like it better.
I would caution against spending the extra money on a 4X4 model that you can't really put to much use.

The 3.42 ratio can feel a bit anemic if you operate at high elevations or hilly country such as Denver but for flatlanders at low elevations it is virtually a non-issue.

Remember that it is a personal preference, there is no right or wrong way to go, the reason that most dealers order the 3.73 for stock units is that it is a good compromise ratio.

Old  January 23rd, 2008, 8:54 PM
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RE: Rear axle ratio, need some advice.

ZX, didn't you mention once that the 4.10 may be better suited for the powerband and netted the best MPG (although I think you said it was slight)

Old  January 23rd, 2008, 9:07 PM
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RE: Rear axle ratio, need some advice.

I remember that also.

Old  January 24th, 2008, 8:38 AM
RE: Rear axle ratio, need some advice.

Yes, I did say that, the 4.10 reduces the load on the engine much like a lower gear on bicycle reduces the load on your legs, this has the potential to allow the engine to operate in 4-cylinder more often and save a little more fuel, this is a benefit for those people that want 4-cylinder to activate as often as possible.
On the flip side of the coin a 2WD Tahoe with 3.42 operated in flatland country at near sea level (and not towing) should yield very good MPG at highway speeds at the cost of reduced (compared to lower ratios) MPG city, but keep in mind that we are talking about very minimal differences here, variations so slight that the average person will not be able to detect the difference.
Driving style still plays the largest role in fuel economy hands down.

Old  January 24th, 2008, 9:59 AM
RE: Rear axle ratio, need some advice.

So if the mpg difference is negligible, why not opt for the 3.73 or 4.10 to get the better towing ability? Chevy's site says a 3.42 can tow 6500 pounds and a 3.73 can tow 7500 if equipped with a heavy duty trailering package.

Or is the towing advantage almost negligible as well? If your trailer weight is less than 6500 pounds, will the 3.42 pull just fine?

Central Texas hill country does have some decent inclines especially around the lakes I frequent.

I currently drive a 2005 Sierra 4x4 and it feels sluggish up hills. Not sure of the rear axle ratio though.

Old  January 24th, 2008, 12:09 PM
RE: Rear axle ratio, need some advice.

Powertrain wise a Tahoe and your current Seirra are almost identical, I would check the gear ratio in your GMC and get a lower ratio if you are not satisfied with it's performance.

Old  January 25th, 2008, 11:24 AM
RE: Rear axle ratio, need some advice.

ZX, what is your average mpg with your 4x4/4.10 setup on the highway? You mentioned on a previous post you averaged about 12.5 pulling a large boat.

Old  January 25th, 2008, 1:32 PM
RE: Rear axle ratio, need some advice.

Not pulling it averages 18-19 at 80mph over the highway and about 16 city.


Old  February 1st, 2008, 3:56 PM
RE: Rear axle ratio, need some advice.

I was able to test drive a 3.73 rear end Tahoe and it pulled my boat without a problem. Probably even better than my current Sierra with 3.73. Both were 4wd.

The only problem is the vehicle that has all the specs I want has a 3.42 rear end. I've asked all the service techs at all the dealerships and they say the 3.42 would do just fine to pull a roughly 3000 pound boat. I'd only be towing the boat maybe once or twice a month.

So do I buy the 3.42 off the lot, or wait to order a 3.73?

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