Suspension Configuration Question - Snowmobile World : Your #1 Snowmobile Forum
 
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post #1 of 5 (permalink) Old 12-25-2007, 12:08 PM Thread Starter
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I see a lot of mountain suspensions set up where basically the front limiter is let out long enough that the sled, when braking, slowing, or stopped, it will ride essentially up on the front curved part of the slide rail. The rear axle literally sits up off the ground a little when parked. Then when you accelerate you get a lot of weight transfer and ski lift as it rocks back to the flat part of the skid. So I assume that's why some people are doing this, the ski lift. Question is, is this really a good way to go?

I have my mountain tracks set up where if it were sitting on concrete the track is almost completely flat. If anything, the front limiter is short enough to lift up the front of the skid just slightly with the rear limiter out as far as possible. I was told this helps the sled climb up out of holes. I don't know if this is really true or not. I can see how this would also make the skis slow you down by putting more pressure on them. But it would seem that with the front limiter too long you would be digging down into the snow instead of up out of the snow...but maybe the skis prevent that and then after the weight transfers it's no longer digging down? You might get a better turning radius too because the full track isn't resisting the turn?

I get my ski lift from setting the rear springs fairly soft; my front skid spring is not adjustable. Mind you I don't get a whole lot of lift but I don't know if I really want any more than what I am getting. I see a lot of messed-up setups so I don't know if there is anything good about this "rocking-chair" type of suspension setup or if it's just another dumb thing that people do for no good reason.

Can anyone comment?

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Sleds -
2015 Summit SP 800 E-TEC 146"x2.5"
2015 Summit SP 600 E-TEC 146"x2.5"
2000 RMK 800 @ 151"x2.25" 19/40/9T
1992 Indy 500 Chassis, piped 700 engine, Mesh Hood, RMK Skis, 136"x1.75" 18/40/9T

History -
1990 EXT Special 530 @ 136"x2.25" finger, 18/39/8T, Camoplast skis.
1996 Vmax 600 Mountain Max, Summit Skis
1999 RMK 700 @ 151"x2" 19/41/9T
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post #2 of 5 (permalink) Old 12-25-2007, 08:01 PM
 
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Quote:
I see a lot of mountain suspensions set up where basically the front limiter is let out long enough that the sled, when braking, slowing, or stopped, it will ride essentially up on the front curved part of the slide rail. The rear axle literally sits up off the ground a little when parked. Then when you accelerate you get a lot of weight transfer and ski lift as it rocks back to the flat part of the skid. So I assume that's why some people are doing this, the ski lift. Question is, is this really a good way to go?

I have my mountain tracks set up where if it were sitting on concrete the track is almost completely flat. If anything, the front limiter is short enough to lift up the front of the skid just slightly with the rear limiter out as far as possible. I was told this helps the sled climb up out of holes. I don't know if this is really true or not. I can see how this would also make the skis slow you down by putting more pressure on them. But it would seem that with the front limiter too long you would be digging down into the snow instead of up out of the snow...but maybe the skis prevent that and then after the weight transfers it's no longer digging down? You might get a better turning radius too because the full track isn't resisting the turn?

I get my ski lift from setting the rear springs fairly soft; my front skid spring is not adjustable. Mind you I don't get a whole lot of lift but I don't know if I really want any more than what I am getting. I see a lot of messed-up setups so I don't know if there is anything good about this "rocking-chair" type of suspension setup or if it's just another dumb thing that people do for no good reason.

Can anyone comment?[/b]
well the rear axle may sit p some because it could be a tipped rail suspension but for the most part your right. the approach angle is the big thing in the mountains. your dont want to trench. with how you were saying people set those up they got it right and wrong. you wnat good tansfer but sounds to me the approach anlge is going to be steep leading to trenching. you wnat a flater angle and good tranfer to pop up on top and stay there.
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post #3 of 5 (permalink) Old 12-25-2007, 11:29 PM Thread Starter
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That is what I thought. I see a lot of STUPID setups but I haven't been in the sport long enough to know for sure what's a good idea and what isn't. I just started experimenting with suspensions this year. My RMK was set up this way (rocking chair) when I got it, so was the sks, and I have seen others the same. I switched them over to the "right" way immediately, but then I started wondering if I was actually the one who was wrong. Good to know I was on the right track. The big difference this year is I'm running my rear springs a lot looser and that is absolutely where it's at.

This seems to be pretty common with rolled chaincases where the suspension needed to be relocated but not enough care was taken in choosing the new mounting points. It seems like when this mod is made and the suspension is moved back, the rear torque arm needs to be dropped more than the front in order to get the angle right, but if you drop the rear too far the track drags on the front torque arm. On the RMK I actually replaced the stock rear torque arm idler wheels with 7.5" wheels which lift the track up an inch higher in the tunnel. That allowed me to drop the rear end another inch (without dragging on the front torque arm) and could get the proper approach angle without taking in the front limiters very much. The result being more travel and max ground clearance. That's working out really nice for me. On the SKS it has funky offset rear torque arm idler wheels that I can't replace with bigger ones (yet), so we have to run the front limiter almost completely in just to get the track flat on the ground. The rear end cannot be dropped another MM unless I find some bigger wheels for that rear torque arm.

Anyway, thanks for the info, I needed that confirmation. There is a lot of misinformation in snowmobiling. Would you say I should run it as flat as possible parallel to the ground, or should the front limiters be slightly short so that the front of the skid is a little bit off the ground and most of the weight sits on the rear axle?
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Subscribe to my channel:

www.youtube.com/beaxch



Sleds -
2015 Summit SP 800 E-TEC 146"x2.5"
2015 Summit SP 600 E-TEC 146"x2.5"
2000 RMK 800 @ 151"x2.25" 19/40/9T
1992 Indy 500 Chassis, piped 700 engine, Mesh Hood, RMK Skis, 136"x1.75" 18/40/9T

History -
1990 EXT Special 530 @ 136"x2.25" finger, 18/39/8T, Camoplast skis.
1996 Vmax 600 Mountain Max, Summit Skis
1999 RMK 700 @ 151"x2" 19/41/9T
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post #4 of 5 (permalink) Old 12-28-2007, 12:55 AM
 
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When it comes to limiter strapes lenght, you don't want them too lose because if your climbing a really steep hill and your track can drop all the way, the front end will rear right up on you and the sled will become really hard to keep strait. I set up my limiter straps almost on the longest I can but not all the way. This way when i'm riding around trees it's really easy to menouver and wip it around really quick. And in the alpine climbing the steep, my skis don't touch the snow, just track, and steer the your body.
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post #5 of 5 (permalink) Old 12-30-2010, 05:36 AM
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What would be a good approach angle to have?
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