91 ctd axles 4x4

[odieub]

in the process of buying a 91 ctd 4x4 and was wandering what axles it had in it it has 3. 07 gear. figured it had a 60 in the front and a 70 in the rear but was told it had a 61 and 71 something about dodge could only go no lower (numaracly)than a 3. 54 in the 60 and 70 so they went to the 61 and 71 so they could use the 3. 07. is there any trueth to this and would anything interchange if so ?

 

[dpuckett]

That's right- the lowest one can go in a true D70 is 3. 54. So, to get the higher speed capability with a 3psd auto, they had Dana make a 61 and 71, with 3. 07 ratio. Ford also ran a D61 in some of their early 4spd diesel 3/4tons- I almost bought one to do a Cummins swap into. Not much in the differential itself will interchange with a standard D60/70, IIRC. I think brakes and wheel bearings are the same, though.



Are these SRW or DRW axles?



Daniel

 

[Philip]

The brakes and knuckles are the same as a D60. The axles both inner and outer are the same. The spider gears are the same and so is the cover.

 

[dpuckett]

So what you are saying, Philip, is that the only difference between the 70 and 71 is the center chunk? You know, the housing where the pinion comes in, and the carrier gets bolted? Not that its unimportant... ...



DP

 

[cerberusiam]

So what you are saying, Philip, is that the only difference between the 70 and 71 is the center chunk? You know, the housing where the pinion comes in, and the carrier gets bolted? Not that its unimportant... ...



DP

When you get right down to the details, the carrier is probably really the only physical difference between them. There is a limit to how much you change the sizes of the ring gear and the relationship to the pinion before you have to resize the carrier.



While it is possible there could be differences in the width of the carrier supports, depth of the pinion bearing pockets, or pinion offest I would question whether that is true. To swap from 3. 55 to 4. 11 you had to change just the carriers. Would be interesting to see if there is a physical difference in the center section measurements.

 

[dodgenstein]

To swap from 3. 55 to 4. 11 no carrier change is necessary. The break on 60's and 70's is between 4. 11 and 4. 56. Dana 80's are 3. 73 and 4. 10 on the split. The center has to be different as the 3. 07 axle housing is unique.

 

[MMiller]

I have no trouble believing the pinion offset is different in a dana 61. A 307 pinion is massive compaired to a 3. 55 or 4. 10. I've heard of guys taking the dana 61 and putting a 4. 10 gear on the factory carrier. They either have bought a ring gear spacer, or an extra thing ring gear. Now, this also tells me the pinion is offset further away from the carrier. I'd almost beleive the carriers are the same between a 3. 55/4. 10 and 3. 07.



When I had a set of 61/71(they are in Georgia now) I wanted to trade them. I had several guys from a 4x4 webcite tell me to get a spacer for the ring gear, and then my axles would work. I did not want some custom parts in the axle, and may someday have to go to a 4. 56 or 4. 88. Then I would be in real trouble trying to get gears to match up.



I should have taken a picture, in the past I pulled a set of 4. 10s and installed some 5. 13's in an offroad truck. There is a huge pinion size difference there. I was almost scared to torque on the truck on the initial test drive. But alas, when the 440 started up, and the 44" boggers were installed, that worry went away as the 4 barrels opened up!:-laf



Michael

 

[Philip]

I have spare 3:07 carriers for the front and rear on my truck. If some has a 3:54 carrier laying around we can do some measuring. I also have a 4:56+ carrier for my front axle.