Moderators can you move this to the mountain section.
K Mod and Holz and Timbersled Challenge
- Thread starter byeatts
- Start date
Moderators can you move this to the mountain section.
R
RPS
Well-known member
Raptor
Byeatts, something that I have found that works well on multi chamber air shocks in general is to add a few cc’s of oil to the secondary chamber between the ifp and the fill port. This will do exactly the same thing as shortening the tube without shortening the tube and once you get the volume figured out then you know exactly how much you need to shorten it. Nice work on the fab side! Good to see guys trying to figure it out! Call if you need better explanation on the above. RPS <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" /><o></o>
Byeatts, something that I have found that works well on multi chamber air shocks in general is to add a few cc’s of oil to the secondary chamber between the ifp and the fill port. This will do exactly the same thing as shortening the tube without shortening the tube and once you get the volume figured out then you know exactly how much you need to shorten it. Nice work on the fab side! Good to see guys trying to figure it out! Call if you need better explanation on the above. RPS <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" /><o></o>Byeatts, something that I have found that works well on multi chamber air shocks in general is to add a few cc’s of oil to the secondary chamber between the ifp and the fill port. This will do exactly the same thing as shortening the tube without shortening the tube and once you get the volume figured out then you know exactly how much you need to shorten it. Nice work on the fab side! Good to see guys trying to figure it out! Call if you need better explanation on the above. RPS <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com
Great tip!
Moved as Requested.....
Does anyone have a stock skid that they can film , compression and transfer?
I think we are starting to see the real differences in these skids. Both obviously work good and have progressed very well over the years. I feel that I should add a few thoughts to some of the previous posts that I feel might be mislead.
<O</OOver centering a coupling suspension: A coupled suspension can over center by laying both the shock and arm down flat only if the geometry is not correct. Without the coupling this would not happen.<O</O
Over centering happens when the upper pivot point of back arm is lower than the upper pivot point of the front arm at a low point of the travel. How does it do this you ask? First I will explain how coupling works and then you will understand the over center problem. These are problems that we have all had and we have worked out of the Mtn. Tamer entirely and from it we have been able to make a true progressive rate coupling suspension.
<O</O
1. As the back arm compresses it stops when it hits the coupling adjuster (basically, it binds up).
<O</O
2. At this point for back arm to compress more it has to push the slide rail back.
<O</O
3. To does this, the front arm has to be pulled down for the rail to move back because it is the control arm for the slide rails.
<O</O
4. This is where it gets tuff to explain. If you were to draw a line between the front and back arm on the upper pivot point in the tunnel and the lower pivot point in the slide rail (where the suspension arms bolt to the tunnel and rail) you would see that the two lines are not parallel (the back would be wider than the front).
<O</O
5. There are great load between these lines when the suspension is coupled; these load forces are what makes the coupling action work. The load force from the back arm is pushing back on the slide rails and forward on the tunnel.
<O</O
6. As the suspension travels upward these two lines will parallel each other and the suspension will travel in a one synchronized motion. If these lines stop paralleling each other at the bottom of the travel and become closer together in the back then the front, the load force on the upper pivot point will then push down on the back arm of the suspension and pin the suspension to the rubber bottom out pad on the slide rail.
