Axle Ratio Change

[CapitalTruck]

If I changed the rear end would I have to change the front? For some reason I never thought of that. Is that correct? (it is 4wd)

[PH-Wolf]

 

If I changed the rear end would I have to change the front? For some reason I never thought of that. Is that correct? (it is 4wd)

YES! you need to change the front or when you engage 4 wheel drive your front and rear wheel will be turning at different speeds. You'll blow the T-case or break something else in the drive train at the very least. You have to change both front and rear diff gear ratios.

[CapitalTruck]

Upon further thought you are clearly correct. Yikes, that is major $$. I guess we'll be sticking with.3.42s!

[PH-Wolf]

Upon further thought you are clearly correct. Yikes, that is major $$. I guess we'll be sticking with.3.42s!

Yes your better off staying with the Stock 3.42's you have now. Going from 3.42's to 3.73's and with all the torque management these trucks have. You'll hardly notice the difference and be a waste of money IMO.

[pm26]

With lower axle gearing, your truck will gain proportionally more torque at the rear wheels and this means easier moving from a standing start, especially if you are towing something. I wish I had got 4.10s on my truck. I do OK with the 3.73's but for heavier towing 4.10 ratio would be better. As mentioned, lower gearing will mean somewhat lower fuel economy when cruising on an open road, but you will likely get better mileage in town in stop and go traffic and definitely better mileage when towing.

[nakedicarus]

My truck has 4.10 gears and I've never been able to get over 12mpg city. What am I doing wrong?

[Badass69]

ppl are saying going from a 3.42- 3.73 will lower your fuel mileage. I disagree. I think an engine working below its powerband will need to work much harder to maintain speed especially under load, or in wind, hills, etc. In a test cell, or a controlled environment that may be the case, but in the real world, I think putting a higher gear (like a 3.73 or a 4.10) would make your vehicle burn less fuel, due to not working as hard, and also accelerating easier. For someone like me, who drives 50-60% city, better acceleration would really benefit me. I get as low as 10-12mpg in town. At $4.60 a gallon, that's a lotta $dough$

If I could increase my trucks torque being transmitted to the wheels by say 15% AND maintain or gain fuel economy, I would. My 11 will be getting 4.10's, as soon as the warrantee is up, or I have to buy my next set of tires! (I just bought new Duratracs this year, so around the 100,000km mark I should need tires.)

 

I respectfully disagree with the above statement, the higher the rpm's the harder the engine is working, therefore the more gasoline the vehicle uses.

 

With Sara (2001 Z28) with the stock rear end gearing (3.23:1) I was turning 2400 RPM's doing 82 mph.

 

With the 3.73:1 rear end gears I am turning 2800 RPM's doing 82 mph.

 

JMHO

Weight and aerodynamics have a tremendous effect on this. What you get away with in a 3500 lb Camaro is like comparing a pickup truck to a bicycle. ... If low rpm was all that we would all have 3.08's with 35" tires. You have to find the medium of a vehicle with the lowest load on the engine while matching the engines torque range.

 

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[Gurrzt]

Weight and aerodynamics have a tremendous effect on this. What you get away with in a 3500 lb Camaro is like comparing a pickup truck to a bicycle. ... If low rpm was all that we would all have 3.08's with 35" tires. You have to find the medium of a vehicle with the lowest load on the engine while matching the engines torque range.

 

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Point well taken.

[PH-Wolf]

It all depends on what the trucks used for on what gear ratio will give the most benefit to that application. For me for example: my 2011 Silverado is my daily driver spends most of it's time on the Hi-Way and back country roads. I see little stop and go and will never tow anything with this truck. The only thing this truck hauls fits in the bed. I wanted 3.23 gearing to keep the RPM down at highway speeds. I'll gladly give up a bit in acceleration for better fuel economy. I only turn about 1,600 RPM at 65 mph. I drive with a light foot and baby the heck out of it. keeping the shift points around 2,000 rpm, drive the speed limits mostly and regularly get over 20 mpg. Bought her brand new and my truck has never seen red line nor have I gone over 3,500 rpm ever and I now have approx. 62,700 miles on her. Yesterday I did a 650 mile round trip and averaged 23.00 mpg even, not bad for the 'ol 4.3L V6 and 4L60E trans.

 

My 2006 2500HD with the Duramax and Allison only came with 3.73's and I tow both "bumper pull" and "goose neck" trailers. With the 605 lbs-ft of torque and the 6-Speed 3.73 are a good combination. at hi-way speeds the engine is near it's peek torque in the RPM band which in diesels is the most efficient.