TMCC engine starts very shakey only at slow speeds and bucks heading down grades -DR EVIL EXPERIMENT WORKS!

I have had a few TMCC engines that the motor was not tight.  This was a symptom.  I would check and make sure the motor is mounted securely on the truck.

Thanks Marty ... I will add that to the list

Checked the screws. All are tight.  Changed the motor driver board. No changes. 

Changed the motor driver board. Did you call lionel and see if the ones they are supplying have the updated firmware. I recently fix a santa fe scale set. It had the lurch. The magnet for speed control had also loosened on the flywheel.

I could have ordered the lionel board. But, the electric railroad board was a better alternative Cruise M. I called ken at ERR and he verified the R2LC firmware..and I believe if the model was one that had issues.

The only thing is if you have a powered B unit I would replace both motor driver boards if using err...their is a nudge feature to make the unit run in harmany a bit better..

Ok so it was a late night last night. Yes ERR is a better way to go. But I would have to buy 3 ERR boards and I have 7 universal motor driver boards here that I bought at the 50% off part sale last year. They are the latest Universal boards Mike R. recommended.

When I change the boards ... there was no change. So I am now pretty convinced that it is the magnet/ odyssey/ motor interface... which has plagued these engines since day one.

So I adjusted the magnet / flywheel by increasing the gap to the board and flywheel... Does anyone know if there should be a specified gap for this... here is a video. The engine runs better... in forward  and reverse... does the magnet appear to be out of round? Could that be the root cause?

Look how the motor tends to hop up and down?  Has anyone seen this?

The motor armature hopping up and down is because it's getting varying power and when it slows down, the gearing pushes one way, and when it's accelerating, the gearing pushes the other way.  You can demonstrate that action with the engine unpowered and just pushing back and forth slightly, the motor armature will hop up and down like you see in your video.

My sense is this is mechanical binding, if the motor/gears bind, the Odyssey will attempt to catch up and cause the bob in the armature.  Have you suspended the trucks and rotated the flywheel by hand through a complete rotation of the drive wheels?  Do that on both trucks and see if you feel any resistance or binding.

If you suspect the magnet ring, flywheel, or sensor, you can replace the parts.  The whole motor isn't available, but the sensor and replacement flywheel and magnet is available.

My vote is its a mechanical issue also. The motor should not have that much thrust movement. Ideally the armature should be shimmed inside the can but not easy. You could try a piece of brass shim stock placed either between the motor worm and case or between the flywheel and case and see if that helps. Also check the worm gear on the axle for wear. If it is mechanical a Cruise M won't fix it.

Pete

Top suspect is certainly some mechanical issue, I agree Pete.

Yep, being a mechanical engineer that is what I suspected as well. The units are brand new. I had added grease to the worms and gear box. There is no binding what so ever. I have noticed a big improvement as I pull the flywheel magnet further from the odyssey board.  Thus the question, should there be a constant min/ max gap so the board can read the magnet? If the magnet was too close, is there a chance it damaged the odyssey board? I say this only because as the magnet gets closer to the board... the engine become more jumpy.

shimming would be a good idea.  But where to put it is the issue...

This is a good picture. Trying to understand the mechanics of this board... the sensors to the right or left of the motor shaft clearance hole count the rotation of the magnet correct?.... if the magnet has an awkward shape or excessive up and down motion... will it cause these hesitations?

J, I was thinking of a piece of brass shim stock with a slot that could be placed between the can and either the flywheel or worm to see if the thrust movement is the issue. If so then a more permanent fix would be in order. I have not tried taking a Mabuchi motor apart but it appears the brush/terminal end could be pried off maybe with the help of a little Dremel action.

Pete

Thanks Pete - I have tried and failed, causing an early life of the motor... I have plenty spares but with the wrong worm diameter on them ... thus my previous post of a nightmare of finding these parts.  I have had no success of removing a worm and pressing one on with a new motor either... just don't possess the tooling to do that.

The can and flywheel gap have the board placed in between them. So I cannot envision how I could package a shim here. The more logical place maybe between the worm and housing at the lower end... at the base of the worm to the actual truck frame.

Just to investigate the motor situation more... There is a spacer on the motor shown in area B... maybe this one is the incorrect size... since the unit is new.

Also if a force is applied the end shaft from "end to end" at dimension A and the slop is taken up maybe that would solve the excessive up and down motion.

If this is a new motor, that could be the whole problem!  More than once I've seen the "right" motor ordered, but it comes with the wrong gear.

Try comparing the worm to the other motor and see if they're exactly the same, they should be.

