Rear Axles Won't Go In.

Discussion in '40- & 55-Series Tech' started by Steamer, Jul 12, 2018.

  1. Steamer

    Steamer SILVER Star

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    I can't slide my axles into the new bearings.
    My axles were in rough condition, so I sourced used replacements. The new bearings and seals I ordered came first so with the third member out I flushed and lubed the housing then installed the new bearings and seals and installed the cleaned and serviced third member minus the spider gears as I’m going to put in a Lock Right locker.

    The old bearings that came out are the same number as the new bearings. “Koyo RNU-0727”

    As I Insert the replacement axles, that appear to be in very good shape, they stop when the bearing surface area of the axle meets the bearing itself. I’ve got everything well-greased up and did plenty of wiggling, rotating and medium tapping with a dead blow hammer. They start to go in just a bit but just stop. I’m afraid to pound on them anymore as it took a bit of whacking to get them back out the little bit I got in.

    I’m able to install the outer part of the Lock Right into the side bearing and onto the axle splined end so I know the axle is centered and aligned. The Lock Right flange slides in and out freely so it’s not keeping the axle from going in.

    Besides these replacement axles I have the old pair that were a bit pitted and another pair I pulled from a spare axel that were also pitted. I wired wheeled and cleaned very well the two pair of pitted axles and tried to install them also with the same results. The old bearings BTW drop right onto all six axles.

    Is it possible I got some bad bearings or am I doing something wrong? I thought possibly the used axles could be mushroomed out to the unused surface, but I can’t detect that with a digital caliper.

    Any ideas?
     
  2. B y r o n

    B y r o n

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    Did you measure the area that slides into the bearing on the new axles to make sure they are the same diameter as your old axles?
     
  3. pardion

    pardion SILVER Star

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    What vehicle is this?
     
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  4. Steamer

    Steamer SILVER Star

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    Sorry. It's a 74 FJ40. Rear semi-floating axle.
    These are the larger diameter axles that do not use the inner race.
     
    Last edited: Jul 13, 2018
  5. cruisermatt

    cruisermatt ランドクル62! SILVER Star

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    Bent housing?
     
  6. Steamer

    Steamer SILVER Star

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    Possibly, but I don't think so. But if it was, I'd think an axle would still go in without the Lock Right flange holding it centered and wiggling the axle around. I also tried all three short axles in the long side with the same results.
     
  7. Steamer

    Steamer SILVER Star

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    So I just found the specs on my bearings “Koyo RNU 0727” Specs

    The bore is 47mm. But, all of the six axles I have measure at 47.5mm. No wonder it won't go in.
    Can anyone confirm the part number Koyo RNU 0727 ?


    I also have the bearing with the inner race for the older axles that used the inner race pressed onto the axles. That inner race also measures 47.5mm. The bearing that comes with the race slips onto all six axles (without the race) and seems to be a proper fit. I can’t find the specs listed on this bearing.

    AxleBrng 01.jpg AxleBrng 02.jpg
     
  8. Steamer

    Steamer SILVER Star

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    Strange, this post just now appeared on my pc anyway. But yes. all of the 6 axles I have measure 47.5 mm.
     
  9. Steamer

    Steamer SILVER Star

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    Well checking around on the net I’ve seen a handful of suppliers that say the Koyo 0727 is the right bearing for my axle. I’ve also found several more places listing the specs for that bearing and I see multiple inner bores listed as 47mm, 47.5mm, 47.7mm and even 48mm. I seriously doubt all those bore dimensions are correct and attribute some of them as misprints or just rounding off. I wish I knew which one is correct.

    So, while waiting for someone who’s familiar with my situation to chime In, and figuring these axles just ain’t going into these bearings, I’m going to pull them out. I should have test fit the bearings first, but I had the bearings and seals long before the axles came in, so I thought I’d get as much done as I could while waiting and put them in first.

    I’ll pull the third member back out and push the bearings and seals out from the opposite side and try to not damage them. Well, I gotta try anyway.

    I’ll post up my findings as it might help someone someday or maybe just satisfy some curiosity out there.
     
