Rear Diff Gears

[Vertin]

I've got a '99 GMC Yukon SLT 4WD with a 4" lift running BF Goodrich All-Terrain K02 33s. I use it for 4WD & towing my boat. The stock rear diff gears are 3.73 & it has/ had the G80 Posi option.
I'm thinking about changing out the stock Posi to a Eaton Detroit TrueTrac limited slip diff & was curious if I should also change out my Rear Diff Gears. Any advice? Thx

 

[Mechanic421]

Not unless they make noise or you want too change ratio. I have seen gears with 300000 plus miles that show almost no wear! I do lots of diffs and gears. I recommend lots of reading before you try a diff change on your own.

 

[drakon543]

depends on your boat and location your doing the towing and what kind of mpg your getting. if your area is fairly flat with small hills only and your boat is light enough that you dont really notice an impact when your towing then i would say no. 33s aren't too much different than 265 75s so honestly if you want some more umph when you have your boat then yes. if not then your fine with your stock gearing.

 

[alpinecrick]

I've got a '99 GMC Yukon SLT 4WD with a 4" lift running BF Goodrich All-Terrain K02 33s. I use it for 4WD & towing my boat. The stock rear diff gears are 3.73 & it has/ had the G80 Posi option.
I'm thinking about changing out the stock Posi to a Eaton Detroit TrueTrac limited slip diff & was curious if I should also change out my Rear Diff Gears. Any advice? Thx

If you are going to change the gears in the rear you better be changing the gears in the front diff too....

 

[Vertin]

Not unless they make noise or you want too change ratio. I have seen gears with 300000 plus miles that show almost no wear! I do lots of diffs and gears. I recommend lots of reading before you try a diff change on your own.

The stock rear diff gears are not making noise. The stock Posi is not working so I figured if I'm paying someone to swap out the stock Posi for the Eaton Detroit TrueTrac I should check into changing gears since it will be opened up (& I have larger than stock tires).

 

[Mechanic421]

Like said earlier u will have to regear the front if u change ratio.

 

[asand]

The pinion gear doesn't need to be messed with to swap out the the diff. Jus swap your ring gear on to the new diff and set the backlash according to what you have now.

I swapped in a Yukon Duragrip a couple months ago. Backlash was 10thou before I tore it apart and 9thou going back together. Wasn't worth fiddling to get it closer.

Replacing the ring and pinion will cost more than just swapping the diff because it will be a couple extra hours of trial and error with pinion depth.