Yamaha Rail Profile

[boondocker97]

Has anyone read the recent issue of SnowGoer? They have an article in there discussing some of the engineering that went into each of the manufacturers sleds. The Yamaha section specifically discusses the changes they made to the Cat M8000 chassis setup to make it handle better with their 4stroke. Most notably was the rear suspension and rail profile. They had the CAD images of both rails laid over each other so you could see the differences. I thought it was interesting that some of those changes have been discussed here already. Here is what I gathered:

1. Front of the rail profile is curved, instead of just having a bend and then straight.
2. Front track shock is 1.25" longer with softer valving and has more sag.
3. Front arm mounting point on the rail is 0.75" further up (taller rail) to accommodate longer shock without track tension problems. I suspect this has some impact on the rear arm action since it also moves its shock attachment point up.
4. Lower shock mounting location is also moved back to help accommodate the longer shock.
5. Rear suspension arm mounting location is slightly different. I'll have to look again to double check if it was forward or back.
6. Softer rear shock valving.

Main goal of all of this was to improve maneuverability by better transferring weight to the rear. Not sure if any or all of this would benefit the Cat setup. Weight transfer doesn't seem to be an issue with my current sled. Just thought I would bring it up for discussion.

I am intrigued about the longer front arm shock. In the Cats they have seemed to be pretty short, comparatively, to what you see on other sleds or aftermarket suspensions. Been this way since the M chassis days. Right off the bat the valving needs to be much more accurate with a shorter shock stroke than if you are getting the same travel numbers with a longer stroke shock. The shock just has more travel length to get its work done. Right now I'm trying to nail down a happy medium with the front track shock for trail and deep snow performance, and it's taking a little work to get it done.

 

[stingray719]

LOL! That is what I did to the girlfriends Viper last year after long tracking it with track extensions. Funny to see it on production.

 

[bradburck]

I saw that as well and thought it was very interesting. Obviously I think there is more to be gained from the stock rear skid, both in valving and design. becomes more and more evident as you take weight off the sled and add power. That being said I'd love to see those changes made on a 800... other then the coupling, isn't this the basis of the Kmod? Long front arm and lengthen shock? Guy would for sure have to move the mounting location to accommodate this, but that short front shock seems as though there is something left on the table with this. Longer means it would have more valving potential as well. great topic for sure. Can a guy buy a Yahama arm and shock and relocate himself??

Has anyone read the recent issue of SnowGoer? They have an article in there discussing some of the engineering that went into each of the manufacturers sleds. The Yamaha section specifically discusses the changes they made to the Cat M8000 chassis setup to make it handle better with their 4stroke. Most notably was the rear suspension and rail profile. They had the CAD images of both rails laid over each other so you could see the differences. I thought it was interesting that some of those changes have been discussed here already. Here is what I gathered:

1. Front of the rail profile is curved, instead of just having a bend and then straight.
2. Front track shock is 1.25" longer with softer valving and has more sag.
3. Front arm mounting point on the rail is 0.75" further up (taller rail) to accommodate longer shock without track tension problems. I suspect this has some impact on the rear arm action since it also moves its shock attachment point up.
4. Lower shock mounting location is also moved back to help accommodate the longer shock.
5. Rear suspension arm mounting location is slightly different. I'll have to look again to double check if it was forward or back.
6. Softer rear shock valving.

Main goal of all of this was to improve maneuverability by better transferring weight to the rear. Not sure if any or all of this would benefit the Cat setup. Weight transfer doesn't seem to be an issue with my current sled. Just thought I would bring it up for discussion.

I am intrigued about the longer front arm shock. In the Cats they have seemed to be pretty short, comparatively, to what you see on other sleds or aftermarket suspensions. Been this way since the M chassis days. Right off the bat the valving needs to be much more accurate with a shorter shock stroke than if you are getting the same travel numbers with a longer stroke shock. The shock just has more travel length to get its work done. Right now I'm trying to nail down a happy medium with the front track shock for trail and deep snow performance, and it's taking a little work to get it done.

 

[boondocker97]

I think the actual front arm may be the same length. The mounting point on the rail is just further up vertically (like adding the Holz brackets to the 05-06 M rear suspension). Would have to get the Yamaha rails as well, or add a bracket.

 

[catothom]

On a Youtube video with the 2015 model M8000, I believe they say something about the rear arm in the suspension is being longer on the new models.

 

[Oinakka]

Hav'nt the m7000 have the same changes, thats what i understand anyway?

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[summ8rmk]

Look on the cat site. The M7000 has the front suspension mount moved ahead a couple inches

 

[Oinakka]

Cant see that. Look like the shock is mounted further back on the rails then The 6/8/9000.... Like its longer.

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[summ8rmk]

 

[Oinakka]

In my eyes it looks like The 7000 has The lower mount further back on those pictures... Or are we missunderstanding eachother?

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[summ8rmk]

The 7000 lower shock mount looks to be mounted a couple inches forward. I would think that would use a shorter shock.

 

[WyoBoy1000]

View attachment 235933View attachment 235934
The 7000 lower shock mount looks to be mounted a couple inches forward. I would think that would use a shorter shock.

Same mount just the wheels are moved, pretty obvious.


As for the point of the thread, this is exactly what I have been talking about for a long freaking time!!!

 

[summ8rmk]

Now i feel stupid. I didn't even notice the shock position. I forgot cat doesn't have the wheels mounted on an axle that is also the shock mount like it used to be on my old ZR.