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  10. Steamer

    Steamer SILVER Star

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    So,,, I just knocked out the bearing and seal from one side. Then I slid the bearing onto the axle and it goes right on by hand like it should being snug with no play. Perfect fit. “Are you kidding me”? With a little checking and measuring of the removed seal & bearing and the installed ones on the other side, I see that the seal could go in some more, maybe a ¼” or more. When I installed them they went in smoothly without issue using the tool and I really thought I felt them bottom out when I wacked them in but apparently not. They appeared to be right up to the bearing but I now think I may have been looking at bead of grease formed while going in.

    But wait! When I looked in the diff hole at the Lock Right flange, it appeared it needed another ¾” to go to get a C-clip on. Ah! The flange must have push out a little when I was tapping ton the axle. So I was into the bearing partially but I was pushing the fatter part of the axle beyond the seal surface into the seal itself and therefore rotating the axle had lots of resistance that I mistaking thought was the bearings getting in a bind.

    Jeeeez! Dumb mistake but at least it’s solved. I'm surprised no one mentioned "Make sure the seal is in all the way". I did find a discussion here about how far to know them in. A few said all the way till it bottoms out but some said not to far as the seal could interfere and rub on the bearing. Not so if you have a good look at a seal slid on an axle. The rubber is recessed back a bit from the outer metal part and it's obvious you push the seal in right up against the bearing with out issue. Well that's how I'm doing it anyway. And one good thing to come out of this is, while searching info here I found out about the washers behind the bearings. I hadn’t known about them nor did I have them in there. So sor will deliver them Thursday along with another pair of seals. I feel confident I didn’t hurt the bearing I knocked out and won’t hurt the other one either. I’ll post some pics of my removal method as it went pretty well.
     
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  11. Steamer

    Steamer SILVER Star

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    So here's how I removed the seals and bearings.

    The handle on my Lisle bearing & seal tool was a good fit into 1" emt.

    A 5/16 eye bolt would have worked good but I had plumbers strap on hand. I wanted to keep tension on it with a bungee so I could keep the disk of the tool centered on the bearing.

    I had to insert the tool into the pipe through the diff housing opening.

    Seal and bearing popped out with a couple of whacks and fell into the plastic tub catch basin. The bearings are fine and I'll re-use them when the washers arrive. I'll use new seals even though the ones removed look fine.

    BrngRmv01.jpg

    BrngRmv02.jpg

    BrngRmv03.jpg

    BrngRmv04.jpg

    BrngRmv05.jpg
     
  12. Steamer

    Steamer SILVER Star

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    UPDATE: So, I thought my insufficient seal insertion was my hang up. "Not". I got my new seals and tried again.

    I slide a bearing onto the axle and it drops right on. I then install a bearing & a seal into the housing with both fully inserted. The axle won't go in. Even with some moderate wacking it won’t go in. I go to the other side and after a bearing test fit on the axle I install the bearing only without the seal. The axle will not go in.

    So, I figure there’s no way I could be compressing the bearing race to a smaller diameter but when I measure the axle tube inside I discover it is not round but elongated vertically. So I am theorizing that the outer bearing race gets distorted out of round upon insertion and that is why the axles won’t go in.

    My wrenching buddies claim, no way I’m flexing a hardened bearing race out of round. The race will force the axle tube round again.

    So, moments ago I do this test. I put a bearing in my vise just tight enough to hold it and slide in and axle. It goes right in. I measure the OD perpendicular to the vise jaws. Then with one hand on the vise and the other on the caliper I give a tug on the vise handle. I get a 0.200” increase with not a whole lot of effort. I try the axle and it won’t go into the bearing. Ease off the vise and it slips right in.

    I never would have thought a bearing race would be that flexible, but I just saw it for myself. The vertical elongation makes sense given the direction of the force of the load. I do know that the PO abused this rig by overloading it like crazy and did break more than one set of rear springs. I’ve been rather rough on the rig myself, so I can probably share the blame some.

    The best thing is, I now know the problem and can start on a solution. I feel confident I can come up with something to squeeze the housing tube ends round again. At least good enough to get rolling again and then I can think about building up my spare axle assemblies.

    I’m wondering if out of round axle housing tube ends happen on occasion or is mine a rare case.
     
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