MTH F3s - Wheelie Bars!

Now I'm going to have to look closer at mine. I have so many engines, I never got around to converting mine to 2 rail. I have run them as is and they were fine. I did order P&D fixed pilots, just never got around to mounting them.

I prefer modern stuff so these have sat around waiting for another rainy day.

Talk about wheelies? I had to think of this engine that I bought that's a shelf queen. She can't go around the layout even once without jumping the rails.

This is someone's attempt at a 2 rail conversion that doesn't work for me. It is another brand (L) that the electronics, also don't get along with my stuff. So it sits on the shelf. The wheel profile is very different (round tire edges) and the trucks swing wildly when the power is applied so that they jump the rails. Someone added screws to limit their travel?

So I also took mine apart to see what I'm up against. I tried to fit a replacement pilot that would need to be cut down. The problem is that it's shaped flatter and doesn't match this model's profile shape.

So I cut the tabs off of the MTH pilot and drilled new holes to body mount it. For some unknown reason MTH went thru the trouble of drilling and tapping holes that look like they'd work for mounting the KD couple. Trouble is they are drilled too far apart. So I'll have to make new holes and see what shimming is needed to mount the KD to the pilot.

I also found my PSC #56210 coupler pockets that I ordered to convert the Alco S2 switcher for KDs. Someone suggested to me on a previous post that they might be so small because they are for scale couplers. I threw them aside and now that I'm looking at them again, they are for either HO or even N scale and are packaged wrong. I ordered several things and waited for them only to find that nothing worked!!

 It gets frustrating having to do this work and move backwards with every step of the process. We all have limited time and resources and it's just plain frustrating to me. So things get thrown aside until I can start all over and figure out what and where things went wrong. URRGGG!

 I hope these trucks run on two rail now when I swap out the wheels.

I just ran mine around a quick run with the wheels swapped out to the scale wheels. It ran fine as stock. No wheelies, no derailing.

I can only guess then, that this maybe limited to people who convert to 3RS? Maybe it's the center pick-up rollers causing the jump? (without the weight of the large electro-coupler?) or something with your particular track or switches?

Mine ran good before as well as a stock 3 rail model. So I'm not seeing what you are here. I'll film a video and post again.

So are you saying it was fine with the 3 rail wheels and traction tires, but without the pilot and coupler?

I think if you are using scale wheels, you are probably less likely to see this. I swapped one of these guys to all metal wheels at one point, just as a test. It didn't do wheelies like that, but didn't pull much, either, lol. I think with the reduced traction of all metal wheels, either 2 rail or 3 rail, it's probably not an issue.

I think most engines with the pilot and coupler on them are probably fine as well. Just the 3RS combo of high traction, but no pilot/coupler that's an issue. For example, I have an early SD90, pre 3/2 convertible trucks, with the two real axles and the floating plastic axle in the rear of the truck. It does the same thing, but to a lesser extent, and not enough to derail. I'll see if I can grab a video of it at some point.

Engineer-Joe posted:

 

Just watched your video, Joe. Mine were fine with no load and light loads as well, even before the mod. The wheelies happened when they were pulling a decent load, or getting pushed or pulled by another engine.

Realistically, every engine with trucks like these is going to offload the front outer axle when it's pulling going forward (conversely, the rear outer axle will see increased load). That's just the physics of it. Just a question of degree whether it really presents a problem.

I did not test this engine with three rail wheels and no pilot! Sorry for the confusion there. I did not attach a train as the rear coupler on this lead A unit is still the dummy lobster claw.

I missed your comment that it's being shoved.

I will also test it with a loaded train and matching engines. I'm working on converting the rest of the A-B-A set and I will see how they'll run together then. I'm undecided on what to do with the connecting couplers and the tethers yet. The tethers seem to fight themselves mounted down low under the couplers.

I may move them up in the doors.

I am surprised there's any issue here as I have other MTH 4 axle engines that behave fine. I would think they are mounted the same and would act the same.

I have the Genesis, F40PH, some GPs, etc., in MTH 2 rail that all run fine. Maybe there's something different about this model's trucks that you are seeing?

Well...?

Here they are as a team working together fine. Maybe it is the fact that now they are 2 rail without traction tires. I could put those back in. I just don't think it's worth my time for the effort.

