C81 rear HUB keeps moving inwards ??????

[Tonyp 284]

Odd, I have taken the real wheels off several times, cleaned the axle, cleaned the keyway, clean the hubs , reinstalled the HUBS, locked them down , then reinstalled the rear wheels.  After some rigorous work duty, the right rear hub keeps slipping inwards right up to the tranny.  So I take it apart again, repat the cleaning etc,, lock down the hub over the keyway and after a bit of work duty, the hub moves back inwards.    I have even taken the HUB bolt , put the end on the wheel to make sure its FLAT before locking it down.    

 

So what am I doing when this happens ? ? I have a Johnny Bucket on the front end and I am moving mulch , yes the real wheels spin when the load gets to heavy to push when loading the bucket. Only the right side HUB moves inwards. the left is fine. 

 

Any thoughts ? Maybe I'll swap the hubs and keyways, left to right-  see if the issue goes with the hub/keyway. 

 

The parts photo shows the hub and the keyway . 

 

 

Edited August 24, 2023 by Tonyp

[wallfish 17,078]

21 minutes ago, Tonyp said:

 

Any thoughts ? Maybe I'll swap the hubs and keyways, left to right-  see if the issue goes with the hub/keyway. 

The cups on the end of the set screws are probably worn. New square head set screws should help because they will "bite" and many have also drilled and tapped a second hole for a second set screw at 90 deg from the first one.

 

 

[Tonyp 284]

wallfish-  Thx for the reply, are you referring to item 20 on the parts diagram ? I didn't know they were cupped.  I put it on the wheel to flatten it, it still moved.  I'm not understanding why cupped would help.   Its possible there is a worn spot on the keyway, I never looked but now I will.   I appreciate your response, thx !

[pfrederi 17,856]

Flattening the tip of the bolts only made things worse.  The cup tip will dig into the key or axle if you make a second hole. 

 

 

[rjg854 11,471]

For as inexpensive as they are, replace the Woodriff key when you change the set screw.  

[Ed Kennell 38,598]

Like John and Paul said,  Buy new cup point set screws and do not grind off the sharp cups.   Add the second set screw at 90 degrees.     

Also check the fit of the key in the axle and hub slot.       A new slot can easily be cut in the hub if it is worn.   Replace the key if it is worn.    I have used oversize (wider) keys and hand fit them to worn axle and hub key slots.      Badly worn axle keyways can also be repaired by welding.

 

Two part tapered locking hubs can also be purchased from A-Z Tractor.

 

[ineedanother 1,369]

These are some of the things I try to keep on hand. I believe the screw should be torqued to 35 ft. lb. and the nut to 30. Someone will probably confirm or correct me on that.

[JoeM 7,874]

9 hours ago, ineedanother said:

screw should be torqued to 35 ft. lb.

wet  with oil at 35 dry 45

 

One very much overlooked problems is If the hub bore is worn (the bore not the key). The bore, key way and sets are all part of the mechanical system to hold the hub on to the shaft.

Hubs should not be lubricated when installed. Remember, we are trying to keep it together not come apart.

When the set screws are tightened this applies a mechanical tension to the bore. Lubrication causes all the stress to shift to the small set screws. Of course the key is there for the rotating forces. 

A big mistake is using a hub with a worn bore. As a frugal member myself, I know replacement hubs are not cheap and we try to avoid that expense. If your going to use it for heavy duty work or where safety is a concern, (hills/inclines) replacement with a good part is essential. 

In part, if the hub when slid on to the shaft has any play, the chances of the hub staying tight under high loading is slim.

Extreme looseness example.

 

Also, if your shaft is worn the same problem will exist. 

Three fixes for a worn shaft. Of course the worse case is a new shaft and replacement.

Another option is using a substance in the joint to take up the space. I have used Loctite 660 retaining compound when the shaft had a couple thousands play. with good results.

If the shaft is worn and you have a good hub this stuff works pretty good.

 

 

Another option is the taper-lock hub manufactured by A-Z. A little pricey but is solid and will work on a shaft worn up to .005 even with a bad key. 

I have used these on a 522xi, a thousand pound machine, loaded tires and being run hard with no issues. 

 

 

[Tonyp 284]

THX guys , much appreciated.  I am getting new set screws, a couple of KEYS and I am going to use a Nylock NUT to lock down the set screw.  I did check the axle shaft and did not notice anything NOT correct.

 

I now know why CUPPED set screw tips rather than flat, yes, I made it worse.  I did notice on the KEY   that the cup screw location was worn from tightening  over the years. This is a 1979 /C 81,    I love it to death ! 

[TonyToro Jr. 1,525]

Same thing happened with my Raider 12. All we did was take it to a machine shop and had the drill another hole just to secure it even more. Haven’t had a problem since.

[wallfish 17,078]

For $20 you can just do them yourself plus have the tool to tap anymore holes in the future.

If you don't have a tap handle, a small adjustable wrench works too but but support it with the other hand until it gets deep enough

 

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[Tonyp 284]

Thx wallfish, I will at some point drill and tap a new  set screw hole, I have the resources. to do it right here at home ! 

[Lagersolut 669]

I've run into this almost every time I reuse the cup point screws so I ordered a bag at Mcmaster and carr - black oxide grade 8 with a little blue Loctite - if a hub has to come off it gets new screws ....if the cup is rounded or mushroomed they won't hold .

[Tonyp 284]

Ok finally got around to it,  removed BOTH rear wheels and rear hubs  cleaned and wiped DRY both axle shafts and  keyway slots,  cleaned and wiped dry the  hubs, replaced both keyways , they went into the slots very snug which is good, replaced  the cup screws and locking nuts on both hubs, put it all back together and  put the C81 back to work !   

 

 Mulch and Soil duty is over , but leaves duty is coming up. soon.  Lets see what happens 

 

Thx all for the comments and great advice.   

 

In the meantime, I picked up another 310-8  with two sets of rear  wheels, farm and turf,  no deck, brand new battery, Hi and Lo ranges all ok,  very clean overall.  It runs strong , no smoke, but has a slight ticking which may be valves. I see a weekend  project coming up soon. Check the valves adjustment,  pull the  head etc..    I've already used this 310 to pull the Aerator for Fall seeding.  Its # 4 !   

 

tp

Edited September 23, 2023 by Tonyp