Split Universal joint repair

[Desert Rose]

I purchased 25 new Bachmann SD40-2 engines prepping for my retirement. I inspected 25 SD40-2's, drive trains, 6  universal joints where split. I am in the aerospace industry and have all kinds of structural adhesives for gluing spars and stuff together. So, in the turbine shop I found a 30+ year old bottle of Loctite 271 thread locker. I'm in the kitchen, the oven is running about 200°F, this is where I get a lesson in crossover chemistry for model trains. Loctite likes a flat clean surface, the inner surface of the universal joint hub is flat enough, the outer surface of the worm gear shaft is flat enough, I cleaned off the universal joint hub and worm gear shaft with electro-wash cleaner degreaser (plastic safe) P/N: ES1210. Loctite likes oxygen starved places with tight fits, I put a drop of Loctite 271 in the universal joint hub and a drop on the worm gear shaft, with my thumb I pressed the universal joint hub onto the worm gear shaft flush with the bottom of the universal joint arms. Now you have a thin oxygen free layer of Loctite tightly between the universal joint hub and worm gear shaft. Now you let it cure overnight. However, I sped up the process so I could see the results. I took the gear drive and chucked it in the oven on the cookie sheet for 60 seconds at 200°F then pulled it out and let it cool. I tried to pull the universal joint and worm gear assembly apart with my fingers, I couldn't pull them apparat. 



Clean off the universal joint hub and worm gear shaft with the electro-wash cleaner degreaser (plastic safe) P/N: ES1210. Inspect the outer end of the universal joint hub for splitting or separation of the universal joint and worm gear shaft.


                                                                                         
Apply a drop of Loctite 271 in the clean universal joint hub.



Apply a drop of Loctite 271 drop on the clean worm gear shaft.



Inserted the worm gear shaft into the universal joint hub receptacle. Pressed the universal joint hub onto the worm gear shaft flush with the bottom of the universal joint arms, remove excess Loctite. Put the universal joint hub and worm gear assembly in the oven on the cookie sheet for 60 seconds at 200°F then pulled it out and let it cool. Inspect the universal joint for proper adhesion, Inspect the bearing for freedom of movement.

NOTE:  Do not allow any Loctite on the bearing, the bearing will
            seize up and not spin after curing!!



NOTE:  Loctite 271 is a high strength, low viscosity, red, methacrylate-based adhesive. It is a
            permanent solution. Once cured Removable by heating up parts to 500°F(260°C).
            If you screw it up, you can heat the assembly up to 500 °F which is the release temperature for
            the Loctite 271, clean it off with acetone and start over, or you can go to Bachmann Parts and buy
            their Worm Gear Assy. w/ driveshaft (Truck) (HO SD40-2) kit.



 

[jonathan]

Wow!  Great stuff. Thanks for sharing this.

Regards,

Jonathan