MTH: Challenger Repair/Modifications page:

(Click here for MTH; Challenger - Photo & Video Page)



Model Info:



Model Overview:

The Challenger is part of MTH's very first One Gauge steam offerings. 




MTH Challenger Repair/Modifications:

Modifications/Topics list:






MTH Challenger Smoke unit not puffing fix:

If you are having issues with the smoke unit not flowing air properly then you may have:

    -  Oil inside the fan chamber causing it to slow / bog down.

    -  The rubber gasket has swollen or shifted position and is now blocking the air passage between the fan assembly and the fluid reservoir.



If you have overfilled the smoke unit or have tipped the engine over with the unit filled with smoke fluid and have fluid in the air chamber you can simply just allow it to dry out over a period of time and it will return to normal operation.


If the rubber gasket is blocking the air passage, you may need to disassemble the smoke unit to trim or reposition the gasket to eliminate the blockage.


Picture of the gasket:








Tender plug problem & repair:

See this link:  Tender plug repair




Reduce front driver wheel slippage: 

To reduce the slippage of the front engine set it requires additional weight be applied to the wheels.  To do this you need to add additional weight to the front of the engine and add suspension springs to transfer that weight.




STEP 1:  Adding weight


    Add between 1-3 lbs (depending on preference)  in two areas.  (Use hot glue to adhere the weights in the boiler)

    1.  Inside the boiler on the sides near the front with the motor as the center point (same amount of weight before and after).  (Photos not yet available)

    2.  To the front engine set near the front.

                -  Option 1:  Add weight to the inside of the front engine set (Not visible but harder to accomplish and requires some disassembly)

                -  Option 2:  Add weight to the front of the pilot between the front air pumps (will be visible)




        Option 1:  Add weight to the inside of engine set:

                       - PHOTOS NOT YET AVAILABLE



        Option 2:  Add weight to the front of the pilot between the front air pumps:


                        The photos below illustrate how it's done.  (This adds about 7oz.)



STEP 2:  Add Suspension Springs:

    Add springs in two locations:


        1) Between the bottom of the boiler and front engine set

        2) At the articulation hinge-pin at the back of the front engine set


Spring between boiler bottom and front engine set:

The photos below explain the steps.  The plate is made from aluminum and obtained from Lowe's Hardware Store.  The Spring is the same one I used on the Big Boy pilot and is from Ace Hardware and is spring #138(Item#18649).


Spring at the articulation hinge-pin:

See the photos below.  Use Ace Hardware spring #182.  You may want to experiment a bit with different spring types and lengths to get the right amount of tension and allow for proper range of motion.  A metal washer was used to protect the plastic from the spring. 



Final Step:  Check wheel slippage with pull test

To test whether you have the right amount of weight in the right locations and have the right spring tension, do a pull test by starting the engine moving and hold the engine in place by holding the tender coupler and see which set of drivers loose traction first.  If you have the right balance of weight and spring tension, both driver sets should start to slip at the same time or close to it. 





MTH Challenger front driver binding at slow speed fix

If you see hesitation when running (usually at slow speed) you may have an issue with connecting rods drilled slightly off center/out of spec on one of the driver sets.   Driveline binding / not running smooth   (MTH resolved these issues with their Triplex and the 2015 production run of Big Boys.)

First best option is to try and replace side rods on the affected engine set with others to see if this helps the situation.

You can also try shimming rod holes as noted below.  If you attempt to shim, an analysis will need to be done in order to determine where the best placement is for any shims and this will come from observing the drive set running slowly and where in the rotation it's binding.



Shimming rod holes:

My solution was to purchase a package of brass sheets in various thicknesses and use them to reduce the play between the connecting rods and the connecting rod driver pin by making a spacer bushing.   (Note:  This shim solution will likely only work if the rod holes aren't too far out of spec.  If they are too far out of spec, they will likely need to be replaced.

Using scissors, cut a strip from the thickest sheet and looped it to create a spacer bushing.  Make sure the bushing isn't taller than the width of the connecting rods.  (Wrapping the strip around a properly sized screw driver helps when trying to make it round.)  Next, cut a strip of a medium thickness sheet and looped it to create another spacer bushing.   In this case, a thicker spacer bushing was used on the: first driver left (fireman's) side, and both second drivers.  The second medium thickness bushing was added to both second drivers.  By adding the second medium thickness bushing, this made it so there is very little slop between the connecting rods on the second drivers and the connecting rod driver pins. 

I found out that the second inner bushing was needed through much trial and error and the fact there was still a lot of slop in the second driver pin even after the first thick bushing was made.

Below is a picture of the two bushings combined before they were inserted onto each of the second drivers.  The thinner bushing is inside the thicker one. 

Next, insert the bushing into the connecting rod hole.  In this case, the single thick bushing.

Then fit the connecting rod onto the driver connecting rod driver pin and press down on the connecting rod and the bushing with your thumb.  I jiggled the bushing and rods with my thumb until the bushing conformed to the curvature of the connecting rod pin.

Repeat the above steps for both second drivers using the double bushing. 





