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GEN II, our home built snowbike project

swedenturbo

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Dec 4, 2009
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Hi guys!
This gonna be a long first post but I´d like to share our progress so far. Hopefully I will post you more as we go...
I think photos tell more than plain text especially when I work hard to write in english ;-)
Hope you enjoy my pics ;-)
Seen lot of DIY snowbike kits here, great work guys!


2 years ago, me and my buddy built two Mountain horse replicas, well it may look like a copy but we designed it only from pictures seen on the web.
We didn´t dare to build the suspension so we used a MXZ skid. An easy way out but doesn´t work as well as the original suspension.
Here's a link to some photos of our first build.http://www.snowest.com/forum/showpost.php?p=3083479&postcount=2

We have ridden with it for the past two years an it works pretty well.
There are some things we would like to improve. Instead of motifying existing kit, we took the decition to build new kits.
Things we saw could be improved:
1. Less weight. We aim for a weight reduction of 15 kg, hopefully more.
2. New suspension. The build used a modified MXZ bogie , greatly oversized snowmobile suspension that is basically for hard trail riding. Instead we plan to build a pure snowbike mountain suspension . It will be much lighter and designed just for snowbikes, not sleds.
3. New track. Last track was 3050mm with 44 mm lugs. The new build will use 3460 with 59 mm lugs. As we ride 96 hp turbo bikes, we believe they can pull that track easily ;-)
4. New tubular frame. The first build had steel tube with 2 mm thicknes, way too heavy. Now we´ll use 1,2 mm thicknes. A Swedish steelquality called SSAB Docol. Its reminiscent of chrommolly but promises to be easier to weld and less risk of cracks.
5. Movable jackshaft. We had some issues with the tension pulley on the motor chain. Moreover, it has been difficult to get the right chain tension, especially with some gearings. By being able to move the jackshaft equal when tightening the chain on a motorcycle rear wheel , we will be able to run any kind of gearing, less parts and also lighter .
6. 6005 bearings with updated custom made housings. Less weight
7. A slender and more sturdy chain case that reduce the risk of hitting rocks and stubbles.
8. Newly designed tunnel panels that are more slender and exposes the track so that any stubs or rock collisions are hit by track and drive wheels and not the front tunnel area and chain case.
First challenge is the design of the bogie.
We will try to design a suspension similar as EZ ryde. Believe that it is passable for these machines with good options to adjust ski pressure and suspension stiffness. In addition, the EZ ar well known for its good powder snow properties.

