So I have been experiencing a gnarly vibration coming from somewhere in the drivetrain. The slip yoke into the transmission and the entire driveshaft is brand new so I'm inclined to rule them out. Nevertheless I inspected them and the u joints as I removed them and did not find any slop anywhere. Once I had the driveshaft off I noticed that the pinion had quite a bit of play both in rotation and in-n-out movement.

 

I decided to tear down the pumpkin just to see what it looks like in there (I'm planning on changing gearsets in the next few months and thought exploring a bit in there couldn't hurt). I noticed the wear pattern seems to be way off toward the heel (outer circumference) of the ring gear and a lack of wear on the toe end of the pinion (see pictures). I've never built an axle before but this wear pattern would seem to confirm that the pinion is too loose and pushing itself out of the ring gear under acceleration and then just kind of wobbling around in there at cruise speeds and making the vibration. Before removing the axle shafts I rotated the carrier back and forth and found that the spider gears visibly moved in and out on their shaft adding even more play as the carrier spins.

 

Lastly, when I removed the last carrier bearing bolt the whole carrier fell out, plop, and landed right on the sway bar. I have heard stories of people needing case spreaders to get carriers out, so this too seemed odd. I also noted the lack of a crush sleeve or anything to set preload on the pinion.

 

So my questions are this:

1. How much of this seems odd to me just because I have zero experience in this part of my truck?

2. What are the chances that I'm going to damage something if I goop up the cover, add fresh oil, and run it for another few months?

3. What's the best source of info for setting up the rear end so I can get everything set up properly when I do swap gears?

4. Does anyone have a good 4.10 ring and pinion set for sale?

I'm not an expert by any means, but it doesn't look to bad. It seems to be in the middle on ring maybe a little out on pinion. You could reshim carrier towards pinion more to get slop out to spec and then shim pinion out towards center some. Dana didn't use crush sleve just shims. If you have enough thinner shims in there you can take .010 out one side of ring and put it on the other, same on pinion. Pinion you'll need a large bearing separator and a press more then likely. And a dile indicator that reads in thousands on a magnetic base that you can get at Harbor freight along with everything else.  

I attached a service manual for the Dana 70 (PDF).

 

Also in the Dodge FSM...

 

(267RBI is the Dana 70)

 

For info, any of the Dodge factory service manuals go into great detail as well in regards to disassembly/install (as one would expect).

 

Dana 70 FSM.pdf

Edited July 15, 20186 yr by sooxies

Thanks @sooxies this will be daily reading until I do the gear swap. The rear axle of my truck odd one of the few parts I know for sure will be sticking around indefinitely so I plan to treat it right. Already swapped to disc brakes and added traction bar mounts. I'll be doing all of the seals and bearings with the gear swap and hope to make it last another 200k miles.

So I know what I'm about to describe is extremely unorthodox, and I'm not recommending anyone to try it, but I've been rebuilding engines since I was 12 years old and I've learned to trust my gut on these things. Plus, this is only a temporary fix and ALL parts involved are slated to be replaced in the next few months. More for experimentation sake than really trying to correct any issue or problem. Believe me, when I go to put a new set of gears in my truck that I want to last the next 20 years I will have every tool and brand new part available.

That being said, I know the pinion was too loose and looking at the wear pattern on the gears I felt I had enough room on the ring to adjust it with pinion shims rather than preload. So I found a thrust washer leftover from a transmission rebuild and ground it down slowly until, when I torqued the pinion nut as tight as I could, I was able to spin the pinion with some difficulty with one finger midway between the center of the pinion and the outside of the yoke. Each time I checked the preload I also installed the carrier to check for binding between the pinion and the ring. As it would happen, when I got the preload to the point it "felt" right to me the carrier also turned freely and I could hear just the slightest hum as the gears meshed deeply but no bind whatsoever. With the pinion in and torqued, and the carrier in and torqued, I could still turn the pinion at the same midway point with one finger although occasionally when it stopped it would take slightly more effort to get it started again. I then disassembled the whole thing one more time, greased the bearings, and put it back together. I did reuse my pinion nut but, because I plan on installing a new one with the gear kit I buggered up the threads right where the nut threads meet the pinion threads with a cold chisel. Like real good.

