Sabaton
Newbie
Nikolai
TY 4 Stroke God
Something very similar to that.
Sportsterdanne
TY 4 Stroke Guru
Whats the dimension on the turbo charge tube is it 1.750" ?
ruffryder
TY 4 Stroke Junkie
Note that lynx now uses the latest rev platform, with full a - arms.
While the upper a-arm can be made much lighter, the lower a-arm, spindle mount, and inner spindle need to be much more stronger. You also have more bushings and longer bolts too.
I would look closer to F1 technology for lightweight building of suspension... at least ideas anyways.
While the upper a-arm can be made much lighter, the lower a-arm, spindle mount, and inner spindle need to be much more stronger. You also have more bushings and longer bolts too.
I would look closer to F1 technology for lightweight building of suspension... at least ideas anyways.
No need to reinvent the wheel. Polaris already has a front end that works great. Graft that front end onto your Nytro and ride the damn thing. The nice thing will be both the Yamaha and Polaris parts are available from the dealer or eBay, Craiglst, etc.
If you want to be unique, contact the Yamaha race dept and see how cheap you can get one of last season's XC race front ends. They will be running the Viper for this season and will have no use for those kits. They already figured out the geometry, the kits improved the handling and were lighter than stock. You could custom build some shorter a-arms to make it better for mountain riding.
If you want to be unique, contact the Yamaha race dept and see how cheap you can get one of last season's XC race front ends. They will be running the Viper for this season and will have no use for those kits. They already figured out the geometry, the kits improved the handling and were lighter than stock. You could custom build some shorter a-arms to make it better for mountain riding.
Nikolai
TY 4 Stroke God
This will be a completely new chassis, so "riding the damn thing" all winter won't be an issue. My sled is 100% ready to go.
ruffryder, I'll take a look at the F1 stuff. I've been trying to gather ideas from anywhere and everywhere. One idea I had was to use lightweight threaded bushings with a short bolt on each side instead of through bolting.
ruffryder, I'll take a look at the F1 stuff. I've been trying to gather ideas from anywhere and everywhere. One idea I had was to use lightweight threaded bushings with a short bolt on each side instead of through bolting.
It's 2" at the throttle bodies and then 1.75" to the turbo. You can see where it necks down to 1.75" after the second elbow.
ruffryder
TY 4 Stroke Junkie
Nikolai said:
I guess the big thing is that most motor sports use a knuckle that turns, rather than a knuckle that has a spindle inside of it that rotates.
Most of F1 just use carbon fiber a-arms and mount the shocks in the center of the chassis using an aluminum or probably magnesium linkage. Getting the shock out from the a-arms would protect it better, and also allow for better evacuation of snow from the front of the suspension. I think this would have more of an impact while riding in deep snow.
On this idea, maybe take one of your pictures of your sled in deep snow / covered in snow, and build / design to shed the snow much better. Just some thoughts.
Oh, and start building carbon a-arms already and use more epoxies then traditional fasteners..
Nikolai said:
I didn't realize that. A good place to find suspension design inspiration is with RC Cars. I've seen them use front end designs I've never seen anywhere else.
If you want the ultimate boondocking sled you might consider going old school with struts. They don't ride the best but for light weight, low drag in deep snow, there isn't anything better. Custom fit some upside down MX bike forks to a sled, shorten them down to 9", might work pretty well. The Ski-doo Tundra Extreme is a heck of a sled in tight, technical terrain. Do something similar with a wide belly pan to help float the 4-stroke, I think it would put a stock MTX to shame.
Off Trail Mike
Gone Riding!
Caleb
Very cool concept. Hard to believe there are still no "mountain specific" chassis in snowmobiling. Nytro RTX/XTX/MTX, ProCross/ProClimb, Poo Assault/RMK, Skidoo REV-XP/XM, all a degree of compromise, thus the clean sheet is a real interesting question.
Here's my 2 cents on the subject of a rewrite of the front end.
