To Railsplitter. Thanks for the info. That is really weird that they would package it with a coupler and that they would only list it under GP35s.

I have an older Spectrum DD40. One of the plastic pieces that connects the drive shaft and the gear shaft is slipping on the gear shaft. The parts department does not seem to carry that piece. Does anyone have any idea about how to repair or replace that piece. I have tried using a small amount of various glues, but that does not last long. In my opinion that part seems prone to failure since it is thin plastic and it only depends on friction to stick to the gear shaft.

Thank you for your responses. Since Bachmann would not replace the GS4 with another one I decided to try and fix mine. I removed the damaged wheels and axles and cleaned them with mineral spirits to get the grease off. Then I cleaned them in hot soapy water. When they were dry I glued them with CA, being very careful that they were in gauge.

The axles were cracked lengthwise, but since the wheels had a metal ring that surrounded the end of the axles I figured that would supply support to the end of the plastic axle. I figured the CA would basically serve to keep the wheels from sliding off the ends of the axle.

I ran the locomotive for about an hour pulling its normal load of 2 express reefers and 7 Athearn passenger cars. It worked great so far! The RR club I belong to is setting up its modules at the mall for the next week. I will probably take the GS4 and its passenger train and give it a work out.

Thank you for your responses.

I did contact Bachmann service department. Their suggestion was to send it in and they would replace it with a smaller steam loco since the only GS4s they had were the new versions. I offered to pay the difference to upgrade but they said that was not possible. The previous responder mentioned the quality of my 20+ year old loco. My question is, how likely would it be that a replacement loco would have the same problem or one of equal seriousness?

I have not decided wether to try and glue the axle or send it in to Bachmann to be replaced.

I have a Bachmann GS4 that is about 20 years old. It has run very well until this last weekend. I put it on the track to run and it ran around the loop one time and then the rear two drivers on the right side fell off. Has anyone ever had this problem before?

Upon examination it looks like the drivers have a short metal axle with square end, that fits in the end of the plastic center section of the axle. Are these supposed to be a press fit or were they glued in some way? If I clean all of the grease off will CA glue work to attach the drivers to the axles?

Any observations or suggestions would be appreciated.

One of the most important items that you need is a NMRA gauge. If you have one you can check your wheel spacing, flange size and track spacing. If any of these are out of gauge it will lead to a lot of problems.

I have an HO Bachmann Spectrum DD40AX that runs very well. It is one of the pre DCC ready models. Has anyone installed a sound decoder in a DD40AX?

I understand that the prime movers are the same as what was in a GP40. Is there any way to use a sound decoder for a GP40 and make it sound like 2 prime movers?

I have a HO Bachmann Spectrum Union Pacific GP-30 shell that is about 6 years old. I want to transfer it to a current Spectrum GP-30 frame that has DCC on board. In order to do that I need to glue a couple of short styrene tubes to the bottom inside of the shell so that I can screw the shell to the frame. I have tried both styrene glue and CA and neither seems to adhere to the shell. Does anyone know what kind of plastic is used for the shell.

I called Bachmann and asked them but they acted like it was a dumb question. They said I would need to ask the Chinese! Surely someone at Bachmann must give the Chinese some sort of specs when they order something.

FYI. The older Spectrum shells snapped around metal ridges on the side of the fuel tank. The newer Spectrums have a screw on each side of the fuel tank that screw into the shell.

The plastic pieces sound like some that came with my Spectrum DD40AX that I purchased recently. They are roughly 1" x 1.25" and they have two small holes, one in each corner along one side. I have no idea what they are.

I am considering using optical sensors to activate crossing signals on my HO layout. I want to embed them in the roadbed between the ties. I like to run my trains in a "night setting" so there are no ceiling lights on, just building and street lights. How much difference do optical sensors need between light and dark. Will a nearby street light on the layout provide enough light to work? Can most sensors be adjusted for sensistivity?

From what I understand IR sensors are usually placed beside the track and I do not have any place to hide them.

I have an HO scale Bachman GS4 that is about 7 years old, which has run very well until the last time I put it on the track. It now has a grinding noise when running at slow speed. When it is running fast the sound is not noticeable. I do not know if it goes away or is just covered up by the normal noise.

I removed the drive wheel cover plate and lifted the center drive axle so that its gear was not engaged to the rest of the gear assembly. I could still hear the sound at slow speed. This seems to indicate that it is something in the motor or worm gear assembly.

Any suggestions about what to do next?

I understand that the DD40AX is two GP40s on one frame. You may be able to modify some GP40 handrails. I noticed on Walthers that they have handrails from Smokey Vally RR Products for a GP40. They are specifically for a Bachman GP40. The part # is 676-12.

I have an Athearn Challenger and I think it runs wonderfully. It has run on my own layout and the club modular layout (which is not ideal somethimes). The only time it has ever derailed is when it encountered a turnout which was not set correctly. Both layouts are DC so I have not been able to try it on a DCC layout and hear its full sound potential.