Jeep Dana 35C Tech

Damn, I can't believe I just lost an hour of writing. Crap. Ok, so I got some new Yukon 1541H 27 spline axles, new axle housing bearings and seals, an Eaton True-trac diff and new diff bearings. I spoke with Randy's Ring & Pinion and they said for my use, this combo was an excellent choice. Right on.

So, I whack out the old bearings and install the new bearings and seals, have the ABS tone rings pressed off the old 1040 steel axles and pressed on the new axles, have the new bearings pressed on the new True-trac. Cool, ready to roll. :) At this point it's time to set the bearing preload and ring gear backlash via shims. What ***** this was while the axle housing was still on the jeep. The diff came out 4 times until I reached my perfect preload and gear backlash: .006" backlash and just enough preload that I had to gently whack in the diff with the shim pack with a 2 lb plastic hammer. BTW, the True-trac has to weigh at least 35 lbs, double the original diff and I swear I needed 3 hands to align the diff and hold straight the outer bearing races while tapping in the entire assembly with a plastic hammer. I kept the shim packs in place with grease. Remind to never do this ever again.....

Now I thought I had everthing where I wanted until I installed the axles, c-clips, pulled out, installed the button which takes place of the cross pin and lo and behold....I have .062" of axle end play. Granted it beats .240" but Dana mid-spec is .015". I called Randy's without much help so I called Eaton directly and they informed that the Dana 35C axles came with two different size cross pins. One was .686 and one was .718. The .686 version was far more common so that's the button they provided. I said "Ok, what's the larger button cost?" and they responded that "We don't make them and we suggest welding the ends of the axles and grinding to fit." :stop:

No way was I going to compromise the heat treat of my new axles right next to the clip groove. Not happening. :bootysha: My fix was to have a new button made. I did a bit of research and found a custom machine shop that has been in business here in Denver since 1905. :read2: That's a good sign, lol. Anyway, I showed up with the part and a mic and once the sales dude realized I had a clue, he brought their custom guy out and we a 15 min conference. The original button scratch tested to Rockwell 56 which in my mind was crazy hard given the task. I was given a quote of $250 to replicate it.

They saw the shock and the machinist mentioned 4140 steel with no outside heat treating. I agreed stating that I'd rather have the button wear than the axles, lol. We all agreed that this made perfect sense and after 30 seconds of math I setteled on a width of .722 which gives me .012" of axle end play. It allows for wear plus expansion for heat.

In conclusion, if you are considering a True-trac in your Dana 35, measure your cross diameter first. :)