The original servo mod was done with a Losi servo and a HS-55 by cagedmax on One18th.com.
That mod can be seen by going to the link here:
The following is simply carrying this one step further to apply to a HS-81mg and stock electronics.
|The mod is essentially the same - remove all electronics from the losi servo. Now cut he motor leads - red and blue and toss the motor. Notice that the Losi pot is soldered directly to the circuit board.||Click on an image to enlarge it for clarity.|
Then disassemble the HS-81MG and remove the bottom plate.
Remove the little circuit board and then the retaining screw for the pot
and then remove the top and the metal gears from the pot shaft side. I
used a small handle screwdriver to press the pot shaft down until it
slid as far as it would go loosening it self from the interior retaining
slot. Then I removed everything except the motor which seemed to be
glued in.. I cut the motor wires (brown and orange in this case) fairly
close to the circuit board so that you have about 1 1/4" of wire and set
the case with the motor aside for now.
Strip the ends of the Red-Yellow_Green HS-81 pot leads.
Finally strip the ends of the blue and red motor wires so
that there is about 1/8th inch of bare wire. Twist each and tin with
solder. Now get the HS-81MG case with the motor wires and strip each of
these similarly and tin. Just slightly twist the RED and ORANGE wires
together and solder them. Do the same for the BLUE lead from the circuit
board to the BROWN motor lead. After the wires are soldered - NOW you
will need about 3/8" of small heat shrink tubing for each of these motor
joints. Just slide it in place and use the hot soldering iron to shrink
it down by "circling" it with the hot iron until it is snug. This will
keep the wires protected from shorting in the case.
I didn't create this - 22benjamin22 of One18th.com did and here is the link to the article if it is still available.
I merely cleaned up the images and corrected the for gamma - they seem a little clearer now and I also added my own.
Chassis uncut with RED box showing area needed to be smoothed flat.
Chassis after dremeling of area.(You really don't need to have the chassis bare to do this mod - but it does make it easier!)
Here you see the servo laid in in a preliminary fit. Yep it fits!
|Here are several shots of the servo after installation. The servo hold down bracket which serves as the battery hold down clip needs to be modified also for a good fit.|
|The bracket - if you look closely at the first photo you will not
the area to be flattened is markes with a marker - unfortunately it is
black and hard to see in this photo.
The second photo shows the bracket AFTER the mod.
|Here it is AFTER the mod and fully installed in my Mini-T. After
this mod the stock four cell battery box will NOT fit - but if you want
to run four cell stock class - just solder up some AA Nimh's and you're
in business as I checked and AA's will fit in the tray without the
The HS-81 is SOOOoooooo fast that I needed to turn the steering rate down almost completely to be able to steer the car. But wow is it solid!! I really like it! And since it will work with the stock electronics it's even better!!
All of the real work on this project was done by cagedmax and 22benjamin22 at One18th.com so I will not take any credit for that. I simply didn't want their effort to disappear so I made this page incorporating it all in one area. I will include other mods as I find them - most especially if I fine them to actually work. These guys did their homework and I appreciate it! Thanks fellas!