<O</O
7. The power of the back shock will overcome this but the suspension will have a soft spot and will bottom easily when it gets to this point.<O</O
This is near impossible to overcome with an equal length arm suspension because they pull the front arm up much slower. This is the reason we couple our front arm up at a faster rate than the back arm goes down to prevent this over centering problem. We are able to do this with our slide mechanism rear arm because it is contently changing length. You can do a test to see it for yourself if you take your back shock out of your Kmod suspension or pre 2011 and older Mtn. Tamer and simply pushing down on the back bumper with the suspension fully coupled. It will pin the back arm down so hard that you will have to put your foot on the track and pull it up to get it to come back.<O</O
Bottom out positioning: The bottom out pad on the back Mtn. Tamer arm is used to fine tune the max compression of the jounce bumper in the shock. If you do not have this it is near impossible to fine tune bottom out when we have 4 different shock options in our lineup to help fit our customer’s budget.<O</O
Our bottom out pad does not give the skid less travel like what is stated in the above post. Our bottom out adjuster hangs down 1.25” from the bottom of the back arm and our rubber bottom out pad on the slide rail is 1.25” lower then what is on the Kmod. This make the bottom out point the same for both skid.<O</O
Single rate verses Dual rate springs: We do not use duel rate springs because we cannot get them but because we do not need them. On a single rate spring the first inch of travel it not what the rate of the spring is, it is much softer. The rate is measured after 1” of compression.<O</O
Kevin has talked a lot about pre load and that he uses the same spring for 120lbs rider all the way up to a 260lbs rider and compensates with spring preload and compression adjustment. My questions would be this; if you adjust the spring pre load way up for a heavier rider doesn’t that defeat the prepuce of a multi rate spring and when preloaded that much the spring still does not have the rate to support that wide of a range of riders and to compensate you add compression dampening to stop it from bottoming? I disagree with this. The spring rate needs to match the rider’s weight and we think that the least amount of preload is the answer to keeping the suppleness of the skid. This defeats the purpose of needing a multi rate springs and the need to jack the compression dampening way up.<O</O
Ride height: I strongly believe that keeping the stock ride height of a sled is very important in keeping the sleds slow speed handling for boondocking purposes. Yes you are able to adjust the ride height with the spring preload (we can do this too) but that is only when you are setting still and has nothing to do with what the sled does in the snow. If the suspension is able to extend upward more than the stock ride height the sled will push the front end making it feel heavier then it is in many situations. This will happen when the weight is taken off of the back like when going downhill or trying to initiate a down hill turn the suspension float up in the back too far and pushes the front end. It can also affect jump take offs by kick the back end up when the sled leaves the ground.<O</O I have sudsy sled ride height a lot by working with pro back country riders and building custom sleds. <O</O
Allen from Timbersled<O</O
<O
</OOver centering a coupling suspension: A coupled suspension can over center by laying both the shock and arm down flat only if the geometry is not correct. Without the coupling this would not happen.<O</OOver centering happens when the upper pivot point of back arm is lower than the upper pivot point of the front arm at a low point of the travel. How does it do this you ask? First I will explain how coupling works and then you will understand the over center problem. These are problems that we have all had and we have worked out of the Mtn. Tamer entirely and from it we have been able to make a true progressive rate coupling suspension.
<O
</O1. As the back arm compresses it stops when it hits the coupling adjuster (basically, it binds up).
<O
</O2. At this point for back arm to compress more it has to push the slide rail back.
<O
</O3. To does this, the front arm has to be pulled down for the rail to move back because it is the control arm for the slide rails.
<O
</O4. This is where it gets tuff to explain. If you were to draw a line between the front and back arm on the upper pivot point in the tunnel and the lower pivot point in the slide rail (where the suspension arms bolt to the tunnel and rail) you would see that the two lines are not parallel (the back would be wider than the front).
<O
</O5. There are great load between these lines when the suspension is coupled; these load forces are what makes the coupling action work. The load force from the back arm is pushing back on the slide rails and forward on the tunnel.
<O
</O6. As the suspension travels upward these two lines will parallel each other and the suspension will travel in a one synchronized motion. If these lines stop paralleling each other at the bottom of the travel and become closer together in the back then the front, the load force on the upper pivot point will then push down on the back arm of the suspension and pin the suspension to the rubber bottom out pad on the slide rail.
<O
</O7. The power of the back shock will overcome this but the suspension will have a soft spot and will bottom easily when it gets to this point.<O
</OThis is near impossible to overcome with an equal length arm suspension because they pull the front arm up much slower. This is the reason we couple our front arm up at a faster rate than the back arm goes down to prevent this over centering problem. We are able to do this with our slide mechanism rear arm because it is contently changing length. You can do a test to see it for yourself if you take your back shock out of your Kmod suspension or pre 2011 and older Mtn. Tamer and simply pushing down on the back bumper with the suspension fully coupled. It will pin the back arm down so hard that you will have to put your foot on the track and pull it up to get it to come back.<O
