Bachmann SD40-2 issue & report

[DougC]

Hello, I'm a newbe here but have been model railroading since I was about 13 years old (starting with an American Flyer S Gauge set). I'm 62 now and have had my 2nd HO model RR layout for the last 17 years.

Even though this model railroad forum site is not the biggest, to me it's one of the friendliest and most helpful. I really liked the tutorial on yards. Thank you all for your many comments.

I run 3 trains of about 55 cars each plus a couple of small trains, have no grades (on purpose), and it's all DC. (As far as I'm concerned progress peaked with the invention of Little Debbie Chocolate Donuts, so no DCC for me. )

This year I sold all of my old Athearn engines - all diesels, mostly GP35s (they easily pull some small trains around my 12" radius curves; my normal curves are 22", 19" and 16" radius.)

Anyway I purchased some Atlas Trainman and Bachmann Spectrum diesels. Except for the Bmann SD40-2s all the engines seem to average 2 out of 3 "good" ones - i.e. they run quiet (or quiet enough) and smooth. The "bad" ones do run but they're noisy, and/or a little tight and don't run smoothly MUd, and/or draw too much power (one Atlas.) Since I'm better at trouble-shooting and fixing railcars I've set these "bad" engines aside.

To the Bmann SD40-2s - I got about 10 because I like SD40-2s (I used to ride in the real ones a lot when I was head-end braking on the MoPac in the MO Ozarks in the late 1970s), they were reasonably priced (Modeltrainstuff), and I figured (from what I'd read on the net) possibly 1 out 4 would be fine as-is and I could MAYBE fix the others.

After receiving the first few I found they looked very nice, overall were engineered well (the exception is below) and visually ran smooth as silk with no derailments on all my 22" and 19" radius track (Atlas Code 100 flex track, and all track switches are old Model Power electric #4s - which worked great after I spent 10 minutes on each one tweaking them 15 years ago.) Now to the problem.

Three of the ten engines were pre-DCC board and the flat part of the gear teeth in the trucks were extremely rough (I ran the point of a hobby knife over some.) So they were extremely noisy (wheel chatter on the rails) - I'll say 90% unpleasant. Bachmann's service dept. (which is pretty good for such a large company) at my request sent me 6 new trucks. These cut the noise from 90% to 20% - not bad. However 20% noisy is still unacceptable to me.

Of the other 7 engines (all with DCC boards) 2 were about 5% noisy and I've been using them regularly. The other 5 of these 7 are all about 20% noisy out of the box. And yes I've run the point of a hobby knife over the flat part of some these gear teeth and they feel smooth.

Over the past few weeks I've taken 2 of the 8 20%-noisy engines and over time as I thought about it did about 6 different "fixes" between them. None of my "brilliant" ideas have worked (including shimming the worm gear shaft and interior shaft bushing so neither can jump around), and in one of the fixes I screwed up something enough that I just neutered the whole thing and turned it into a gelding (dummy engine.)

I've noticed that (a) the worst wheel chatter comes from the lead truck (no matter if the engine is cab-forward or not), (b) both trucks chatter on their leading end, and (c) most all the chatter comes on straight track (they usually really quieten down on curves.) I did some extensive testing of pushing the leading edge of a truck down with weights or shims because the pivot point of the trucks are not centered on the truck but off-set toward the center of the engine. Didn't matter or I didn't do my test well enough.

Did I try asking Bachmann about this? I asked one service person who was nice but clueless and he said talk to Lee Riley (VP Production I think.) So I've dropped this approach.

I've wondered if it's the angles OR spacing of the slightly-beveled (slanted) gear teeth in the trucks - if this could maybe cause the chatter. I just looked at a set by popping the bottom truck cover off. The gears' teeth interfaces form alternating up-side-down and right-side-up "V"s all the way down the gear chain. I guess that's the way they're supposed to be. Any of you know anything about gears and their teeth interface?

Once when an engine was on the track and running I stopped its forward motion and put my finger under the lead wheels - the wheels vibrated noticeably.

Anyway, does anyone have any thoughts, ideas, or have you done any testing on these? Have you heard or read of any fixes or know where I could look? Or do I need an aftermarket set of gears (that don't exist as far as I know)? Do any of you have 3 or more of these engines and they all run basically about 100% quiet out of the box (implying I got a bunch of unusual ones)? Or are these SD40-2s generally just not worth your (our) time?

