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Rear Suspension Talk

cacsrx1

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Feb 7, 2008
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Highmore SD
...what was your fix?

Ace

Properly valved Raptors and locked out Zmotion. Stock limiter position, very little preload on the FTS and a couple clicks of dampening. Torsion springs on 4, then set the dampening on the RTS for whatever terrain your riding. More dampening for climbing, less for trees, meadows, trail rides in and out. It is a well rounded set up for me.
 
J

JJ_0909

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Properly valved Raptors and locked out Zmotion. Stock limiter position, very little preload on the FTS and a couple clicks of dampening. Torsion springs on 4, then set the dampening on the RTS for whatever terrain your riding. More dampening for climbing, less for trees, meadows, trail rides in and out. It is a well rounded set up for me.

Wait Raptors + Torsion Springs? I'm confused...thought they deleted the torsions...
 

cacsrx1

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Wait Raptors + Torsion Springs? I'm confused...thought they deleted the torsions...

You can get either set up, one is a lot more expensive than the other. I went the cheaper route and it wasn't quite what I was looking for, so I added the Zmotion and lockout and now it does what I want it to do. Now I can back off a trailer without ripping the snowflap off, and pushing down on the rear bumper is a lot more progressive and doesn't just collapse like a stocker. It allows some sag, a compliant ride and keeps the track in the snow without making the front end feel heavy or loosing its playfulness. Hope that makes sense.....
 
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JJ_0909

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You can get either set up, one is a lot more expensive than the other. I went the cheaper route and it wasn't quite what I was looking for, so I added the Zmotion and lockout and now it does what I want it to do. Now I can back off a trailer without ripping the snowflap off, and pushing down on the rear bumper is a lot more progressive and doesn't just collapse like a stocker. It allows some sag, a compliant ride and keeps the track in the snow without making the front end feel heavy or loosing its playfulness. Hope that makes sense.....

10-4 - You could always bump up to a stiffer torsion bar from Ski-Doo. Probably wouldn't need a revlave on your RTS either.

But yeah, in a nutshell, this sounds like a good setup but is exactly the kind of story I'm trying to showcase as being similar to my own - and ultimately why I went to Tom (and then started helping him out!)

I started with a setup direct from Fox. Good, but not great, even with the ability to firm up my rear track shock's compression damping.

I needed something very adjustable as terrain, conditions and what I'm looking for out of the skid can change a whole bunch day to day. A coil setup out back generally won't allow this change to happen. Air and the quick adjust compression lever does allow for me to make this sort of change in a matter of minutes.

Even if I am a set-it-and-forget it guy, being able to find this best setup without spending more money, or sending stuff back to the tuner is a big help.

Just my experience, and my $0.02.
 
F
Nov 27, 2007
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medicine hat
So is the shock 100 percent locked out if I want to climb a shoot, or does it still leak back on lockout mode??

I have left Tom a few messages on this and he was trying to have manufacturer comply to that, said in the past they always leaked back

If your into a 60 second wot pull up a shoot, you don't want ski lift at the top, theirs is where there is ussally a ulgy overhang or cornice and any sag or lift will just add to endowing effect.. We currently run Elko coil spring shocks with heavy springsand lots of preload.. If I sit on the rear bumper, it don't ussally move more than a inch.. Makes it very stiff on the trail, but once in the deep snow, life is good.. And if doing a steep line threw trees, one needs good stering control, I would probably have it on lockout most of the day


I've got it on my sled. If you want a pict you can find one here...

https://scontent-ort2-1.xx.fbcdn.ne...=681a3b54f619939ab0760c837c984731&oe=5B0E58EB
 

cacsrx1

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Feb 7, 2008
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Highmore SD
10-4 - You could always bump up to a stiffer torsion bar from Ski-Doo. Probably wouldn't need a revlave on your RTS either.

But yeah, in a nutshell, this sounds like a good setup but is exactly the kind of story I'm trying to showcase as being similar to my own - and ultimately why I went to Tom (and then started helping him out!)

I started with a setup direct from Fox. Good, but not great, even with the ability to firm up my rear track shock's compression damping.

I needed something very adjustable as terrain, conditions and what I'm looking for out of the skid can change a whole bunch day to day. A coil setup out back generally won't allow this change to happen. Air and the quick adjust compression lever does allow for me to make this sort of change in a matter of minutes.

Even if I am a set-it-and-forget it guy, being able to find this best setup without spending more money, or sending stuff back to the tuner is a big help.

Just my experience, and my $0.02.

Some people aren't air shock guys, they are easy to adjust on the trailer but in the field not so much, and from what I have seen even just the stock X package shocks benefit greatly from an oil change and a revalve. More than one way to skin a cat.
 