</OBottom out positioning: The bottom out pad on the back Mtn. Tamer arm is used to fine tune the max compression of the jounce bumper in the shock. If you do not have this it is near impossible to fine tune bottom out when we have 4 different shock options in our lineup to help fit our customer’s budget.<O
</OOur bottom out pad does not give the skid less travel like what is stated in the above post. Our bottom out adjuster hangs down 1.25” from the bottom of the back arm and our rubber bottom out pad on the slide rail is 1.25” lower then what is on the Kmod. This make the bottom out point the same for both skid.<O
</OSingle rate verses Dual rate springs: We do not use duel rate springs because we cannot get them but because we do not need them. On a single rate spring the first inch of travel it not what the rate of the spring is, it is much softer. The rate is measured after 1” of compression.<O
</OKevin has talked a lot about pre load and that he uses the same spring for 120lbs rider all the way up to a 260lbs rider and compensates with spring preload and compression adjustment. My questions would be this; if you adjust the spring pre load way up for a heavier rider doesn’t that defeat the prepuce of a multi rate spring and when preloaded that much the spring still does not have the rate to support that wide of a range of riders and to compensate you add compression dampening to stop it from bottoming? I disagree with this. The spring rate needs to match the rider’s weight and we think that the least amount of preload is the answer to keeping the suppleness of the skid. This defeats the purpose of needing a multi rate springs and the need to jack the compression dampening way up.<O
</ORide height: I strongly believe that keeping the stock ride height of a sled is very important in keeping the sleds slow speed handling for boondocking purposes. Yes you are able to adjust the ride height with the spring preload (we can do this too) but that is only when you are setting still and has nothing to do with what the sled does in the snow. If the suspension is able to extend upward more than the stock ride height the sled will push the front end making it feel heavier then it is in many situations. This will happen when the weight is taken off of the back like when going downhill or trying to initiate a down hill turn the suspension float up in the back too far and pushes the front end. It can also affect jump take offs by kick the back end up when the sled leaves the ground.<O
</O I have sudsy sled ride height a lot by working with pro back country riders and building custom sleds. <O</OAllen from Timbersled<O
</O
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I think we are starting to see the real differences in these skids. Both obviously work good and have progressed very well over the years. I feel that I should add a few thoughts to some of the previous posts that I feel might be mislead.
<O
Over centering happens when the upper pivot point of back arm is lower than the upper pivot point of the front arm at a low point of the travel. How does it do this you ask? First I will explain how coupling works and then you will understand the over center problem. These are problems that we have all had and we have worked out of the Mtn. Tamer entirely and from it we have been able to make a true progressive rate coupling suspension.
<O
1. As the back arm compresses it stops when it hits the coupling adjuster (basically, it binds up).
<O
2. At this point for back arm to compress more it has to push the slide rail back.
<O
3. To does this, the front arm has to be pulled down for the rail to move back because it is the control arm for the slide rails.
<O
4. This is where it gets tuff to explain. If you were to draw a line between the front and back arm on the upper pivot point in the tunnel and the lower pivot point in the slide rail (where the suspension arms bolt to the tunnel and rail) you would see that the two lines are not parallel (the back would be wider than the front).
<O
5. There are great load between these lines when the suspension is coupled; these load forces are what makes the coupling action work. The load force from the back arm is pushing back on the slide rails and forward on the tunnel.
<O
6. As the suspension travels upward these two lines will parallel each other and the suspension will travel in a one synchronized motion. If these lines stop paralleling each other at the bottom of the travel and become closer together in the back then the front, the load force on the upper pivot point will then push down on the back arm of the suspension and pin the suspension to the rubber bottom out pad on the slide rail.
<O
7. The power of the back shock will overcome this but the suspension will have a soft spot and will bottom easily when it gets to this point.<O
This is near impossible to overcome with an equal length arm suspension because they pull the front arm up much slower. This is the reason we couple our front arm up at a faster rate than the back arm goes down to prevent this over centering problem. We are able to do this with our slide mechanism rear arm because it is contently changing length. You can do a test to see it for yourself if you take your back shock out of your Kmod suspension or pre 2011 and older Mtn. Tamer and simply pushing down on the back bumper with the suspension fully coupled. It will pin the back arm down so hard that you will have to put your foot on the track and pull it up to get it to come back.<O
Bottom out positioning: The bottom out pad on the back Mtn. Tamer arm is used to fine tune the max compression of the jounce bumper in the shock. If you do not have this it is near impossible to fine tune bottom out when we have 4 different shock options in our lineup to help fit our customer’s budget.<O
