Nice write-up ridgewalker. I got one of these recently and trying it stock with the 9 feet per second speed and 15 feet of radio range, this setup had to go.
If I’m hijacking this thread, mods please delete this response.
This Polaris model is probably one of the nicest authentically looking snowmobiles I’ve seen.
For my modification, I wanted more speed and better radio range. This meant having to change the radio system which is non-conventional and replace the brushed motor drive. The plan was to put in a brushless motor and speed controller, hi-torque steering servo, and spread spectrum receiver.
The before picture…
The after picture…
The brushed drive motor, the brushed steering motor and assembly, and the controller/receiver board are removed.
The servo mount is made out of 1/8” plywood. I didn’t want to spend too much time and money on this in case it wasn’t going to work. I am mounting a Hitec HS-465MG metal geared servo with a Kimbrough lager servo-saver #124.
Here is a picture of the servo mount installed in the frame. I wanted to use the existing 4 mounting holes so the reason for the funky layout. The plywood passes over one of the screw locations so I notched out a hole big enough to accommodate the insertion of the screw and screwdriver.
I set the height of the servo on the base so that the motor saddle would rest on the servo providing additional support to the saddle. This also gave the proper clearance for the servo-saver arm and steering linkages passing though the frame.
Next thing I did was cut the ends off the original steering linkages as I wanted to add ball links for adjustability and less binding during operation. I cut off enough to ensure the total length from the z-bend to the ball was the same as the original length with 3/8” of thread in the link. I threaded the cut end of the linkages with a 4-40 thread to match the ball links I was using.
The electronics used was the Castle Creation 4600kv brushless motor and Sidewinder ESC, and Futaba 603FF 3-channel FASST receiver. I cut the original battery leads near the controller board and solder on a female Deans connector. I soldered a male Deans to the battery leads on the speed controller. I left the Tamiya connector at the end under the seat. I soldered a 100 ohm resistor in series with the one wire coming from the tail lights under the seat and cut the ends near the controller board. I added a male servo connector to these leads, observing proper polarity, plugged it into channel 3 of the receiver to light them up during operation. I cut the switch leads of the speed controller at the switch and installed a female servo connector on them. I cut the stock switch wires near the controller board and installed a male servo connector there and connected to the female connector on the ESC. This way when I remove the top cover, I can disconnect the wires. I am not hooking up the head lights at this time as I want to replace them with super bright white LED’s. In the meanwhile, I have cut those wires near the controller board and tucked them away under the hood. The speed controller is velcro’d to the steering bulkhead. The receiver is velro’d to a board that was cut and fit into the original controller board slots. The antenna is run through a small chunk of antenna tubing glued in under the seat. The motor fits the existing mounting holes, but I filed a slot in one of them so I could adjust the motor gear mesh for different pinion gear sizes.
Measuring just under 24" from tip of skis to the rear most plastic piece, it's probable close to 1/4 scale.
Final notes. I tried it with a 7.2V NiMh battery pack and a Robinson Racing Products 32 pitch 12 tooth pinion (RRP-0120) and got the faster speed that I was looking for. It was okay...., but not good enough. Today, I tried a 14 tooth pinion (RRP-0140) and got great speed on the hard pack and good speed in the deeper hard packed snow. I was out for maybe 10 minutes and noticed after that that I injected 1500mAh back into the pack. Also, one nice thing about the Castle speed controller is you can program in a throttle curve if you have the Castle Link cable. I relaxed the throttle output with a curve that didn't kick in some serious power to about 60% of throttle trigger input from my Futaba 3PM radio. When we get some fresh snow, I plan to try it out with my 3-cell LiPo’s and see what she can do. I am expecting a jump in speed. I like it! [sm=thumbup.gif]