Nikolai
TY 4 Stroke God
Usually being on bottom means you're submissive.
Maybe a dumb question but I'll ask anyway ... Are you going to be able to use shocks without spherical bearings? Seems you've been maintaining OEM geometry for the most part, but I was wondering if the subframe shock mounts have been moved (further forward?). Don't get me wrong. I'm not suggesting you go back to the drawing board with your design. Just thinking it might make it easier to run different shocks setups. Love what you guys are doing BTW ... really great thread. 
Nikolai
TY 4 Stroke God
My Ohlins have spherical bearings, had to with the Skinz kit.
That's kinda my point Nikolai. If the shock mount were to be moved (a little further forward I think), you wouldn't necessarily have to install spherical bearings in order to run the Skinz kit. Just sayin' it might be worth considering if you're going to use the new subframe as a jig.
Um, maybe not. Taking another look at the upper Skinz arm and the clearance of your Ohlins coils, there doesn't appear to be enough room for forward movement of the upper shock mount. My bad ... carry on.
Sportsterdanne
TY 4 Stroke Guru
If you have the skinz a-arms and matching shocks then i would have made it like this. The stock plastic will also be easier to put back on.
But my future plan is to remake the subframe and make the a-arms wider to get rid of the bends that skinz have to do to get the spindles i the right place. And that would make it easier to mount the shocks in the middle of the a-arm, like the cross country subframe and eliminate the need for spherical bushings.
This build is awesome keep it up !
But my future plan is to remake the subframe and make the a-arms wider to get rid of the bends that skinz have to do to get the spindles i the right place. And that would make it easier to mount the shocks in the middle of the a-arm, like the cross country subframe and eliminate the need for spherical bushings.
This build is awesome keep it up !
sorenson1610
TY 4 Stroke God
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What are you going to do for a skid plate? The front of the motor looks like it is exposed from were the subframe is moved up into the new tubes.
207nytro
Pro
Are you planning on building your own a arms when you go wider? What are the disadvantages of running spherical bearings? It seems like mounting the shocks in the middle of the a-arm would increase the need for them unless you modified the top shock mount by moving it forward. Even if you made the shock mounts line up to fit normal bearings, since the a arms compress pretty much going vertically, and the shocks would be mounted on an angle and as the shock compresses the mounts would no longer line up.
So how would you plan to move the shock mount into the middle of the a-arm and still use regular bearings? and whats so important about mounting in the middle of the a-arm? Just trying to understand your reasoning.
So how would you plan to move the shock mount into the middle of the a-arm and still use regular bearings? and whats so important about mounting in the middle of the a-arm? Just trying to understand your reasoning.
Nikolai
TY 4 Stroke God
sorenson1610 said:
There will be a 3/4" tube that runs side to side right in front the motor to help protect it and I'll also be running a skid plate.
The Skinz arms re-position the spindles and improve the Nytro's handling. Skinz designed them to be a bolt-on product. I can see why it was probably easier to stick with OEM geometry in terms of a-arm and shock mounts ... there would be a lot of angles to figure out in order to get it to work right. The goal here is to drop weight without sacrificing strength ... no sense re-inventing the wheel in regard to what Skinz has done.
When I first looked at the photos of the new subframe bolted up to the delta box, I noticed the Ohlins shocks and wondered (since I didn't know they would accept spherical bearings) if Nikolai had moved the upper shock mount forward. But when he said he had to install spherical bearings in his shocks, I looked closer at the photos and realized that there just isn't enough room to move the shock mounts forward ... the coil springs wouldn't clear the front of the upper arm.
The only reason I suggested moving the shock mounts forward was to eliminate the need for spherical bearings so you'd have more options in terms of the type of shocks that can be used. But as it is, there does seem to be a variety of good shocks that will accept spherical bearings, so why bang your head against the wall trying figure out different geometry when the OEM angles will work with what you want to do.
When I first looked at the photos of the new subframe bolted up to the delta box, I noticed the Ohlins shocks and wondered (since I didn't know they would accept spherical bearings) if Nikolai had moved the upper shock mount forward. But when he said he had to install spherical bearings in his shocks, I looked closer at the photos and realized that there just isn't enough room to move the shock mounts forward ... the coil springs wouldn't clear the front of the upper arm.
The only reason I suggested moving the shock mounts forward was to eliminate the need for spherical bearings so you'd have more options in terms of the type of shocks that can be used. But as it is, there does seem to be a variety of good shocks that will accept spherical bearings, so why bang your head against the wall trying figure out different geometry when the OEM angles will work with what you want to do.
