Diffirental/Gear Help Please!

DwayneJ · March 11, 2015

RPM has less to do with MPG than folks assume. People think higher MPH cruise hurts MPG because of rpm BUT that neglects the fact it is wind resistance that hurts MPG and that luggin the engine is terrible for MPG.

the_canadian · March 11, 2015

RPM has less to do with MPG than folks assume. People think higher MPH cruise hurts MPG because of rpm BUT that neglects the fact it is wind resistance that hurts MPG and that luggin the engine is terrible for MPG.

Yes but there is also A LOT of other things that come into play for MPG but thats another story of which i dont want to get into right now lol..

So that aside, i think the 4.56s will be what i choose. unless im missing something in which case if i am, some one..please point out!

Could any one explain backlash for installation in detail? I recall it being easy to do with just my self or maybe a buddy to help out, surprisingly enough i actually have the gauge used for measuring the backlash and such but i dont ever remember using it for doing gears..

And when i did gears ( along time ago, surprisingly enough ) i dont recall using it but since i have it i must of used it.

Been out of the mechanical scene for a few years and seems like ive forgotten quite abit of knowledge unfortunately..

DwayneJ · March 11, 2015

I have 3.42s in my truck stock, it moves OK till you drive something geared appropriately.

Often times people are only happy with things because they don't know any better.

If you look on youtube or offroad forums you can find install instructions.

The short version on backlash is you put the tip of the indicator on a ring gear tooth that is near horizontal, hold the pinion steady and rotate the ring gear back and forth to see how much play there is.

Setting up the pattern is harder and I honed out a bearing to use for mocking up the pinion depth and then only install the new one once happy with the shimming. The first few times you do it is is a BIG project but gets easier with experience like anything else. Betting the trucks are a little easier than the cars I have done just due to access.

the_canadian · March 11, 2015

yea sounds about right, i went out an looked at some of my specialty tools i got in my box an i slowly started to remember how it all works again lol. And man im not and old guy just was lucky enough to get a head start early.

I haven't even checked out what my dif is to start getting prices on the trutrac and gears for more accurate.

Also called an old buddy at a shop, worse case its 2grand to install front and rear, if i supply the rings and the trutrac, they supply the rest.

Compared to what else ive seen for quotes i think its pretty fair for a 'worse case' quote. Any thoughts/comments?

seansharley · March 12, 2015

I'm sure you don't want to hear this, but I would save my $$ for other things, 3.73 is a great gear set up. What's the gain going to 4.10's, 2-300 rpm on the highway?

the_canadian · March 12, 2015

I'm sure you don't want to hear this, but I would save my $$ for other things, 3.73 is a great gear set up. What's the gain going to 4.10's, 2-300 rpm on the highway?

I'm going to 4.56.

seansharley · March 12, 2015

Copy that, got some stumps to pull? That's gonna have some serious low end snot to it

the_canadian · March 12, 2015

Ain't nothing wrong with some torque ;)

xXZ-71Xx · March 18, 2015

I have never had a G80 break, As a matter of fact I want to add it to my 99 as it is the best of both worlds...Posi when it needs to be and open when it doesn't.

DwayneJ · March 18, 2015

I'm sure you don't want to hear this, but I would save my $$ for other things, 3.73 is a great gear set up. What's the gain going to 4.10's, 2-300 rpm on the highway?

He is going to larger tires, larger tires affect gearing. He needs to compensate for the tire size change with a gearing change just to maintain current performance and is going a little firter to try and improve.

I have never had a G80 break, As a matter of fact I want to add it to my 99 as it is the best of both worlds...Posi when it needs to be and open when it doesn't.

This goes back to the post I made about people who don't know any better are often happy with things that aren't so good. A decent posi drives well all the time.

You don't seem to know the difference between a posi and a locker, lockers have downsides when not needed and there is some benefit to having one act open at times to mitigate the bad manners. The gov-loc is open till it locks, no posi.

xXZ-71Xx · March 22, 2015

He is going to larger tires, larger tires affect gearing. He needs to compensate for the tire size change with a gearing change just to maintain current performance and is going a little firter to try and improve.

This goes back to the post I made about people who don't know any better are often happy with things that aren't so good. A decent posi drives well all the time.

You don't seem to know the difference between a posi and a locker, lockers have downsides when not needed and there is some benefit to having one act open at times to mitigate the bad manners. The gov-loc is open till it locks, no posi.

I have had many rear ends believe me. Saying posi may have been a mistake but that does not change what I said.It runs open when needed and locks up when needed.Try driving a locker or a LS on icy roads and then drive a open rear, The open rear is the best in those conditions. Now take those three in deep snow and the locker will be the better choice.

DwayneJ · March 22, 2015

Before this truck my choice in daily driver for the preceeding decade was V8 full size rear wheel drive cars(Caprice/Roadmaster) and I live near Green Bay.

I have had open diff. stock car Auburn posi, Eaton aftermarket posi in the cars and now the gov-loc all in the truck. The cars used the 8.5" 10-bolt too.

I have plenty of experience with clutch type posis in snow. Heck I used to make regular trips to the Kewenaw Peninsula with my cars even in winter, average snowfall there is 180".

You don't need to try try and tell me how a posi works in snow or ice. Open diff on snow and ice is perfect for stupid people who punch the pedal when the tire spins that way the other side tire keeps them anchored. If your not an idiot a posi is great.

xXZ-71Xx · March 22, 2015

Before this truck my choice in daily driver for the preceeding decade was V8 full size rear wheel drive cars(Caprice/Roadmaster) and I live near Green Bay.

I have had open diff. stock car Auburn posi, Eaton aftermarket posi in the cars and now the gov-loc all in the truck. The cars used the 8.5" 10-bolt too.

I have plenty of experience with clutch type posis in snow. Heck I used to make regular trips to the Kewenaw Peninsula with my cars even in winter, average snowfall there is 180".

You don't need to try try and tell me how a posi works in snow or ice. Open diff on snow and ice is perfect for stupid people who punch the pedal when the tire spins that way the other side tire keeps them anchored. If your not an idiot a posi is great.

You assume I haven't, My first car was a 77 olds cutlass Supreme with a posi that I still own to this day and I live in Michigan.

The fact of the matter is that you can punch the pedal in an open diff and not fishtail. If your not an idiot you can drive on street slicks in the snow but why? You seem quick to attempt to insult in a very passive aggressive way.