Purpose built snowbike

[fgauvin7]

Hi Eric, the lower frame section is just a temporary piece, one straight tube like this was a lot easyer to modify to get the idea. Later I will build a proper frame section with integrated engine mount and a connecting link to the top frame. But still a good advise!

For the ball joint, on the bottom clamp I will use a 3/4-16 QA1 Chromoly rod end and on the top I use a Polaris RMK lower a arm press in ball joint. In my design the lower one will not take much axial load, so it is just to keep the forks where the need to be and take the load from a front impact. The upper one will take the axial load and I already use this exact RMK ball joint in my first build and steering is still super smooth. So it should be strong enough.

Nice to see that you had sucess turning down the forks! It will be a more reliable solution than shimming. On my part I want to machine a custom clamp with a split on each side to be able to install it without turning the forks on the lathe. What bother me the most now is that I dont think the actual top clamp have enough grip on the forks to take the abuse without them slipping up in the clamp.... With your photo I see that you added a frame tube to connect the lower to the upper ball joint.... This might be the optimal solution to use both ball joint in axial load and double the clamping force.

My ''plan b'' is to add a third clamp in the middle (where the loer clamp is designed to be) and connect all three with a center post. That would be bullet proof but I prefer to avoid toing that since it add few parts and a couple pounds... So connecting the top to the bottom one like you have done is the way to go I think!

Thanks for the input!

 

[Mendomotox]

Just wanted to suggest the option of using an auto ball joint, like from a 1994 toyota or similar truck. It will be heavy but should be very strong. And the 4 bolt mounting flange may be a real advantage. I own a newer polaris ATV and the suspension components are one of the first things to wear out on those machines.

Keep us updated on your progress! Looking forward to seeing what you come up with.

 

[bgraff1]

is this the propex that got you into the project? this was the maiden voyage for the first one Laird built back in the day. spring ride and didnt even have a seat on it. was a beast!

 

[fgauvin7]

Here we go again! It is working before all the snow is gone! Not much snow left but getting the feel for it is a good motivation for all the work left on it.

Really surprised with the amount of torque theses 450 have! Weighted it at 276lbs ready to ride full of fluids (about 5L of gas). All the systems are not that pretty, assembled the cooling, gas, exhaust and shift system in a hurry with what I had to make it work but everything will be redone in a proper way.

It will be a lot nicer with all the body panels and everything painted.... The goal for next winter!

 

[fgauvin7]

Here is some better shot!

 

[Brett Kobernik]

Good work man. Simple. Solid. I'm going to be starting my next builds using the similar front fork configuration. That really opens up some options.

 

[Sheetmetalfab]

Agreed.

Looks great!

A full exhaust really wakes up those motors.

 

[fgauvin7]

Agreed.

Looks great!

A full exhaust really wakes up those motors.

Thanks for the info!

Good work man. Simple. Solid. I'm going to be starting my next builds using the similar front fork configuration. That really opens up some options.

Thanks! As simple as it gets was one of the main the goal here for sure! Weight was not a huge concern, I was more focussed on reliability. Overall weight (RTR) is still pretty good in my opinion.

really looking forward for your next one! I was torn between a sled and a bike engine and I want to see what this design can offer with a snowmobile engine!

Feel free to ask if you have any question, I will do my best to help

 

[eric82930]

Looks great! That short spindle should be bomb proof. What did you do for a brake?

 

[Sheetmetalfab]

Looks great! That short spindle should be bomb proof. What did you do for a brake?

Looks like engine brake only.

I ran my ninja 636 that way. ??‍

 

[fgauvin7]

Looks great! That short spindle should be bomb proof. What did you do for a brake?

Thanks! For the brake It is very similar to the Yeti setup except with a wildwood caliber. Driveshaft mounted is not ideal but I can move it if I don't like it.

Only downside I see now That is did not see in the CAD, the access to it is as worst as it can be I will try to improve on that haha

 

[Colo moto]

Here is some better shot!

Awesome build again! I have been mentally working through my own custom build for a while now. It’s amazing to me how many aspects of my imaginary design you have actually built in real life. Major props to you for two incredible builds.

Any chance you have detailed pics or drawings of your shaft connecting the countershaft sprocket to the drive chain? My idea for this is to machine a reverse sprocket pattern that would couple to the countershaft sprocket.

 

[fgauvin7]

Awesome build again! I have been mentally working through my own custom build for a while now. It’s amazing to me how many aspects of my imaginary design you have actually built in real life. Major props to you for two incredible builds.

Any chance you have detailed pics or drawings of your shaft connecting the countershaft sprocket to the drive chain? My idea for this is to machine a reverse sprocket pattern that would couple to the countershaft sprocket.

Thanks! I think a good portion of the design is just some pure common sense... With all the builds that we see on all the forums and groups, there is some design choice that stand out. In the end I used what I learned from previous project and what I learned from everyone else build and made my own package.

For the shaft extension it is pretty simple, I have a quick cad drawing (only part I don't have in 3D haha). I built an adapter for the engine output shaft by turning a piece of 3in shaft and bored a hole to weld a turned down 520 sprocket in it. then the shaft is just a piece of 3in solid shaft turned down to 1in with a shoulder and a keyway. The 3in flange bolt to the adapter on the engine with 6 M8-1.25 bolts and a locating boss on the middle. Finally, I mounted a bearing on the end of the shaft to take the radial load from the chaincase. The extension is around 3-4in long, leaving it unsupported is just asking for trouble. But the hard part is to install the outer bearing concentric with the engine output shaft...

I will try to take a photo this week of the drawing.

 

[Brett Kobernik]

I was kind of curious about your driveshaft extension also. Looking forward to seeing a photo or two.

 

[fgauvin7]

This Is what I have done on this one. The part fixed to the engine output shaft is fixed with the original nut but I added an O-ring to allow a bit of flex. This will prevent the output shaft to have too much bending force and create fatigue. This is also the reason we need the outer bearing on the end of the shaft extension.