Our bottom out pad does not give the skid less travel like what is stated in the above post. Our bottom out adjuster hangs down 1.25” from the bottom of the back arm and our rubber bottom out pad on the slide rail is 1.25” lower then what is on the Kmod. This make the bottom out point the same for both skid.<O
Single rate verses Dual rate springs: We do not use duel rate springs because we cannot get them but because we do not need them. On a single rate spring the first inch of travel it not what the rate of the spring is, it is much softer. The rate is measured after 1” of compression.<O
Kevin has talked a lot about pre load and that he uses the same spring for 120lbs rider all the way up to a 260lbs rider and compensates with spring preload and compression adjustment. My questions would be this; if you adjust the spring pre load way up for a heavier rider doesn’t that defeat the prepuce of a multi rate spring and when preloaded that much the spring still does not have the rate to support that wide of a range of riders and to compensate you add compression dampening to stop it from bottoming? I disagree with this. The spring rate needs to match the rider’s weight and we think that the least amount of preload is the answer to keeping the suppleness of the skid. This defeats the purpose of needing a multi rate springs and the need to jack the compression dampening way up.<O
Ride height: I strongly believe that keeping the stock ride height of a sled is very important in keeping the sleds slow speed handling for boondocking purposes. Yes you are able to adjust the ride height with the spring preload (we can do this too) but that is only when you are setting still and has nothing to do with what the sled does in the snow. If the suspension is able to extend upward more than the stock ride height the sled will push the front end making it feel heavier then it is in many situations. This will happen when the weight is taken off of the back like when going downhill or trying to initiate a down hill turn the suspension float up in the back too far and pushes the front end. It can also affect jump take offs by kick the back end up when the sled leaves the ground.<O
Allen from Timbersled<O
Great info Allen. Also I have spent some mountain time on Tom,s skid and it works very well. I haven't had much time to study everything thats going on with the coupling and perhaps he can educate us on his setup. His E-vol shox valving setup he provided was exceptional.It sure changes the game when grinding through the deep.
I have heard a lot of good things about Tom’s suspension. I had the opportunity to ride a XP last winter that had one of his skids and I must say it rode extremely good. I do not know him but from what I have seen he really knows his stuff with these Fox Shocks.<O</O
We have had the opportunity last year to use some new internal parts in the Fox shocks that is not even out yet. I cannot say what it is but they work so much better it is ridiculous. So for any one that might think that the Fox stuff is not up to par with some of the other brands they very wrong.
Allen from Timbersled<O</O
</OWe have had the opportunity last year to use some new internal parts in the Fox shocks that is not even out yet. I cannot say what it is but they work so much better it is ridiculous. So for any one that might think that the Fox stuff is not up to par with some of the other brands they very wrong.
Allen from Timbersled<O
</O
First of all let me say, I think all the aftermarket skids in the market place are better than stock. It is the aftermarket that drives the industry.
Allan, I could go on and on about the Mountain Tamer and how I would do it different, but I won’t.
I will address our difference of opinions on some things about design.
Through our exclusive testing we came up with equal length arms for a coupling skid. We have found that with equal length arms the skid works more in unison rear to front when coupled.
To have three different front arm lengths means three different geometries; all designed to fit different vehicles, just to mount in the stock position in the tunnel. With all of our testing it is not as consistent in the way the skid works vehicle to vehicle in our opinion.
We mount in the tunnel for the skid, not build the skid different for the vehicle. That way each vehicle can be tuned similar and predictable. We can mount the same skid into an M Cat, Ski Doo XP, XM, and Polaris Pro with just minor tunnel mounting adjustments. (On Yamahas we mount higher in the vehicle to lower ride height but takes a different rail).
Ride height is addressed with spring preload,(as mentioned before) along with tunnel mounting higher in the rear to lower the ride height close to stock; we are a little higher in the rear if you pull up the entire ride in, but have longer travel than most (near 19’’ of rear axle travel).
Our springs are designed by Raptor Shocks, (they are not off the shelf springs) they are designed on a CAD spring program and then field tested to come up with our rates and design. Spring rates are not rocket science (1’’ stroke = pounds of rate) but packaging it to a custom length and stroke along with a higher rate at some point in the stroke, that’s when the pros earn their money.
The preload in our dual rate springs are just that; we increase the load not the rate (don’t confuse the difference between load and rate). We can run little pre load with our spring for lighter riders and then increase the pre load for a heavier rider to help hold them up, but the rate never changes so the characteristics of the skid acts the same. With our full 4.95’’ of shock stroke we can preload the spring up to 1.5’’ of pre load and still not coil bind the spring at jounce. (This is how we can get to the broad range of adjustability for different weight of riders).
Dual rate spring rates, are so many pounds per inch with a shift point, and then it transitions into a higher rate per inch for the remainder of the stroke. Now with a heavier rider we may need to increase the dampening a little firmer for a bigger load, no problem just a few clicks on the Raptor piggyback and you’re ready to go. That is how we get to a skid that will perform equally for a 120lb to 250lb rider all in the same spring and shock package.
