I recently got in a busted up SD70MAc Athearn Genesis engine that well was rough and rather than re-sell the engine for profit I decided to keep it. I am turning the engine into a flared radiator 70 with the phase II cab to increase my UP roster.
I first tore the whole locomotive apart right down to the gears in the trucks. I then soaked all the drive axles and gears in soapy water to clean out all the gunk and crud. After cleaning everything up I started to reassemble the locomotive.
When putting the trucks back together I noticed the gears really turned hard. The trucks consist of 6 small gears and 3 drive gears which were assembled correctly. I then added a fair amount of labelle 106 grease thinking that working it in would help the gears turn easier, they did not.
I then took out all 12 small gears and drilled the holes out just a bit larger and then put them back in and now problem solved. My question is about the ramifications off doing this. Will this create any long term damage to the gears. I didn’t overdue drilling them out so the gears are not binding and do not move around hardly at all they just have a bit larger axle opening.
Just curious if anyone else has had to do that and if so what was the long term effects of doing so.
If you didn’t overdo the hole re-sizing you are probably going to be OK. The only problem I can see is possibly an effect on the meshing of the gears causing an increased noise level. It willbe interesting to see your long term results and what others will have to say on this.
Did you actually check each gear withing the case individually for fit and rotation? Was there any possible twist or rack of the case halves once covers installed? The tolerances of these molded parts is generally right on. Are you saying that the assembled truck without the worm did not have free movement? I find it hard to believe that a truck of this quality would have issues. If by drilling and adding excessive clearance you may have created troubles w/ gear side play and proper meshing. Not sure if there is some inherent problem w/ these trucks and you have machined to clear it up. Let us know how well the assembled chassis runs. As said, I hope that future wear doesn’t cause gear wobble and mesh problems.
Many times the old BB “B” trucks would “snap” together and show a slight twist, I used to file the bronze bearing slot to allow all 4 wheels to sit perfectly on test track. The “C” truck would normally not do this, however there is that possibility. Any mismatch or twist of the halves could affect the gears on their “axles”
Never heard anything like this but considering the source of manufacturing, anything is possible. I have a couple of questions:
How did the individual gears spin on the pegs prior to drilling. In other words, did the gears tighten up after they were all installed or were they tight individually on the pegs?
Do the trucks sit on the rails squarely, with all wheels touching the rail heads equally?
Hey guys thanks for the replies. When i got the engine it didn’t run as the leads from the motor to the trucks were broken and so I just tore it down and started the process of fixing it back up. As far as the gears spinning before, not sure didn’t test them.
I opened the trucks up and the setup was really simple and so I never thought that this would have been an issue. But when the gears were put back in and the trucks screwed back together the gears were really and I do mean really tight. I tried flipping the small gears and still tight and some not turning at all.
The splines the gears sit on are tapered and when the trucks are screwed together those gears get pushed further up on those tapered splines and turning becomes very difficult.
Worse case scenario, is the gears are shot by me doing this and I just order a new set or two, I have replaced everything on this engine already so whats another set of gears or two.
Assuming you drilled out the bearings, and not the gears, and that you drilled them out to the correct diameter, then the only concern is how clean the drilling job was, and how smooth the inside of the bearing is.
It’s possible that soaking in the soap solution did not remove all of the hardened grease & when you drilled them out you merely removed the last of the caked on grease. That would be my guess because if you drilled them oversized you would be experiencing a problem…jerry