I did notice that when I put the carrier back in the housing I was not able to move it side to side at all, even with the cap bolts just over hand tight. I feel like new bearings here will require some persuasion to get the carrier back in, but no shim. We'll see. 

Anyways, one more odd observation I made was the lack of a press in seal where the axle tubes meet the center housing. There was what seemed to be a bead of caulk there but it was way to uniform and neat to have just been squeezed in there. I'll have to post a pic when I swap gears. This is just my observation about the innards of my Dana 70 rear end and is in no way intended to be a guide or advice to others. I will be driving the crap out of it between now and then to fully test how my "feelings" translate to real world usability.

On 7/14/2018 at 2:39 PM, Scottfunk said:

So I have been experiencing a gnarly vibration coming from somewhere in the drivetrain. The slip yoke into the transmission and the entire driveshaft is brand new so I'm inclined to rule them out. Nevertheless I inspected them and the u joints as I removed them and did not find any slop anywhere. Once I had the driveshaft off I noticed that the pinion had quite a bit of play both in rotation and in-n-out movement.

 

I decided to tear down the pumpkin just to see what it looks like in there (I'm planning on changing gearsets in the next few months and thought exploring a bit in there couldn't hurt). I noticed the wear pattern seems to be way off toward the heel (outer circumference) of the ring gear and a lack of wear on the toe end of the pinion (see pictures). I've never built an axle before but this wear pattern would seem to confirm that the pinion is too loose and pushing itself out of the ring gear under acceleration and then just kind of wobbling around in there at cruise speeds and making the vibration. Before removing the axle shafts I rotated the carrier back and forth and found that the spider gears visibly moved in and out on their shaft adding even more play as the carrier spins.

 

Lastly, when I removed the last carrier bearing bolt the whole carrier fell out, plop, and landed right on the sway bar. I have heard stories of people needing case spreaders to get carriers out, so this too seemed odd. I also noted the lack of a crush sleeve or anything to set preload on the pinion.

 

So my questions are this:

1. How much of this seems odd to me just because I have zero experience in this part of my truck?

2. What are the chances that I'm going to damage something if I goop up the cover, add fresh oil, and run it for another few months?

3. What's the best source of info for setting up the rear end so I can get everything set up properly when I do swap gears?

4. Does anyone have a good 4.10 ring and pinion set for sale?

Funny I’m doing a 4:10 swap right now, watch eBay for a genuine Dana to pop up if your patient lol I got one for 70 bucks to my door. Dana 70 parts are a little more expensive so I just bought new genuine Dana off rock auto for 200 bucks.

Scott,

The Dana 70 and 80s do not use a crush sleeve to maintain a preload on the pinion.  Part of the initial set up for the pinion (you will read it in there) is finding the point of shims that there is zero axial movement of the pinion.  From this point you will remove a set amount of shims to set the initial preload of the pinion. 

 

Your carrier fell out because the carrier bearings are worn out.  The preload that was originally there is gone from wear.   

 

I just re-setup my brother's 70u a few months ago.  I can remember a good bit of what I went through.

 

Send me a PM it will be easier to discuss a bit of this on the phone first.

 

GL  HTH

 

Hag

Will do. Seems like the hardest part is the pinion cd. After playing around in there this weekend I know I don't want to be on and off with the inner pinion nearing over and over. I'll make the old bearings into setup parts and everything else seems pretty simple. With the slop that I had I don't feel right about using the old pinion cd +/- the new (plus my old pinion doesn't even have numbers on the top of the head). The process for finding that from scratch seems really complex but I want it perfect.