New tug axle ratio

[Rick kl]

I purchased a 2005 trailblazer EXT LT to replace my 99 S10 Blazer this new one has a lot more power as it is equiped with a V8. I have a question about gear ratio the two options are 3:73 ( mine has this one) and the other is 3:43, I am assuming one is for better gas mileage and the other is for power which one does what ?

[Morgan]

I purchased a 2005 trailblazer EXT LT to replace my 99 S10 Blazer this new one has a lot more power as it is equiped with a V8. I have a question about gear ratio the two options are 3:73 ( mine has this one) and the other is 3:43, I am assuming one is for better gas mileage and the other is for power which one does what ?

The 3.73 is the [b]lower ratio of the two; better for towing.

[Al V]

3:73 is the way to go the 3:43 only get you one extra mpg at least that has been my experience with the silverado's. 3:73 there is a very noticeable improvement in acceleration form a stop or merging traffic conditions. the other is on trunpike overpasses the silverado with 3:43 wants to downshift at every single one.
where the 3:73 silverado does not. the 3:43 is a 4X4 and the 3:73 is 2 wheel otherwise same truck now 3:43 in a 2 wheel version might be get you more then the one mpg i see.
food for thought

[Pete Dumbleton]

I would also be inclined to go with the 3.73 ratio.

[Rick kl]

Thanks for clearing that up, I always wondered what the difference was.

[Darwin Maring]

The higher the number, the more power.
A 3:73 has more power than a 3.43.
A 3:43 has more speed than the 3.73 and should give better fuel mileage.

With a powerful motor you can tow with a lower number.
The horse power of the engine should me matched to the correct rear end to give the performance you require.
The new Silverado's have a switch for towing that allows the transmission to remain in lower gears for longer periods of time. The books also state that in hilly country to shift the transmission into 3rd. You may find that having a lower number on the rear end would be most cost effective because you would drive in 3rd while towing and when not towing you would get better fuel mileage, seeing that you do the most of your driving NOT towing anything.

[Chris Z]

Not sure we are talking apples to apples but my TV:

2006 Suburban 1500 2WD
VORTEC 5300 V8 FLEX FUEL ENGINE
4-SPD AUTOMATIC TRANSMISSION
17" ALUMINUM WHEELS
REAR AXLE 3.42 RATIO

There has to be a really steep hill to get it to downshift when I'm travelling 70mph. Getting nearly 20mpg w/o 17' Casita and approx. 14-15 mpg w/Casita at ~70mph. Gets around 15mpg around town w/o.
there's a tow button on end of stickshift but I never use it pulling the Casita.

[Darwin Maring]

You are right about the V8 that you have and the rear end. Enough HP to tow without problems.

If you use the tow button it will keep the transmission in the lower gears just a little longer B4 it shifts. This allows you to do quicker starts and get up to speed sooner. Once it is up to speed it is the same as not having it on at all. I'm not sure if it keeps the lockup clutch from locking up.

R U Sure you have a 4 speed. The last thing you feel and/or see on the Tach is the lockup clutch engaging (Locking Up). That is why you do not want the transmission locking / un locking, etc as it wears out the lockup clutch.

[Pete Dumbleton]

It's still apples-apples -- You just have a lot of power available to pull a relatively light-weight trailer, so you can use the higher 3.42 ratio and derive some fuel savings.

BTW, f you are going to consistently tow at 70 mph, which is over the sidewall limit of 65mph for ST tires, you should research the notes on higher tire pressures. This would be especially true for high ambient temperatures.

[Dan Meyer]

My wife and I bought an '06 GMC Envoy with the 5.3 liter motor brand-new, and have been pleased with the truck, but not GM or the three dealer's I've taken it to for service and other questions - but thats a topic for another discussion group.

When my wife and I bought it we specifically looked for a V-8 engine and towing package - this included the 3.73 axle ratio. It is a really nice truck, both for towing and commuting to and from work. In the summer I get 18 - 19 MPG, and in the winter MPG is about 3 MPG less. Towing our Scamp we get around 15 MPG at 55 MPH, and 1 MPG less for every 5 MPH higher speed. It has towed our Scamp 16 without any issues of any kind in all kinds of weather and terrain.

If you have any questions about your Trailblazer, join the folks at www.trailvoy.com. They are not quite as 'polished' as the nice folks here, but I have found a lot of good information about my truck on the site.

-- Dan Meyer

[Chris Z]

Darwin
I copied and pasted my spec's above right off the electronic sticker I have.
I realize what the tow button does but I just don't need it.
I do have D rated Khumo tires now also.
Strange..... I had all kinds of problems with the 14' Marathons on the Casita but the 13" tires on my 16' Scamp were great. Before I knew any better, I returned out from "Out west" at 85-90 mph with that Scamp just to keep up with the traffic. Maybe I should just count my blessings! Never had a trailer before and no manuals and didn't find these forums until after.

[CD Smith]

You are right about the V8 that you have and the rear end. Enough HP to tow without problems.

If you use the tow button it will keep the transmission in the lower gears just a little longer B4 it shifts. This allows you to do quicker starts and get up to speed sooner. Once it is up to speed it is the same as not having it on at all. I'm not sure if it keeps the lockup clutch from locking up.

R U Sure you have a 4 speed. The last thing you feel and/or see on the Tach is the lockup clutch engaging (Locking Up). That is why you do not want the transmission locking / un locking, etc as it wears out the lockup clutch.

He is right about the four speed transmission. It is the standard light duty 4L60E (used in all GM light duty trucks and SUVs). The "locking up" you refer to is the Torque Converter Clutch (TCC). It has a gear ratio of 0.7 and could be refered to as a 5th gear.

I have modified the electronic transmission controls to prevent the TCC/4-3 downshift until I maunaly (switchs/relays) command them. I find that it improves MPG about 1.5 to 2 MPG when towing. I also consistently get 16.5 MPG while not towing around town and 20 MPG not towing on the Iinterstate.

[Rick kl]

[
If you have any questions about your Trailblazer, join the folks at www.trailvoy.com. They are not quite as 'polished' as the nice folks here, but I have found a lot of good information about my truck on the site.

-- Dan Meyer
[/quote]

by shear coincedence I joined this forum a few hours before reading your post, there is a lot of information to be gained about this breed of tugs