As info I've not done the Pearl Drops Toothpaste-on-the-gears routine. From all I've read this "usually" helps gear growl but almost never fixes it.

I could have asked Bmann for newer trucks but I figured that the 6 new ones I did receive (chatter 20%) would be same kind I would get if I asked for more.

Thank you for your patience in reading through all of this and any info.

DougC

 

[Larry]

Well, If the Athearns are chattering that could only mean 1 thing. Broken axles. The wheel axle pushes in from both sides of the gear housing. When the axle breaks free from the gear housing it slips & causes the engine the jump around, derail, vibrate or slip bad w/a long load of freight cars. I've bought brand new engines(or thought they were brand new) from friends, Ebay & trainshows & hobby shops & had some w/broke axles.
I buy the axles from Athearn by the dozen. As far as Bachmann & Kato goes, same problems. Also, I have a tuneup How-To that I printed off of the internet, can't remember where, but, maybe some of the other guys can tell you. If you want my copies, PM me & I'll send them to you.
Also, you can get a lot of noise from loose rubber motor mounts or loose screws on the newer motors to frame engines. Sometimes a loose rubber mount will be loose on 1 end & tight on the other which causes the motor to set cockeyed in the frame. It puts a strain on the shafts & causes the engine to chatter or make a grinding sound.
I could go on forever about problems that I have found & fixed in the past 10 years. I've been model railroading since 1961 & just started repairing my own stuff 10 years ago.
I'm almost 72 & i guess you can say, I've seen it all, but, you're never to old to learn something new, so, keep asking & someone on this forum will find a solution or help you fix it or if you live close enough to someone here on the forum they will come to your house & fix it. LOL

 

[DougC]

Thanks for info

Larry:

Thanks for your info above. I'd not thought of broken axles (or even broken gear axles) or skewed motor mounts; I will do some checking.

Also I sent you a PM.

Doug

 

[bobwrgt]

I have also had the problem with a Bachmann SD40-2 front truck. I think it does not have enough engine weight on it. The truck housing might be bent (warped) OR the axel groves not all at the correct depth. The weight is not evenly distributed on the axels. . The only way i fixed it was to call Bachmann and they sent me a new truck at no charge. That did the trick. Never did figure out why the old one made noise. Tried all my tricks.
I did have another Bachmann engine with a very noisy truck and found that all the weight was on the center axel only. It would pivot up and down on the center axel. I filed the center axel grooves deeper and the noise went away. The engine also pulled better after the fix.

Bob

 

[DougC]

Bmann SD40-2 trucks

Bob:

Thanks for the info. How long ago did you order and receive the new truck?

I think I'm beyond the freebe time but I would gladly pay for some new trucks if they worked (quit chattering.)

I'll admit if one or more of the gear's axle spacing is off - whew, I'm not sure I would know how to fix that. And of course I don't know how find it either. Just had a thought - I could experiment by making an axle's shaft holes larger but I wouldn't know which way (up, down, sideways?) High probability here of ruining the truck.

Anyway pls let me know how long ago you received the new truck. I think I got my new 3 pairs of trucks in March/April/May time frame. Maybe they got a batch of newly engineered/machined trucks in since then. Thanks.

Doug

 

[bnsf971]

These locomotives do have Bachamnn's lifetime warranty. You can call them, tell them what you have, and if they want to send you replacement parts, or have you send the locomotive back to them for replacement.
I know they do charge a fee if the locomotive is more than a year old, but it's less than the cost of a new one.

 

[DougC]

Bmann SD40-2 problems

Terry:

Thanks for the reminder; I'd kind of forgotten about Bmann's warranty. I'll hold this as the last option (probably just a few weeks, well within a year of purchase) while I try a few more things out.

My thinking is that the units they send me will have the same problem; however I don't know that and maybe at least 1 or 2 will work fine. I guess if that worked I could, within a year, cycle back the "bad" ones, and receive 1 or 2 good ones in each batch, about 3 or 4 more times until I end up with all normal engines.

Thanks again for the reminder.