 

[Oinakka]

It looks like its a bit more back. And you can also see that the mount for the front arm is higher up. And has a shallower angle.

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[bradburck]

I've always been a proponent of getting the skid out of the sled as much as possible... proper valving on the front shock combined with a different rail profile should allow the skid to get "out of the tunnel" as much as possible creating less drag and theoretically more traction and contact with the snow. This seems like a good thing to me... proper valving on the front shock should allow the skid to collapse under pressure and drop out when it can. Means different mounting on both the skid and tunnel and running the rear axle looser.

Used to do this back in the day on the mid 90's powder special, making longer drop brackets to get the sled out of the snow and stop dragging the running boards. And now Skinz is doing the same with the adjustable ones.

Who's going to guinea pig this one??

 

[boondocker97]

Same mount just the wheels are moved, pretty obvious.


As for the point of the thread, this is exactly what I have been talking about for a long freaking time!!!

WyoBoy you were the first person I thought of when I saw this!

The mount is not the same, it is further back on the rail as well as moving the idler wheel forward to get it out of the way. There are little changes all the way along the rails when you look at the M8000 rail and this one laid over the top of each other. I might have to see if I can scan the picture and post it up. The rear arm mounting point is further back back too so yes the rear suspension arm is longer.

Also, If you guys haven't noticed, all of this moving around has changed the angle of the front linkage that the rear shock is attached to. Looks very similar to the angle on the Holz alpha X skid now. As the rear arm rotates as the suspension collapses and pulls on the linkage rod that is below the shock, it pulls the front link arm so it rotates rearward. This new angle puts more of the link arm's movement rearward instead of upward (uses more shock stroke). This again lets the valving in the rear shock work over a greater distance. Just like having the longer front shock.

Initially I was thinking that since my rails are still bent from this spring, and I want to upgrade the front track shock that I could pick up a set of the M7000 rails and put in it. Looking more like it would take rails, front shock, rear arm, and possibly rear arm shock and link rod if they are different lengths. At that point, might as well go a little extra and slap a full aftermarket skid in it. We basically need someone that has a M8000 as well as a M7000 and have them swap the skid into it to see what kind of difference all the little changes make. You know the kind of thing the Cat R&D department should be doing.

 

[Oinakka]

Thanks for clearing things up boondocker97. Think i'll go out and Hunt for that sno goer magazine IF its out yet here in in sweden.

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[stingray719]

WyoBoy you were the first person I thought of when I saw this!

The mount is not the same, it is further back on the rail as well as moving the idler wheel forward to get it out of the way. There are little changes all the way along the rails when you look at the M8000 rail and this one laid over the top of each other. I might have to see if I can scan the picture and post it up. The rear arm mounting point is further back back too so yes the rear suspension arm is longer.

Also, If you guys haven't noticed, all of this moving around has changed the angle of the front linkage that the rear shock is attached to. Looks very similar to the angle on the Holz alpha X skid now. As the rear arm rotates as the suspension collapses and pulls on the linkage rod that is below the shock, it pulls the front link arm so it rotates rearward. This new angle puts more of the link arm's movement rearward instead of upward (uses more shock stroke). This again lets the valving in the rear shock work over a greater distance. Just like having the longer front shock.

Initially I was thinking that since my rails are still bent from this spring, and I want to upgrade the front track shock that I could pick up a set of the M7000 rails and put in it. Looking more like it would take rails, front shock, rear arm, and possibly rear arm shock and link rod if they are different lengths. At that point, might as well go a little extra and slap a full aftermarket skid in it. We basically need someone that has a M8000 as well as a M7000 and have them swap the skid into it to see what kind of difference all the little changes make. You know the kind of thing the Cat R&D department should be doing.

Funny you say that. Last year I had a 2014 M8 153 Ltd and a 2014 Viper XTX converted to the same as the M8 except the rails. I used the stock rails and put a track extension on it for the 153.

WOW was that a problem, stiff rear and heavy front no matter how hard I jacked the front skid shock up. Even ran the back so soft I had excessive sag...no good.. So after alot of experimenting I sat both sleds side by side on the sled deck and started measuring. The only thing I could see from the outside was the lower mounting point of the front skid shock.(and wheel moount location)

So I measured the distance from the wheel to the shock mounting hole and drilled a new hole the same distance on the other side of the wheel.

BINGO!!!! Now it handled like the M8 no more heavy front stiff riding.


SO when I did the New Viper (girlfriend owns old one) I put on Ice Age rails and in the shop it is nice and cushy not like the Viper rails did.

Hope that helps.

 

[ACMtnCat]

It's kinda like Arctic Cat R&D has had their heads sooo far up their arses that they couldn't listen to what real mtn riders have been btching about since 2011 demo rides. Sht!.... It goes back farther than that! I can remember threads from 2009 that we were talking about these needed changes in our skids.

Here we are 4-5 years later and Cat still doesn't get it!


I like this YamaCat relationship! Yamaha is on the right track, 3-4 years from now I think we'll have a 4-stroke mtn sled that will actually work and feel the way we need them to in the mountains.:face-icon-small-dis

 

[WyoBoy1000]

There could be other changes but without an exact overlay its hard to tell. I wouldn't be suprised to see something closer to a holz geometry.

wonder how it all would compare to a poo skid.