Castor: 25 degrees, slightly steeper than the 23 degree Nytro, slightly less than Skinz 27 which is what mine has..seems to work well.
At first I was thinking castor in a snowmobile was similar to a car, but in the case of a mountain snowmobile we are pitching over the sled pretty dramatically, say 20 degrees plus, which has the effect of steepening caster even further (relative to the snow). The combined effect leads me to think that the castor works on the pivot action of the lower front ski. You can think of it as a drag point that the sled can pivot around. Makes sense to some degree because at really high angles of pitch over and fully cut skis, if you could stay balanced on the sled, the track wants to pivot about the lower front ski like the ski is anchored to the ground.
On the single arm concept, I am not sure it will work as well as a 2 arm system, but more because of caster than camber. If you think my reasoning above holds true, then a single arm will have the opposite effect of making the caster geometry remain basically the same as the suspension compresses, which will slow the turning radius a bit. I have a 2007 Tundra with the single arm front suspension, and it is an incredibly tippy fun sled, but lacks the HP to make a comparison. Someone with a 2007-09 Skidoo Freeride 550 Fan with the 1.75" BC track might be able to shed some light on handling characteristics, but to me, it won't be as good.
I think camber is not as big a handling issue on a mountain sled, except to say you want your skis relatively parallel to the snow when going in a straight line and handling bumps/terrain.
Shock length and travel? There is a trade off with a-arm weight as shorter shocks will require stronger and stiffer a-arms as the lower shock pivot moves further away from the spindle so I think what fits with the shock closest to the spindle is the best (lightest) setup.
I would be pushing the shocks forward (like the skinz) to slow the pogo effect when going side to side.
Too bad its so damm hard to test different configurations, cause I don't think we have the design "nailed" yet. I am continually surprised at how a very long snowmobile (153/162) with the skinz front end pushing the wheelbase (if I can call it that) even longer can change directions like a 121. Pretty amazing how far we've come already.
Good luck on the build...it'll be awesome!
OTM
Very cool concept. Hard to believe there are still no "mountain specific" chassis in snowmobiling. Nytro RTX/XTX/MTX, ProCross/ProClimb, Poo Assault/RMK, Skidoo REV-XP/XM, all a degree of compromise, thus the clean sheet is a real interesting question.
Here's my 2 cents on the subject of a rewrite of the front end.
Castor: 25 degrees, slightly steeper than the 23 degree Nytro, slightly less than Skinz 27 which is what mine has..seems to work well.
At first I was thinking castor in a snowmobile was similar to a car, but in the case of a mountain snowmobile we are pitching over the sled pretty dramatically, say 20 degrees plus, which has the effect of steepening caster even further (relative to the snow). The combined effect leads me to think that the castor works on the pivot action of the lower front ski. You can think of it as a drag point that the sled can pivot around. Makes sense to some degree because at really high angles of pitch over and fully cut skis, if you could stay balanced on the sled, the track wants to pivot about the lower front ski like the ski is anchored to the ground.
On the single arm concept, I am not sure it will work as well as a 2 arm system, but more because of caster than camber. If you think my reasoning above holds true, then a single arm will have the opposite effect of making the caster geometry remain basically the same as the suspension compresses, which will slow the turning radius a bit. I have a 2007 Tundra with the single arm front suspension, and it is an incredibly tippy fun sled, but lacks the HP to make a comparison. Someone with a 2007-09 Skidoo Freeride 550 Fan with the 1.75" BC track might be able to shed some light on handling characteristics, but to me, it won't be as good.
I think camber is not as big a handling issue on a mountain sled, except to say you want your skis relatively parallel to the snow when going in a straight line and handling bumps/terrain.
Shock length and travel? There is a trade off with a-arm weight as shorter shocks will require stronger and stiffer a-arms as the lower shock pivot moves further away from the spindle so I think what fits with the shock closest to the spindle is the best (lightest) setup.
I would be pushing the shocks forward (like the skinz) to slow the pogo effect when going side to side.
