2020 sluggish running forward

[Anonymous]

I have a 2020 i have redone completely. After cleaning the armature replacing the motor brushes and springs, along with the rebuilt E-unit. The engine runs smooth in reverse, but runs erractic going forward.  the E-unit sequences perfectly . Anyone have an idea why she runs ok backwards but does not run smooth going forward. thanks

[gottcent]

Could there be a problem with the gears? for instance, is there too much grease on them?

                                                           John Gottcent

[sulafool]

Check out how much end-play the worm shaft has; be sure all the shaft bearings and thrust washers are there. You may also have to monkey with the worm shaft/gear engagement by adding (or possibly removing) shims between the motor and the frame. Worm drive mechanisms are notoriously finicky about their alignment. Once dialed in, tho, they sure are sweet!

[wrmcclellan]

Also check out the side-to-side play in the driven axle. I have fixed a 736 with the same problem by making a shim from a brass washer (file out a section and make it like a C clip that you can snap onto the axle between the gear and the frame). To determine of this is the problem, run the unit upside down and press on the axle from one side or the other and see if it runs better to determine which side to shim. Make sure if you shim it that the shim does not mess up the reverse running.

[msacco]

Certainly would check everything everyone has mentioned but it sure seems like it related to the brushes and springs. I know you said you replaced them but are springs and brushes seated properly and making even contact? My 681 had this problem and need brushes and springs and all is well. I would double check it again.

 Mike S.

[cwburfle]

How is the tension on your replacement brush springs?

I am of the opinion that most of the coil type brush springs that are available today have too much tension.

[Anonymous]

A few weeks ago I had the same problem with my 726.  You can read the trial and error process I went thru. 

Check out this thread:http://www.trains.com/trccs/forums/1049661/ShowPost.aspx

Bottom line was,.. "My problem here was side to side action of the axel moving the worm wheel to the far right of the loco and binding in the grease pit. Therefore using a 3/16" polished washer cut with my dremel tool into a C-Clip type spacer of 0.04" thickness, clipped over the axel on the right side,  set the worm gear in the center and has not failed all day!! I shall run this unit with the added modification and will tear down in approximately 2 weeks to investigate any excessive wear to worm wheel. No problems negotiating around curves, runs great!!"

 

Let us know what you find, I hope this helps.

 

 

[Jumijo]

Also check out the side-to-side play in the driven axle. I have fixed a 736 with the same problem by making a shim from a brass washer (file out a section and make it like a C clip that you can snap onto the axle between the gear and the frame). To determine of this is the problem, run the unit upside down and press on the axle from one side or the other and see if it runs better to determine which side to shim. Make sure if you shim it that the shim does not mess up the reverse running.

Roy, did you use a brass washer so it would not interfere with the magnatraction?

Jim 

[wrmcclellan]

Jim,

Yes I used a brass washer.