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JJ_0909

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So is the shock 100 percent locked out if I want to climb a shoot, or does it still leak back on lockout mode??

I have left Tom a few messages on this and he was trying to have manufacturer comply to that, said in the past they always leaked back

If your into a 60 second wot pull up a shoot, you don't want ski lift at the top, theirs is where there is ussally a ulgy overhang or cornice and any sag or lift will just add to endowing effect.. We currently run Elko coil spring shocks with heavy springsand lots of preload.. If I sit on the rear bumper, it don't ussally move more than a inch.. Makes it very stiff on the trail, but once in the deep snow, life is good.. And if doing a steep line threw trees, one needs good stering control, I would probably have it on lockout most of the day

Good question. I don't know what "leaked back" specifically means but "locked out" in Fox world really means (with respect to this style of shock) an *incredibly* firm low speed compression shim stack. This means if a bump is hit hard enough, it will blow-off to the high speed circuit (meaning it'll move). This is important as to not break, bend or blow anything up in the situation your suspension is required to move

Also to be clear, in locked out mode, it does not have an effect on spring rate. EG, if you set your skid up with sag, it'll still have sag when locked out.

Hope this helps. Its a great tool for getting up something an minimizing transfer.

Tom is also looking at some simple coupling options for his rear arm. This, with the lockout, wow- that'd be something for your crazy chute climber guys who also want a compliant ride elsewhere.
 
J

JJ_0909

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Some people aren't air shock guys, they are easy to adjust on the trailer but in the field not so much, and from what I have seen even just the stock X package shocks benefit greatly from an oil change and a revalve. More than one way to skin a cat.

Understood on the air shock thing, I do however think people need to give the modern air stuff a chance, especially on a skid. I can say this as a guy who has come from an extensive background in mountain bike suspension testing, which is fortunately where a lot of Fox's modern air shock technology is coming from int he sled world.

10 years ago nobody would have ever wagered air suspension would be where it is in the mountain bike world, winning WC DH, and EWS stuff alike. I see the same exact thing happening (it going toe to toe with coil) as this same air spring technology trickles into the sled world. I can say I really prefer it on a skid.
 
T
Feb 8, 2010
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Nelson, B.C.
A number of members here have commented that this thread has the opportunity to open up an interesting dialog, what I believe would be suspension components and their independent roles and how they work together, as well as suspension set-up. I think there is some confusion in what each component does, for example springs are not a compression dampening adjustment and likewise a shock is not for ride height / sag adjustment. I think having a better understanding of what each component does allows everyone to have a discussion on how adjusts work.


for example one of the first things any suspension manufacture recommend is the importance of setting ride height or sag with the machine fully loaded. sag is very important for absorbing terrain features and reducing damage to the vehicle and person. if during this process one finds they can not achieve proper sag/ride height one would need to increase spring rate (change springs). springs do a couple of things they set the ride height, they return the vehicle back to that proper height. if one finds they require heavier springs one would then need to think about how this affects compression dampening (increasing the effect but not the dampening) and rebound (decreasing the effect but not the dampening) which would typically require shock adjustments to the dampening. Doo dampens their set-ups very lightly and as such any increase in spring rate will feel like an increase in compression damping or resisting bottoming out and on the other end rebound will feel like it's been decreased pogo stick effect. If one really wants to fix bottoming out compression dampening is required and this is weight related, the heavier one is the more dampening is required, to think that a shock set-up with fixed compression damping would work for me (5'7" 140 lbs) would also work for anyone 6'4" 260lbs is misleading. Rebound damping is not quite as critical but also requires attention to function properly, it plays an important role in insuring the suspension returns to proper ride height/sag quickly enough for the next hit however too quickly and it'll pogo stick on you and too slowly and the suspension will not recover for the next hit and eventually one could pound the suspension flat due to continuous compression impacts.


now I'm no expert, guys Like Andy at GSR, or Kevin from Kmod would be ideal to get into the conversation....I know there are lots great people with great information out there to share so please join in.
 
