Author Topic: Broken U-Joint  (Read 803 times)

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BCR751

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Broken U-Joint
« on: October 14, 2017, 03:51:22 PM »
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Recently, I did the 'bearden' mod to the drive train on an old Kato F7B to get rid of the "coffee grinder" noise.  Well, when I put it back together, it worked well for a short time but developed the grinding noise again but it wasn't the same.  So, I went through it, eliminating various parts as I went and finally found the cause.  When I took off the little u-joint that goes into the motor's flywheel for the mod, I must have pulled too hard because there is a hairline crack in it.  Now, when the unit goes in motion, that u-joint slips on the motor shaft which causes the one good truck to have to take all the load.  This is causing the grinding noise.  It's really bad going around curves.

I checked the KatoUSA website and this part is no longer available.  Does anyone have a couple of these kicking around they would be willing to part with?  Failing that, is there any known fix for a cracked u-joint?  Maybe CA or epoxy??

Doug

Doug G.

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Re: Broken U-Joint
« Reply #1 on: October 14, 2017, 04:59:23 PM »
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I'll sell you two for 5 thou apiece. Just kidding, I don't have any. :D

Is there room to fit a thin-walled brass sleeve around it? That's how I fixed the cracked axles in my Bachmann white box 4-8-4.

Doug
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John

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Re: Broken U-Joint
« Reply #2 on: October 14, 2017, 05:04:44 PM »
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would something from an old Bachman work?

narrowminded

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Re: Broken U-Joint
« Reply #3 on: October 14, 2017, 05:09:16 PM »
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Give these guys a chance to cough one up but worst case, send me the part(s).  I should be able to machine one from Delrin. :)
Mark G.

John

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Re: Broken U-Joint
« Reply #4 on: October 14, 2017, 05:21:16 PM »
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BCR751

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Re: Broken U-Joint
« Reply #5 on: October 14, 2017, 05:29:15 PM »
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does it look like this?
http://www.katousa.com/images/X03-0769.jpg

No, it has four 'fingers' that nest into similar fingers in the flywheel.  Here's a photo of it.



Doug
« Last Edit: October 14, 2017, 05:51:56 PM by BCR751 »

u18b

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Re: Broken U-Joint
« Reply #6 on: October 14, 2017, 07:30:21 PM »
+1
When I saw that you Beardenised with "u-joint" I was concerned.

Kato did make an F unit with a pivoting u-joint and a kind of star joint.
Those kinds of joints will not work with this procedure.

But you have the old joint- which is good for this procedure--- but yes... they are ageing and getting hard to find.

I see them on ebay- usually attached to a worm like yours.
Remember, Atlas sold them to on the non-china Alcos RS3/11 late and RSD4/5. GP7/9.  and U25B.

In a worst case scenario (besides selling the loco) you could put flywheels on it that have the hex nut hole and use the hex nut which is so common now.

« Last Edit: October 14, 2017, 07:34:42 PM by u18b »
Ron Bearden
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"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

u18b

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Re: Broken U-Joint
« Reply #7 on: October 14, 2017, 07:32:05 PM »
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Ron Bearden
CSX N scale Archivist
http://u18b.com

"All get what they want-- not all like what they get."  Aslan the Lion in the Chronicles of Narnia by C.S.Lewis.

BCR751

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Re: Broken U-Joint
« Reply #8 on: October 14, 2017, 10:03:08 PM »
+1
Well Ron, you said the magic words.  "Remember, Atlas sold them to on the non-china Alcos RS3/11 late and RSD4/5. GP7/9.  and U25B."  As I read that I remembered I have an old Atlas/Kato RS-3 that ran horribly and I was going to make a slug out of it.  I dug it out, took it apart and there they were....not one but four of the little four-fingered couplers ( I should have used that word instead of u-joint in the first place :facepalm:).  This was one of the locos that didn't have a flywheel and used those couplers on the motor shaft and the worm.  I VERY CAREFULLY took one off, put it on the F7B and voila, it once again runs like a dream.  Thankfully, it fit on the shaft. 

Once again, thank you Ron for coming through with the good information.

Doug

trainforfun

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Re: Broken U-Joint
« Reply #9 on: October 15, 2017, 10:27:42 AM »
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For future Bearden modifications :
I did a lot of these modification and I have never remove the "4 pin forks" or whatever is the name , I just cut the bearing in 2 with an exacto .
I was always afraid that the joints would slip if I remove it once .
Thanks ,
Louis



BCR751

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Re: Broken U-Joint
« Reply #10 on: October 15, 2017, 01:31:48 PM »
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For future Bearden modifications :
I did a lot of these modification and I have never remove the "4 pin forks" or whatever is the name , I just cut the bearing in 2 with an exacto .
I was always afraid that the joints would slip if I remove it once .

Good tip.  I'll keep that in mind.  But, what if I need more bearings :o :D

Doug