4.10 vs 3.73 gears?

[mic1hael]

This is probably a stupid question but which one is better or does it make a difference? I just thought it might spark a nice debate. If it does please be nice.

[chris199]

I believe the higher the number the better the towing capability of the tow vehicle. I believe my Tundra has a gear ratio of 4.3 which is outstanding. (2012 Tundra, 5.7L, V8, Double Cab, with tow package, approx 10,000 lb tow capacity using new method of calculating).

[SAD]

Originally Posted by mic1hael

This is probably a stupid question but which one is better or does it make a difference? I just thought it might spark a nice debate. If it does please be nice.

Better is hard to define.

All else being equal, the lower geared vehicle (higher numerical rear end ratio) will spin up RPMs faster and have a higher cursing RPM than the identical truck (transmission, tire size) that is geared higher (lower numerical rear end ratio).

When comparing those two exactly equipped vehicles, the lower geared vehicle will have a better launch from a dead stop. And will be less likely to loose speed on a hill or drop a gear.

When comparing different vehicles, there is minimal value in looking at the rear end ratio..

For example, say you have a gas V8 3500/350 with 3.42 gears and are trying to compare it to a 5.7 V8 Tundra with the 4.30 gear set... At first it seems that the Tundra has the leverage advantage.. But it may not.

Assume (hypothetical) the 1 Ton has 30" overall diameter tires and a manual transmission with a 6.7:1 first gear ratio.... And a 0.79 6th overdrive (with direct 1:1) being 5th...

And the Tundra has 33" overall diameter tires (less revolutions per mile = less leverage).. Assume the Tundra auto has a 3.5:1 first gear... And a 0.50 overdrive (6th) and a 0.69 overdrive (5th) with the direct (1:1) gear in 4th.

Both above vehicles would move/pull your average travel trailer just fine due to similar power.. But because of the larger tire of the Tundra, the engine may not be in the power band as much.. And would likely do a lot more shifting... And in hilly terrain, the launch would be a lot harder on the tranny.

So it would stand to reason that putting a 4.30 or 4.54 in the 1 ton example would be 'better'?? Based upon the tire size and transmission ratios, it would likely spin up too fast... Shifting to 4th gear before making it across an intersection.... And if spinning at 2100 rpm at 65 mph with the 3.42 rear end, with the 4.30/4.56, it would likely be closer to 2800 - unpleasant and very little room to downshift for a hill.

The ratios are of course hypothetical, because I haven't researched the Tundra transmissions.. But hopefully you can see how simply looking at the rear end ratio isn't enough. And when talking about different vehicles, the 'better' ratio may not be what you think.

This may be an example that more at the extreme end, but it's good to understand how all the three pieces fit together.

[Jay D]

Should be better fuel mileage with the 3.73's then the 4.10's.

[christopherglenn]

Back in the days of three speed trannys, the rear end ratio was more important. Now with 6 speed trannys being everywhere, the rear end ratio os more of a off the line thing. If you oversize the tires, you can get shorter gears (larger numbers) to offset the increased leverage from the tires. My Duramax can tow in 4th, 5th, or 6th gear at 60. When there is not enough power, I can drop a gear and still have decent empty mpg's with a 3.73. Most of what I would gain towing with a 4.10 I can do by locking out 6th gear.

[SAABDOCTOR]

Well sad that was well written. Now he is conffused! the taller ratio is usually better for towing but drive one with the diff you are thinking of buying and see if the engine reves too high and drives you nuts. i had 2 dodge diesels same everything except rear ends and the higer one numaricly 4.10:1 really did not run the rpm up that much but it pulls stronger on the hills. so it really boils down to what you can deal with better fuel econ and more shifting plus a slower pull up the long hills or a little less milage and more power up the hills your choice no wrong answer. enjoy

[mhs4771]

With a GM Diesel the only thing you're going to get is 3.73s from the Factory unless you change them yourself.

[Englishman]

With a 2011 Chevy 2500 HD Silverado it makes a big difference in the amount you can tow. 3.73 has a max of 9600 with the 4.10 it increase to 13500 but the mileage drops.

[SAABDOCTOR]

Well if your going to change the chevy gears and it 4wd make sure you do the front axle too! I know it's almost an insult to post this but I have seen it happen and oh boy shift on the fly 4wd... if you do get it engaged hello windshield. both diffs must be the same ratio.

[mhs4771]

Yep, forgot to add that tidbit about 4x4s or 6x6s. Now GM may have changed their info, but as I posted earlier, the last I knew for a 2500 ro 3500 the only gears were the 3.73s if you got the Duramax/Allison combo unless you went with a 4500 or larger.

[therink]

Originally Posted by Englishman

With a 2011 Chevy 2500 HD Silverado it makes a big difference in the amount you can tow. 3.73 has a max of 9600 with the 4.10 it increase to 13500 but the mileage drops.

X2-If going with GM gasser and ever plan to tow over 9000 lbs, go with the 4:10. The fuel milage diff not towing is minimal.
Steve

[Englishman]

We pickup a Chevy 2011 2500 with 4.10 on the second attempt the first truck the dealer gave us was 3.73 lucky we spotted it with in an hour of getting it home
they then shopped round and found the correct truck that was request at the time of purchase. make sure you check the window sticker a couple of times as this is the only place that its listed.

[Laredo291OH]

I don't understand the huge difference in towing capacity on the GM gasser's between the 4.10 and 3.73. The trucks are identical except for the rear gear. The trucks have to be able to pull the same amount, starts just wouldn't be as quick, I can't believe it makes a huge difference in pulling hills either, might just drop down a gear on the tranny.

[therink]

4:10 very hard to find, hence I factory ordered my last 2 trucks with it. $150 option.

[Englishman]

I get better mileage with my 2500 6L 4.10 then i did with my F150 5.4L pull a smaller trailer. The F150 with Tonneau cover pulling Hi-Lo less then 4000 was getting around 8 miles to the gallon. The 2500 pulling the bullet up to 6500 get 9 without a cover and just over 10 with Tonneau cover.