J

JJ_0909

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A number of members here have commented that this thread has the opportunity to open up an interesting dialog, what I believe would be suspension components and their independent roles and how they work together, as well as suspension set-up. I think there is some confusion in what each component does, for example springs are not a compression dampening adjustment and likewise a shock is not for ride height / sag adjustment. I think having a better understanding of what each component does allows everyone to have a discussion on how adjusts work.


for example one of the first things any suspension manufacture recommend is the importance of setting ride height or sag with the machine fully loaded. sag is very important for absorbing terrain features and reducing damage to the vehicle and person. if during this process one finds they can not achieve proper sag/ride height one would need to increase spring rate (change springs). springs do a couple of things they set the ride height, they return the vehicle back to that proper height. if one finds they require heavier springs one would then need to think about how this affects compression dampening (increasing the effect but not the dampening) and rebound (decreasing the effect but not the dampening) which would typically require shock adjustments to the dampening. Doo dampens their set-ups very lightly and as such any increase in spring rate will feel like an increase in compression damping or resisting bottoming out and on the other end rebound will feel like it's been decreased pogo stick effect. If one really wants to fix bottoming out compression dampening is required and this is weight related, the heavier one is the more dampening is required, to think that a shock set-up with fixed compression damping would work for me (5'7" 140 lbs) would also work for anyone 6'4" 260lbs is misleading. Rebound damping is not quite as critical but also requires attention to function properly, it plays an important role in insuring the suspension returns to proper ride height/sag quickly enough for the next hit however too quickly and it'll pogo stick on you and too slowly and the suspension will not recover for the next hit and eventually one could pound the suspension flat due to continuous compression impacts.


now I'm no expert, guys Like Andy at GSR, or Kevin from Kmod would be ideal to get into the conversation....I know there are lots great people with great information out there to share so please join in.

Nice comment! I dig it.

Few thoughts...

1) I do agree sag is very important for a number of reasons. I would really like to post a video of a trophy truck through gnarly terrain but will abstain ;)

I know, mountain sled riding is not the same thing as rallying a truck through the desert, but there are plenty of excellent skids out there that run a fair amount of sag and still control transfer very well. For a variety of reasons, running some sag is going to be a good thing (front and back).

Part of me wants to get into the idea of transfer, instant center and antisquat, but I'll leave a lot of that alone for now.

2) Yes, the system has to work in harmony. One of the best videos out there is that Skinz Shock Therapy video. One can learn a LOT from this.

3) The way you are explaining damping isn't quiet right. Damping is speed sensitive control over the shock package. Some damping is also position sensitive. This means when the shock cycles, it is able to control the speed at which the shaft is compressing (or rebounding). In certain cases damping can change depending on the position of the shaft.

Yes, damping can help control bottom out, but so can your spring rate.

As far as needing a revalve for heavier springs or heavier riders, no argument. However, in practice its not always true. Depends how much one is bumping up in spring rate (and to some degree, what their preference is and if the - most importantly - the rebound damping is suitable/matches the other dampers)

To add, for those that jump, rebound damping is incredibly crucial, especially if one part of the sled is rebounding at a different rate than another (say the front is slower than the back...good way auger in that front end!)

The really trick part is a lot of this kind of goes out the window with respect to mountain riding. Or rather, it doesn't but your suspension's ability to track the smallest bump while still maintaining its composure while sending a huge double isn't quiet as important as say, Snowcross.

What we are really looking for is a sled that can control weight transfer well, EG: Keep the skis down, unless the rider wants to be able to lift them for one reason or another (there are plenty of reasons)

So having a way to control AND adjust this transfer is crucial. There are a number of variables in play, including how your FTS is sprung, how much preload you are running here (or sag), how your rear track shock is sprung, damping, the shape of the front/rear arm etc etc. As many have pointed out, lots of ways to skin the cat.

Obviously, suspension up front has a lot going on too that'll impact not just the way the sled rolls over (or doesn't roll over) but how the sled transfers weight. (more sag vs less sag)

So yeah, it gets complicated, but its also really cool, as you can have a pretty dynamic machine.

Finally, like most things in the sled world, taste impacts this immensely. Funny thing is, "feels good" is often not what we are after when it comes to control and best setup for a certain condition.

The point of suspension has less to do with comfort and more to do with control. To me anyway...

...yeah that got long.
 
T
Feb 8, 2010
406
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Nelson, B.C.
So lets talk about transfer because I think people use the limiter strap incorrectly as a wheelie control. I find that when the limiter strap is pulled up too far there is no more transfer and weight shifts to the skiis and the tail end of the skid. while yes it will change the attack angle of the skid, it also reduces the suspensions functionality. This is where coupled suspensions come into play, ask a trail guy how he/she controls ski lift while maintaining transfer....adjust the coupling. Does this apply to mountain riding? it does on both hill climbing with and without trees.


I understand that in some cases dampening is speed sensitive, I had high and low speed dampening on my previous sleds, however I wasn't aware of position dampening....interesting physics involved.


Like I said I'm no expert and I love learning new things.
 
