4.56 gears on the way!

[mudryder18]

I am in the process of getting my gears done, and wanted to know if anyone has put 4.56s in their expys? If so what size tires are you running and what kind of mpgs are you getting. Also what rpms is the engine running around 60-70mph.

 

[tonydiv]

There are a bunch of calculators on the web, but this is the one I always use.

http://www.dakota-truck.net/TIRECALC/tirecalc.html


Let us know your actual results and costs. I'll probably be doing this to my truck this summer.

 

[mudryder18]

Thanks for the website Tony. But it couldnt handle my tire size. I have 355/80/r16 (38.5x14.5x16). The cost for yukon 4.56s front and rear, master install kit for the rear and an upgraded yukon limited slip in the rear was a little under $2250 (labor, shipping, parts, tax). And i will definetly post results once i get them.

 

[Poppa Wheelie]

I got my 4.56 gears done a while back to get more towing power. Stock was 3.31 I think, and the difference is amazing. I am only running 33s now, but with 35s it will be just right.
Of course my speedo is waaaay off now, but at 55 true mph I am turning about 1900 rpm in OD. The increased mechanical advantage lets me tow the weekend warrior in OD most of the time on the freeway, where before I just turned it off.
What is your stock ratio? judging by the way mine behaved with it's "Bonneville salt flats" gearing, your rig must really struggle with those tires. Surprised you haven't broken something