DIY Snowcat build

[trackhead]

I’ve gotten some great tips from Gerauld on his snowcat build and was encouraged to share my build.

I’m not an engineer, professional welder, fabricator, machinist, or perfectionist. I’m a Nordic and backcountry skier who likes snowcats and has owned many in the past. I decided to build my own because it’s an immense challenge, and to build something I could fix myself and source parts easily. I also wanted something easily trailersble and 6ft or less width.

If you want to see true art, follow someone else’s build. I’m a hack inspired by the Russians who build these with inferior tools and low budgets but make great rigs out of scrap. I have a $200 cheap Lowe’s welder, a chop saw, and I weld like a Malaysian in flip flops in my gravel driveway. That said I have a functional snowcat that has been all over in the mountains near my home.

Use is for backcountry access and Nordic ski grooming.

More later.

 

[Rustyiron]

Hey welcome to tbn and don't be so shy with your pictures!
It seems like you have underrated yourself as to your fabrication abilities and it sure looks neat from your (only) picture.

 

[trackhead]

Engine: Yamaha RX1 999cc four stroke snowmobile engine. Chosen because its light, makes enough power, and Yamaha makes good engines.

Drivetrain: RX1 CVT to RX1 gearbox. From output shaft is 16t 530 sprocket to “chain drive differential”

Chain drive differential: From Chevy one ton. Open differential with 60t 530 sprocket. Chose chain drive because its light met my fabrication abilities (fairly easy to build).

Gear reduction: RX1 makes power at well at 6-8000rpm. I added gear reduction to effectively gear it down 4:1 initially on first build, but added more reduction with second set of gears to go effectively 8:1 from stock 120mph sled.

Speed: with current gearing cruises 6500rpm at 10-12mph. Crawls awesome at slow speed with no belt/clutch heat.

MPG: roughly 3-4mpg but highly variable.

Weight: 2000lbs
Width: 76”
Length: 9ft
Ground PSI: about 0.5lbs/sq/inch
Track width:24”
Grousers: 20” wide 1.25” tubular steel

Frame:steel tubular various sizes

Design theory: front bogie wheels 3” higher, rear drive sprocket elevated to create cambered wheel base for easier turning, lower destructive loads on brake steering and drive train. Works great but can cause porpoise effect with throttle input on hard snow. Not a big deal.

Brake Steering: UTV rotor one per side with two UTV calipers per rotor. Plenty of force to turn. This is a crux on many builds. I got lucky more or less. More on that later.

 

[trackhead]

Chain drive differential initial build. It has since changed to what has proven to be a much better design. More on that later.

 

[trackhead]

No engine lift, made a pulley system out of an old rope and some old climbing gear. Sketchy **** but it worked.

Donor sled had 1000 miles.

Lotta guess work. No blueprints for building these types of things. Just guessing and reacting to mistakes as they come. Lots of staring and thinking.

 

[trackhead]

Building mounts/bearings for the primary/secondary drive took weeks. It has to be perfectly aligned on every axis or it’ll self destruct.

Getting the secondary sheave the right distance and belt tension was also very tedious. It has to be perfectly aligned again, on three axis’s. Photo shows sprocket on output shaft. All this stuff was initially bolted in place before welding to be sure it would actually work. Belt alignment is perfect. Huge pain in the ass figuring all this out. But did it first try.

 

[Rustyiron]

Nice!!
That's a lot of work that turned out great

 

[trackhead]

Current gear reduction. I added an intermediate gear reduction for better low speed engagement and torque. Without this clutch would get too hot. Now it’s just fine.

 

[trackhead]

Track building is a horrendously tedious task. I copied the Russians. They are the true experts. Plenty of YouTube builds from Russians.

Initial sprockets. Russians do similar. Tried UHMPE teeth but didn’t hold up. Will be pouring polyurethane sprockets this summer.

 

[Rustyiron]

Track building is a horrendously tedious task.

WOW! I'd say so.

 

[trackhead]

Super sketchy trial run.

Found some galvanized steel at the dump and used it to tub the frame.

Smooth bottom to slide over snow better.

 

[trackhead]

About four months after starting it was going around my yard. Everything worked. Sprockets were initially very rudimentary and track tension was too loose. Had a new belt on that was squealing a bit.

Home Built Snowcat test

 

[trackhead]

Walls are thin fiberglass reinforced plastic. Cheap, light.

Early trial run. Still had long exhaust from snowmobile. Cooling fans found to be unnecessary.

Rebuilt a new chain drive system with better bearings.

 

[trackhead]

Sprocket replaces ring gear in this scenario.

Chain drive differential

First version that changed this winter.

 

[trackhead]

Neighborhood testing.

Prior to gear reduction.

1.25” grousers have their limitations but are a lot easier to turn.#snowcat #trackedvehicle

 

[trackhead]

After gear reduction. Busting drifts in the spring about 8 miles back in the mountains.

Helping a friend gain access to his remote mountain cabin.
Last day of the year. Tearing it down to the nub to recoat the frame, etc etc.

 

[trackhead]

This summer I’m cleaning up the wiring, fabrication of new muffler, making final output shaft 2” diameter hardened steel vs 1” el-cheapo that I snapped. Working on the very spartan interior. Rebuilding new polyurethane sprockets.

Will also fabricate new six way blade with tilt function to better level ski trails. Oh, and fabricating a new drag for grooming.

Plenty to do

 

[Richard001]

Wow, looks like a lot of work, must be a labor of love. Some questions,

Is the cab heated ?
Where did you get that differential from?

Richard

 

[Rustyiron]

Ok, you just got another subscriber for your YouTube channel!
Fantastic stuff
And I was right in my first post, your too modest and my hat's off to you and your build!

 

[trackhead]

Wow, looks like a lot of work, must be a labor of love. Some questions,

Is the cab heated ?
Where did you get that differential from?

Richard

Diesel heater in cab. Diff is from 1 ton Chevy.