Gear change=better gas mileage???

Chad H · February 29, 2004

Hey guys,

I was wondering if swapping to 4.10's would maybe help my highway mileage since it would keep the truck in the powerband? Has anybody had any experience with this?

Mule · March 1, 2004

Hi Chad,

When I switched to the 4:56s (with the bigger tires), my gas milage increased a lot around town and it seems some on the highway. You will be at a higher RPM, but it is an RPM that is more efficient. The engine is not lugging at too low of an RPM.

It seems that the engine is working less to get moving at city speeds and working more smoothly on the highway, especially if the highway has hills.

superbee · March 1, 2004

The answer is: it depends. What kind of terrain do you usually drive on? The simple answer is this: If you drive on I-80 across Nebraska daily, 4.10's won't help, they will hurt. If you drive mostly city anywhere, they will help. If you live where I do (western PA, VERY hilly), they will definitly help. A good rule of thumb is: If your vehicle won't stay in top gear (OD) in almost every normal highway driving situation, you don't have enough gear (numbers too low). I pull a trailer with the Burban from Pittsburgh PA to Albany NY several times a year. The 6.0L w/ 4.10's

hauls the 5500# load over the Laurel and Appalachian mountains in OD 98%+ of the time, getting about 11.9 mpg @ 75mph. Not too shabby. Consider this, a hill is a the same as pulling a trailer, how big the hills (trailers) are should decide your gears. Hope this rambling makes some kind off sense.

Superbee

firecadet613 · March 1, 2004

My Blazer has 3.42's, I'd kill for 4.10s. Any idea how much I'd be out for the swap. Sorry to take your thread OT kinda Flowdine, nice truck again man!

Joe

superbee · March 1, 2004

You could be looking at $1500 or so. It really depends, this could cost as much as 3k. Get some quotes and shop for parts prices on your own.

Superbee

Durkin · March 2, 2004

Folks:

The Z71 likely has 3:73's front and rear. Discussions with Drivetraindirect http://www.drivetraindirect.com/html2/dtdf...framehome3.html indicates that aswitch to 4:10 will not show much improvement, and 4:56 is their recommendation. But you could use 4:27s.

Gears, for both differentials, Eaton posi and installation are less than $1,600 from them.

Hope this helps!

Regards,

Durkin

Mule · March 2, 2004

I went with the 4:56s because I was told the same thing, then punched some numbers in a calculator and looked at an RPM chart. Just not $1500-2000 worth of change from 3:73 to 4:10 for me.

GM GIMP · March 3, 2004

My Blazer has 3.42's, I'd kill for 4.10s. Any idea how much I'd be out for the swap. Sorry to take your thread OT kinda Flowdine, nice truck again man!

Joe

My '96 Tahoe 4x4 came with 3.42's. I changed to 4.10's to help with towing.

I did the work myself. Both gearsets cost me total about $500 including

shims and oil. My mileage didn't seem to change, but the power felt

much better.