Too bad its so damm hard to test different configurations, cause I don't think we have the design "nailed" yet. I am continually surprised at how a very long snowmobile (153/162) with the skinz front end pushing the wheelbase (if I can call it that) even longer can change directions like a 121. Pretty amazing how far we've come already.
Good luck on the build...it'll be awesome!
OTM
Nikolai
TY 4 Stroke God
Just for clarity here, I'm not trying to build a razor sharp handling bump sled that I can huck 100 feet. I want a very rigid, strong, simple, sub 400 pound 190 HP 4-stroke mountain sled that that will maneuver effortlessly in the nastiest mountain terrain.
You bring up some great points Mike. There's certainly a lot to think about when you're starting from scratch.
I decided to go back and look at the Ski-Doo freestyle some more. Even with a fixed spindle/a-arm (think camber changes), the ride reviews from magazines are pretty good. Ski-Doo's specifications for the 2009 Backcountry Freestyle list the front travel at 6.3". Not great by any means, but maybe if the Ohlins were setup with just the right valving you could get the shorter travel to work good. When I was looking at the microfiche, I noticed the tie rods bolt directly to the steering post similar to my current sled which makes for a clean chassis design. If you pieced together the front "nun" so to speak which is about $350 worth of parts(could probably find them used), it would give you the a-arm, shock, and steering locations to jig. Find a couple used a-arms/spindles to jig and build stronger, lighter versions out of 4130 and you'd be good to go. You could even run the factory aluminum tie rods. Here's a couple pics from the microfiche of the front suspension and steering. Obviously the handling wouldn't be near a Pro, but it would be extremely light, clean, and BRP has already figuring out the correct geometry.
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So many options
I also bought a couple used Diamond Drive brake calipers off Snowest (bought two so I could lighten one and have a spare), and got a great deal on a new BDX lightweight ceramic brake rotor off ebay. In a month or so I'll order the BDX Diamond Lite drive and lightweight track shaft.
You bring up some great points Mike. There's certainly a lot to think about when you're starting from scratch.
I decided to go back and look at the Ski-Doo freestyle some more. Even with a fixed spindle/a-arm (think camber changes), the ride reviews from magazines are pretty good. Ski-Doo's specifications for the 2009 Backcountry Freestyle list the front travel at 6.3". Not great by any means, but maybe if the Ohlins were setup with just the right valving you could get the shorter travel to work good. When I was looking at the microfiche, I noticed the tie rods bolt directly to the steering post similar to my current sled which makes for a clean chassis design. If you pieced together the front "nun" so to speak which is about $350 worth of parts(could probably find them used), it would give you the a-arm, shock, and steering locations to jig. Find a couple used a-arms/spindles to jig and build stronger, lighter versions out of 4130 and you'd be good to go. You could even run the factory aluminum tie rods. Here's a couple pics from the microfiche of the front suspension and steering. Obviously the handling wouldn't be near a Pro, but it would be extremely light, clean, and BRP has already figuring out the correct geometry.
So many options
I also bought a couple used Diamond Drive brake calipers off Snowest (bought two so I could lighten one and have a spare), and got a great deal on a new BDX lightweight ceramic brake rotor off ebay. In a month or so I'll order the BDX Diamond Lite drive and lightweight track shaft.
mike g
Extreme
Why a diamond drive instead of belt drive?
Nikolai
TY 4 Stroke God
The main reason is because of the minimal space the brake setup takes up. One of my biggest goals with this next chassis is to narrow it up as much as possible. You can machine the inside of the cat clutches to slide them further onto the shaft, which I did with the DD I put in my Rev. I want to move the driven clutch in as far as possible, and then move the engine over until the primary is aligned. This is the only way to really get the sled narrower. Back to the point of the Diamond Drive, the oil tank is in the way of moving the engine over (and narrowing that part of the body), but with the DD brake setup, I can move the oil tank rearward to right in front of the brake disc and then I have all the room in the world to move the engine over. With the oil tank moved back, and the engine moved over (even an inch would be good) it will make for very slender body work and a sled that will hold an incredibly steep sidehill without washing out. Lightweight, narrow, and compact are the name of the game this time.
