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Thanks Moses. It's clearer now.

Moses. I uploaded two video for you to watch: https://youtu.be/X3-SDb37XOs https://youtu.be/Id4kjOWqckY Note the sidegear clearance in my old 10 spline with new thrust washers is 0.55mm and the new 19 spline was 0.65mm. The tolerance in the book you provided is a maximum of 0.15mm. Is it possible they never began shimming the sidegears until 1967? See this parts listing: https://www.amazon.com/Omix-Ada-16512-20-Differential-Pinion-Bearing/dp/compatibility-chart/B000FQ1MTC In all my books I do not have anything describing this sidegear shimming. My M38 power train manual TM-9-1804B only shows one thrust washer in the parts diagram and repair description. My "Spicer Axle Maintenance Manual" shows this:

Moses. I did have the side gear thrust washers in place. It was my understanding that there was only one per side as that's all that came with the cluster set. In looking now, I haven't found a shim set for this purpose. In the pdf there is a statement "measure the clearance between the side gears and the case as illustrated" but there is no illustration. I found this one in my books.

There was no leakage outboard of the seal and I had expected the seals to be in bad shape, but they were not, they were like new - I don't need to replace them. Odd eh? Thats good news in a way as the axle wasn't eroding the seal. If the spindle is sealed (RTV) to the axle flange and the free-wheeling hub is water tight (gaskets at both the hub and cap), then there shouldn't be a concern for stream fording. If I use driveplates instead of free-hubs, then there is a gasket at the hub and a grease cap on the end. How would water penetrate? The regular swapping of driveplates for free-hubs is not ideal, as you have pointed out another "con" - gasket reusage. I might have to make a batch of gaskets. I have looked harder at the Warn hubs and feel they are much more robust than the AVM ones, so hopefully they will stand up to the job. The weak spot is still the spline gear bushing.

Moses. The new full float conversion uses an axle seal in the axle tube end. On the axle a smooth shiny spot has been machined where the seal runs. The space is now empty where the old grease was pumped in from the grease nipple on the tube end. Heres a photo

Thank you Moses. I used Crown spider/side gears (which failed) but in my rebuild I will use Spicer (at the suggestion of a fellow jeeper). Maybe the Spicer gears are harder. Not sure what you mean by How will you keep axle lube from creeping out the splines at the plates? Is that a concern? Cheers.... Wes

Hello Moses. Thank you for a prompt and comprehensive reply. I am a big fan of yours – my CJ Jeep Rebuilders Manual has plenty of grease and oil stains on the pages. I call it “the Jeep Bible”. The AVM hubs were selected based on the full float kit builder’s recommendations. He felt they were stronger than the Warn hubs, which I think I have refuted. I also feel that new Warn hubs are not of the same robustness in the splined ring bushing as Warn hubs from days gone past. On the floating nature of this setup, I would like to note that I have a centering block that travels on the spider gear center pin. That block holds the axle from moving inward too far. As you can see in the video, when the axle is pushed as far it as it can go against the block, it has full spline contact on the free-wheeling hub. At the hub side, the axle cannot move outward past its own splines on the splined hub ring. Thus lateral movement in the floating axle does not appear to compromise any spine contact at either the side gear or hub and the float range is rather narrow. I neglected to mention that I too had questions regarding the trueness of the axle run. If the jeep had left the ground and violently returned to earth (before I owned it) then the axle tube may have become bent. The tubes appear to be pressed into the differential housing and look to be a weak point in the design. Thus I undertook to assess the trueness. With everything out of the tube and the hubs/spindles off, I sighted down the tube. It looked very straight. Being an analytical scientist by occupation, I didn’t trust my eyeballs completely (as is turns out I think we have a very good perception of “straight” with our binocular vision… I digress). I took a straight pipe and put it through the axle and observed and measured offsets left and right, up and down. I looked pretty true to me. Then, I measured from the top of the axle tube outer flange to outer flange and then the bases. Both measurements were identical. I clamped a straight block onto each outer flange, to extend the surface up and down, which would accentuate any discrepancies – re-measured top and bottom, back and front – all measured the same. So it appears to be true. Lastly there was no wear on the spindles where the axle shaft passes through. Several thoughts come to mind as I read your reply. · -The free-wheeling hub is required to act as a stop for the axle shaft. Torque in the shaft will translate to lateral movement, thus laterally stressing the hub splined ring. The weak point in that stress is the bushing that the spline ring rotates about. That is the bushing that wore out so badly on my hub. · -The free-wheeling hub is required to act as the outer end support for the axle shaft. The inner end support is the side gear. There is no bearing in this setup to provide weight support for the axle shaft. These axle shafts are heavy, so gravity will push them down, and that weight alone may be enough to cause wear in the bushing of the spline ring of the free hub. Hummm, now how would that impact the spider/side gears? · -Many of the full float kits I have seen installed on the internet use internal Warn hubs, not external. Perhaps internal hubs are integrally stronger weight bearing the axle shaft and stopping outer float. · -I have purchase drive flanges which could be used instead of free-wheeling hubs. They would easily support the axle shaft and provide a strong lateral float stop. However, it defeats the purpose of having free-wheeling hubs for flat towing. I could swap the drive flanges in upon reaching my destination. Initially I was focused on resolving the free hub wear issues and that’s why I made the videos. However, I also have excess spider gear wear to resolve. See the "In the Carrier" section of my original post. I do not want to reassemble with new spider/side gears only to ruin another set. My current working hypothesis is that the wear in the hub was sufficient to allow the axle shaft to wobble, which translated to excessive wear on the spider gears. If that’s the case, a stronger Warn hub may fix this issue or just go with drive flanges. But if there’s another underlying issue, then it needs to be fixed. Thoughts? Regards…Wes