Fully tested and customer indorsed.
We also have a big guy spring that will handle guys from 250-350 lbs.
We each have our own way, which is what aftermarket is all about.
Thanks, Kevin
Allan, I could go on and on about the Mountain Tamer and how I would do it different, but I won’t.
I will address our difference of opinions on some things about design.
Through our exclusive testing we came up with equal length arms for a coupling skid. We have found that with equal length arms the skid works more in unison rear to front when coupled.
To have three different front arm lengths means three different geometries; all designed to fit different vehicles, just to mount in the stock position in the tunnel. With all of our testing it is not as consistent in the way the skid works vehicle to vehicle in our opinion.
We mount in the tunnel for the skid, not build the skid different for the vehicle. That way each vehicle can be tuned similar and predictable. We can mount the same skid into an M Cat, Ski Doo XP, XM, and Polaris Pro with just minor tunnel mounting adjustments. (On Yamahas we mount higher in the vehicle to lower ride height but takes a different rail).
Ride height is addressed with spring preload,(as mentioned before) along with tunnel mounting higher in the rear to lower the ride height close to stock; we are a little higher in the rear if you pull up the entire ride in, but have longer travel than most (near 19’’ of rear axle travel).
Our springs are designed by Raptor Shocks, (they are not off the shelf springs) they are designed on a CAD spring program and then field tested to come up with our rates and design. Spring rates are not rocket science (1’’ stroke = pounds of rate) but packaging it to a custom length and stroke along with a higher rate at some point in the stroke, that’s when the pros earn their money.
The preload in our dual rate springs are just that; we increase the load not the rate (don’t confuse the difference between load and rate). We can run little pre load with our spring for lighter riders and then increase the pre load for a heavier rider to help hold them up, but the rate never changes so the characteristics of the skid acts the same. With our full 4.95’’ of shock stroke we can preload the spring up to 1.5’’ of pre load and still not coil bind the spring at jounce. (This is how we can get to the broad range of adjustability for different weight of riders).
Dual rate spring rates, are so many pounds per inch with a shift point, and then it transitions into a higher rate per inch for the remainder of the stroke. Now with a heavier rider we may need to increase the dampening a little firmer for a bigger load, no problem just a few clicks on the Raptor piggyback and you’re ready to go. That is how we get to a skid that will perform equally for a 120lb to 250lb rider all in the same spring and shock package.
Fully tested and customer indorsed.
We also have a big guy spring that will handle guys from 250-350 lbs.
We each have our own way, which is what aftermarket is all about.
Thanks, Kevin
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K Mod can we see a vid of yours on a stand going through the motions?
http://www.snowestonline.com/forum/album.php?albumid=2979&pictureid=26382
yes its gen1 but it makes a very big difference
yes its gen1 but it makes a very big difference
KMOD;3118995 The [B said:
thats a good clarification..
Another skid issue which hasnt been discussed , When skid is fully compresses the track does not contact the hyfax for aprox 12 to 15 inches behind the drivers, This causes the track to cup/curve in the wrong direction,just the opposite of its normal curvature [inverted dogleg]and causes a feeling just like hammering the brake.A skid which tightens the track under compression will minimize this., This also can be seen if pics of the skid are shown through the compression motion and another primary reason I raise the bottom stop...The aftermarket skid/rail designs are great but a little enhancement can make them function even better.JMO
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That’s a good point but I think the skids seldom ever get compressed that much when climbing a hill. When your sled cavitates in the snow and you feel it slow down, that normally is from excessive track angle boring into the snow. Coupling skids will also help this simply because they stay flatter to the snow.
<O</OAllen from Timbersled<O</O
<O
</OAllen from Timbersled<O</OThat’s a good point but I think the skids seldom ever get compressed that much when climbing a hill. When your sled cavitates in the snow and you feel it slow down, that normally is from excessive track angle boring into the snow. Coupling skids will also help this simply because they stay flatter to the snow.
<O
You bring some valid points to enlighten ..Appreciate all the insight
If you first elevate the front and to simulate that it is going up hill. Turn the coupling adjuster all the way in and then push down on the back bumper you will get 2” of travel before it starts to couple.
<O</OAllen for Timbersled<O</O
<O
</OAllen for Timbersled<O</OIf you first elevate the front and to simulate that it is going up hill. Turn the coupling adjuster all the way in and then push down on the back bumper you will get 2” of travel before it starts to couple.
<O
my question is two inch's measured at the bumper, because that changes on different length tunnels
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