Doug

 

[bobwrgt]

It only took about 10 days to get the new truck back in June or July.
The Bachmann engines have a life time warrenty. I don't think there is a time limit on when they will not send new parts. I have received new parts for 3 year old engines. They don't make any money even if you sent in the engine with money for repair. The amount they charge isn't enough to cover their overhead.
When i received the new truck i was going to do some further work on the bad one to see if adjusting the holes would work. Since i had a new replacement if i screwed up the old one. Never got around to it since all 6 of the ones i have are running fine.
The front and rear trucks are the same. You could take out a good truck from one of your good units and compare it to the bad one.
I was also going to look at the way the truck is mounted in the frame. If the top plastic tab that clips into the frame is thick or bent it may not allow the truck to float up and down.
I have one engine that ran fine but i made it into a dummy to run with my sound engines so i can always use those truck if i get another noise one.

Bob

 

[DougC]

Bob:

Thanks for the info on when you received the truck. I can't imagine how you have 6 Bmann SD40-2s that ALL run quiet! That's great. It makes me wonder if Bmann put whole batch of bad ones together just for me! Just kidding.

I did check all the wheels on both trucks of one of the chattering locos to see if each of the 3-wheel sets were at the same level (i.e. the center wheel not protruding.) Using two different straight edges and my eye they looked perfectly level to each other.

Since I now have proof that it is possible to own a small fleet (6) of these engines that are all quiet and function properly, I think I'll go ahead and start proceedures with Bmann to exchange at least 7 of the locos (I think I'd prefer the locos vs. trucks since the problem MAY be further up into the motor/motor mount and/or drive chain - I'm just assuming the problem is in the trucks themselves.) Two of my "fleet" of 10 run okay noise-wise and Bmann may not accept the one engine I made into a dummy. I'll ask them.

Thanks to all who responded. I'll let you know how this saga turns out. And if you have any other ideas please post them - you know, an idea like using these engines as targets at the local shooting range.

DougC

 

[diburning]

The bachmann lifetime warranty is great, and they are slowly but surely improving their product.

What I've found with all manufacturers is that the gears may have burrs on them. They get ground off over time when you run the engine, but sometimes people take the gears out, clean the grease off, and file every tooth, or put in toothpaste to smooth things out. I do it the old fashioned way. I run the engine at full speed around the layout a few times and it usually quiets it down.

 

[DougC]

diburning:

Thanks for tip on loco gear noises. I hadn't thought of running them fast around the layout and then running them slow to see how they sound. I'll give that try.

DougC

 

[DougC]

All:

Well, I did run a couple of my 20%-chattering locos around the track, forward and backward, on full, about ten times each. They ran a little smoother but the darn noise didn't change. However I'm going to try and remember to do this to all my new locos.

So I emailed Bmann service explaining all the work etc. I did and asked if I could exchange some locos for other loco models. They wrote back and said yes, let us know what you want, and send your engines in! As some of you said, and I've read many places, Bmann has excellent customer service.

So 5 have been shipped with my request list - one 2-8-4 (if it works it will be the only steam loco on the RR), and 3 GP30s. Why these GP30s? I have 2 of Bmann's GP30s that run very quiet, draw little power, and MUd together pull my Train #3, a 64-car train, around two 300 degree, 16" radius, curves with no problems. I'm impressed.

As an aside, here is some info about my freight cars - 5 of the cars have metal wheels and the rest are all plastic wheels. My maximum car length is 52 prototype feet, and ALL the railcars' target weights are 2.5 to 3 oz. per car, no matter car length (I have 19 52' cars in the 64-car train.)

Also, on these "cheap" engines I always open them up and "oil around" - on about half of the motor shaft bearings when that little bitty drop of oil hits the bushing it disappears in a nano second - the bushing needed it.

Back to the topic, yes, I could have tried a few more things but to tell the truth I was/am burnt out on trying to make these SD30-2s run quiet. I have kept the two quiet SD40-2s, the one I turned into a dummy, and obviously the two that I had modified somewhat.

Thank you all very much for your input. Hopefully I can be of help in the future.

DougC

 

[pjohnson1980]

I have the same problem. Chatter in the front truck. I pulled the drive shaft and the gear connecting to the worm gear and the sound went away. I then noticed that the plastic coupling that the drive shaft snaps into that is attached to the worm gear shaft came off with the drive shaft. If this is slipping, in theory, it would cause chatter from the drive gears fighting the worm gear. I am going to try gluing that piece back place and see if that fixes it. It is the only place that could be causing the chatter on mine because i left in all the other gears and it's perfectly quite. I could leave it, but i lost a lot of torque with the front truck acting as a dummy. I'll let you know what happens. Otherwise it's $9 for a new front truck.