I've disassembled this GP40 so many times I could probably do it blindfolded!

The Santa Fe GP40 is now spinning quietly like a champion!

I tried many things to stop the screeching. I'm not 100% sure but, lubricating the motor shaft (as described by Len in this thread) seems to have fixed the problem.

I removed the motor and ran it unloaded on the bench, no screeching. I noticed that when I reassembled the unit...if I left the 2 castings screws slightly loose it helped. Then carefully seating the motor I think I found a "sweet spot" that allowed the 2 casting to mate without any squeezing required...Maybe there was some misalignment???

Thanks for all the quality input!

Thanks guys, I appreciate all the useful input!

Thanks BM

I've checked both gearboxes and made sure they're lubed and turning freely...I've turned the worm gear with my finger and made sure the plastic gears are turning the wheels. No resistance, I think they're good.

The motor is sealed, so How can I lube the motor shaft bearings? Can I apply contact cleaner to the motor bushes?

Could bad / intermittent electrical pick up from the wheels to the contacts (H61207-1) cause the motor to whine / screech?

I haven't contacted Bachmann. I figured that once I've taken it apart it the warranty is voided?

Thanks for the information.

Electronics isn't my area of expertise, but it's good to know why the wiring is like it is, and what purpose it serves.

I've got another post called "HO GP40 Motor Constant Screeching"...do you have any idea what might be causing the screeching?

Thanks for the input. This is much more than a hum...it's a horrible screech. I swapped the decoder board from another Bachmann loco that runs perfectly quiet, but the problem persists in the original loco. So, I don't think it's the electronics, unless they're causing the motor to screech somehow?

I've got to say that I'm really disappointed that Bachmann Quality Control allows a brand new loco with a huge problem getting to a customer. This problem could easily have been caught with the simplest of QC checks.

Positives: I enjoyed stripping it down and most of the components seem to be reasonable quality.

Negatives: Soldering of the wires looks like it was done by a 10 year old in a hurry, and a couple of soldered connections broke off during disassembly and handling.  Make sure you have a soldering iron handy if you're going to take apart.

Overall this is a BIG Bachmann fail...1 out of 10 (1 is generous)

What is the difference between HO GP40 motor with resistors Part # 63525 and without resistors Part # 63525-1?

Thanks!

I'm experiencing a constant "screeching" sound from a Bachmann HO Scale EMD GP40 Diesel Santa Fe Flyer DCC that came as part of the Bachmann Commander set.

I've stripped the unit to base components and lubricated everything. All parts are turning freely.

Could this be a problem a problem with the DCC controller onboard or is it a mechanical problem?

Thanks!