Bachmann HO GP38-2 Fix
I hope this info is useful or helpful or at least informative for you.
Per one of my other topics on this Forum I’ve been tweaking some of Bachmann’s GP30s and 35s to the point where they are almost silent runners. If you grade Atlas locos as “A”s in the “silent department” when pulling heavy trains, then these Bman GP 30s and 35s now operate between A- and B+. And, this hasn’t changed after I’ve added about 2.5 to 3 ounces of weight to each loco.
I’ve had one Bman GP38-2 (has an almost empty computer board and is non-DCC) for a while and finally decided to tweak it like I’ve done to my GP30s and 35s – lubing, add weights, add new 3-13 volt LED soft white headlight, take out the computer board, etc. After finishing this with the GP38-2 I thought I had it right, but it when running the engine it produced a strange noise. After listening to it I addressed the only thing I could figure, and I was right the first time (doesn’t happen often – I’ll admit I tried 7 different “fixes” on Bman’s SD40-2s’ wheel chattering and failed; returned most of them.) After fixing the problem the engine turned into a very quiet runner, and a smooth, fine-puller (the engine weighs 14.5 ounces as is, and I added 2.25 ounces toward the front to balance it out. It has space for more weights but I wanted it to MU well with the other Bman GP30 and 35 engines, and it does (the 30s and 35s come about 12 ounces each and I added 2 to 3 ounces each). And I think all three models – 30, 35 and 38-2 – use the same motor and gearing, even though their frames differ.
So, what was THE problem? On this GP38-2 (and probably all the other GP 38-2s) the two plastic split-jaw pieces on the motor drive shafts bind the drive shafts’ ball and T arms. The split-jaw pieces’ openings for the T arms AND its ball are not parallel -they taper inward toward the motor.
Out came the Dremel tool with cut-off disk and I carefully cut and ground out the open jaws so they were parallel and wide enough to accommodate the T arms with a little slack to spare. I also found that a 1/8th drill bit was the perfect size to ream-out the open jaws’ “tunnel” so the ball on the end of the drive shaft would go in and out without binding. And that was so easy I just used my fingers to rotate the drill bit. When finished I cleaned up the split jaw pieces with a sharp hobby knife and a rag, lightly oiled them, reassembled it all, and they now work great with no noise.
I’ll admit I’ve only had this GP38-2 running for a couple of days, but since it’s been fine so far I think it’s fixed for good.
As info, if you don’t use DCC you can still find some non-DCC GP38-2s on-line; they cost less than the ones with the DCC boards. Also, removing the non-DCC fake computer board in my engine is what provided the room for the weights.
I’m 99% sure the non-DCC engines are exactly the same as the ones with the DCC boards except for the road number change and a fake computer board (almost nothing on it). I say this because earlier this year Bman customer service answered this question about their GP35s – they are the same internally - and I found this to be the case.
Lastly I know that for many of you these types of fixes are a pain, and that by purchasing for example an Atlas engine (even a Trainman) you almost always avoid any of this irritating, not-supposed-to-be-there tinkering and sometimes exploration hassles. On the other hand for me it’s satisfying to take a “cheap” engine, spend about an hour on it, and see it running quietly and pulling just as well as an engine that costs twice as much or more.
DougC
I hope this info is useful or helpful or at least informative for you.
Per one of my other topics on this Forum I’ve been tweaking some of Bachmann’s GP30s and 35s to the point where they are almost silent runners. If you grade Atlas locos as “A”s in the “silent department” when pulling heavy trains, then these Bman GP 30s and 35s now operate between A- and B+. And, this hasn’t changed after I’ve added about 2.5 to 3 ounces of weight to each loco.
I’ve had one Bman GP38-2 (has an almost empty computer board and is non-DCC) for a while and finally decided to tweak it like I’ve done to my GP30s and 35s – lubing, add weights, add new 3-13 volt LED soft white headlight, take out the computer board, etc. After finishing this with the GP38-2 I thought I had it right, but it when running the engine it produced a strange noise. After listening to it I addressed the only thing I could figure, and I was right the first time (doesn’t happen often – I’ll admit I tried 7 different “fixes” on Bman’s SD40-2s’ wheel chattering and failed; returned most of them.) After fixing the problem the engine turned into a very quiet runner, and a smooth, fine-puller (the engine weighs 14.5 ounces as is, and I added 2.25 ounces toward the front to balance it out. It has space for more weights but I wanted it to MU well with the other Bman GP30 and 35 engines, and it does (the 30s and 35s come about 12 ounces each and I added 2 to 3 ounces each). And I think all three models – 30, 35 and 38-2 – use the same motor and gearing, even though their frames differ.
So, what was THE problem? On this GP38-2 (and probably all the other GP 38-2s) the two plastic split-jaw pieces on the motor drive shafts bind the drive shafts’ ball and T arms. The split-jaw pieces’ openings for the T arms AND its ball are not parallel -they taper inward toward the motor.
Out came the Dremel tool with cut-off disk and I carefully cut and ground out the open jaws so they were parallel and wide enough to accommodate the T arms with a little slack to spare. I also found that a 1/8th drill bit was the perfect size to ream-out the open jaws’ “tunnel” so the ball on the end of the drive shaft would go in and out without binding. And that was so easy I just used my fingers to rotate the drill bit. When finished I cleaned up the split jaw pieces with a sharp hobby knife and a rag, lightly oiled them, reassembled it all, and they now work great with no noise.
I’ll admit I’ve only had this GP38-2 running for a couple of days, but since it’s been fine so far I think it’s fixed for good.
As info, if you don’t use DCC you can still find some non-DCC GP38-2s on-line; they cost less than the ones with the DCC boards. Also, removing the non-DCC fake computer board in my engine is what provided the room for the weights.
I’m 99% sure the non-DCC engines are exactly the same as the ones with the DCC boards except for the road number change and a fake computer board (almost nothing on it). I say this because earlier this year Bman customer service answered this question about their GP35s – they are the same internally - and I found this to be the case.
Lastly I know that for many of you these types of fixes are a pain, and that by purchasing for example an Atlas engine (even a Trainman) you almost always avoid any of this irritating, not-supposed-to-be-there tinkering and sometimes exploration hassles. On the other hand for me it’s satisfying to take a “cheap” engine, spend about an hour on it, and see it running quietly and pulling just as well as an engine that costs twice as much or more.
DougC