Another reason for the DD is that it's about about $700-800 less for a complete BDX lightweight DD setup (l/w gearbox w/ the new high torque gears, l/w trackshaft, 10.4 clutch, l/w disc, caliper, Avid drivers) versus the CMX belt drive, and BDX's DD's are pretty bulletproof and make for a really clean chassis. A lot of people hate them, but nearly all of the durability issues are with the oem cat gearboxes, also a lack of good oil, and variations in M series bulkhead widths putting strain on the driveline. With a rigid chassis built to the correct width I don't foresee any problems. I wanted the next tunnel to be narrower anyway to improve handling.
Another reason for the DD is that it's about about $700-800 less for a complete BDX lightweight DD setup (l/w gearbox w/ the new high torque gears, l/w trackshaft, 10.4 clutch, l/w disc, caliper, Avid drivers) versus the CMX belt drive, and BDX's DD's are pretty bulletproof and make for a really clean chassis. A lot of people hate them, but nearly all of the durability issues are with the oem cat gearboxes, also a lack of good oil, and variations in M series bulkhead widths putting strain on the driveline. With a rigid chassis built to the correct width I don't foresee any problems. I wanted the next tunnel to be narrower anyway to improve handling.
Nikolai
TY 4 Stroke God
Pic of the bottom of a Freestyle.
Malmlof
Veteran
Great thread guys, and great job Nikolai!
With weight being the primary target I would consider a carbon or fiberglass leafspring with fixed spindels.
Like on a truck but upside down, with a rigid center mount it would double as "arm" and the shocks will be springless!
The hard part would be to figure out the right "spring" and any impact could be an issue also.
Other then that I think Akrider suggestions/idea is good, like the old V-max with the the "thermos" suspension.
The one thing to consider if using rotation of the shockshaft from a bike for steering is friction, it could become very heavy on the steering with load on the suspension.
The freestyle concept is also very lightweight, I dont think camber change is the big issue rather then the trackwidth/skistance change that occurs with fixed spindels.
If you could make the arms longer it would be less. Let them "cross" each other at the chassi to lenghten them would be an solution for that.
Maybe you could use a McPherson type of setup, with the shock controling the spindle then the lower arm wouldn´t have to be so strong/heavy either.
Just some ideas and thoughts.
/Richard
With weight being the primary target I would consider a carbon or fiberglass leafspring with fixed spindels.
Like on a truck but upside down, with a rigid center mount it would double as "arm" and the shocks will be springless!
The hard part would be to figure out the right "spring" and any impact could be an issue also.
Other then that I think Akrider suggestions/idea is good, like the old V-max with the the "thermos" suspension.
The one thing to consider if using rotation of the shockshaft from a bike for steering is friction, it could become very heavy on the steering with load on the suspension.
The freestyle concept is also very lightweight, I dont think camber change is the big issue rather then the trackwidth/skistance change that occurs with fixed spindels.
If you could make the arms longer it would be less. Let them "cross" each other at the chassi to lenghten them would be an solution for that.
Maybe you could use a McPherson type of setup, with the shock controling the spindle then the lower arm wouldn´t have to be so strong/heavy either.
Just some ideas and thoughts.
/Richard
Nikolai
TY 4 Stroke God
Even if leaf springs were lighter I'm not sure I could put them on a sled, haha. Something I have to take into account is the chassis complexity with each front end design and the amount of body work needed to enclose it. A suspension similar to the Freestyle would require very little front tube work and not much in the way of body panels. With a pogo suspension similar to the new Tundras, I could see the frame work being much more complex and needing larger body panels which means more weight. I'm by no means ruling any ideas out, but there's more to factor in than just the weight of the suspension components.
Keep the ideas coming!
Keep the ideas coming!