Dana 70 vs. Dana 80

[SixShooter]

What are the major differences between the 70 and 80 axles? I want the truck to have an DTT automatic but in order to get the 80 I have to get the one ton. What are the size differences between the two, any comments are appreciated.

 

[THubbard]

I have a '01 2500 6spd with 3. 54 and I am told it has the Dana 80. My truck is the early model that does not have the rear disc brakes or the 4. 10. It also did not come with a limited slip diff and I am playing hell trying to get one. It is a $250 + option when you purchase the truck and $2000 problem to correct that error. I know that the Dana 80 can be had in the 2500.

Tom Hubbard

 

[mikel]

I believe that the manual trannys in 2500's get the 80 no matter 5 or 6 speed. The auto in 2500 gets the 70 and in the 3500 gets the 80.



Mike

 

[Dave Fritz]

On the 2500, the only difference between the 70 and the 80 is the ring gear size. The 70 has a 10. 5" ring gear, the 80 has an 11" ring gear. The axle shafts, brakes, and hubs are the same. Even the 3500 version of the 80 is the essentially the same with a different hub to accommodate dual wheels.



Because the automatic transmission couples the driveline to the engine through a torque converter, it does not shock the driveline as hard as a manual transmission can when someone dumps the clutch with a load on or behind the truck, or the when truck is used off road.





Dave

 

[Texas Diesel]

3500 = Dana 80

2500 Auto = Dana 70

2500 Stick = Dana 80

 

[Okie-Go]

I think Txdiesel got it right. I was not satisfied with the lsd in mine. I put in a locker and know for a fact mine has the Dana 80. I just sold the old lsd that came with my truck. The guy that bought sounded like he was just tickled to death to get it.

 

[Texas Diesel]

Read my post on the "unLimited Slip Differential" and see my sig, get an open diff and add an aftermarket one. It is cheaper I think

to add a locker to an open diff than to a OEM limited slip, Okie is this true?

 

[fj40charles]

Just exactly what does a "modified Dana 80" mean? Just curious.



Also, do you think a locker (detroit, lockright, or ARB) would hold

up as well as a limited slip for mostly street use?



I use an ARB locker in my offroad

vehicle (very hard core offroad) and it is fine, but I don't think I'd want to put 200,000 miles on it.



Charles

 

[pcorssmit]

2500 sticks use an hybrid Dana 70/80.



I would never put a lock right in the rear. I wouldn't hesitate to put a Detroit in (from a reliability stand point), but they don't make one for the hybrid rear end.



Pete

 

[Mr. Brewski]

Modified Dana 80 or Hybrid Dana 80 is a 80 differential (Center section) with Dana 70 axel tubes and brakes. My service manual shows the following ring gear sizes.



80 = 11"

70 = 10"

60 = 9"



I'd guess that an 80 out of a manual transmission 2500 would bolt right up to a automatic truck except maybe for some driveline modifications.

 

[pcorssmit]

I know the 60 is 9. 75, and I thought the 70 was 10. 5"





Pete

 

[Dave Fritz]

The "hybrid" or "modified" Dana 80 uses:



- Dana 80 center section and carrier

- Dana 70 35 spline axle shafts

- Dana 70 hubs



I know that the 2500 manual uses 80 Hybrid axles. There has been conflicting information published about 3500 version of the 80, but I think the 3500 also uses a hybrid with 35 spline axles.



Ring gear sizes:

Dana 80 = 11"

Dana 70 = 10. 5"

Dana 60 = 9. 75"

Dana 44 = 8. 5"



more axle specs



Dave - Woo Hoo, working toward 200 posts!

 

[Mr. Brewski]

I stand corrected... My ring gear sizes were incorrect. (Looks like a little Ginko Biloba is in order )



For grins - GM ring gear sizes



1500 - 10 bolt 8. 5"

Light Duty 2500 - 14 bolt 9. 5"

HD 2500 - 14 bolt 10. 5"

Duracan 2500 & 3500 - reported as being 11. 5" (Cannot confirm)

 

[SixShooter]

can someone post a pic of the 70 and of the 80 please. Do they look completely different? is one taller than the other?

 

[fj40charles]

You should be able to see a "70" or "80" cast into the center (pumpkin) housing to verify what you have.

 

[PHaller]

Uhh, one item not mentioned above is axle tube thickness. The tube on the Dana 80 is roughly twice as thick as the tube on a 70 and presumably twice as strong.

-Paul R. Haller-

 

[Pete Peterson]

Also even though the brakes are the same diamater the width of the 3500 rear shoes is wider than the 2500 shoes... ... ... Pete

 

[THubbard]

I think the big question is: " What are you going to use the truck for?" Unless I am mistaken I think the Dana 80 is an #8000 axle and would assume that mean the Dana 70 is a #7000 axle. If you are not going to carry heavy load why worry about the 80.

 

[Extreme1]

Tickled to death with my new LSD!

The 80 center section (housing casting) and tubes are much larger than the 70. As mentioned above, 70 ends and axles are installed on the 80 to get the hybrid.



The way to get a good locking diff (if your LSD isn't LS) is to get an open carrier (the part that the ring gear bolts to) and add a lock-rite. My open carrier will be available in a few weeks if anyone is interested.



I chose to go with an LSD (which I am pretty sure I can get to work) because I tow in the winter and don't like to slow down too much. A lock-rite would get a little too exciting, that's what the race sled is for.



Last I heard, a Detroit locker is available in the Ford version of the hybrid 80 but I don't know if it fits.



Thanks Okie!!

 

[Speedo]

As far as I can tell the reason for the Hybrid 80

is a matter of practicality. If you used a standard 80 you couldn't use an 8 on 6 1/2" wheel, the reason being that an 80 uses 1. 625 axles which

requires bigger spindles and a larger hub and the

8 lug wheels we now use won't fit. While I can see

that for the SWR trucks I would like to see the standard 80 for the DWR trucks, easier to find 19. 5 wheels. If you look at F*&d with an 80, older Super Duty or the newer 450's with the 80, they use

a 10 lug wheel with a bigger center hole.