Overhaul of a Dana 44 FBJ front axle, and Dana 60 rear. Pics of the 44 only.
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While playing in the sand (and some mud) I did something very stupid. I climbed a steep little hill (no BIG hills in this country...) under full throttle, and forgot to release the throttle when I came at the top. The fast spinning front wheels were abrubtly stopped by mother earth when the front of the truck landed, while I still had it floored, resulting in the spider gears parting with most of their teeth. (Only three left on each spider), or at least this is where I think this happened.
I had a bit of luck, too. No damage whatsoever on the pinion, and very minor damage on the ring. The bearings were in good shape as well, but hardly knowing anything about the history of the truck, I thought it would be smarter to replace the bearings. As far as I was concerned those bearings were of 1977 vintage.
Since 2 spider carriers can't survive my enthousiasm, I thought it would be wise to start improving things. After asking a few questions on some message boards, and a few phone conversations with a number of U.S. experts I had my options narrowed down to either a Dana Powr Loc or a Tractech Truetrac. I chose the PowrLoc, because it's supposed to be almost as bullit proof as a Detroit locker, and Truetracs aren't recommended if you use tires over 32-33 in. diameter. Since the W200 has full time 4WD, a Detroit locker for the front was not an option. Neither were ARB or Ox lockers, both are way over my budget, with the ARB being a little cheaper. Unfortunaly, with the ARB you need an onboard compressor, and then there's the vulnerable airlines going to the diff.
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Checking the pattern, in this case, was only an extra check, since I measured the thickness of each and every shim I found, and made absolutely sure I put the same thickness shims in the same places.
I found reading the gear patterns extremely difficult with the yellow stuff that came with the bearing and seal kits. Then I tried Prussian blue, which was even worse. A mixture of Prussion blue and the yellow stuff didn't work either, other than that I found out that such a mixture turns a nasty shade of green. I talked with a local expert about this (Thanks Nico !), and he suggested lipstick, which, apart from smelling funny, worked great ! On the top left pic I just put lipstick on 4 teeth. The second pic (centre-left) got me worried. Where are the 'islands' I was promised by the shop manual ? Then it dawned on me that these are used gears, and in that case you want to match the wear pattern that's already there. Still, the second pic didn't look good, but the shop manual said to turn the ring several revolutions, while simulating rolling resistance. (officially: holding the carrier with a breaker bar while turning the pinion, I did it by setting pinion bearing preload, and turning the carrier...) After trying that, the right patterns started emerging, on the teeth that got their lipstick put on the by the pinion teeth. (third and fourth picture, on the right). Also the teeth I had put the lipstick on myself started looking ok after a few revolutions (last pic). Basically, replacing the bearings and carrier on the Dana 44 was a breeze. Most work went into getting everything clean, especially the axle tubes. Getting the pinion bearing preload right only took 2 shim changes, and carrier bearing preload, backlash, and pattern were right the first time, so I didn't have to mess with carrier bearing shims, or the the pinion depth shims. Since I don't have an inch-lbs torque wrench, I used the bar of my hydraulic jack, which fit exactly in the semicircles of the pinion yoke, with a weight of 924 grams, which I started moving out from the yoke to the outside. When the pinion started moving I noted the distance I had shifted the weight out. After a bit of math I found a resistance of 2.2 lb-in. |
To save on shipping cost, I decided to include a Detroit locker for the Dana 60 rear. Boy, was I glad I did that. When I took the rear-end apart, I found twice the prescribed amount of backlash, rough rollers on the drivers-side carrier bearing, and no noticeable carrier bearing preload. Also I found a burr, or chisel mark on the seating surface of the top pinion-bearing outer ring. That must have been in tilted. Fortunately conical roller bearings don't mind a certain amount of misalignment. After removing the burr I had to take the pinion in and out 8 times, before I got the pinion bearing preload right again.
I left the setting of the pinion depth shims as it was, as the wear pattern before disassembly looked good. I first installed the carrier with an extra 0.002" behind the drivers side carrier bearing. It slipped in way too easy, and I couldn't measure any noticeable backlash. After taking it in and out a few times, I ended up with an extra 0.014" behind the passengers side bearing, resulting in the shop manual specs for carrier bearing preload, and 0.005" backlash, which is within specs also. After all this I did a final check on the gear pattern, which looked similar to that of the Dana 44.
If you decide to tackle a job like this yourself, make sure you have access to a micrometer, for measuring the shims, a dial-gauge for checking backlash, and a bearing puller. Without the latter you'll destroy the the roller cage of your precious new bearings, if you have to pull them off again for a shim change. Be prepared to spend a large amount of time. In case of the 44 I was lucky, but the 60 cost me many evenings.
I left the setting of the pinion depth shims as it was, as the wear pattern before disassembly looked good. I first installed the carrier with an extra 0.002" behind the drivers side carrier bearing. It slipped in way too easy, and I couldn't measure any noticeable backlash. After taking it in and out a few times, I ended up with an extra 0.014" behind the passengers side bearing, resulting in the shop manual specs for carrier bearing preload, and 0.005" backlash, which is within specs also. After all this I did a final check on the gear pattern, which looked similar to that of the Dana 44.
If you decide to tackle a job like this yourself, make sure you have access to a micrometer, for measuring the shims, a dial-gauge for checking backlash, and a bearing puller. Without the latter you'll destroy the the roller cage of your precious new bearings, if you have to pull them off again for a shim change. Be prepared to spend a large amount of time. In case of the 44 I was lucky, but the 60 cost me many evenings.