Nikolai
TY 4 Stroke God
If i would have built a jig first, itd be easier to change the geometry, but since I'm building off the subframe its just easier to leave some things unchanged. If I moved the shock mounts I'd also have to modify the plastics more. Keep throwing opinions out there though, you guys might see something we didn't. None of us are engineers by any means, just three guys that can't leave well enough alone.
Sportsterdanne
TY 4 Stroke Guru
Yes, planning on building my own A-arms, spherical bearings may not be an disanvantage but it limits the use of stock shocks and lots of aftermarket ones and its an additional cost to modify the shocks. and of course the upper shock mount have to move "forward" the same distance so it only travels vertically and not in an angle.
Widening the A-arms and mounting the shock on a plate thats distributing the shock force to both tubes rather than just on tube should theoretical allow the use of smaller tubing (less weight) due to smaller amount of force going trugh the tubing (look at the A-arms on the cross country nytro), And the A-arms would be easier to build with straigther tubing and maybe allow the use of straight tie rods without the bend in them, when you dont have to route them around the shock.
to go even farther would be a taller spindle (like arctic cat) that twould make it possible to make the upper A-arm even lighter (smaller tubing) due to less forces in the upper a-arm.
i am not an engineer either but its really fun to try to improve and modify stuff, and the building and designing part is just as fun as riding.
the easy way would be to buy a polaris Pro RMK and be happy with that, but the reliabilty of the Yamaha engine and the awesomness of 4-stroke turbo and the fact that im a former Yamaha mechanic (blue blood in my veins) makes the Yamaha my number one choice.
Widening the A-arms and mounting the shock on a plate thats distributing the shock force to both tubes rather than just on tube should theoretical allow the use of smaller tubing (less weight) due to smaller amount of force going trugh the tubing (look at the A-arms on the cross country nytro), And the A-arms would be easier to build with straigther tubing and maybe allow the use of straight tie rods without the bend in them, when you dont have to route them around the shock.
to go even farther would be a taller spindle (like arctic cat) that twould make it possible to make the upper A-arm even lighter (smaller tubing) due to less forces in the upper a-arm.
i am not an engineer either but its really fun to try to improve and modify stuff, and the building and designing part is just as fun as riding.
the easy way would be to buy a polaris Pro RMK and be happy with that, but the reliabilty of the Yamaha engine and the awesomness of 4-stroke turbo and the fact that im a former Yamaha mechanic (blue blood in my veins) makes the Yamaha my number one choice.
207nytro said:
207nytro
Pro
Judging by other things I have seen done to your sled, you seem worried about weight. Which is most likely why you are wanting to use smaller tubes for your a-arms. Instead of messing with geometry have you thought of just using ways to strengthen the side the shock mounts to by putting some sort of crossmember from where the shock mounts to the other side, similar to the one on the top arm.
207nytro
Pro
Here is what im talking about, the red is what you could add. Another thing to think about is that the a-arns should be stronger than the shocks but weaker than the subframe. So that if you take a hard hit or landing the arms would bend rather than the subframe, but also to the point where the only way the forces are put on the a-arms is if the shocks bottom out. Therefore making sure the a-arms can take more force than the shocks do during travel. Im sure you know most of this already. But by adding the bar i showed it should transmit some of the forces to the other side rather than causing that one bar to bend. Is there any problems with the strength of the skinz arms? It seems like since the mounts are in fact so close to the joint at the end of the arm that it can take more force as opposed to placing it in the middle of a long length of bar that isnt supported to something else. You also mention the XC racing arms, do you know what those are made of? they may look smaller but could they possibly be much thicker metal? Just some things to think about if you havent already.
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HYFLYR
TY 4 Stroke Guru
I think it would be more of an issue and also decrease the handling of the sled by mounting the shocks further forward on top. By increasing the angle of the shock and the rate to which it transfers energy to the chassis is very important and what I belive was a major drawback from the factory. With vertical shocks it would send the force directly to the other side of the sled, not allowing the any force to be tranfered through the rest of the sled. In a sidehill for instance, it would pitch the sled back against the force you were applying to hold that sidehill. With a raked out front end, it allowed the shock angle to direct its force into the chassis, not across it.
Yes it means you have to run sphearical bearings or angle the shock tabs, however that one drawback far exceeds a vertical shock angle. I think skinz nailed it with their design, moving the skis forward and also changing shock angle, I have said from day one when the nytro came out that was one of the biggest flaws was their front geometry, in shcok angle and spindle.
Call me crazy but thats where my head is at.
Yes it means you have to run sphearical bearings or angle the shock tabs, however that one drawback far exceeds a vertical shock angle. I think skinz nailed it with their design, moving the skis forward and also changing shock angle, I have said from day one when the nytro came out that was one of the biggest flaws was their front geometry, in shcok angle and spindle.
Call me crazy but thats where my head is at.