which axle ratio to pick for new Chevy silverado?

[tic]

We are going to get a 2007 Chevy 1/2 ton silverado, 6.0 liter V-8, max tow package.. etc. etc. There are two axle ratios available..The 3.73 will tow 8,500lbs and the 4.10 will tow 10,500... Both trucks are EPA rated for 15/19mpg????.. I would think the 4.10 axles would make the truck run at higher RPM and worsen fuel economy.. I have driven the 4.10 axle but not a 3.73 however the dealership says they can get one... We still haven't picked the new boat but it will be in the 22-25 foot range, Cuddy or small sport cruiser probably weighing 5000-6000 lbs.dry max... Would I be better off with the 4.10 axle and a better margain for max towing weight?.. Or should I pick the 3.73 axle and go for the quieter ride, reduced rpm and hopefully slightly better mileage....

 

[JB]

Re: which axle ratio to pick for new Chevy silverado?

4.10.

By the time the boat is loaded for launch it will weigh near 7,000lb.

Conventional safety margin says limit tows to 70% of tow rating. That would mean a truck rated for 10KLB.

 

[Silvertip]

Re: which axle ratio to pick for new Chevy silverado?

The next question is how big are the tires you are ordering and do you plan to put on aftermarket wheels and larger tires after to take delivery. If you do, by all means go with the 4.10. In fact my recommendation is go with the 4.10 anyway. The larger diameter tires you install, the more you take away from the axle ratio. In other words, increasing tire circumference by 5% takes 5% away from the axle ratio.

As for higher RPM, that is not a problem as the engine is loafing at 65 MPH as it is. I have an S10 CrewCab with 3.73 gears and at 70 MPH it runs at 2100 RPM. Your truck with much bigger tires and the same gears will be in the 1800 - 1900 RPM range. 10% increase in axle ratio raises rpm 180 - 190 RPM which is insignificant and which is why fuel economy will likely be no different with the 4.10 than the 3.73. In fact driven properly, the 4.1 may actually perform better because the tranny will be a tad less busy in windy/hilly/towing scenarios. I feel the 4.10 is the best choice. Put another way -- it takes a lot of horsepower to make up for a bad choice in axle ratio. Expect 15 MPH average unless you know how to out-drive cruise control. What I mean is cruise controls can't anticipate a hill. When approaching a hill if you simply add a little gas pedal as you enter the hill, you can often prevent converter unlocking. If you simply let the cruise do the driving it adds throttle as the truck loses speed but it is too far into the hill before it knows its losing speed and therefore has to sort of "over react". What the 10% relates to in towing ability I can atest to. My fishing buddy also has an S10 Crew Cab but his has a 3.42 axle. We have nearly identical boats. I can tow in OD with the air on and he cannot. That provides 2.5 MPG fuel savings. I get 17 - 17.5 He gets 15. Not towing we both get 21 MPG.

 

[Rob454]

Re: which axle ratio to pick for new Chevy silverado?

4.10.


Conventional safety margin says limit tows to 70% of tow rating. .

BS on that. Ive taken all my work trucks and towed the max rating and I never had a problem. ive towed 10 000 pound generators, bob cats etc. I dont buy trucks so i can tow 70% of the tow rating.


As for the gear question unless you have this truck STRICTLY as a tow vehicle get the 3.73s your wallet will thank you. Figure your average towing will be 10-15% of your trucks use probably more like 7% ( unless you go around with your boat hooked to the truck) your drives will be unloaded without your boat. the 4.10s will give you crappier gas mileage.

Now if you plan on adding bigger tires ( always a plus when towing ( sarcastic) then get the 4.10s depending on the height of the tires you will actually be changing your final drive ratios
but if you plan on running stock size tires then you dont need to worry abotu what I said.
The gears wont do anythign for a quieter ride. Lets say youre not happy with the 3.73s you can always go install 4.10 gears. Believe it or not the gas mileage savings could be up to 2 miles per gallon. I recently swapped down from 4.56 to 4.10s and its a 2.5 MPG difference in savings on a dodge dually I have as a work truck.

 

[Reel Poor]

Re: which axle ratio to pick for new Chevy silverado?

I agree with Rob. If you will be driving the truck as a driver and the using it to tow a boat to the boat ramp get the 3.73. You might opt for a limited slip differential instead of the 4.11. You won't regret it.

 

[Silvertip]

Re: which axle ratio to pick for new Chevy silverado?

