So, I am swapping out my 8.25 axle in my 96 Dak 5.2 short bed 5 speed 4x4 with a 8.75. Much easier to work on and it was FREE. Came with two 489 cases.

Now, here is my dilemma. Came out of an E body so fitment will work, just have to relocate some perches and stuff, having a professional place set up my pinion angles and geometry for me.

The GEARING is giving my a bloody headache. Right now my 8.25 rear is a 3.21 and the front is 3.23? or vice versa, the off set teeth always confused me, I know they did it for a reason so they played nicely together.

I was going to go to a 3.55 anyway in the 8.25 so I reckon I can put those in my 8.75. GREAT. Now what the hell do I do about the front axle? Match them with 3.55? Or do they need some odd ball off set gear set? aka 3.53 or something.

Ideally, since it is 4x4 and I only ever engage the front axle when I plow or snow shows up, I can run a nice 4.10 ratio on the second 489 case for summer time running since I'll be in 2wd. Come winter I put in my matched set for 'normal" driving.

Seem's plausible, unless this is an absolute terrible idea.

Anyone have any insight on this? I'm sure folks have done gear ratio's swaps in the past 100 years or so and must have some knowledge on this.

Thanks!
-Tom

 

What I'd do is call the gear manufacturer you want to use and ask them for a recommendation. They're the experts, and a call costs nothing. Since there are experts to call on, I don't bother trying to remember what works with what.

 

If all four tires on the same size, you want the same gear ratio front and rear.

 

Front and rear ratio need to match, even in 2WD.

Don't ask why. Let's just say "expensive reasons".

Keep in mind there are no hub disconnects, so both sides of the transfercase are spinning, even in 2WD

 

Oh but there is hub disconnects. 6 Bolts and a nut per side for CV shafts or take out front drive shaft and no worries about mismatched ratios.

Either way is super easy and only doing it for the summer.

 

You cannot drive it without the outer CV stubs bolted into place. They hold the hub/bearing unit together. If you drive without the front axles, you are in serious danger of losing a front wheel. Not a fun experience.