Question - Axle Ratios

[diesel]

I am purchasing a new Chevy Crew Cab 1500 with 5.3L and am on the fence a bit about axle ratio's. Most driving will not involve pulling much but weekends I will be pulling a 17' Lund Pro Angler and gear or 2 to 3 snowmobiles. I'm curious what others would do given the option of a 3.42 versus 3.73 axle ratio?

Does anyone know what the difference in gas milage would be given regular daily driving between these two?

Thanks!

[Gissert]

It all comes down to how much you are going to be pulling for the most part.

When I bought my Dodge (Cummins 5.9 diesel) I had the choice of 3.54 or 4.11 gears. Since I run unloaded most of the time, I went with the 3.54 ratio and have never regretted it. This includes some pretty heavy tows through the Rockies. I have a six speed manual transmission.

You will get better milage with the 3.42, but it should not be a huge difference from the 3.73.

What kind of transmission are you getting?

[crappace]

If you are going to leave your tires the stock size then the 3.42s sound fine. I put larger tires on a dodge with 3.55s in it and it was a dog. The MPG was bad too. With the bigger more aggressive tires the 3.72s would have been much better for me.

[diesel]

Gissert:

I am going with an automatic transmission. What would your guess be on the gas milage difference? Are we talking maybe 1 MPG difference?

Thanks!

[WaveWacker]

Without a doubt go with the 3.73. I have a 4.10 in mine and get close to 18mpg on the highway and average around 13-14mpg when towing my 1775 pro V.

[caster]

Don't forget to consider the tire size. If you go with the 265 option, I don't think you will be happy with the 342 gear ratio. I have a Chevy extended cab with 373 gears and the factory 265 tire option. I have a 16 1/2' Alumicraft side console with a 75 four stroke that I can pull in overdrive on the freeway. My two-place enclosed aluminum snowmobile trailer usually requires me to drive in Drive (3rd gear) especially if there is a headwind or a lot of hills. I hope this information helps.

[diesel]

Thanks! I am leaning towards the 3.73, just need a push!

[jwhjr]

I also have the 3.73 in my 04 with the 265 tires. No issues towing, and I consistently get 18-19 mpg to and from work.

[Gissert]

Not really sure how much the MPG difference would be. Mu guess is it would not be all that much.

With a gasoline engine/auto tranny, I would go for the 3.73 personally.

[diesel]

Thanks for the help. I think I'll stick with my initial thought of the 3.73.

Now I need to sell a 1996 Chevy Diesel 1500 & a 2004 VW Diesel Jetta which gets 48 MPG. I am going to miss that!

Thanks again!

[caseymcq]

I think you will be fine with either gear ratio. I have a 2004 with 3.73's and I am very happy with it. One piece of advice I would offer is that no matter which you go with, get the locking rear differential. It will make a big difference in both 2 and 4 wheel drive. To have both back tires spinning will help in low traction situations.

[Capt. H (Ret.)]

Okay here we go!!

In your post you didn't say if you are buying a new 2007 or a hold over 2006. I recently went on the hunt for a used Chevrolet Tahoe with the 5.3 liter V-8 and found out that the 3.73 rear end was not offered in 2005 or 2006 four wheel drive Tahoe or pick-up truck. It was available in 2 wheel drive. I purchased a 2005 with the 3.42 rear end but was concerned about pulling a boat. What I found out was that as long as you drive with your foot and not with the cruise control the transmission does not seem to shift up and down too much. It does shift but the rpm's don't jump that much. I like the 3.73 for towing because for the most part I can use the cruise control most of the time. I needed to buy a 2005 or 2006 Tahoe because my Otter Lodge fish house won't fit in the back of a 2007 Tahoe.

As far as gas mileage is concerned, with everything stock I found the 3.42 better when I am not towing (18 mpg) and about 2 miles per gallon better (14 mpg) when towing. I am not your average "tow it to the lake which is 15 miles away guy", I tow to Texas (850 miles one way) twice a year.

What ever you do, make sure you get the tow package for your vehicle.

Good Luck.

