Does anyone remember how to make MT B dummy unit roll smoother?

JoeS Apr 29, 2020

  1. JoeS

    JoeS TrainBoard Member

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    I realize these days MT B units are powered but does anyone recall how to make those old F7 B units roll freer? I have a few that just seen to be sleds being dragged. Any ideas?
     
  2. rray

    rray Staff Member

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    Oh boy, I vaguely remember someone posting a how to on those. They had to take them apart and do something, file and shim or something.

    Maybe it was the guy who put a sound decoder in the B unit who first fixed the dragging issue? You are talking 15+ years ago stuff.
     
  3. animek

    animek TrainBoard Member

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  4. rray

    rray Staff Member

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    I found it:
    http://www.conrailray.com/

    You cannot direct link to his F7B fix page, instead you have to navigate their the slow way.
    Go to:
    http://www.conrailray.com/
    Then click his Z Scale link.
    Next click his F7 ABBA link.
    Now click his Rolling Mods link, and you will find 4 links for different truck and frame mod links.
     
  5. JoeS

    JoeS TrainBoard Member

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    Thank you very much I am going to try that modification. Exactly what I needed!
     
  6. cjm413

    cjm413 TrainBoard Member

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    Modify the trucks and axles with micro bearings to minimize friction?

    The link is for modifying Bachmann's N scale "lead sled" Amfleet coaches with micro bearings, but their problems aren't too much different than the old MTL F7B

    https://www.therailwire.net/forum/index.php?topic=39504.30

    Sent from my LM-X410(FG) using Tapatalk
     
  7. SJ Z-man

    SJ Z-man TrainBoard Member

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    People have polished, milled the 'pillow block' surface as thin as is could be (on the inner side, so the axle side of the wheel still stays tracking), lubes with Teflon, 'super lubes', etc. and the end results . . . still a 'Lead Sled'. But the A will easily pull it.
     
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  8. strummer

    strummer TrainBoard Member

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    ...what Jeff said...

    Mark in Oregon
     
  9. Curn

    Curn TrainBoard Member

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    I think the easiest way is to improve the performance of the unpowered B is to buy a power unit for these. Pennsylvania and Conrail seem to be the cheapest paint schemes. Think of all the time you will be saving based on what Jeff said.

    Matt
     
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  10. Curn

    Curn TrainBoard Member

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    Welp, I’m wrong on that count. The old B dummy units have a larger shell wall thickness in the center and will not fit over the powered chassis. So it looks like you have to modify things

    77DF44C0-0A1A-4D07-A35C-E5C014B853F1.jpeg

    Matt
     
  11. BillMock

    BillMock TrainBoard Member

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    Conrail Ray did a nice series of modifications a few years ago that you could try.
    http://www.conrailray.com/

    Naturally, it's under the Z scale menu, MT F7 A-B-B-A

    I remember doing the "Easier Fix" and it did help the rolling resistance.

    Have fun!

    Bill Mock
     
  12. strummer

    strummer TrainBoard Member

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    The odd thing about all this is there's only so much you can do with the un-powered engine, whereas I find the powered unit easier to trouble-shoot and improve.

    Speaking of which... :)

    I picked this up the other day:

    5:15.jpg

    It's one of those "semi-early" models in that it's got the molded-on horns, but has the little "peep hole" on the motor to look at the commutator.

    Of course it didn't run initially (I never expect any Z scale locos to run when I get them used), but after the usual hour or so of fussing it now runs as well as can be expected...I picked it up for under 50 bucks, so what the heck.

    It's been a while since I've done any work in Z, so it was fun to get back into it...

    Mark in Oregon
     
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  13. JoeS

    JoeS TrainBoard Member

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    Well I did the fix and I’d say I got 50% improvement. So it’s worth it. A word of warning the drill cab slip off the center. 3 of my 4 were perfect. The other I had to shim with thin piece of metal on inside to get the axel in correct position. The fix is a win
     
  14. JoeS

    JoeS TrainBoard Member

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    Hey mark I picked up new brushes and springs for my oldest unit and for a few bucks boy it made a difference and it’s an easy thing to do.
     
  15. strummer

    strummer TrainBoard Member

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    Indeed it is.

    The first time you do one of these is the hardest; after that, it's just a question of being very careful...which is what working in Z scale is all about, it seems. :)

    Mark in Oregon
     

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