Noisy Bachmann 70 Ton Switcher

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Greg@mnrr

Section Hand
#1
I just received my new DCC equipped Bachmann 70 Ton Switcher and out of the box was very noisy, like a roto-tiller running on concrete.

I ran it for several hours for a break-in and the noise decreased slightly. I removed the shell and lubed all the gears and the motor bushings and the unit did get again slightly better. I ran it again for several hours without the shell and the locomotive was as quiet as a KATO unit. Put the shell back on and it was again noisy. Only two screws hold the shell to the chassis.

Read on the Bachmann Forum that some guys added sound proofing to the interior of the locomotive and that helped quiet the locomotive as they claimed the shell acted as an amplifier for the motor and gear noise. I never ran ito a problem like this before and have had noisy locomotives that after some lube and break-in ran quiet.

I know this isn't an expensive locomotive but Walthers Mainline locomotives run much quieter. I know Chet sent his back to Bachmann since it wouldn't run properly and Bachmann claimed that the motor "bearings" needed lubrication. His now runs fine.

Any ideas or suggestions?

Thanks.

Greg
 
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#2
I just received my new DCC equipped Bachmann 70 Ton Switcher and out of the box was very noisy, like a roto-tiller running on concrete.

I ran it for several hours for a break-in and the noise decreased slightly. I removed the shell and lubed all the gears and the motor bushings and the unit did get again slightly better. I ran it again for several hours without the shell and the locomotive was as quiet as a KATO unit. Put the shell back on and it was again noisy. Only two screws hold the shell to the chassis.

Read on the Bachmann Forum that some guys added sound proofing to the interior of the locomotive and that helped quiet the locomotive as they claimed the shell acted as an amplifier for the motor and gear noise. I never ran ito a problem like this before and have had noisy locomotives that after some lube and break-in ran quiet.

I know this isn't an expensive locomotive but Walthers Mainline locomotives run much quieter. I know Chet sent his back to Bachmann since it wouldn't run properly and Bachmann claimed that the motor "bearings" needed lubrication. His now runs fine.

Any ideas or suggestions?

Thanks.

Greg
If motor & chassis runs quite, start looking for an isolation fix. Try some small (thin) fiber washers between the body and chassis interface. .. OR the body may not be seating properly on the mounts.
 

bnsf971

AKA Gomez Addams
Staff member
#3
On that engine, the decoder tends to be a little "buzzy". The shell will make that sound worse. I've had a couple of them, and making aure all the little bits were secured to each other really helped. The cab is just clipped to the shell, and there are some other things not firmly secured. Those things will vibrate against each other, and contribute to the noise.
I also put a 1/4oz. stick on wheel weight inside the roof of the cab, which also quieted it down a little more. I'm not sure it the weight or sticky tape made the most difference.
It's really a matter of degrees with it, there's no one thing that you could point at and say "That's the culprit".
If, after all that, you still don't like the amount of noise coming from it, you can fit a replacement decoder inside. A decent one is less than $30 for a quality one.
 

Greg@mnrr

Section Hand
#4
Terry: I'll try the weight approach and tape a washer to cab roof since a little more weight is a good thing. The decoder seems to run quiet so I'll rule that reason out.

ShermanHill:
I'll also try to isolate the shell from the frame as you suggested and check to see ho the chassis is seated on the frame.

Thanks.

Greg
 

montanan

Whiskey Merchant
#5
I can't understand how the chassis can run quietly without the shell and then be noisy with the shell. He's mine and it runs dead quiet.

 

Greg@mnrr

Section Hand
#6
After several hours of working on the Bachmann 70 Ton switcher, I'm starting to think that there are several problems with the locomotive being noisy.

- The DCC decoder is partly at fault being of lower quality. And, the decoder is sending on and off electrical impulses (modulation) vibrates the motor.
- The loco will run best under DC control.
- With only two small points of contact between the frame and shell, the shell will act as a amplifier with it being loose and not tightly fitted .

Also, I found dirty wheel sets on one set of trucks.

I emailed Bachmann Friday I got a reply within 30 minutes asking for the model number, but as of today no return email from Bachmann. Before I do anything more I'll wait to hear from Bachmann.

Greg
 
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Greg@mnrr

Section Hand
#7
Chet: See above about the chassis and frame having only two small points of contact causes the shell to act as a amplifier. The locomotive without the shell runs as quiet as a KATO.

I only wish mine ran as quiet as yours on DC. Chet, thanks for the video and the time it took for you to film the video.

Just for kicks, tomorrow, I'll run the locomotive on the test track using DC power.

Greg
 

bnsf971

AKA Gomez Addams
Staff member
#8
Chet: See above about the chassis and frame having only two small points of contact causes the shell to act as a amplifier. The locomotive without the shell runs as quiet as a KATO.

I only wish mine ran as quiet as yours on DC. Chet, thanks for the video and the time it took for you to film the video.

Just for kicks, tomorrow, I'll run the locomotive on the test track using DC power.

Greg
Greg, see post #3...
 
#9
Did you go to "Ask the Bach Man" on their web site ? If you sent in your warranty card you can get a different one or even a different loco. Maybe you'll see the same complaints there, proving it's not just your engine, but all of them of that same type unit...
 

Greg@mnrr

Section Hand
#10
MHinLA: I did go to the Bachmann Forum and it wasn't much more help than this Forum and the good suggestions. I did contact Bachmann and they asked for the Item Number, but I haven't heard back from them.

Many of the owners of the Bachmann 70 tonner on the Bachmann Forum have the same complaints about the noise. I'm not alone.

Terry: Yes, I do believe that the shell is one of the main reasons for the noise problem since only two screws hold the shell in place. When I look at other locomotive there maybe be a combination of clips and the coupler screws holding down the shell to the chassis in more than two spots.

I don't want to start adding sound deadening material if the locomotive will be sent back to Bachmann.

The quality of the decoder is another concern. It could be modulating with the AC voltage.

Stay tuned.

Greg
 

montanan

Whiskey Merchant
#11
Try putting a couple of Kadee fiber bolster washers where the screws hold the body to the chassis if you have some. ????????
 

Greg@mnrr

Section Hand
#13
Worked on the Bachmann 70T and did a break-in of an hour at all speeds and lubed the universals on the drive assemble. The locomotive without the shell is so quiet. When the shell goes on that's a different story.

But I think I know why the locomotive is noisy with the shell on......

The decoder has six plastic retainers for the truck pick up leads and the motor. These retainer protrude enought to touch the shell at perhaps and many as six points of contact. I believe these retainers are transmitting the frame and motor vibrations on to the shell which amplies the sound.

The wires should be soldered to the decoder, but that takes time on Bachmann's part. I would solder them if I I think the locomotive will be improved and stay will me and not sent the loco back to Bachmann for repair or replacement.

Greg
 
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