Started by cutting the 59 mm track. A really crappy job, but what do you do? Smokes and smells like hell but at the end a good result.
The reason we start by cutting track is that we want to strip that is left.
With it, we will make a simple mockup of the suspension to try different geometries.
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As said the GEN II will have a new custom designed rear suspension.
We begin with an analogue "drawing" to test geometries.
By doing all out of wood and chipboard we can easily test various attachment points and see how it affects the suspension travel.
We're onto something, but need to adjust some attachment and get a slide function on the swingarm rear mounting.
Unfortunately, this type of bogie has an "impossible geometry" of track tension and, therefore, the sliding function combined with the front shock will push back the rail
therefore tensioning the track. Have done shockdummies with the correct length and stroke.
We also printed the blueprint from our first build at a scale of 1:1 to get some known references.
That way we can see how our analogue drawing will fit the new design.
We try to be thorough with the design and all the drawings.
This way we can order most parts pre-cut with almost every drilling done.
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The first build was more or less a replica build of original Timbersled Mountain Horse. Here´s the new design of the tunnel panels.
Looks similar to the previous build but is completely redesigned.
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The bogie will remind EZ-Ryde's design.
We believe one advantage is that it is completely uncoupled and enormously lighter than Ski-doo SC4 suspension.
Also, the front of the rails will hopefully flex in a way that can be beneficial on snow bikes.
The rear travel is more than 400 mm.
Here we test the suspension travel more theoretically.
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EZ ryde on sleds have a swingarm that can go almost straight back. On a snowbike the swingarm has to move into upper bogie wheels due the narrower the track.
If the swingarm would go straight back without a waist, it would be in the extreme compression hit in the bottom of the upper bogie wheels.
For that reason, the swingarm to get a little odd design.
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This image shows better how the upper bogie wheels sit in relation to the swingarm.
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Yes, finally all the laser pre-cut parts and done! Here we go! Many parts .... All this for two kits + one set of welding jig.
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These parts are cut out of 3 mm steel, made for just templates for jigs.
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Here you can see some of the design in the movable jack shaft. As the shaft are moved, the brake calipper mount also moves.
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There are some differevces in the design between the first build and the GEN II. Side panels are of a more modern straight lines and kind of duck tail ;-)
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Starting to work with "the mother of all jiggs". Spent some time on it but we will regain that work later on.
This piece is thick and heavy and stands up against anything! Laser cut drilling template facilitates that the attachment points will the right place.
May seem a little over-ambitious, but but it will help us in the long run ;-)
I would highly recommend to order precut jig templates. We feel confident that all the measurements are correct and that it is straight.
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Tried some notching with the mill.
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Lathed and milled the upper bogie wheels. They will have a diameter of only 100 mm.
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This time, we ordered pre-bent tubing to tubular frame and swingarm. The drawing was of great help to get all the measurements and angles right. The swedish dragracing frame company ME-racing has done a good job of bending. Fits correctly!
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Ordered the front suspension FOX Float shocks. They are originally to a Honda ATV for correct length and stroke 330 by 259 mm.
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Lathed and milled hub of the brake disc.
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Made the rear axle.
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A little start with the tubular frame. The fit seems to be better than expected.
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A little work left on the drive shaft as we await delivery of the drive wheels. The gearing may be a bit unusual : 14-19-18-16 give a final speed of 91 km / h at 8,500 rpm at 5th gear. 6th can be considered as a cruise gear.
If gearing will be too high , we can easily switch to 17 or 18 tooth on the drive shaft .
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We want the sprockets to be as lightweight as possible .
Started with a simple drawing to get the right dimension spacing of holes. Want to be a bit careful with the holes so no strength deteriorates.
"Spoke" thickness is 8 mm in small, ranging between 9.1 and 5.9 mm on the large gear with large center hole.
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Partition table is a big help to drill the holes with correct spacing.
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The sprockets seems to be as strong as solids. Total weight of all sprockets incl. clamping sleeve on one sprocket was 1,007 grams.
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Here is the drawing on the drive shaft and jack shaft .
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The shafts will be drilled with 16 mm long drill.
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8" Slydog rear wheels weighing 350 g. Of course in KTM colours ;-)
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The work with the first tubular frame proceeds. A little work left before we can remove it out the jig. It will be interesting to see if it warped after welding.
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Notchning of the rear connection of the arch was improvised. We clamped the pipe at 45 degrees and then tilted mill head 67 degrees for it to be the right angle. The results exceeded expectations.
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On this kit we ordered precut base plates, of course, with lightening holes.
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The holes in the jig was made ​​that we can turn it upside down and weld the bottom without having to remove the frame.
Anything to prevent warping when welding.
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Here you see how the arcs connects almost to swing attachment.
We have made a solid box construction on the sleeves in 3 mm steel. The arch goes down to right next to the swing arm sleeve.
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The last build we used a cut off Ski-doo REV-spindle in the lower part of the ski bracket.
Clearly the easiest thing to do for the home builder but this time decided to make it a bit more advanced made out of billet aluminum.
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Started by making a drawing to get the coordinates and angles .. The material is a circular block with a diameter of 100 mm.
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Lots of material to be milled ...
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Round feeding table made ​​it easy to get the right angles. Hole drilling seemed to go as planned.
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The outer round part of ski bolt bushing was kept while the rest was milled around using circular feed table.
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Edit:
Forgot to upload the final overview drawing:
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More to come....
 
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Wheel House Motorsports

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I love it. Been following these builds on the facebook group.

Lots of really well thought out parts! as well as some darn good MFG capabilites you guys have!
 

Jon Mutiger

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Wow, that is some great work! It's great that your open about it.

My recommendation from what I saw, you were welding the top side almost completely before flipping the jig over. I'd recommend tacking the entire thing up as minimally as possible then spread the remaining welding around from front to back to avoid the pulling that happens when you weld like that. Getting nit picky, I'd also recommend terminating your welds off the centre line of the tubes, as that's where all the forces are. Without FEA analayis on that, I'd guess you'll have some cracks forming around the mount to the bike which will need gussets in the future. For this early kit, I'd keep the coating (paint) something that won't hide cracks, ie don't powder coat it just yet.

