Reposting previous post, now with working photos
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/showpos...79&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.
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.
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.
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.
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.
This image shows better how the upper bogie wheels sit in relation to the swingarm.
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.
These parts are cut out of 3 mm steel, made for just templates for jigs.
Here you can see some of the design in the movable jack shaft. As the shaft are moved, the brake calipper mount also moves.
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 ;-)
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.
Tried some notching with the mill.
Lathed and milled the upper bogie wheels. They will have a diameter of only 100 mm.
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!
Ordered the front suspension FOX Float shocks. They are originally to a Honda ATV for correct length and stroke 330 by 259 mm.
Lathed and milled hub of the brake disc.
Made the rear axle.
A little start with the tubular frame. The fit seems to be better than expected.
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 .
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.
Partition table is a big help to drill the holes with correct spacing.
The sprockets seems to be as strong as solids. Total weight of all sprockets incl. clamping sleeve on one sprocket was 1,007 grams.
Here is the drawing on the drive shaft and jack shaft .
The shafts will be drilled with 16 mm long drill.
8" Slydog rear wheels weighing 350 g. Of course in KTM colours ;-)
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.
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.
On this kit we ordered precut base plates, of course, with lightening holes.
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.
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.
Started by making a drawing to get the coordinates and angles .. The material is a circular block with a diameter of 100 mm.
Lots of material to be milled ...
Round feeding table made it easy to get the right angles. Hole drilling seemed to go as planned.
The outer round part of ski bolt bushing was kept while the rest was milled around using circular feed table.
Edit:
Forgot to upload the final overview drawing:
More to come....
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