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Wrencher Extraordinaire
2005 K1200LT
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Discussion Starter #1
Yup sure enough I changed the oil last night and it was dark compared to the gear box oil. Both were 20K miles old. Guess I got out of the habit of changing it every 3k to inspect. There was also a noticable wobble to the rear wheel, no grinding and it was very smooth.

Any way tear down shows the taper bearing had spun on the shaft and "made" a lot of aluminum. The bearing ID is listed as 25mm. The spindle as measured at the base was near 25 so there was some wear there. The worn area measured 24.26mm.

The wobble was not there after my last tire change @ 73K , at least I did not notice it. The bike now has 76K on it.

Here are a few pictures.

I am putting the spare FD on for now but I am toying with the idea of machining the spindle down and making a sleeve to press on and install a new bearing. No reason it wouldn't work.
 

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John....could you let us in on your step by step process as you proceed? I've watched Charlie's video but the more times I see it done the more confidence it gives me for when it's my turn.

Always appreciate your posts and knowlege!

Ron
 

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Wrencher Extraordinaire
2005 K1200LT
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Discussion Starter #3
This is not the typical 99-2003 large bearing failure that so many have experianced but rather the more rare and elusive small taper bearing spin out. Normaly this requires a complete gear set change out ($685) plus all the shimming and setting making it cheaper to buy a used drive. I am challenged by the though of a sleeve fix for this and will, of course, post the details and develop a procedure for it.
 

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I would clean every bit of oil off it & wipe both the OD & ID surface with lacquer thinner. Then I would spray a Q-Tip with Loctite primer & coat both the OD & ID surface. Then I would coat both OD & ID surface with Loctite 620 (high temp retaining compound ) & install the bearing & wipe off any excess Lockite.

Let it cure for at least 24 hrs. ( more if you have time ) & then heat to between 120 & 150 F. Let it cure for another 24 hrs. Then I would go about rebuilding the FD as usual.
 

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aluminum sleeve or steel sleeve ?

diffferent rates of expansion
 

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Wow! That's some gap! After checking out your drawing, how about some tig or mig action and then a trip to the lathe followed by the Loctite?
 

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John,

I wouldn't trust Loctite to fill that gap, or for that matter any epoxy. A sleeve sounds like a good idea, but assuming you turn that stub shaft down to 24mm to fit a 25mm OD sleeve, the bending stress on that shaft increases by about 22% and the shear stress by about 8%. One will have to do a more detailed analysis to see whether that is really an issue, nevertheless it has a safety implication. Personally I think an 0.5mm thick steel sleeve is too thin, but trimming more from the shaft will increase those stresses even further. Probably worth a detailed analysis.
 

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John - I'd go with a machined steel sleeve made of 4130 chrome-moly tubing. Go for a heavy shrink (like .002"/") onto the alum shaft & machine the OD after the shrink job. For shrinking, you should be able to slip it together if the sleeve temperature is ~ 400 degF more than the alum hub. Liquid N2 on the hub would really help if it is readily available around you.

Locktite etc won't do it. Do you have lathe access? I have 1" seamless 4130 tubing. PM me if interested. I O U one. :)
 

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Hi John, nice idea to work with a sleeve, but....
There are to many shrink fits and the wallthickness is to thin to hold the pressure.
In my opinion is there a big chance to find a bearing with a smaller ID, 24 or 23 mm. Should not be really a problem.
U can't turn the shaft to far down because its get to weak.
Maybe gives you some ideas.

Manfred
 

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Interesting that you noticed a wheel wobble. It seems that damage at the tapered roller bearing is much more likely so result in a detectable wobble than is damage at the crownwheel bearing.

I have used Loctite 660 to seat tapered roller bearings when I have found the loose, but have never done that if there was detectable wobble of the bearing race on the aluminum shaft.

