Troublesome Kato F7...

[strummer]

Flush with confidence after the recent (successful) tear-down and rebuild of my Kato-built Atlas U25, I felt I was ready to take on another project: this time a Kato F7, model #176-217.

Unlike my other Kato F units, this one needs a fair bit of "juice" to get going; once it's moving it runs ok, but I would like it to run as well as my others. So, with that in mind, I took it apart, and like the U25, I cleaned everything, carefully lubed as needed, re-assembled, and...

...it still runs less than perfect. Displays the same somewhat "sluggish" performance. Am open to any and all suggestions as to what to look for next.

Thanks.

Mark in Oregon

[Rasputen]

I would try running it with no trucks installed, and then with one truck at a time installed.  Maybe you can narrow down the source this way.  It sounds like something is bound up if the starting voltage is high.

[strummer]

Sounds like a good place to start; I will try that, and let you know.

FWIW, when I had it apart, the trucks appeared to be ok (no binding detected), but it's entirely possible I missed something.

Thank you.

Mark in Oregon

[mmagliaro]

I would think that the binding isn't in the trucks per se, but in the worm mesh between the motor and the trucks.
Running it with one truck engaged at a time will show you that.   Y

[mecgp7]

I've had the flywheel actually rub on one side of the frame if not installed correctly.

[bobdobbs]

Also check the motor brushes, you may have a a cracked one.

[u18b]

It needs some magic.

You need to Beardenize is.

http://u18b.com/wp-content/uploads/2013/03/Bearingblock.pdf

[peteski]

First question we need answered is which version is it?  There were several and they are very different.
http://www.spookshow.net/loco/katof.html

[strummer]

Peteski et al:

Thanks for all the input. I had hoped that by mentioning the model number (176-217) in my opening post, that would be enough info to determine what "issue" it is, but I guess not.

It came in the older(?) blue box, UP road number 1464. I suspect it originally came with Rapido couplers, as when I got it, it has a Unimate on the back, and a Micro Trains on the pilot.

Other than that, I don't know how to date this model...

Mark in Oregon

[u18b]

If it is blue box, then removing the inner bearing blocks per my link will make a HUGE difference.

As well as cleaning.

[superchief]

Mark, the blue box are the original run from the 80's, non free rolling trucks but very heavy and still good runners with the beardon block treatment, most are a bit noisey. the green box are the revised version with free rolling trucks and still very heavy (great pullers-and quiet) but both original and revised are NOT dcc friendly and the frames need to be milled. Also almost all parts are gone for these so if you need something you will need to pull it from a spare unit. the final run is the newer DCC friendly with free rolling trucks and about half the frame gone for the decoders and a cab interior and are great engines but just do not pull like the early runs, parts are still on Kato website for the lastest run. hope this helps, Gordon

[strummer]

If it is blue box, then removing the inner bearing blocks per my link will make a HUGE difference.

I had thought that about the U25, but apparently that wasn't needed; I guess I will have to try your treatment on this unit.

What's the best (and safest) way to pull the hex nut from the shaft?

Mark in Oregon

[u18b]

Totally remove the worm shaft.

I just hold the worm and pull on the nut.
It will come off even if a bit tight.

The article describes how the critical stem is adjusting the placement of the nut on the shaft.

I did this to a old blue box F unit and was AMAZED at how quiet and smooth it ran afterwards.

[peteski]

I had thought that about the U25, but apparently that wasn't needed; I guess I will have to try your treatment on this unit.

What's the best (and safest) way to pull the hex nut from the shaft?

Use your teeth! 
Seriously, it should come off just using your fingers.  If not, use the prongs of a pair of tweezers as wedges inserted between the bearing and the hex coupling (nut).

While in many instances it seems to work to quiet the mechanism, I'm not a fan of  removing the worm bearing.  But that's just me. Many modelers swear by it. However if there is a bind in the mechanism somewhere, I don't think removing the bearing will make it any better.  That is assuming that the chassis is properly aligned and assembled.  Removing the worm bearing simply creates more slop in that area. of the mechanism.

So your loco is the initial release (one in which the trucks have 2 metal frames in them?  I would loosen the fram halves, remove the trucks, re-tighten the screws and place it upside down on your workbench.  Then as it was mentioned earlier, hook up the thrittle output wires to the fram halves (you can just hold them with your fingers. Then crank up the throttle ans sww when the motor starts and how smooth it runs.   Also, since  there are flywheels, crank the throttle up high and then remove the power leaqds and see how long the motor coasts. If it it stops rather quickly then the problem is with the motor/worms.  If it coasts for a while (maybe around 2 seconds) then the problem is elsewhere.

Those trucks are fairly high-friction compared to the needle-point/bearing-cup trucks used nowadays. But they should still run freely.  If they had some sticky lubricant applied, that would create friction.  But if you cleaned them then they should roll fairly freely.

You really need to play a detective to isolate and find the problem (assuming that there is a problem and not that your expectations are just too high for this loco).    Does the U25 have trucks similar to the trucks in this loco, or are they the later low-friction ones?

[strummer]

Hmmm...well there you go.

I took your (and everyone else's) advice, and removed the trucks. I did just as you suggested; ran the mechanism for a short bit, and sure enough, the unit coasted for a few seconds after shutting down, so everything seemed good there.

I then re-checked the trucks for friction, sprayed them again with contact cleaner, reassembled everything, and viola! It now runs as good as my other F units.

Not sure what the problem was; it's almost as if it needed to be run a bit sans trucks, just to "loosen things up".....?

Thanks to everyone for all the input. I appreciate it.

Mark in Oregon