The above stuff comes from working with tubular race car frames and jigs, the order of your welding does affect the end trueness of your product. In your case, it really isn't that important.. But I'd say the end coating is important, as catching cracks early will allow you fix issues before they completely fail.

That truly is a great project, great job!
 

CATSLEDMAN1

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goooood job guys

Love your jig, yup turn it over, got to have those holes for back side welds.

When I took my frame from my jig I knew it would tawng of shape to find its stess. Been there. To overcome that, after final welding top bottom as best I could, stood back with big propane weed burning torch and heated the whole works jig and all for 20 minutes or so. Let it cool, frame goes in and out of jig no issue.

Tig weld these frames and looks good but toooo much heat. Mig weld it and a little more ugly. I have had that argument with myself over and over, tig sounds cool and look great, mig is cool and looks ugly.......so ride in the dark?

Loaned out my track trimming to two kids at engineering school to they could mock up a suspension dummy like you did, great idea.

so I would say I'm about a kit behind you guys, I'm going to have to suck it up, maybe machine a new kit from solid block of carbon fiber......looking now for good 8 speed air shift tranny for the next power up kit.
 

Robster

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Love your jig, yup turn it over, got to have those holes for back side welds.

When I took my frame from my jig I knew it would tawng of shape to find its stess. Been there. To overcome that, after final welding top bottom as best I could, stood back with big propane weed burning torch and heated the whole works jig and all for 20 minutes or so. Let it cool, frame goes in and out of jig no issue.

Tig weld these frames and looks good but toooo much heat. Mig weld it and a little more ugly. I have had that argument with myself over and over, tig sounds cool and look great, mig is cool and looks ugly.......so ride in the dark?

Loaned out my track trimming to two kids at engineering school to they could mock up a suspension dummy like you did, great idea.

so I would say I'm about a kit behind you guys, I'm going to have to suck it up, maybe machine a new kit from solid block of carbon fiber......looking now for good 8 speed air shift tranny for the next power up kit.


Since they use Ultra High Strength Steel tubes, the reheating will destroy the hardness of the tubes. They need just to be very careful when welding these and doing it as mentioned above on different places and finishing the weld offcentre from where the stress on the tubes are the highest. I am confident that this build will be a true beast! They are very thorough and carefull when building. Great work Håkke and a superb post!

//Rob
 

swedenturbo

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First frame completed. We are pleased that it hadn´t warped during welding and was completely straight. The jig must have prevented this in a very good way. We had predicted a weight around 5 kg. A little disappointing that the scale showed 5.4 kg. However, we believe that this frame is stronger. The reinforced swing mount sleeves adds a little weight.
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Here you see the laser cut template which is temprary bolted to bearing housing mount plate. This way we can ensure that it´s welded in exactly the right place. Same template will be used when we drill the mounting holes on the tunnel panels. Just to ensure that both bearings will be alligned correctly.
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S
Nov 20, 2010
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Awesome work my friend! I'm blown away at how many Swede's are building such advanced kits.

Thankfully your English is MUCH better than my Swedish! ;)

Keep up the amazing work!
 
M
Mar 14, 2012
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I am very interested in the steel you are using. I would like to know how it works out for you and if you think it welds, machines good. Also is the price decent for what it is. I have only heard of this twice and this is the second time.

Go machining work.
 

Robster

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I am very interested in the steel you are using. I would like to know how it works out for you and if you think it welds, machines good. Also is the price decent for what it is. I have only heard of this twice and this is the second time.

Go machining work.

The Docol R8 tubes are as good as it gets.
Very easy to weld, easy to machine (a lot harder though, so takes more time not to heat them so that they loose their strenght.

