Lionel 6-18001 Rock Island 4-8-4 from 1987 - basically a 736/746 - hesitation and slow in curves.

I would open up the play on the rear wheels axle a tad. I would try to get the play as observed on the front wheel sets. I looked at my Northern and the wheel sets all have the same play. 

It took me several months to work the bugs out of my 5100. If you need me to get out a feeler guage for wheel to frame spec let me know.

It appears gauge wise that the front and rear driver sets are within about .007" of being the same. Must be some other reason there is more play in the front, the worm on the rear certainly being a factor.

Comparing it to my 736, even after 60ish years, the 736 also has no play on the worm axle and considerably more play up front. It also is very easy to turn by hand!

I would suggest checking the gears for some foreign object.

Nothing in the worm well

Mine is a little noisy and not very smooth but runs OK. I haven't tried to tune it up any.

If your armature has side to side slop, you need new bushings - you ruled this out. If you have front to back slop, you need a new thrust bearing and/or additional thrust washer. I believe the part numbers are The 681-121 and 671M-23 respectively. It is a very inexpensive fix and makes a difference in my experience.

The issue is with the chassis. You can feel the resistance when you push it with NO motor installed. It drags around curves and has does not roll smoothly on straight track. 

Frisco Chris 1522 posted:

The issue is with the chassis. You can feel the resistance when you push it with NO motor installed. It drags around curves and has does not roll smoothly on straight track. 

Chris, excellent concise statement. Based on that, I would look for a bent axle or a driver that is out of time.

My Wabash 4-6-2 #672 was like that when I ran it for the first few times since 1986 or so.   It had only been tested to make sure it ran before I got it this year.   Every night I ran it, it got better.   And took less throttle.  Oiled it once a week for 4 weeks.    Now it even takes less throttle.    Just crank up the voltage and make sure it is oiled!  Hope that works for you! 

 Edit.   Mine would stop in 0-36 curves also.    Now it just glides on through! 

Did you take the side rods off to see if the problem disappears? If it does, you have a quartering problem. Also, this loco is old enough to have the zinc pest problem, this crops up once in a while, no matter who made the loco. Keep us apprised of your findings. 

Check the back issues of OGR.   There is an excellent article on how to fix this engine and the DLW.  The problem is the parts it was manufactured with.  If I recall the motor guide bushings are incorrect.  The article is several pages  with color pictures, mfg parts needed, and procedure.   I would start with that.  I have an 18001 mint and was going to dump it just based on its bad reputation, till i came across the article.  I found some of the parts at last York.  I  just haven't had time to work on it.  Supposed to be great after the bushings are changed.

There is also an good article on tuning up the chassis in that *other* mag-whose-name-may-not-be-invoked early on, in the second issue, actually, and written by Dennis Brennan.

Check OGR Runs #166 and #172 - if I have it right - those are the ones being referred to that will help you fix your engine.

These engines are notorious for their troublesome performance. With some persistent TLC, they can be made to run so-so. 

I had he final entry, the No. Pacific, and it ran somewhat better .

They are nice looking locos, though. 

Hi Frisco Chris:   Just a note.  If the  side-toside- play in the armature is okay, then shim the vertical movement of the armature to within 0.010ths which is the spec. set by Lionel. Additionally, align the poles of the armature even with the pole of the field so that the laminations line up. That's what the  671-XXX shim washers are for; either add below the poles or at the end of the shaft.   Finally, if you haven't noticed, this loco has an additional magnet at the front end of the chassis for the magna-traction. The added magnet will have  "MORE GRIP" on the rails and that is what you may be feeling as you push the motorless chassis with your hand down the track  The earlier design of the  736 had the concept to have two magnets, but the Lionel Corp. engineers decided not to follow thru with there plan.  And as all the others have stated: " LUB,  LUB,  LUB and run it in.  Let us know how you make out.   Dennis M.

It seems like it's getting better around curves. It's still not a smooth runner, compared to my 736 or "pullmor" equipped diesels. It's just "sluggish". Takes a lot of power to get it going, and has no low speed operation; just stopped and medium speed on up and a little jerky.

This morning before leaving for work, I took all the rods off, but left the motor in the chassis. It was still sluggish. I did note the smoke unit lever may be responsible for some of the uneven force required to push the chassis on straight track - when I spin the front drivers (now disconnected) you can feel the force required to operate the lever. It doesn't seem to bind or anything, it's just the way it's designed. The cam works very close to the pivot point and the lever is very long, so the cam is just at a lot of mechanical disadvantage. Not a huge deal.

None of the wheelsets seemed to bind when spun by hand. I'll take the motor out on my lunch break and try rolling it without the rods then.

I am starting to think that CARSNTRAINS may have it - it may just need to break in. I can't seem to find anything specific wrong with it, it's just "tight". 

To DENNIS M: The armature has more back-n-forth travel than .01", for sure. Not enough to cause the commutator to rub on the brush plate nor enough for the windings to rub on the bottom casting of the motor, but more than .01", maybe .03", would need to get out a scale for an accurate measurement. 

I checked the wheel gauge versus the 736, and they seem the same. Checked the side to side play in the axles and the 736 is even tighter on the rear (NO perceptible play at all) but looser on the front. The 736 spins freely with the motor mounted (it takes some force but will spin in both directions). The Rock Island I can only spin the wheels forward. Backward is seizes up.

I got lucky on this one as my Lackawanna version seems to be ok. 

A few thoughts, some of which will repeat what has been said:

1 - smoke lever causing binding: I have noticed that some Modern era engines have a problem with the smoke lever trying to push the piston past it's end of travel. I've fixed this by adjusting the bends in the lever

2 - article about fixing engine: It would be a good idea to find a copy, and read. As I recall, most of the fixes were about removing burrs from the side rods, and maybe reaming them.

3 - binding rods / out of quarter: Try running the engine with the rods removed to isolate the problem.

4 - Side to side play on rear (driven) axle:

A- Sometimes one of the wheels will rub against the frame or magnet, This can be fixed by putting a small washer between the wheel and the frame. I usually use 671M-23 or 671M-19 washers for this.

B - Sometimes the worm wheel (gear) rubs against the side of the well it sits in. It might need to be centered.

IMHO, neither of these issues can be fixed by opening up the gauge a bit. If you eliminate one source of rubbing this way, you will create another.