Sunset 3rd rail drive repair? FP7 and running the A and B together under TMCC?

Where are the cover plates that fell off? ….how are they attached to the truck? …….that’s step # 1,….then we’ll look into your running issue,…..my philosophy is always fix known problems first, then see what the locomotives do.

Pat

What ^^Pat said.  It's possible that the gearboxes were loose all along.  Lack of proper gear mesh would definitely impact starting / running characteristics.

You probably know this, but before attempting to run locos in an MU configuration, it's best to place them on the same track separated by a foot or two, and gradually advance the throttle until both units are moving smoothly.  I would test in conventional mode first, in case one of the locos isn't reliably receiving the command signal.  I'm not sure what boards were in those.  But if there's a momentum setting, I would set it to "low" in both locos for the initial test.  Observe the starting characteristics and any speed difference as you increase the throttle.

If one of the locos hesitates at start-up, it could have a mechanical bind.  Take the shell off and turn the flywheel by hand for 15-20 full turns, you should be able to feel if it's sticking.  It might also be necessary to separate the lower drive shaft and check each truck separately.  Check for rubbing brake shoes or debris jamming the wheels.

If the issue is some sort of programmed starting delay, or the on-board circuitry is getting out of synch with regard to forward, neutral, and reverse then it might be preferable to power both units from just one of the TMCC boards.  These are single-motor units if I recall.  Of course you would have to add a tether between units.  But I imagine that you wouldn't ever run the B unit by itself.  And by tethering, you would never have to sync them again!

If you do the test, perhaps you could post a video.  In any case, don't give up, let us know what you find!

I have the cover plates and screws that fell off the inside axles,   you can see them still attached to the outside axles. 2 very short screws hold them on.

OK I will take them apart and look further. Will that TMCC board run both motors they pull a lot of amps?

Thanks for tips. Will take a look tonight.