LIGHTBARS MOD

DISCLAIMER: If you choose to attempt any of these modifications, you assume all risks thereof. I just wanted to share my experiences here. Neither Fanhome, nor myself, are responsible for any damages that may occur.

During the assembly of the first Code 3 Force 4 XL Lightbar on our 1:8 scale Ghostbusters Ecto-1, I realized there are a few things we can try to make its operation more realistic to the real car and even quiet it down a bit. The basic changes I made are covered in Stage 128 and Stage 129, but these are the more advanced changes. Be sure to read this entire page to fully understand how it was done.

During Motor Installation

In stock form, the main culprit in the obnoxious noise these Lightbars make comes from where the worm gear on the Motor shafts contact the teeth of each Gear 2. Much of this is due to how the worm gear was crimped onto the shaft. It is very likely you will find this worm gear is not straight, but bent at a slight angle to the center of the shaft. Therefore, it wobbles as it spins and rattles the heck out of the other gears.

To fix this, I used a couple pairs of pliers and very gently bent my worm gears to be as straight as possible to the shaft. The worm gear is made of brass and is therefore fairly soft metal:

Next, and this is optional, you may find some noise reduction by wrapping one or both Motor housings in a thin self-adhesive felt sheet. I simply cut a small piece that fit around the Motors. This helps to reduce any vibrations that could be passed into the Lightbar Base:

During Gear Installation

The Gears themselves are fairly quiet. However, there are a few updates we can make to reduce friction and therefore extra noise. First, check all of your Gear 3 installations. One side of these Gears has a small raised lip around the center hole. You may find them to be quieter if this lip is facing down when you install them:

Next, I sanded off the circular ridges on the bottom of each Gear Cover and made them smooth. This was preparation for the following step:

Then, I installed Nylon Washers (M5 sized and 1mm thick) onto the post at all four Gear 3 locations:

For the wider Gear 1 posts, I cut some M5 Nylon Washers in half. Sadly, simply going up a washer size would make them too thick (1.2mm):

I used super glue to secure these ‘half’ washer around the Gear 1 posts. Be sure not to get any glue on the top surface of the washers:

Correcting the Motors

Not only do the Motors spin too fast, they also spin in opposite directions – both are inaccurate to the real lightbar. We can fix these problems with a bit of simple electrical work. First, I hooked up one of my Motors to 5VDC to see how fast it was spinning the Rotators:

I timed the actual lightbar used in the Ghostbusters film and determined the real rotators spun at about 60rpm or one full revolution per second. Therefore, we need to slow the motors down.

Now, some might think a Resistor would be perfect here, but actually this is not ideal. A resistor limits the current through a circuit, but a DC motor’s torque is current based. This is why electronic motor controllers change the current and not the volts (volts typically controls RPM). We want to slow the motors down, not decrease the torque (turning power) they make to drive the Gears.

Therefore, we want to lower the voltage and leave the current alone. To do this, I wired up a few 1N4001 50V 1A Rectifier Diodes in series. Each diode I added to the circuit created a voltage drop, but did not affect the current to the Motor. I determined that three (3) of these Diodes would slow our Motors down to approximately the proper speed:

I then designed a circuit I could create that would include the three Diodes AND change the direction of one of the Motors by wiring it in reverse. These tiny Motors are coreless and have no brushes that might be damaged by running them backwards, which is perfect:

Building The Circuit

First, I soldered the three Diodes together in a triangular pattern to keep them compact. Each diode feeds the next in series. While it can vary, typically the end with the silver band coloring is the negative (-) side of each diode:

At the negative lead of this tri-diode (just what I call it), I trimmed the lead down and soldered on the black lead of a female 1.25mm pitch Micro JST pre-wired plug. I cut the leads of this plug to be about 1″ long. This style of plug is extremely common in the partworks we build and come in 2, 3, and 4 pin variants. This plug will eventually connect to our Code 3  Force 4 XL LED circuit board:

TIP: While not absolutely necessary, I do recommend using heat-shrink tubing over all bare connections like this:

Next, I grabbed two male 1.25mm pitch Micro JST pre-wired plug and cut the leads to about an inch long. These plugs are what will eventually be connected to our Motors:

Then, I soldered the black lead from one plug to the red lead of the other:

In the same way, I soldered the remaining red lead and black lead together. This is what will reverse the direction of one of our Motors:

One pair of these leads was soldered to the positive (+) end of our ‘tri-diode’. It does not matter which pair is connected here.

Note that I pre-installed two pieces of heat shrink tubing here. One for this connection and a much larger one to protect the diodes:

The thin heat shrink tubing was secured first…

… followed by the thick tubing. Doing this will help protect you connections and help to prevent any electrical shorts:

Finally, the remaining set of leads from the Motor plugs was soldered to the red wire of the board plug:

Installing The Circuit

Installation of our new ‘tri-diode’ assembly is quite simple. Plug the single female plug into one of the plugs of the Code 3 Force 4 XL LED circuit board, as shown here. We will not use the second plug on this board:

Next, connect the two male plugs to the Motors, as shown.

If you have a way to supply 5VDC to the Code 3 Force 4 XL LED circuit board, I would do so now to test it. This is where you can swap these plugs around if the Motors are turning in the wrong direction. When looking down from above, the Rotators should all turn counter-clockwise:

Adjustments and Cleaning up

During reassembly, the five screws of the Gear Covers may need to be loosened a bit to allow the Gears to turn (and in a small way dial in the rotational speeds). As for the wiring, I was able to fit my tri-diode assembly just next to the center box of the Motor Retainer and keep everything in place with a piece of aluminum tape:

When fitting the main top Lightbar Lens, if you find that it contacts the Rotators and stops their movement, loosen the six screws holding the Lens in place slightly. On my model, this was due to a slight bend that both of my Lightbar Base parts had right out of the bag – when we attach the Lens, it straightens out the Base and can cause interference:


The Results

I feel the results need to be heard and seen in motion, so I put together a short video demonstration on YouTube:

 


Thoughts

I know there are a few aftermarket Lightbar mods out there, but I don’t feel any of them replicate the beautiful appearance of the stock parts – especially the main crystal clear blue Lightbar Lens. Therefore, I attempted to do what I could without completely changing out the drive mechanism and custom printing any parts. It is not perfect, but I feel it vastly improves the original parts, both in operation and appearance!

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