Thanks John - yes, did that... its is the infamous .326 inches in dia worm gear... the next step up I believe Lionel used a .345 inch worm...

I can spin both motors in their associated trucks freely.

I'm running out of ideas, could be wear on the gears in the power truck.  When you replace a motor, sometimes the gears have worn into the old motor worm and don't like the replacement.  I ran across this with an MTH diesel, no reason it can't happen to Lionel.

agreed but these units are brand new... the gears had no wear, no grease and the rollers had no marks... I am going to pull the motor and see if the bushing has excessive play and report back.... I am going to mic the magnet too.

I am just not sure of the mechanics of this reader and how it was engineered...how much variation it can deal with?

Well the reader is a Hall Effect device and gauss strength varies as the inverse square of the distance. I assume it triggers at some threshold so the trigger point may vary enough to destabilize the controller. If you have calipers you can probably measure the armature play while still mounted in the engine.

Pete

If the armature has too much play, that could affect the hall effect sensor.  I measured the end play of three Lionel Odyssey motors, all had end play between .01" and .012", yours seems to have more movement.

Thanks... that is a good start... I will check the end play to tonight.  This maybe the RED X. Note that the travel in reverse is not as bad in the first video, torque is pulling the magnet down to its proper "read range" or gap.

It would be nice to record a dimension for further reference that would reveal a bad motor.

The other question is do I have a bum magnet with a low gauss reading?

I think that would only happen if you had a partial crack. Not sure that is possible. If its cracked all the way through then it changes the pole positions and it doesn't work at all, usually characterized by off or full speed, nothing in between.

Pete

I think the magnet being defective is a very low probability as Pete says.  As far as the dimension for end play, the three I measured were all pretty consistent.

Ok . Well the shaft up down movement measures 0.028 inches. So its time to take up the slop.

That is a lot more than I measured, that is quite a bit of play.

Ok... so another late night last night ... but not so late.

First thing I tried was to close dimension A shown in the above picture... and let me tell you this is NOT and easy thing to do w/o a press.

I had a Jo block and small hammer and did a small tap.. tap.. tap.... tapping on the end of the shaft and anchoring the worm on the metal Jo block.... nothing...

Next tried a large  C clamp and  I could not keep the motor centered while turning and compressing ... so no go

Next I took it to the BIG vice in the garage. I thought this will move it! Nope - the axel was just flexing in the shaft as I applied the force.... The worm was applied with some serious tonnage guys....

I could not apply heat for the nylon bushing would have been history. So this was not an option.

So it came down to desperation and the use of one of my favorite tools... the big hammer  and anvil

I was able to smack it and tighten it up to the suggested 0.01 to 0.015 range... checking with a feeler gauge at location B.

Putting it back together at 12 am ...

Reverse is even better!

Forward is excellent and much improved....

Usually my Dr. Evil experiments end up in the garbage... but this one was voted a HUGE success.

Excellent J but you dodged a big bullet. You are lucky you didn't bend the shaft.

Pete

Norton posted:

Excellent J but you dodged a big bullet. You are lucky you didn't bend the shaft.

Pete

LOL... yes... as soon as I applied pressure I could see the shaft start to flex and I immediately backed off the vice.

So excuse my ignorance but what did you move?  The Flywheel or the gear?  I couldn't follow and it maybe I just haven't had enough coffee yet. Was there too much slop at the nylon bearing?

One  thing I did not take pictures which helped as well... I cut out a thin piece of brass shim and trimmed it in a circle... I hammer formed it in place,  at the truck base where the worm spins inside the journal... this also helped as a thrust cushion... which became my thrust washer... this kept the shaft from shifting up and down rapidly....

This is a picture of the application but from another members locomotive....

MartyE posted:

So excuse my ignorance but what did you move?  The Flywheel or the gear?  I couldn't follow and it maybe I just haven't had enough coffee yet. Was there too much slop at the nylon bearing?

Hey Marty,

What was moved essentially was the worm gear higher up on the shaft to eliminate the gap at B causing the erratic acceleration.

You are EXTREMELY lucky that you didn't kill the motor, usually hammering on the armature axle kills them by shifting the commutator.

All's well that ends well, glad you had a success.

At that point, I had nothing to lose but a broken motor anyway.  Thanks for the help guys.

J Daddy posted:

MartyE posted:

So excuse my ignorance but what did you move?  The Flywheel or the gear?  I couldn't follow and it maybe I just haven't had enough coffee yet. Was there too much slop at the nylon bearing?

Hey Marty,

What was moved essentially was the worm gear higher up on the shaft to eliminate the gap at B causing the erratic acceleration.

Thanks J Daddy.