i have the 4:10 diff. would different gearing help my top speed issue? i dont tow at all. what would need to happen to get a different gear ratio, what would be ideal for fuel mileage and would i have to do the front to? sorry for this question but what do the #'s mean?

 

Yes. 3.54 gears would help alot, what most trucks came with. Weird your truck has 4.10's.


Find a pair of D70/D60 axles with 3.54 gears already in them (like from a 1st gen truck being parted out)...........Or buy the front and rear Gear sets aftermarket.

a set of factory 3.54 gears would get great mileage......yes you have to do both front and rear... or when you put it in 4x4 stuff will go boom because one axle has lower gears and one axles would have higher gears, making them work against each other inside the T-case until it eventually just ripped it apart.

4:10 , to make it simple

Means it takes 4.1 turns of the Trans/Driveshaft to turn the tires one time. So more driveshaft rpm (Or RPM measured at the transmission output) speed is required to turn the wheels, hence making the engine RPM go higher on the freeway which in turn means crappy fuel mileage. benefit to NUMERICALLY HIGHER gears is you get more torque, meaning bottom end power and ability to get moving. simply because the torque is being multiplied much more.

3.54, 3.5 turns of the driveshaft to turn the tires one time.

Still don't get it? read here http://en.wikipedia.org/wiki/Gear_ratio

 

i get it! thanks for the quick reply. these aftermarket gears you speak of, how are they installed? about how much do they cost? i like to get my hands dirty, should i try myself or take my baby somewhere?

 

I've done my rear-ends about 5 times now. Its something that most would goto the shop for, just because of the difficulty to get the gears to align right. The Chrysler 9 1/4 was by far the easiest i have done simply because of the adjusting nuts inside the housing didn't require shims to install a new gear set. As far as dana rears go... you need to get shims when changing gear size, in my experience. While replacing the current gearing because of a breakage doesn't usually require different shims. Its a long tedious process sometimes, and other times it just "goes together like pees and carrots".

 

Well to give you a hint. You have to pull the whole rear apart to do the gear swap. and getting everything back in correctly and setting lash is a PITA.

Randy's ring and pinon.

Yukon gear.

Precision gear.

....................all places to buy gear sets from.

here's precision- http://www.precisiongear.com/dana70.htm < thats your rear.

Here's your front diff.- http://www.precisiongear.com/dana60.htm ..
Don't forget about your install kits.

Look around for a someone parting out a cummins truck near you, it wouldn't be that hard to swap a complete set of axles in with 3.54 gears already in them. Replace some front suspension parts while you're there, some new springs, new shocks, paint the diffs up all pretty

 

what if i had access to a lift and several knowledgeable mechanics? i work at an auto service center but we don't "specialize in gearing".

 

This is by far easier, only 4 U bolts and 2 shock nuts and 4 universal bolts holding the thing in, Then there is just the brake line. The front has an additional 3 or 4 bolts and your set. No fiddling with this and that and doing the same thing over and over and over again until you get it close enough where you don't mind the Subtle gear wine.

 

I'm sure you guys can handle it. As long as you have a dial indicator and a magnetic base, you will be OK. You're supposed to use a case spreader, but reasonable caution and a brass hammer will get the diff in without damaging anything.

 

If they have a case spreader and if they have the time and patients to reassemble the rear and front axles two or three times to get the gears right go for it. The factory service manual has a chapter devoted to this. It is a good read.

 

is a case spreader similar to a wire stretcher? or left handed screwdriver? or henweigh?

 

As Wanna said the case spreader is not really needed. It makes the job nicer but also makes it a little more of a pain (if that makes since). Just be nice with a brass drift or a brass faced hammer any you'll be ok. I've done it both ways and I will do it withOUT the spreader the next time I have to.

 

The real case spreader goes into the two holes that you see on both sides of the diff cover.

 

homemade one