The Loctite 660 spec sheet says that the material is good for the size gap that you are reporting, but the challenge is to ensure that the bearing is properly aligned when the Loctite is setting up. I wonder if assembling the FD before the Loctite is set would allow for proper alignment.




jzeiler said:
Yup sure enough I changed the oil last night and it was dark compared to the gear box oil. Both were 20K miles old. Guess I got out of the habit of changing it every 3k to inspect. There was also a noticable wobble to the rear wheel, no grinding and it was very smooth.

Any way tear down shows the taper bearing had spun on the shaft and "made" a lot of aluminum. The bearing ID is listed as 25mm. The spindle as measured at the base was near 25 so there was some wear there. The worn area measured 24.26mm.

The wobble was not there after my last tire change @ 73K , at least I did not notice it. The bike now has 76K on it.

Here are a few pictures.

I am putting the spare FD on for now but I am toying with the idea of machining the spindle down and making a sleeve to press on and install a new bearing. No reason it wouldn't work.
 

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Wrencher Extraordinaire
2005 K1200LT
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Discussion Starter #12
Lots of great ideas from the group. I will have to do some more analysis before I choose a path. I have another trashed crown wheel to cut into to determine thickness of material so i should have good data to work with.
 

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John
The aluminum gets thicker the farther in towards the crown gear . Turn the bearing journal down to flush and bore the remaining aluminum to a dimension tolerable for the load and wall remaining. Make a stub shaft with an interference fit and press this into the hub. Then setup in centers and grind the journal to dimension for the bearing.
I did one like this for a friend a while back, He has 50,000 miles on it so far with no problems. We have kept a close eye on it and have not seen any changes.
 

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1dbweldor said:
....Turn the bearing journal down to flush and bore the remaining aluminum to a dimension tolerable for the load and wall remaining. Make a stub shaft with an interference fit and press this into the hub. Then setup in centers and grind the journal to dimension for the bearing....
That really does sound like a viable solution. I had thought of a skilled welder building the aluminum shaft up and then turning it down, but don't know what that might do the the metal. Drilling for a replacment shaft is a really neat ideal.

I wish I had machinist skills and a good lathe.
 

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On a related topic....... I saw an interesting way to heat the crown bearing for assembly yesterday. Slow cooker, gear oil, and a piece of safety wire attached to the bearing for removal from the hot oil. Pure genius, and a bunch faster than an oven if the oil is pre-heated.
 

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Wrencher Extraordinaire
2005 K1200LT
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Discussion Starter #18
1dbweldor said:
John
I'll drag out the nomenclature and get the dimensions if you need them.
Please do as this sounds like the best option. I respect your advice greatly.
 

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CharlieVT said:
That really does sound like a viable solution. I had thought of a skilled welder building the aluminum shaft up and then turning it down, but don't know what that might do the the metal. Drilling for a replacment shaft is a really neat ideal.

I wish I had machinist skills and a good lathe.
John - I do have a lathe & could bore and measure a steel sleeve that would be 25.4 mm stock outside dia. I was asking if you had lathe access to do the final OD machining of the hub/axle after the parts are shrunk together.

That shaft is hard aircraft quality aluminum, which has excellent machining properties. It is impossible to even approach the physical specs of a such an aluminum alloy with aluminum weld material. That's why aircraft are never welded aluminum. They always go either riveted aluminum sheet or are welded from 4130 chrome moly steel.

And - Don't machine away any of the original centers. It will be very difficult to recreate them to anywhere near the accuracy needed in this assembly, unless you start with a whole new block of aluminum (which I supposed could be done).
 

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Wrencher Extraordinaire
2005 K1200LT
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Discussion Starter #20
Thanks. I do have access to both a lathe and a skilled machinist. One other item I noticed was the pinion inner race had worked its way off the pinion tip and has started rubbing though the case. Two whammies at once. Also looks like there was wear at the shim as well so I will have redo the backlash setting as well as pull the pinion to reseat the race. I think I would rather go riding...
 
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