MTH Challenger - G scale Kadee #830 coupler added to the Tender

Most of the individuals I've spoken to that have added Kadee couplers to their Challenger tenders have used a #1 scale 820 or 821.  I prefer the larger G scale size over the #1 scale because they will be more likely to stay coupled on poorly leveled and uneven track and thus provide me a little more peace of mind. 

After a little modifying, I was able to get the G scale 830 knuckle to attach to the existing MTH tender coupler arm.  Here is what the tender coupler looks like in it's original configuration.  (except in these example photos I went back and made for the site, I put the knuckle on the arm upside down , but you get the idea.)

I modified an 830 coupler like you see below.  It required cutting the end off, drilling a hole for the bolt and filing the entire top of the arm to allow the coupler to be level with the tender.  I also filed the bottom of the arm at a slight angle to give the knuckle a slight incline so it would be at the proper height.  In addition, I dug out the parts you see next to the coupler to use for the new assembly.

I then slid the new 830 onto the existing MTH tender coupler arm and bolted it securely in place. 

Next, I set the stock spring in place and reattached the arm to the tender.  I added a modified and polished washer to the pivot screw point to add a little more stability to the arm so the coupler would have less up and down play.  The final screw was then put in place.  I oiled the pivot assembly and the ridge on the back tender wall where the coupler arm now rests against it.

And as you can see, it was a success!  It works better than before and I now have a G scale Kadee on my tender ready to pull revenue runs.





MTH Challenger/Big Boy - G scale Kadee #789 coupler added to the Front: 

The Challenger & Big Boy both come with a non-functioning #1 scale size coupler on the front.  Not an issue unless you plan to do some sort of lash-up behind another engine or consist. 

After a bit of modifying I was able to install a Kadee #789 on the front and eliminate the fake one.





To accomplish this, you need to pull the pin holding the coupler assembly in place.  (from the bottom)  It is very difficult to remove and had to slowly work it out with a twisting motion.

Once out, the Kadee #789 can be modified with a dremel and a file to drill a new hole and file it down so it fits through the front opening. 

The Kadee uncoupler arm needs to be cut off smooth with the bottom of the coupler. 

One benefit from this modification is the coupler assembly is now tight enough to keep from working it's way open after running the engine a while.






Challenger/Big Boy Drawbar upgrade:

I found that trying to back heavy, long trains up a steep grade would put cause the factory drawbar to tip down allowing the tender-drawbar peg to come out of the drawbar.  To eliminate this issue and also shorten the distance between the engine and tender I made this custom drawbar out of scrap steel.

I replaced the stock spring with a few of the plastic washers that were included in the Kadee 881 adapter package.  By using the washers instead of a spring, they help hold the drawbar in place when under heavy load backing up. 

Here is the result. 

Drill bit sizes used:




Power Pickup Sliders getting caught in switch frogs (Particularly #6 switches)

For those having problems with their engine having a slider that dips in the frog which causes the engine get hung up or jerk, you will need to modify the slider just a bit. 

In some cases, the slider screw hole was not drilled perfectly straight up and down.  This results in the slider being tilted a bit front to back.  With the one end of the slider tilted down, that end will have a tendency to drop in the frog as it passes over and get hung up. 

The solution I came up with for this was to take and bend the slider pad to compensate and ensure the slider sits level on the track.

I first check to see if the slider is level front to back.  (The one in the photo here is already level)

Based on which end is dipped down, I know which way to bend the slider head to compensate. 

One way to fix is to take the slider off the engine and then use two pairs of pliers to bend the slider shoe pad so it is oriented correctly against the rail.   After you bend, reinstall it and check.  You may have to repeat these steps a few times to get it just right.  To speed this process you may be able to bend the slider with it on the engine by hand.


The other thing to check for is to make sure the outside edge of the slider is level as well.  If the outside end is dipped too far down it can get caught as well.  To tell if it's level, put the engine on it's side and look down the bottom of the drivers and see how the slider looks in comparison.  The slider inner to outer level should match.

This is level

This isn't.


If you still have a slider getting caught in a #6 switch frog, it's probably with the engine entering the main from the siding.  (see photos below)  If this occurs, you will need to take (likely with a pair of pliers) and bend the end of the slider that's dipping down in frog out just a tad.  So in this case below, the left side of the photo is the front of the engine, you need to make the front end of the slider bend out further to the left some. (Assuming the slider is already flat and level from the checks above).  Don't bend it too much and remember you are bending it out on the horizontal axis, you want to keep it flat and level.   Also, make sure the slider screw is fairly secure in the hole you may need to tighten it down some.

(Note: you may read where some have gone with the method of bending the outside edge of the slider way up to prevent it from getting caught.  This is not necessary if you go through these steps noted above.  If it's getting caught it's just out of adjustment by likely just a little bit.)


Once you have your sliders set right they will work reliably from then on, it's just a matter of getting any trouble sliders properly set which really doesn't take too much time.







Charging the engine's PS2 on-board battery:

See this link:  Charging engine PS2 battery





Polarity switch location:

All Protosound 2 Challengers do not have polarity switches.  A custom polarity switch can be installed and will post details at a later point.





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