J

JJ_0909

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So lets talk about transfer because I think people use the limiter strap incorrectly as a wheelie control. I find that when the limiter strap is pulled up too far there is no more transfer and weight shifts to the skiis and the tail end of the skid. while yes it will change the attack angle of the skid, it also reduces the suspensions functionality. This is where coupled suspensions come into play, ask a trail guy how he/she controls ski lift while maintaining transfer....adjust the coupling. Does this apply to mountain riding? it does on both hill climbing with and without trees.


I understand that in some cases dampening is speed sensitive, I had high and low speed dampening on my previous sleds, however I wasn't aware of position dampening....interesting physics involved.


Like I said I'm no expert and I love learning new things.

Few things...

First most of what I know in the sled suspension world originated in the mountain bike world (as I stated earlier). Happy to give my resume (lol) there, but this has given me a strong understanding of how a damper works, what a spring is designed to do, spring rate progression bla bla bla. I only say this because it is a slightly different lens on all of this.

All damping is going to have some form of high and low speed damping regardless if there is adjustment to it. Basically all this is in reference to is how a damper reacts to high speed shaft input compared to low speed comes shaft speed. This is influenced by shim placement, damper design oil viscosity etc. One can revalve a non-adjustable damper to have more/less high speed damping regardless of external adjustment.

As far as position sensitive damping, you can often see this with respect to certain dampers' bottom out resistance. I believe Raptor did this. Obviously, this uses the shocks damping at the latter part of the stroke (position) to effect how hard it is to compress the shock at higher shaft velocity (though it'll also effect lower shaft velocity)

Transfer - now yeah, this is the name of the game and point of this thread. Lots of theories and ideas here. I too am interested in learning more.

I personally like Rasmussen's "theory". Run the limiter out, let your FTS sag a realitively high amount, run a progressive FTS spring rate, (through coil or air), control transfer through a stiffer, progressive rear shock.

This gives your skid the maximum amount of travel, helps hold an edge sidehilling, and due to the softer initial rate still gets up on snow well (front arm can easily collapse).

Bringing some form of coupling too, into this system, that'd be the most agile setup I can think of for the kind of riding I do.

Executing this idea to perfection, well, that's a whole other thing. But its the only way I've found to get the G4 chassis to carry weight where I want it, remain fun, but keep the skis down (unless I really want to lift them)

My $0.02.
 

Chadly

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If money isn't an object for the perfect ride, I think the ARC system really does its job. I thought the whole thing was smoke and mirrors and personally had never seen one on a sled. I installed it on my 165 that has an MPI turbo on it along with Tom's Rear skid. With the ARC fully engaged the sled is on rails and has the perfect amount of ski lift. I personally leave it engaged all the time in deep snow, even in steep technical terrain. When it's off, the sled is a lot more playful and you can go around and show off doing turbo wheelies or have a smooth ride on a completely whooped out trail. I personally never ride with it half on as I don't see a use for this. I have had zero issues with the electronics not working and drive around with sled on my deck in the pouring rain with no cover. The system does 100% as advertised even though it is pricey.
 

snosumitcsr

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Nov 26, 2007
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If money isn't an object for the perfect ride, I think the ARC system really does its job. I thought the whole thing was smoke and mirrors and personally had never seen one on a sled. I installed it on my 165 that has an MPI turbo on it along with Tom's Rear skid. With the ARC fully engaged the sled is on rails and has the perfect amount of ski lift. I personally leave it engaged all the time in deep snow, even in steep technical terrain. When it's off, the sled is a lot more playful and you can go around and show off doing turbo wheelies or have a smooth ride on a completely whooped out trail. I personally never ride with it half on as I don't see a use for this. I have had zero issues with the electronics not working and drive around with sled on my deck in the pouring rain with no cover. The system does 100% as advertised even though it is pricey.

Got any pictures of your Setup?
I have heavier springs all the way around, revalved stock shocks Zmotion, torsion spacers, remote limiter set up. snow conditions suck, so haven't really got any real rides in, almost out of break in mode. I added stuff a little at a time, so with the current snow I don't know where im at..
 

Chadly

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Got any pictures of your Setup?
I have heavier springs all the way around, revalved stock shocks Zmotion, torsion spacers, remote limiter set up. snow conditions suck, so haven't really got any real rides in, almost out of break in mode. I added stuff a little at a time, so with the current snow I don't know where im at..

I just added the Z motion to my stock sled. This will be my first time riding it this weekend.
 

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ZRP Engineering

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Yeah he asked for a picture or the ARC which is on the turbo sled. I put Z motion in the stocker. The Z motion works really well.
Fyi, to install properly the rear-ward holes in the brace are ment to be drilled out and used as the new mounting holes for the zmotion to function correctly.

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