Help! Postwar F3 Surging / Slow in forward, Fast in reverse.

[Fordiesel69]

I just got done rebuilding the E-unit as my drum was tarnished and one finger broke, the rest were thinner than paper.  All parts were from T-Tender.  I put in a new drum, and 2 new finger sets.  Works great.  Also installed all new brushes and 2 new truck wheels.  Now the train will be slow and kind of surge slightly faster then real slow in forward.  Put it in reverse and it will practically derail it is so fast.  I decided to reinspect my soldering on the e unit and I put in my old drum again and brushes which did not change anything.  The drum I bought looked ever so slightly different so that is why I put my old one back in.  After all the fingers is what was really wrong.  I also inspected the trucks to make sure there was no binding, and there was none.

 History:

You will probably remeber my threads since before Christmas.  I took my F3 out of storage and it was so slow it couldn;t be used.  I tore it down and cleaned and lubed it.  Only microscopically better.  Someone suggested an eraser stick and and WD 40 on the E-unit.  That did the trick!!!!!!!  The train flew around the track, except sometimes it would slow down and the solution would be to just cycle the E unit and that would fix it.  So now I decided to just refresh it, which somehow made it worse.  I am almost ready to throw it thu my front window.

 

Any idea's?

[servoguy]

 It is hard to diagnose a problem like this without actually seeing the locomotive.  However, it is possible you still have a lubrication problem.  Could you post a list of all the places you lubed the engine?  You might have missed something.  The thrust loads on the worm gears are in opposite directions for forward and reverse, and it is not impossible that a thrust bearing is dry and causing a lot of friction.  In order to properly lube an F-3, you have to remove the motors from the trucks.

Also, it is possible to wire around the E unit to test the motors without the E unit.  This would allow you to make sure where the problem is.

 Bruce Baker

[Fordiesel69]

The problem did not occur until I did this recent batch of work.

I did this just after christmas and it worked fine: (See below) 

I cleaned and lubed the gears on the motor and the hole.  I took the trucks apart and flushed all the old crap out with toothpicks and QD Electronic cleaner until the trucks were spotless!!!!!  I applied oil down inside to lube the wheel bushings, then I put a light coating of synthetic grease on the worm shafts, brass pinion gears and on the two end shaft bearings.  I did not over do it.  Nothing leaks out or sprays all over. 

[lionelsoni]

Your description of its behavior, just fine in one direction, hardly moving in the other, makes me wonder whether both motors are being reversed.  Are the brush and field terminals for the two motors connected together?  That is, is one brush of one motor connected to one brush of the other motor, the other brush of the first motor connected to the other brush of the other motor, and the field terminal of one motor connected to the field terminal of the other motor?

[Fordiesel69]

Bob,

I never unsolderd my existing brush plate, but rather just the one field wire from the center when I swapped your motor in.  So the polarity was not reversed.  Also rebuilding the E unit, I paid close attention to wire color.

 I think I got the problem solved.  I swapped a spare rear truck assy in that I bought last week on ebay and it was like new.  There was binding in my rear truck in one direction and I don;t know why it had to be so coincdental.  I did put all the new parts back on, like the new E drum, and the new brushes, and you guys were right, the new repro brushes do cost you some speed.  So I still saved my old worn originals.

What a stumper for me, I never would have thought mechanical after it wa working so well until the E- fingers toasted. 

[servoguy]

 You can sometimes find mechanical problems by trying to turn the wheels with your thumb.  The wheels should turn with some effort in both directions.  If they turn freely in one direction and lock up in the other direction, you now have a good idea where to look for the problem.

Bruce Baker