Friday, February 24, 2017

Rebuilding old Bachmann U36B Part 1 Pancake Motor

Rebuilding old Bachmann U36B Part 1 Pancake Motor

A heavy rebuild project of an old Bachmann Locomotive in HO Scale

I'm going to go over some old topics and some new in this series.  First off I want to answer the common objection of "why rebuild this - it's just junk."

Many of you started out with a Bachmann, Tyco or Life-Like trainset and still have one of these pancake motor locomotives.  For a lot of you they hold a great deal of sentimental value.  I started with an AHM GP18 and I still have it and it still runs.  I'll always hold my first locomotive in the highest place among my trains.

Are these 40 year locomotives junk?  The short answer is absolutely not.  They were built for kids who beat the crap out their trains and ran them at full power all the time.  Too many modelers get this high-brow attitude and just say you should junk them or toss them.

The reality is that if they were junk then there wouldn't be hundreds of them for sale on ebay on any given day that still run.  They can be caked with hairballs and dirt, but still have signs of life in them.  And they are CHEAP to get.  Ask yourself how comfortable you would be taking the hacksaw to your $300 locomotive?

I'm starting this series with Bachmann, which means it will also apply to old Life-Like.  The mechanism in these trains is technology that is accessible to everyone.  They're the simplest trains to really practice on.  A testament to the reliability of the pancake motor is the fact that it's the same motor slot car racers use today.

If you ever have a failure so catastrophic that you just don't know what to do, find you friends who are into slot car racing and ask them to check it out for you.  The whole idea here is that any problem or damage you find can be fixed.  We're going to fix everything and not junk anything.

This includes cracked gears.  If we find broken or cracked gears, we're going to replace them with easily found miniature robot gears.

We're going to strip the old paint and fabricate new handrails.  We're going to make just a few modifications to the body, but we ARE NOT going to go real heavy in super detailing.  Just a few details here and there to make a decent looking fully operational locomotive that could appear in photos looking good from several feet away.

The plan is to do this U36B first, then we'll move up to an AHM GP18, then we'll probably create a dual motor TYCO Super 630.  Eventually we'll get to blue box Athearn and Proto 2000 Life-Like.

This is all practice so that someday you'll feel comfortable taking on more complex and expensive project.

We're going to do a 1 color simple weathering with a paint brush that I think you'll really like.  Here is what we're starting with....

So, right now I've been soaking the shell in 8% pine oil for a couple weeks to remove the tough paint job. The pine oil has done a decent job and you'll see some pix of that shortly.

Step 1 then is disassembly.  Carefully start taking everything apart with care not to lose any parts.  My U36B was one of the dirtiest locomotives I've ever found.

As you can see, the wiring is nice and heavy and in decent shape.  We're going to keep the circuit board.  Next I hooked up some alligator clips to check if there was life in the motor....

The motor did turn a bit and after a short time was spinning.  Even if there is no life at all, we can still fix it.

The slippery plastic can often crumble.  If that happens, usually super glue can be used to make some decent welds, but other glues can really wreck things, so SUPER GLUE ONLY for now.  So far everything seems ok.... lets remove the motor from the frame....sideframes come off first, and be careful not to break them.

OK, looks dirty, grimy, full of hariballs and the traction tires are shot...carefully start removing the gears and wheelsets...

Needs cleaning bad....  rear truck is for power pickup, looks like it's just dirty and nothing is really broken...

Motor Disassembly

Yes you can totally take the motor apart and it will not ruin the magnets.  Ask any slot car racer.  Replacement magnets that are much stronger are actually out there if you must, but I'm pretty sure we'll be just fine.  No need here to take out the magnets, but we can if we need to....

With a soft toothbrush and a small pan of Dawn dish soap we can clean everything.  Don't lose any parts down the sink.  Don't wash the motor, but do carefully clean it just a bit, then you can polish it with a soft metal wire wheel on your dremel.  Also, those little springs and the tiny motor brushes are things you don't want to lose or you'll be searching ebay to buy some new ones.  On the motor housing side with the magnets are 2 metal collars, leave them where they are.  You will need to clean the grease and hair out the posts that hold the gears in place.