70 - 75% of rated tow limits is a very valid "safety" suggestion -- "for recreational trailering". Work trucks are a very different situation but the safety issue does not go away because one is driving a "work truck". Nearly every day we see accidents involving "work trucks" which are caused by inexperienced drivers who think they are truck drivers. Granted, chances are they drive the same way in the family car. I've seen so many work trucks towing bobcats involved in accidents that I get the willy's just being around them on a freeway. There is also an issue with towing that is not discussed much and that involves manifold vacuum. High throttle settings results in very low manifold vacuum and while I don't remember the number, I believe continuous loading that results in anything under 5 or 6 inches of mercury can cause engine damage. There is also a post in this forum about Dodge Hemi's having exhaust problems due to high throttle settings. My points in this discussion are two fold: 1) safety, and 2) longevity for the vehicle. If any vehicle damage will occur, it is more likely to occur because of too low an axle ratio rather to too high. (A 4.1 axle is a higher ratio than a 3.73 so don't confuse higher ratio and higher gear.) As for fuel mileage, under absolutely ideal road conditions (flat, no wind, cool temps) the 3.73 will provide the best economy. Add some wind and the barn door you are pushing through that wind will benefit from the 4.1. When towing, depending on the load you may be able tow in OD rather than direct so you will see better economy than with the 3.73 in direct.

 

[bruceb58]

Re: which axle ratio to pick for new Chevy silverado?

Absolutely no question...I would get the 3.73. It will be fine for the load you are pulling. As far as going up hills, you will be shifting down sooner than you would with the 4.10 ....but so what!

As far as safety goes and comparing the precentage of the max allowable tow rating for this particular vehicle, the only difference bewtween the 3.73 and the 4.10 is the gear ratio. The springs, brakes, frame... are all exactly the same. To say the 4.10 is going to be safer because it has a higher tow rating is not true here.

 

[klicknative]

Re: which axle ratio to pick for new Chevy silverado?

Another thing to consider is the terrain where you live or where you are going most of the time. If it's flat to gently rolling the 3.73's are fine. If you are up in the mountains go with the 4.10's.

 

[tic]

Re: which axle ratio to pick for new Chevy silverado?

Definetly two schools of thought here on axle ratios!... The primary use of the truck will be towing the boat in summer and the snowmobiles in winter. It's a two hour drive to our favorite lake and includes some significant grades. Towing the snowmobiles ALWAYS includes significant grades but the two sleds and trailer weigh less than even our current 16' bowrider and trailer. The truck will most likely become my daily driver as well, but I don't do much driving (less than 7,500mi. a year). Still undecided on the axle ratio but I really appreciate the input from you guys, right now I'd say I'm leaning torwards the 4.1 axles but the decision is keeping me up at night. Spending 40k on a truck and not being happy with the axle ratio would be a real bummer.

 

[Rancherlee]

Re: which axle ratio to pick for new Chevy silverado?

get the 3.73's, 4.10 theroetically give you roughly 9-10% more torque at the tires but not really. As far as the EPA estimated fuel mileage goes the only test ONE gear ratio (whatever the Standard ratio is) and are allowed to use those figures for other "optional" gear ratios. I've done lots and LOTS of towing with an old 88' F150 4x4 with a 170hp Inline six, granny 4 speed, and 3.08 gears and never have an issue pulling a -5000-6000# load. Its slow off the stoplights and I might have to downshift to pull a long grade but it handles the load just fine, A new truck with double the hp and 100# more torque should have NO issues with 3.73 gears. The only thing 4.10's are going to do for you is allow you to eat gas faster by being able to accelerate slightly faster pulling a load.

 

[Bigprairie1]

Re: which axle ratio to pick for new Chevy silverado?

...I'd go for the 3:73's unless you are going to be towing non-stop for a living and up and down a bunch of grades. 4:10's are usually for work trucks only. Make sure you consider what you will be using the truck for most of the time.
I agree with the previous comment regarding the mileage advantage when you aren't towing and this will make your wallet smile at the pumps...at least somewhat.
As for the tow capacity...what it states is what you can safely do. Not 70% of what it states. From an engineering perspective, the manufacturer has already 'built-in' his factor of safety (overbuild characteristics) relative to the brakes, suspension, frame, tires, trans, etc, etc....and it usually probably double what they will give you. Just a like a safety rating on a chain or a hoist. You would probably be surprised at what you could tow with that truck...maybe not all day....but if you had to at some point.
Good luck...it sounds like you are well on your way to a great rig!!

 

[tic]

Re: which axle ratio to pick for new Chevy silverado?

With a 25' boat and trailer I could be close, or even OVER the 8,500 lb. rating with the 3.73 axle ratio when loaded with all the gear and another couple along for the weekend. I realize they engineer these so you won't get into any trouble if you stay at or below the reccomended weight, but I'd rather have a 2500lb. buffer on that weight than be right at it or slightly over it. If for nothing else but peace of mind.. I wish I could test drive both axles with the same engine towing 8500lbs.. No way that's going to happen... I also can't seem to find in any of the Chevy literature if it comes with a class 4 hitch or class 3.. it just says "heavy duty".. I believe a class 4 is needed when towing over 5000 lbs.? I'd think they'd include a class 4 with the max tow package but I can't find where it says it and of course the dealer will tell me what I want to hear.

 

[tommays]

Re: which axle ratio to pick for new Chevy silverado?