[caseymcq]

Quote:

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... What ever you do, make sure you get the tow package for your vehicle.

Good Luck.

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Capt. H made an excellent point that I forgot to mention. That two package comes with the reciever hitch, trans cooler, etc. You definately want to get that too.

[crappace]

Quote:

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Now I need to sell a 1996 Chevy Diesel 1500 & a 2004 VW Diesel Jetta which gets 48 MPG. I am going to miss that!

Thanks again!

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You had a 1/2 ton 1996 Chevy with a Diesel in it???

[Gissert]

Chevy did have half tons with the 6.5 for a while.

[JohnMickish]

Chevy had half tons with diesels (6.2L) dating back to the early 80's.

If I where you I'd get the 3.73's and not even think about anything else.

[Valv]

I would also go with 3:73. it's avery good compromise.

If you get a 3:55 you will moss many chances to tow something bigger (you never know), add larger tires, do some mods to truck.

Your mileage will drop more then 1mpg empty but I believe it will be same if you are towing if not better.

Definitely add a transmission cooler, and even if many will consider it not necessary as transmission temperature gauge, you will learn A LOT how it is doing while you drive.

Now, I will square it off with Rick for this but email me about your 1500 with diesel.

[IFallsRon]

Chevy had a diesel Chevette, too.

As a point of information for future posters, please explain why there are different ratios and how one would determine what a particular vehicle has.

[Try Too Fish]

I have a ford diesel with auto trany and 373 rear end. If i buy again i will buy the 4 11's. The reason is I pull a fifth wheel camper with a boat behind that sometimes. And at the 55 to 60 mph speedlimit the auto does not like to stay in overdrive! When it shifts out of overdrive the RPMS go up and the Economy goes down. With 4 11's it should hold in overdrive better,Keeping the rpms down and the economy higher!

Ifalls

The rear end ratio is usually printed on the stickers on the door posts or glovebox!

[upnorth]

Hmmmm.....ever thought of taking it out of overdrive when towing a heavy load and saving your tranny?

[huntingislife]

My dad had 3.42 in his gmc with a 5 spd. I raced motocross for quite a few years and we pulled my 16' enclosed trailer with that everywhere each weekend. Downshifting out of overdive was quite common. His new truck had 3.73's and we just set it on cruise and went. The mileage difference was minimal if any. So I would say definitely go with 3.73's.

[Try Too Fish]

Upnorth

The tranny temp is always low no matter where the shifter is. Heat is what kills auto trannies, keep em cool and your fine.

It takes a bigger way bigger load than my fifth camper to raise the tran temp. Like a 26 foot fifth full of cattle. Then you stay out of OD.

Nothing is being abused!! Just wanting to improve the economy! And i beleive 4:10's would!

Also when I run in SD and speed limit is higher shifting out of Od is not a problem.

The root of the problem is that with 3:73'S @ 55 to 60 mph

The auto shift point is right there causing the trany to never decide where it wants to be. 4:10's will change that shift point.

[Valv]

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U

It takes a bigger way bigger load than my fifth camper to raise the tran temp. Like a 26 foot fifth full of cattle. Then you stay out of OD.

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Do you have a temp gauge for your transmission ? You will be surprised the temperature it reaches while towing, going empty or especially going in reverse, it doesn't take a load of cattle for it.

[Try Too Fish]

Do you have a temp gauge for your transmission ? You will be surprised the temperature it reaches while towing, going empty or especially going in reverse, it doesn't take a load of cattle for it.

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Yes I do! Ford F350's With a Lariat pkg. Its Standard! I dont Know how many years it was, but was in 2002! It does not read in Degrees. But Has the red warning area when too hot. I do not disagree that the temps may be high ,but do not get even near the warning level with my camper. Cattle trailer different deal. Probably the extra 20K in weight!!

[upnorth]

Try To Fish, that is advice that I got from a Transmsission expert when I was having a transmission rebuilt. He said the only time you want to use OD with any vehicle is when it is pretty much unloaded. And this a guy trying to help keep vehicles out of his shop.