I can understand your points made above. I just feel it maybe a combination of factors for you. The traction tires maybe putting effort on tilting your trucks like you say, combined with the center rail rollers adding extra lift. If they also hit high parts of track joints or switches, that may add to your problems? That is just a guess on my part. You'd have to test further and I'm not seeing any issue here on my end so far. I'll have to run more and wait to see if anything develops. I just notice more (slight) jumping or bouncing on my 3 rail loop than my 2 rail with any equipment. I feel that the 3 rail track makes these things look slightly more toyish in operation vs. 2 rail.

 If I finish the conversion, I may run them swiftly in and out of my yards to create extra harsh environment. Maybe I can still recreate what you're seeing?

I have other issues to deal with first like the Atlas electro coupler not firing and the tethers and B unit conversion too.

Perhaps you've heard of "Armstrong brackets," developed by THE John Armstrong to solve similar problems with the 2-rail Atlas F-units from the early 1970s.  The issue reared its ugly head again when the Roco-designed high-pivot gear cassettes were re-used in the Red Caboose GP-9.  I've never heard of this issue in a vertical-motored drive. Not my favorite drive configuration, but variations of a truck-mounted vertical motor go all the way back to the General Models switcher of the 1940s.

I personally hate rubber tires.  If these locos were mine running on 2-rail track, I would replace the rubber-tired, grooved wheels with smooth tread wheels for better tracking and ground pickup.  Then I would add a little weight and/or a 2nd powered unit as needed.  My $.02.

Ted S posted:

Perhaps you've heard of "Armstrong brackets," developed by THE John Armstrong to solve similar problems with the 2-rail Atlas F-units from the early 1970s.  The issue reared its ugly head again when the Roco-designed high-pivot gear cassettes were re-used in the Red Caboose GP-9.  I've never heard of this issue in a vertical-motored drive.  Variations of this drive go all the way back to the General Models switcher of the 1940s.  

I personally hate rubber tires.  If these locos were mine running on 2-rail track, I would replace the rubber-tired, grooved wheels with smooth tread wheels for better tracking and ground pickup.  Then I would add a little weight and/or a 2nd powered unit as needed.  My $.02.

What?

Where do you see that I have rubber tires on my 2 rail conversions?

or are you looking at the OP's on 3 rail track?

Sorry Joe.  I assumed the original poster was planning to operate them on 2-rail track.  My mistake.

no harm. Just curious what I said wrong this time ! 

Engineer-Joe posted:

Well...?

Here they are as a team working together fine. Maybe it is the fact that now they are 2 rail without traction tires. I could put those back in. I just don't think it's worth my time for the effort.

I can understand your points made above. I just feel it maybe a combination of factors for you. The traction tires maybe putting effort on tilting your trucks like you say, combined with the center rail rollers adding extra lift. If they also hit high parts of track joints or switches, that may add to your problems? That is just a guess on my part. You'd have to test further and I'm not seeing any issue here on my end so far. I'll have to run more and wait to see if anything develops. I just notice more (slight) jumping or bouncing on my 3 rail loop than my 2 rail with any equipment. I feel that the 3 rail track makes these things look slightly more toyish in operation vs. 2 rail.

 If I finish the conversion, I may run them swiftly in and out of my yards to create extra harsh environment. Maybe I can still recreate what you're seeing?

I have other issues to deal with first like the Atlas electro coupler not firing and the tethers and B unit conversion too.

Thanks Joe, really good and interesting data points! Don't do any more on my account, lol.

I have a way of doing weird outside-the-box sorts of things, so it's probably just me. I'll have to take one of the springs off again and shoot a quick video though, just so you guys don't all think I'm crazy... 

Ted S posted:

Perhaps you've heard of "Armstrong brackets," developed by THE John Armstrong to solve similar problems with the 2-rail Atlas F-units from the early 1970s.  The issue reared its ugly head again when the Roco-designed high-pivot gear cassettes were re-used in the Red Caboose GP-9.  I've never heard of this issue in a vertical-motored drive. Not my favorite drive configuration, but variations of a truck-mounted vertical motor go all the way back to the General Models switcher of the 1940s.

I personally hate rubber tires.  If these locos were mine running on 2-rail track, I would replace the rubber-tired, grooved wheels with smooth tread wheels for better tracking and ground pickup.  Then I would add a little weight and/or a 2nd powered unit as needed.  My $.02.

Interesting. I'm not familiar with the Armstrong brackets, but I do have an Atlas SW-9, which has the pivot points of the trucks mounted quite high in the chassis. It has fixed pilots, kadees, and traction tires, same as my F3s above. Yet, this guy has never exhibited any tendency to wheelie. Very smooth running drivetrain and a great puller.