They use a weight distribution hitch to get the max weight on the Silverado

Otherwise you have to go aftermarket

Tommays

 

[Sherminator]

Re: which axle ratio to pick for new Chevy silverado?

ive had trucks with the 3.54, and 3.73 rear end, they do everything i need them to do and more, i have a buddy that has a 2004 6.0chevy with the 4.10 and he hates them, says he rapps too many rpms on the highway and it drinks fuel like a mo fo. your new truck will have no problem pulling your toys, more than enough grunt under the hood and the towing package along with the tow haul feature on the A/T the 3.73 WILL DO JUST FINE!!

 

[dingbat]

Re: which axle ratio to pick for new Chevy silverado?

I also can't seem to find in any of the Chevy literature if it comes with a class 4 hitch or class 3.. it just says "heavy duty".. I believe a class 4 is needed when towing over 5000 lbs.? I'd think they'd include a class 4 with the max tow package but I can't find where it says it and of course the dealer will tell me what I want to hear.

If you read between the lines you'll find that anything over #5000 tow weighti (#500 lb tongue weight) requires the use a weight distributing hitch.

A class 4 hitch doesn’t mean a thing if the rear axle is only rated to carry an additional #500 load.

Here is some of the small print from the trailering brochure.

BALL HITCH TRAILERING: There are two types of ball hitches.
A weight-carrying hitch consists of a ball and coupler with no means to distribute the hitch weight. It is used primarily for lightweight trailers. Heavier trailers, however, require a weight distributing hitch, which uses spring bars to transfer some of the hitch weight forward onto the tow vehicle’s front axle and rearward onto the trailer’s axle(s).


RGAWR AND GVWR: Addition of trailer hitch weight cannot cause vehicle weights to exceed Rear Gross Axle Weight Rating(RGAWR) or Gross Vehicle Weight Rating (GVWR). These ratings can be found on the certification label located on the driver door or door frame.

GCWR: The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and trailer. A properly equipped tow vehicle and trailer at the maximum GCWR should be able to accelerate and merge with traffic, climb typical grades at highway speeds, handle the combination on virtually all road surfaces and stop adequately within a reasonable distance

 

[Silvertip]

Re: which axle ratio to pick for new Chevy silverado?

It's the 6.0 that's drinking fuel, not the 4.10 axle. In overdrive at 65 MPH that engine should not be turning more than 2100 RPM give or take a little. Thats barely off idle and hardly "rapping too many revs". My S10 with much smaller tires at 70 MPH in direct is turning only 3100 RPM. Even with 4.10 gears in direct that 6.0 would still be under 3000 rpm. Isn't it ironic that Dodges with the Hemi have a 4.10 axle as the only available axle. Toyota with their 5.8L has a 4.10 standrd and a 4.30 optional. Hmmm -- I wonder why that is. Could it be because it's required for the maximum tow rating. If you want to test this truck with the standard 3.73 axle, take one for a test drive towing one of your friends boats (or any trailer for that matter) as close to the weight yours will be. That's the only way you will know. The tow/haul feature does nothing for towing capacity. It merely alters the transmission shift points so it shifts earlier or later depending on the setting. If you really feel you are going to be approaching the 8500# trailer weight (not GCW) I not only recommend the 4.10 but I strongly recommend it. That's my recommendation and I'm stickin' to it.

 

[bruceb58]

Re: which axle ratio to pick for new Chevy silverado?

Comparing the axle ratios of trucks from different manufacturers is like comparing apples and oranges since the transmission ratio of each manufacturer can and usually is different. The "Total" final ratio is what needs to be compared.

For example, the Toyota Tundra with the 5.7L engine and 6 speed transmission has a 0.588 ration in 6th gear! That gives a final ratio with the 4.3 rear end of 2.53:1.

Bottom line...don't compare the ratios of Toyota or Dodge with what you need to decide on for your Chevrolet truck.

 

[Rancherlee]

Re: which axle ratio to pick for new Chevy silverado?

Not really, when towing a 8500# load ALL the trucks listed should be towing in Direct drive which is 3rd on ford/chevy/dodge and 4th on the toyota Towing 8500# in OD with ANY of these trucks is just asking for the tranny to blow. 8500# I would be looking at a 3/4ton anyhow.

 

[bruceb58]

Re: which axle ratio to pick for new Chevy silverado?

Not really, when towing a 8500# load ALL the trucks listed should be towing in Direct drive which is 3rd on ford/chevy/dodge and 4th on the toyota Towing 8500# in OD with ANY of these trucks is just asking for the tranny to blow. 8500# I would be looking at a 3/4ton anyhow.

Rancherlee,

Please explain how you force a Ford F-150 transmision into 3rd gear with the gear selector! At least on my Ford, you have drive, that allows you to go all the way up to 4th, and 2 and L which forces you into second and first gear respectively.

 

[Silvertip]

Re: which axle ratio to pick for new Chevy silverado?

Bruce -- don't you have an OD "on'off" button on the shift lever. If so, OD off forces third gear.