mshaw130

Ive got a 2005 chevrolet silverado 1500 z71 with a 6 inch skyjacker suspension lift. Im running 35x12.5x17 bfg mud terrain km2's. Ive been told that I should change my gearing around. I dont know much about gearing or what I should change too. I havent touched any of the gearing or messed around with it and im still running the stock gearing. How does it all work, any suggestions on what to do???

country_09

call rons machine shop...they have great deals on everything. you're gonna want to change the fronts and back with 4.56s. That will get you around stock gearing, a little over actually for the tire size, lack of aerodynamics, and added weight for the lift. Also take out the g80 limited slip and get a tru-trac. The whole thing is gonna cost around 1000 for just parts, then around 300 for install on each axle


the list of things:

4.56s front and back
yukon master install kit front and back
tru-trac

mshaw130

that seems a bit expensive. most of the people i know who have done gear changes havent gone close to that in price. im not looking for anything crazy, 456 is a pretty serious change in gearing from 373 also. what is a tru trac?

country_09

you're rollin 3.73s with 35. Those 3.73s performed at peak with the stock 265s that were on there. So with the added weight and size of the tires, you'll need a lower gear. If you were to do the math, a 4.27 gear would get you back to what stock gearing would be like, but you'll want a little more due to the weight of the lift, heavier tires, and less aerodynamics. A tru-trac is a limited slip made by detroit that doesn't have clutches like the stock g80, so it never wears out. Just smooth operation all the time.

And most people probably didn't upgrade the rear diff or were 2wd(being 4wd you have to have the fronts done as well), which is the most expensive part, but probably one of the most vital parts of doin the gear swap. The g80 diff is a tickin time bomb. So why pay for a gear swap and not swap the diff out, have a little fun with the new gears, and blow up the diff only to have to redo the gearin in the rear end because you didn't do it the first time?

So as far as gearing, you could do 4.10s, but it wouldn't be worth the swap because there isn't that much difference between them and the 3.73s you have now. Also there's a 4.30 gear by motive, but they're the only ones who make that size, so they charge out the *** for em. A 4.56 gear will get you back to that stock feelin with 35s. For my 35s, i'm regearin to 4.88s because I live in a small town and do 80/20 city hwy under 60 mph about 90% of the time. So 4.88s will give me more power from stoplight to stoplight, makin my engine work less so i'd be usin less gas. On hwy trips, it'll probably use a little more due to higher rpms, but don't forget that the 2000 and up 4.8/5.3's love the rpms. They operate better at a higher rpm because they're not struggling to keep speeds up. Lower rpm doesn't always mean better gas mileage. You're engine has to work harder to get it up to speed, and keep it there. A lower gear also helps save your trans because it has to work harder to get up to speed and keep it there. Every notice that when you go over an overpass, you have to put more pedal to keep the same speed, causin you do downshift? Eventually, that'll cause your tranny to get to hot and give out on you, causin you to replace the trans as well. Do it right the first time, and you won't have to look back

Gundog

You really want to listen to country-09, he is right on the money.