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Dana 80 gear swap?

39K views 17 replies 13 participants last post by  mauntie256 
#1 ·
I want to do a gear swap from 4.10's to 3.54's. I have a slot to have them changed but in correspondence with a tech guy at 4wheel parts he said I would need a case change also. My question is...

Will 3.54's fit in a stock Dana 80? :confused013:

1997 Dodge 3500 dually 4x4. Thanks, kelley
 
#3 ·
He is right, a case for a 4.10 and up is different than 3.73 and lower. Changing cases is no big deal and they are under $200.
 
#4 ·
its a carrier, not a case. its not uncommon for axles to have a carrier break in the middle. 3.54s and 4.10s are pretty far apart, i would not be surprised that the 3.54 carrier is different from the 4.10 one
 
#5 ·
There are two carrier thicknesses to accomodate the low set and the high set. 4.10 is the split. So basically all the 3.42 to 4.10/4.11 gears will use the same carrier, but past 4.11, you need the low ratio case. Most axles are like this and split at 4.10, but there are a few that don't.

One other thing, is that the low ratio case CAN be used with the high ratio gears, but a spacer is required. You can't go the other way, but special "thin" gears are available for some select applications to use the high ratio case.

To cross reference your gears/cases check out Ring And Pinion Gears, Axles and Axle Shafts, Drivetrain Parts and Tools - Accu Auto Parts great resource for comparing notes on this sort of thing.
 
#7 · (Edited)
Helical/torsen type differentials are fantastic! No funky handling, and they tighten up progressively as you spin a one legger. Sooper dooper posi design. Something to know is there are different bias ratios. I can't begin to explain how it works, I barely get the concept myself. But different bias ratios mean tighter/looser posi's This might be worth considering if there are more than one bias type available. I think it has to do with the angle on the helical gears inside the unit.

Personally, I have NO qualms with using junkyard hard parts. They tend to live forever. They don't wear out, they break. Usually from lack of maintenance or abuse. Inspect for scoring on wear surfaces, though. You'll need a "minor" install kit, at least, though. A minor kit usually includes a set of shims for setting pinion depth/carrier backlash, a crush sleeve, and the seals. Don't put in the crush sleeve 'till you get a good pattern. Start with the original shims, they should be close-40-60% of the time it will set up nicely on the first try with the original shims. I'd still pop 'em off and try for a better pattern, though, even if you get a good one. Better to have the BEST one.

And just so it's not a surprise, you'll need a quality (!) bearing splitter, and a hydraulic press. And a BIG honkin' cheater for crushing the sleeve. Plan on having the thing apart several times before getting the pinion depth/backlash correct, and each time, you'll be popping off the timken bearings to change out the shims. A case spreader isn't required, but can make things a whole lot easier.
 
#8 ·
The carrier break on a Dana 80 is 3.73 / 4.10. They do make a 3.73 "Thin" gear to fit a 4.10 carrier but no 3.54 thin. The spacer is not going to work for you. The spacer is for going the other direction ( 3.73 to a 4.10) The True Trac is a awsome unit and hooks up very well with no bad street manners. If you have the extra coin I would get the True Trac.
 
#9 ·
I have a srw 5speed with 4.10's (4x4) and I'd love to get some lower rpm's. Am I understanding you guys to say I can just swap my gears out for 3.73's or 3.54's? I asked this on another thread and they said I would need to swap axles, an exspensive proposition. If I can just swap gears, how much we talking for used gears and where do I find them?
 
#11 ·
You can just swap the gears out but unless you know how to set them up its gonna be expensive. After buying front and rear gear sets and all the neccasery install parts it might be cheaper to find some junk yard replacement front and rear ends.
 
#13 ·
You can just swap the gears out but unless you know how to set them up its gonna be expensive. After buying front and rear gear sets and all the neccasery install parts it might be cheaper to find some junk yard replacement front and rear ends.
You mean replacement axles, forget changing gears?
 
#14 ·
My truck has 3.54 gears right now in a peg leg dually! Who would ever order a peg leg in a dually should be shot but that is a different story.

Anyway, I need to put in a Limited-Slip in there and may want to put in an even higher gear (2.73 if its available). I have my reasons so dont ask, lol! So what is the highest ratio available and who makes the best LSD carrier?

Joe
 
#16 ·
im gettin ready to swap in a set of 4.10s. like said youll need a new carrier for the rear. but for the front the split is 4.10/4.56 so ya dont need a new carrier rup front. just gears.
 
#17 · (Edited)
i see this ad is really old but i was wondering about my truck? my truck at 70mph runs 2300rpm and gets 12 to 13mpg. im guessing it has 4:10s in it. my question is what gears should i put in and what kind of mpg would i get. most i ever pull is a car trailer with a skid loader on it and thats maybe once a year??
 
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