3.73 Or 4.10

mbriddle · January 31, 2008

Hello all. New to the site here.

I am looking into buying a new GMC CC Z71 4x4 5.3. It appears through initial research that I have the option of either 3.73 or 4.10 gear ratios. I don't plan on towing much nor am I interested in racing anybody off the line. I am looking for all around utility, sportyness, and economy. I do not plan on building a Monster Truck nor putting on huge rims. I do plan on putting on slightly larger tires using stock rims, a leveling kit and/or very mild lift. My question is should I consider the 4.10's knowing that larger tires will drop that ratio down. I haven't done the math so I don't know how much a larger tire would affect the overall gear ratio.

thanks for your input.

mark

born-to-fish- · January 31, 2008

Hello all. New to the site here.

I don't plan on towing much nor am I interested in racing anybody off the line. I am looking for all around utility, sportyness, and economy. I do not plan on building a Monster Truck nor putting on huge rims. I do plan on putting on slightly larger tires using stock rims, a leveling kit and/or very mild lift.

The 3.73 gears would be adequate, will give you better highway mileage, and according to your post, you don't plan on going all out with this rig so that's what I would recommend.

PS. Welcome aboard

Cheers,

Kev

Zembonez · January 31, 2008

3.73s are perfect for what you want. 4.10s mean everything is turning faster, making more noise, and wearing faster.... at least a little bit. People in here don't seem to be getting any different mileage using either one though. Looks like most of us are getting 14 - 16 mpg. Just don't go in believing that 20 mpg stuff and you won't be disappointed with your excellent truck purchase.

Montana Bronco · January 31, 2008

Get the 4.10's.

I did and I am glad.

Especially if you are getting bigger tires. 4.10's with 285 tires will have approximately the same driveablity as a 3.73 with 265 tires.

Get the 4.10's....

VMax2007 · January 31, 2008

Get the 4.10's.

I did and I am glad.

Especially if you are getting bigger tires. 4.10's with 285 tires will have approximately the same driveablity as a 3.73 with 265 tires.

Get the 4.10's....

+1

I am getting 325/60-18's (32.9" dia) Nittos and I now wish I had the 4.10's.

ws6_guy · January 31, 2008

3.73 sounds like what you need

pm26 · January 31, 2008

4.10's with 285 tires will have approximately the same driveablity as a 3.73 with 265 tires.

Not exactly. The effective gear ratio will be decreased by about 3.5 %, which means that with original 4.10 gears you will have an equivalent of about 3.95 gears with bigger tires. You would have to go to something like 305/70 tires to drop to 3.73 effective gear ratio.

mbriddle · February 2, 2008

After doing the math, the effective gear ratio of a 285/70R17 tire with 4.10 is essentially a 3.96 ratio as compared to a stock 265/70R17 wtih 3.73's. Much like the previous poster had come up with. I've done some research on other boards and the Tahoe guys are saying that they get the same milage with 4.10's. Their reasoning is that the engine revs about 200 rpm's higher, thus reducing the load and allowing the engine to stay in V4 mode longer. This is still a dillema for me. I know that I will be going to bigger tires eventually, but not sure how big. Again I am looking for a compromise between milage and sportyness. Not a sled or hot rod.

Now for the stupid question. I assume they match the front diff to the rear. I am not sure if these trucks lock the center diff or not. I currently drive a 4Runner and it doesn't have a center diff at all. I can't put it 4WD on any type of solid surface or it binds up.

Mark

jhoff8487 · February 2, 2008

Now for the stupid question. I assume they match the front diff to the rear. I am not sure if these trucks lock the center diff or not. I currently drive a 4Runner and it doesn't have a center diff at all. I can't put it 4WD on any type of solid surface or it binds up.

These trucks have no center differentials so it'll bind up the same as your 4Runner does.

flatlander · February 3, 2008

I have the 4.10 gears with the 17" tires and 4.8 engine (3.73 was not offered with the 4.8 in 2006) and also had a 2003 with the 16" tires & 3.73 gears. Although the larger diameter tires somewhat offset the effect of the 4.10 gears the 2006 Silverado turns a higher RPM at any given speed than the 2003 truck and I wish I had the 3.73's. There are a number of websites that do the math for you so maybe you could Google gear ratios to find one of them. The websites made it easy as you just enter the tire size, gear ratio, and then because the 4 speed transmission is an overdrive you must enter the overdrive factor (.70, .73, or whatever it is). As I recall there is about a 150-200 rpm difference between the 3.73 & 4.10 at 65-70mph, it is not as much as you might think. Am now looking for a new pickup and will definately go with the 3.73 gears. Have heard that those with the 3.72 gears face constant up & down shifting even on the slightest inclines but have had no experience with the 3.42's.

svensk · February 3, 2008

Looks like my larger than stock 265/75/16 tires at 31.6" drops my 3.73 gears to 3.58 effective ratio.

jhoff8487 · February 3, 2008

I've got 3.42 gears in my truck. I wish I had the 3.73s but they weren't offered in 06' and I couldn't really find any with 4.10s in my price range and in my area. Really, the performance with the 3.42s is plenty. Had I not known they were 3.42s and that there were 3.73s or 4.10s out there I'd have no complaints. Even knowing they're out there, I've got no complaints. I haul a couple loads of mulch, some branches, some lumber, whatever and tow a pontoon boat on occasion with 0 problems. As far as the upshifting and downshifting constantly, I haven't really experienced that but we're pretty flat in Indiana. There are a few times it downshifts and I wonder if it would have if I had 3.73s but really, it's pretty rare.