I have been around snowmobiles longer than I care to admit and have seen a less approach angle and bigger drivers add to less trenching. Now with the smaller drivers on the 15 kit, and the drive axle placement moved forward and up how is this doing in deep snow performance?? I have heard of 14 kits making it where 15 couldn't on some days and wonder if my 14 with new bearings will do as well or if the 15 is the $hit. I just wonder why the smaller driver. Please don't flame me just wondering.....thanks...
2015 track approch angle
- Thread starter the gman
- Start date
I imagine that the front suspension mounts must be moved accordingly, to keep the approach angle. I have also heard that the 14s will hang with the 15 no problem, some even think the lower height is a negative and will cause more drag in the snow.
My best explanation is this, on a sled, we have always have had the center line of the driver above the bellypan, so all exposed track is driving in a somewhat positive direction.
Due to the mounting to the dirtbike, there are obvious space constraints, and as the 11-14 kits have the driveshaft centerline below the base of the bike, as it digs in the track actually is digging itself into a hole at a certain point, kinda like reverse on a sled once the wheels dive in. Just augers. So now by re-orienting things, skid, drivers, etc. and getting that centerline even with the base of the bike, all paddles exposed to the snow are pushing in a positive direction, avoiding the submarining factor that can occur when the bike starts to trench in and get stuck.
also, being that the bike is so long, by moving the drivers up and forward (as well as the skid) we are now getting the rider weight more on the track, this way your riding on the biggest footprint, instead of pushing a ski heavy setup around. again, space constraints of the bike, the ski and skid are too far apart causing weight to be less then ideally distributed, TS has done a good job of making things work with what they have, but their is just to much mass in front of the track causing the skid to have not enough weight on it, resulting in a lot of slippage while pushing around an overloaded ski. ex, pushing something around in front of you on ice. your feet just slip out, pick it up, put the load over the drive system (feet) and now you can move it no problem.
Due to the mounting to the dirtbike, there are obvious space constraints, and as the 11-14 kits have the driveshaft centerline below the base of the bike, as it digs in the track actually is digging itself into a hole at a certain point, kinda like reverse on a sled once the wheels dive in. Just augers. So now by re-orienting things, skid, drivers, etc. and getting that centerline even with the base of the bike, all paddles exposed to the snow are pushing in a positive direction, avoiding the submarining factor that can occur when the bike starts to trench in and get stuck.
also, being that the bike is so long, by moving the drivers up and forward (as well as the skid) we are now getting the rider weight more on the track, this way your riding on the biggest footprint, instead of pushing a ski heavy setup around. again, space constraints of the bike, the ski and skid are too far apart causing weight to be less then ideally distributed, TS has done a good job of making things work with what they have, but their is just to much mass in front of the track causing the skid to have not enough weight on it, resulting in a lot of slippage while pushing around an overloaded ski. ex, pushing something around in front of you on ice. your feet just slip out, pick it up, put the load over the drive system (feet) and now you can move it no problem.
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mtn-doo
Well-known member
That is well said Nick, thank you.
Something else you can play with is the front end. If you make sure your forks are dropped to "flush" with your triple clamp, then install at least a .52 spring or my favorite is the .56. This combo makes the bike feel as though you have a little more rake. It also reduces the soft, sagging front end. With a soft front end you exaggerate the negative effects Nick mentioned earlier. As the bike is driven forward, at times you will push into the overly "soft" front end adding to wasted track spin. Keeping a light front end and a more uniform transfer on the skid seems to really work well. Another benefit is the low front end "spongy" and " diving" goes away for a much better handling bike.
Something else you can play with is the front end. If you make sure your forks are dropped to "flush" with your triple clamp, then install at least a .52 spring or my favorite is the .56. This combo makes the bike feel as though you have a little more rake. It also reduces the soft, sagging front end. With a soft front end you exaggerate the negative effects Nick mentioned earlier. As the bike is driven forward, at times you will push into the overly "soft" front end adding to wasted track spin. Keeping a light front end and a more uniform transfer on the skid seems to really work well. Another benefit is the low front end "spongy" and " diving" goes away for a much better handling bike.
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Blaser
Well-known member
Oh Gman... this one's going to cost you more than doughnuts!
There are 8 main reasons we rolled and raised the chain case for 2015. I'm just going to cover one of them here.
Approach angle is critical in powder on a snowmobile because the track is always breaking its own trail. The snowmobile track is constantly hunting and struggling to get up on top of the powder. Let's assume you're climbing a hill in the powder on your sled, and halfway up you drop into your buddies track. You instantly climb better when poaching a track.
On a snow bike, you have a 10 inch wide ski continually breaking trail for the track. It's like you're following your buddy all day, when you're not. The track is running in a partially ski-packed trench. If you mount a GoPro under your bike looking forward, and another from under the front fender looking back, you'll see what we've studied and tested.
There are times when you have more and less ski pressure breaking trail for the track, and times when the snow consistency plays a part in all of this. But generally speaking our approach angle argument is completely different than that of a snowmobiles'. Approach angle on a snow bike is not critical in the same ways as it is on a snowmobile. Axle positioning, however, is critical on a snowbike for top-secret reasons.
Timbersled's #1 reason for rolling and raising the drive axle for 2015 is because it performs better than the 2014 and prior kits.
We use many methods to be able to test things like that, one of which is having identical bikes in our fleet set up side by side; using both 2014 and 2015 kits.
Call me and I'll fill you in on the other 7 reasons.
And thanks for asking!
Blaser
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Blaser
Well-known member
There are several very important reasons for the smaller driver. Again, forget what a smaller driver used to mean on our old-school sleds that used thick, power-robbing tracks and drivers. We've tested this a lot. New track technology with more efficient thinner ported tracks, variable length rods, etc makes it possible to go with a smaller driver and not find a measurable loss in efficiency.
We did also engineer several efficiency enhancements into the 2015 kit that further compensate for the smaller driver.
One of the main reasons goes back to the super-secret drive shaft placement I alluded to previously.
Another, is a smaller driver allows the kit to be mounted closer to the bike- resulting in a shorter "wheelbase" which yields more traction, more transfer, more weight on the track, quicker handling, etc etc.
Now consider gearing. Everyone wants to gear up a bit, or down a bit; and that requires a masters degree in spreadsheet formula calculations to figure out. Past kits used a 17/20 sprocket combo in the chain case; which also meant the chain case had to be big to fit the 20t gear. With the smaller driver, we were able to now use a 17/17/17 sprocket combo, and achieve the same roll-out (final drive ratio). Now, if you want to gear your 2015 kit up or down, you order a 16t sprocket and either put it on top or on the bottom in the chain case. Super simple, and super easy. If you want more- swap the 17 for a 16 on the primary chain.
Next, consider the tree stump, the rock, or the fence post. They all have one thing in common- we hit them when we ride. A low driver, or a bigger driver is more susceptible to impact damage. Impacts can cause shafts (and spinal cords) to go out of alignment, accelerating bearing wear.
At the end of the day, the smaller driver brings us a myriad of performance and handling enhancements that easily overwhelm what we thought we knew about smaller drivers. In this case (smaller) size matters!
That's a few reasons. Hope that helps!
Blaser
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Corban_White
Well-known member
I love these tutorials from Brett. I would love to see them regularly. Something like a weekly Mountainhorse tech talk explaining (as much as possible without giving away all the secrets) the tech behind the design.
