Simple/quick solution for broken universal inside flywheel in Atlas diesels

[Dirk Jan Blikkendaal]

For my RSD-7 and RSD-15 projects (see WWW.ATSFNSCALEMODELS.COM) I needed Atlas C-628/630 locomotives (chassis only). So I bought a number of used/older ones on eBay. In a few cases the small black plastic universal joint inside one or both flywheel(s) on the motorshaft was broken or slipping. The problem is easily recognized: turn on the power and if the wheels in one or both trucks stop spinning when you apply a little pressure on the shell while the motor keeps going, the little black ring/universal inside the flywheel is cracked/slipping. I tried ACC glue with some succes but found a much simpler and better fix.   
First take some tape to protect the motor against the filing/grinding/drilling you have to do. The tape has an added advantage: the motor will not turn anymore during your work. File or grind (motor tool grinding disk) 2 small flat spot 180 degree opposite each other on both flywheels halfway lengthwise. Drill 0,5 mm holes in the flat spots towards the motor shaft.  Insert a short length of Tichy Train 020 brass wire (part # 1103) dipped in ACC. Cut/grind/file of the exess on the outside of the flywheel.
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I also used a flat file (about 1,2 mm thick) to clear the slots in the universal joint
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The position of the two holes/brass pins is not very critical as long as they are just about in line with each other. There is more than enough play (1,2 mm wide slots versus 0,5 mm thick tabs) to ensure a friction free connection, which will never break down anymore.........! The changes to the flywheels will not cause any noticeable unbalance.
It sounds like a long story but taking the chassis apart (clean out the thick grease in the meantime and replace with some light oil - your engine will run much smoother) and reassembling the engine take mores time than the work described above. Good luck, Dirk Jan Blikkendaal

[peteski]

Hopefully this doesn't get the flywheel out of balance, increasing motor vibration.

[coosvalley]

The changes to the flywheels will not cause any noticeable unbalance.

Hopefully this doesn't get the flywheel out of balance, increasing motor vibration.

No more time off in Poland for you!

I agree with you, though, and that was my first thought as well.

Are replacement parts not available from Atlas?..I've noticed they've basically stopped re-stocking parts, so this is a decent work around for for the correct parts if they are unavailable..

[bman]

Are replacement parts not available from Atlas?..I've noticed they've basically stopped re-stocking parts, so this is a decent work around for for the correct parts if they are unavailable..

Atlas parts have been hit or miss on re-stocking parts at best as of late..  The male universal for the 628/630 shows as a pre-order at the moment.  So there's hope.  How much I can't say.  They re-stocked the high nose GP38-2 bodies a few months ago.  Gobbled up a few to use for future use.

As far as the cracked universal, I have some Loctite Threadlocker Red that I use for other hobbies and interests.  I wonder if it will work on these little universals?  My 628 is fine for now and I'm keeping my fingers crossed.

[Cajonpassfan]

Nice fix Dirk, but it's things like this that drive me nuts: time consuming precision work required to solve what should be a simple little two-bit problem. Just how many expensive inoperative locos do we collectively own for which simple plastic parts are unavailable? I'd much rather be spending my precious modeling time building things (like your cars and tenders).
Rant over,
Otto K.

[coosvalley]

it's things like this that drive me nuts

Me too. First I had a brand new, but older, SD26 do this, still unfixed. And then my S2s started cracking axles, and the replacement ones I got are likely to crack soon too

Now I know why folks get frustrated enough to say things like "steaming yard loaf"..

[peteski]

No more time off in Poland for you!

I agree with you, though, and that was my first thought as well.

Are replacement parts not available from Atlas?..I've noticed they've basically stopped re-stocking parts, so this is a decent work around for for the correct parts if they are unavailable..

Ok, it was early morning (for me) when I read that, and I don't drink coffee. 
Regardless, I'm still worried about the vibration. 

If these are those donut-shaped couplings with 2 tabs sticking out of them, if a replacement is still available, my fix is to ream their opening slightly so they are still press-fit, but much looser than original, then clean and degrease the motor shaft and the coupling, then glue the couplings to the shaft using either CA or Loctite.  The looser fit will prevent the stress-cracking of the coupling while the glue holds it on the shaft.

But if the replacement coupling is not available then another method (like thos one for example) will be needed.  Atlas admired that this was not one of their best designs.

[peteski]

And then my S2s started cracking axles, and the replacement ones I got are likely to crack soon too

Now I know why folks get frustrated enough to say things like "steaming yard loaf"..

Um, but that is a model of a Diesel loco . . .
 
 

[Dirk Jan Blikkendaal]

Gentleman,

First: I could not locate replacement parts + postage/handling on a few of these (if available) would be quite excessive for me (Europe).
Second: its a much quicker fix (and more definite + cheaper) than waiting for parts.....a long time.
Third: regarding vibrations: the holes you drill are filled with the same material (brass wire) and the scratches on the outside are minimal. Given the weight of the anchor + flywheels the disturbance is almost nothing. I tried it on 2 motors and nothing happened:  no vibrations and no extra noise.
Fourth: its only my suggestion to solve this problem (for good) and it works perfectly for me.  I tried ACC first  but even that came loose...... given the location there is not much room for other glues if you want to keep a flexible joint......
Fifth: I agree very much with Otto that we all are not waiting for these kind of troubles. Its a very good running motor except for this very weak design point...... 

Happy N scale railroading to all of you, Dirk Jan Blikkendaal