Check these links for more info and let me know if there are any more questions and I will try to answer them if I can.


http://www.aedmotorsport.com/blog/article/docol-r8-tube
http://club.speedgroup.eu/newsletters/2013/edition3_2013/tubes/tubes.html
http://www.ssab.com/Global/DOCOL/datasheets_docol/en/220_Docol Roll.pdf
 

swedenturbo

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CNC machined housings required little further milling, drilling and tapping but now they're finished!
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This bearing housing will sit on jack shaft closest to the chain case. Has dual 6005 bearings as this will be under double loads. Partly from motor chain and chain in the chain case. The saved "block" is where the tensioning bolt will push.
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The back is milled to run in the slot hole in both tunnel section and the tubular frame.
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Drive axle housings have no locking ring groove as tunnel panel holds bearing in place.
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Here you see the principle of chain tension by moving the bearing housing.
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A small drawing error. The radius of the hole in the tunnel panel does not match the radius of the bearing housing. Gotta grind this to get it right.
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swedenturbo

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We try to make every single part of the kit as light as possible.
Drilled the 27 mm drive shaft and and the 25 mm jackshaft with a 16 mm long drill bit. If there has been a 270 horsepower engine, the shafts probably wouldn't hold up but with a 50-100 hp snowbike it´s a different story.
We plan to temper all axes to further increase the safety margin.

Machined a plug in 16 mm the hole at each drillhole end of the shafts.
Then drill a smaller hole and tap for a M10 bolt so we can pull the whole assembly together at each ends of the shafts.
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Machined the plug by two hundredths of a milimeter oversized for press fitting.
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The plug welded, shaft end machined and tapped.
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Right side if the kit (shafts turns clockwise) is threaded M10 fine left hand thread. Left hand threaded should hopefully reduce the risk of it coming loose, even without Locktight.
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Testing assembly of bearing housings, brake caliper mount and caliper.
As the pic shows, the bolts are too long, need to fix some shorter....
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Here´s the drawing of our shafts.
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swedenturbo

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After a lot of TIG-welding the frames are completed. They didn't warp after welding so the theory worked in practice.
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The strut replacing the rear shock completed. First build, we had a solid 30 mm aluminum rod. This build we try to make it as light as possible by making the strut hollow. Almost exactly 0,2 kg less. Now weighs exactly 0.5 kg. Worth the effort? Well, maybe ....
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A drawing of the strut.
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30 mm rod drilled with 22 mm drill bit. Welded ends machined and threaded.
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Bent the side panels of the ski mount. We will produce 4 units, 2 ski mounts per kit. Good to have an extra if we'll unlikely wrecks a mount.
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When you have no bending machine, just fabricate your own for your tool press
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Works really good!
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The cardboard templates gets the bending angles right.
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Machined axle sleeves. The edge goes inside the aluminum panels, welded both from the inside and the outside.
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Made a wooden template to bend the strip that will form between the side plates.
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Welded inside before the strip were attached.
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First test assembly of the side panels and tubular frame.
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The laser cut template was also used to align mounting holes for the side panels. This we think this is crucial of the alignment of chain case bearing housings.
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swedenturbo

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The work om our build proceeds.

Machined bushings and shaft to the front attachment of the swingarm.
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The first drive chaft we made of hexagonal rod was sent to the scrap box. We have discovered that the steel quality was too low and threatened to break.
Machined a new drive shaft. 32mm shaft of machine steel in good quality. Shaft diameter 27 mm and drilled out with 16 mm long drill.
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Skid and suspension completed.
Rail extensions are nt light weight or pretty. Will run these during testing.
I have some longer rails from a Nytro that I will test when the kit is completed. I Think the Nytro rails has a better design for the LT application.
ST rails and track might be a nice option for the spring season!
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Made ​​the chain case reinforcement rim. GEN II will have a different solution to the chain. A 10x30 mm aluminum rim bolted from the inside of the tunnel. This will stiffen the tunnel panel and we think this is much better compared to the previous solution on the first build. The chain protection lid will only be a thin sheet that covers the chain.
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A laser-cut folding template made bending easy and accurate.
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Both sides of the rim was milled flat.
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Another drilling template makes the holes will line up correctly. Tapped for M6 screw with countersunk head.
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The rim will have a small notch so that the lid will be flush.
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Test assembly. Only the middle bolt hole is pre-drilled in the tunnel section. This is to be able to adjust the position of the other holes that is bolted to the tubular frame and the jackshaft is aligned. The previous build we had some problems when the frame warped during welding. The predrilled holes didn't line up and we had to grind them up to get it right.
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GEN II will tension motor chain by moving the shaft.
The caliper is mounted together with the bearing housing so this will also move with the jackshaft.
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