"Gearing 101"

General Lee 01 · December 28, 2001

Ok, so I'm looking at Avalanches online. I see that the 4.10 and the 3.73 gear ratios are the only ones available on the Av. So here's my question.

FFR (For Future Reference), Which is more likely to Spin wheels?

December 28, 2001

The 4.10 will have more snap off the line and put more torque to the ground.

The 3.73 will turn a few less rpms at any given speed than the 4.10.

I have 4.10's in my truck and turn 2500 rpm at 75 mph. (Stock 245 tires)

ryr8828 · December 28, 2001

4.10

Shaners · December 29, 2001

For everyday driving and medium towing you would want the 3.73's. For heavy towing you'd want the 4.10's.

If all you want to do is "burnouts" buy a 2wd and have aftermarket 4.56's put in...

The lower the gearing number the lower the RPM's are at speed and therefore, generally the better the fuel economy.

At highway speeds the difference between 3.73's and 4.10's would be 500-600 rpms.

chevy4x4trucks · December 29, 2001

FFR (For Future Reference), Which is more likely to Spin wheels?

If you want to do burnouts just buy an old camaro or firebird. You don't want to wreck a 40,000 dollar truck doing burnouts.

But, get the 4.10's for some burner power and lots of pictures.

Jpshostr · December 29, 2001

4.10s would be most likely easier to break loose, but the difference in the two is most likely pretty minimal.

General Lee 01 · December 29, 2001

Well, I wasn't meaning I would just do burnouts all the live-long day, just the "occasional" once every blue moon or so.

Just like having the idea of having a truck to use and know I have the power to "smoke em up".

Shane, what if I put 4.56's on a 4x4?

Import Hater · December 29, 2001

I'd imagine an Avalanche 2500 with the 8.1 could light 'em up with either gearset. I have 3.73's in my 2wd, and I just can't get the wheels to spin for a brakestand. Probably for the better anyways...

Rob

Jpshostr · December 29, 2001

Shane, what if I put 4.56's on a 4x4?

You'd have a great time off-road with those, but you'd hate paying to put them in. Plus your butt would be in constant pain since you would kick yourself there everytime you drove down the road.

Don't use tire roasting as a criteria for selecting a vehicle or modifications for something that will be used as a daily driver.

Shaners · December 29, 2001

Shane, what if I put 4.56's on a 4x4?

Break out the wallet if you want to replace both front and rear differentials!!!!

chevy4x4trucks · December 29, 2001

That would only run you about 1200 bucks roughly for a gear swap. You might as well just buy a supercharger.

76BBSub · January 2, 2002

I'd imagine an Avalanche 2500 with the 8.1 could light 'em up with either gearset. I have 3.73's in my 2wd, and I just can't get the wheels to spin for a brakestand. Probably for the better anyways...

Rob

I had a '99 Sierra 5.3 when they first came out...no problem smoking them down with a healthy power brake...you must be doing something wrong!

Not that I would condone such behavior, I'm an adult now...right??? Right guys????

Jeff

P.S. General...at your age, there is nothing wrong with selecting a vehicle based on it's ability to "SMOKUM!!"

doverarjim · January 2, 2002

General, it makes no difference which gear set if you got the ponies under the hood you can make smoke till your broke with enough cubic inches. Has a 74 GMC with a warmed up 454, Turbo 400, 3:07 rear gears and you talk about some smoke that puppy would make a house fire look like a little smoke bomb, but the best thing about it was at the time the harder the tires the more smoke you make, didn't have any radials on it just old bias tires and the cheaper the better. The best set of tires I ever had to make smoke lasted the longest of any paid like $45.00 each for some L60-15's from Mickey Thompson, I learned how to drive on ice with those tires because every time you drove it you thought you were on an icy highway. They would slip and slide all the time.

CMNTMXR81 · January 2, 2002

Hell, with the 8.1 there ISN'T any need to do a brake torque to break the rears loose and do a "burnie"

I've got the 8.1 and 4.10's in mine and all I need to do is blip the throttle to snap them loose.

Generally the higher the gear ratio, the easier it'll be to break them loose. Here's how it happens

3.73:1 means that the input shaft in the rear end housing (and subsequently your driveshaft) will spin approx. 3.73 times to 1 complete turn of the ring gear in the rear/rear wheel.

4.10:1 means that the input shaft in the rear end housing (and subsequently your driveshaft) will spin approx. 4.10 times to 1 complete turn of the ring gear in the rear/rear wheel.

So with that in mind, the input shaft on a 4.10 gear set is twisting .37:1 times faster than a 3.73 at any RPM's.

THis is very similar to riding a 10 speed. First gear you pedal your butt off to move a minimal distance but as you shift down through the gears it gets harder to pedal. That's because as you go through the gears, for every one crank you twist around, the rear wheel goes around once.

Here's an example of what a gear change can do. On my Camaro, it came from the factory with 3.42's stock. Shortly after, I took them out and put in 3.73's. At the drag strip, I drop my 60' times from 2.0 seconds to 1.8-1.9 and dropped three tenths of a second off through the traps because I was able to accelerate more rapidly. As such, now first gear does nothing but smoke the tires off (on street tires) and second gear can leave a nice 20' patch.

Consequently, I lost some top end speed and lost some MPG due to the increased rpm's thorughout the rev band compared to the 3.42's.