I have a 1952 M38CDN. Engine was upgraded to v6 231. Drive train is original. Rear is a Dana44. Last winter I bought a full float kit from Herm and installed it, so I could free wheel the rear hubs while flat towing. I only drove about 200km on this setup and had a nasty failure. I am putting it back together, but I cannot figure out why it failed and to simply put new parts in and expect a different result is just dumb. I have consulted with jeep mechanics locally, on other forums and talked with length with Herm. Nobody has a solution. I installed a 19pline full float axle. Replace the old 10spline side gears with new 19 spline side gears, new spider gears, new pin, reused old thrust washers. At the hub, I use AVM locking hubs. Symptoms: Driving straight on flat gravel roads in 2wd (rear hubs locked) there would be a nasty clunk, engine would race until I reacted and eased off the gas, no power to the wheels (like it had popped into neutral – but it had not), easing off the gas would allow a re-engagement. Start off once or twice in 40km. By the end, it happened 30+ times returning to camp over 15km. Problems: At the Hub: Upon removal of the locking hubs, I found lots of metallic dust in both hub ends (wheel bearings where spared – dust only inside the locking hubs). Similar amounts on both the left and the right side. The AVM hubs had the outer sliding ring cogs worn very badly (source of the metallic dust). The AVM splined ring was good as was the spline end of the axle. Wheel bearings were in excellent shape. The bushing that the stationary hub ring (splined ring) rotates in had become extremely worn and sloppy – to the point that the sliding ring had trouble coupling with the splined ring since the worn bushing along the splined ring allowed it to wobble a considerable amount. Some videos about the hub problems: Hub Video 1 Hub Video 2 In the Carrier: The differential oil was saturated with metal flakes – looks like metallic paint. The spider gear cogs were worn significantly, such that the spider gear would move up and down ¼”. The cogs on the spider gears were worn rounded in profile with significant wear on the outer chamfered edges of the cogs. The side gears were not worn. The side gear collars and the axle tupe house where these collars rotate were not worn. Only wear was the spider gear. Axle splines were perfect. Question: Why did the AVM hubs fail? It appears they were popping in and out and near the end, they were having trouble coupling due to wear on the hub bushing. Once engaged, there should be no reason for them to pop out. Why did the spider gear fail? The floating axle could have “pushed” laterally on the sidegear, forcing the spider to erode, but there no reason for this to happen. Action Plan: I will install a new spider/side gear cluster and new thrust washers. I have looked at Warn vs AVM hubs and two observations were made. The AVM hubs use the return spring to engage the hub whereas the Warn hubs use the return spring to disengage the hubs. Maybe Warn hubs would stay engaged better. Warn hubs are well lubricated on the bushing that the spline gear rotates about. AVM hubs don’t appear lubricated at all there. I will install Warn hubs this time. Thanks in advance.