TAKE PICTURES OF EVERYTHING BEFORE YOU TAKE IT APART.  That's how you'll be able to put it back together.  After a while it becomes second nature and you'll know this motor inside and out.

Don't break any tiny wires on the motor core, but do polish it with the soft wire wheel.  Remember that the wire wheel with the copper colored shaft is the stiff wheel and will shred this motor core in 2 seconds, so only use the soft wire....

Next we're going to take a look at the wheelsets... they need new traction tires, which I got on ebay, a bag full for around $2. The wheels need polishing, but again, the copper colored shaft wheel will actually take the plating off the wheels, so soft wire only.

If the gears are cracked, which these aren't, you can REPLACE them with gears easily found on ebay, just search for "58 kinds of small gears" - that bag has pretty much any gear you need.  They are little wider, which makes them stronger.

All the gears are washed with a toothbrush and dish soap.  Anything on this locomotive can be washed with dish soap if you are careful.

OK the wheels need work.... in the next part we'll fix them up...


  1. Do you have a part number for the Bachmann motor if you have a bad one or the brushes? I have been checking slot car sites and other train sites with little luck.

    I really appreciate this site. I have been able to fix and save my old engines.

    Thank you

  2. The magnets are the same as Aurora slot cars - there are upgrades where you can get stronger magnets from different places and the springs and brushes that fit Aurora also fit Bachmann and Life-Like. You can also make brushes by get power tool brushes from the hardware store and filing them down - a long process unless you put them in a drill and file while they turn like a lathe.

    I also have made these 10 videos with more useful tips and tricks like wiring 2 motors together -

  3. Ok that is really awesome stuff. But from watching the videos does the motor or core fail or is it more a magnet problem?

    I have one engine has it runs it starts to fade off and starts to go slower and slower till it cant even move. super hot. let it cool and then I can start all over again.

    Sorry if it is covered and I am missing it. This is still all new.

  4. In every locomotive I've ever rebuilt with this motor, the problem has always been dirt accumulation. The only motor failure I have ever had was caused by me, otherwise every one ever has been restored to excellent condition by cleaning like I show in the videos. People commonly think these motors are junk, but if you saw the sets of locomotives where I connected power between 2 engines - they have excellent performance. The pair of U36B's will be wired together also. Next challenge will be to wire 3 of them together.

  5. Nice work! What should I do if I need a new armature? My Tyco Power Torque is built like this, and I'd rebuild it if I could find a new armature (smoked mine back in '82).

  6. They can be found on ebay, usually with the entire housing. There is another way though - the motor from a CD or DVD player (old computer drives also) will fit into the housing with just a little work. There is also a Facebook group for Tyco Trains where it's really easy to find someone who has a difficult to get part.

  7. I have an old Bachmann similar to this, but with one of the pickups in the power pickup truck riding the outside of the wheel. What's the trick to getting this truck open without breaking anything?

  8. is it the one where the wiper touches the top of the wheel? Fortunately Bachmann pickups are usually just friction fit in place and easy to remove. If it's the All-Wheel Drive version, those have a bar that runs all the way through the trucks that can be removed by pressing the correct size punch into a hole on the side behind the shell. Somewhere here I believe I did a write up on disassembly of the All-Wheel Drive version or I did a youtube video or both. I have one of these in operation on my layout and also the GP40 version as well. You would be correct is saying they are non-trivial to disassemble the first time because they are completely different. I will put a note on the workbench here to make some pictures and create an entry for that version.

  9. Thanks for the info! I was able to get the power source truck apart, prying it very carefully from one end. It was more flexible than I thought, so nothing broke. The model had the motor in one truck, and pickup in the other (same as the 4th last photo above), so it wasn't the more complicated one you described.

    1. That's great! Sideframes on these can be pried off from the end closest to the fuel tank and they go back on the same way they came off. I also have a video series on this here: