Recently purchased a Bachmann Spectrum GP30 that makes a lot of growling noise when running on track. Upside down with power applied to wheels, no noise. There was alot of lube in the gears, so I cleaned out what I could. Also, Does anyone know if this body would fit on an Athearn GP35 Chassis?
The growling could be from the motor, since Bachmann’s gearing is typically very quiet. Do you feel a lot of vibration when you run it? I’ve found that vibration from the motor, flywheels, or universals is almost always the biggest source of growling noise in anything.
No, it doesn’t have any vibration to it. Plus, it does not make the noise when the loco is upside down with power applied to the wheels.
In that case, it could be the worm (spiral shaped gear) in one or both trucks. Bachmann’s design for mounting the worm is rather poor, but it can be adjusted to work fine. The bronze bushings must be perfectly aligned to get rid of any binding and noise, and it can be a little difficult to do so. The back (or front) bushing is mounted in a post which often gets flexed out of position, so I use a very fine flat-blade screwdriver to pry the top of the bushing out of the hold just slightly. Once the worm can be turned all the way around completely freely, the bushings are aligned.
The other problem could be a damaged worm. Check to see if there are any small scratches or dents around the edges where it contacts the idler gear. If there are, it is possible to use very fine sandpaper (600+ grit) to smooth it out, but it may never be perfect again.
I didn’t know Bachmann had GP30’s in the Spectrum line. I have two of the under $100 DCC OnBoard GP30’s and they make the same noise. I’d be interested to find out what causes it.
They do, or did maybe. About a year ago I bought a NIB Spectrum Pennsy GP30. Not sure of manufacture date. The Spectrum GP30’s might have become the DCC On Board line.
My Spectrum GP30 (and a Conrail GP40) both make the same noises that the OP is talking about. I’ll have to look into tweaking them if it does help.
None of the DCC On Board engines that I have though have this issue though, they are all pretty quiet runners so far.
Just another example of some of that “fine” Bachmann quality…;-]
Mark
I agree with Mark… I’ve tried it all, disassemble, reassembly, cleaning old oil and reapplying a tiny new drop, checking the worm gears… And none of it got rid of the darn noise on my Spectrum GP30! Heck, as long as it runs well, I’ll keep it, but see if I’ll be a future customer… [:P]
Bachmann’s GP30 started out as one of their usual well detailed models with a 4-wheel drive truck and plastic frame (it was also available from Lionel in different railroad paint schemes). It was later upgraded to the Spectrum line in the late 80s and given separate grab irons and windshield wipers, and an all wheel drive and electrical pickup mechanism with a split metal frame and flywheels. It remained a Spectrum model until it was downgraded to the current DCC Onboard line, where they removed the flywheels, frame blackening, and some of the weight.
That’s odd that everyone’s getting growling noises. The gearing in my DCC GP30 is almost totally silent, but the motor does have poor bearings which are amplified by the shell. It did used to have a rough humming noise that came from the DCC board’s low frequency PWM motor control. I removed the DCC board and put in my own diode controlled lighting, and now the humming noise is completely gone.
My other Bachmann diesels were very nice runners straight from the box. The upgraded Spectrum 8-40CW and F40PH do have a low growl from the design of the gearing, but they’re still pretty quiet and run very, very smoothly.