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Steeper track attack angle=better deep snow performance?

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tkuss

Well-known member
Dec 12, 2007
446
297
63
Fort Collins, CO
Anybody read the 2010 ski-doo updates from the home page. Here is a blurp from it talking about the improvement of the ski-doo summit models.

New improved Summit rear suspension: The angle of attack on the improved Summit rear suspension is plus 7 degrees versus last year. All the tests performed by Ski-Doo engineers and members of its Mountain Technical Council (Dealers and/or consumers) show that this slight increase will not negatively affect the handling whatsoever. In fact it improves the on-trail riding and off-trail sidehilling/boondocking by a large margin—which was the benefit sought.





How can this be? I have never heard this, and it just doesn't make sense. Anybody have any ideas? Am I reading it wrong?
 
S
Mar 11, 2009
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Washington
Where are they measuring the angle that is plus 7° versus last year? If they're talking about the angle of the track bend at the bottom front of the skid/rails, then increasing that angle would make the attack angle more shallow. If they're talking about the angle of the track bend at the drive shaft, then increasing the angle would make the attack angle steeper.

Maybe they're talking about the angle of the track bend at the front of the rails?
 
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E
Nov 28, 2007
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Spokane WA
I dont see why they would do that. If they want to make a mtn sled better for trails, buils a crossover sled like the assult or the crossfire. think of all the people doing drop and rolles to do the opposite of what they did. with a steeper angle they are adding more roll resisntace which robs hp. and its gonna put less track in the snow, which again people put longer tracks on there mtn sled to get away from this. some of the things these companies do boggles me.
 

winter brew

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Nov 26, 2007
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LakeTapps, Wa.
steeper would likely work better on the roads and for sidehilling as stated.....but not necessarily any better in the deep, but that's not what they are saying. Just not any worse. And with the sled being so light they can likely get by with a steeper approach without trenching issues or making its "deep snow-ability" any worse.
 
L
Dec 7, 2007
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steeper would likely work better on the roads and for sidehilling as stated.....but not necessarily any better in the deep, but that's not what they are saying. Just not any worse. And with the sled being so light they can likely get by with a steeper approach without trenching issues or making its "deep snow-ability" any worse.

Ski-doo is blowing smoke up your ( ! ). If you believe that this is beneficial you deserve to own a Ski-doo. The funny thing is alot of people will suck this up like it was the second coming of Christ.
 
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mtn_extreme

Well-known member
Nov 11, 2002
1,692
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Nampa, Idaho
You have to read it carefully. They say that it improves handling and trail characteristics. It "does not" say that it doesn't hurt hillclimbing, only that it won't "negativly affect" handling. Sounds like the XP is going to be a crossover sled next year. Hillclimbing sacrificed for trailability.
 
T
May 2, 2009
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GJ, Colorado
To me, its kinda wierd seeing "improved trail riding" and "Summit" in the same sentence.... There sure is a lot of hype going around these days about attack angles, like the '10 nytro's 18 degree shallow bend, and now ski doo going the other way. We've had a lot of guys looking for the shallow bend on their rails, and even some wanting to get steeper. I guess it all just comes down to how the rest of the sled is set up, and what it's set up to do.
 

sled_guy

Well-known member
Premium Member
Jul 5, 2001
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Riverton, Utah
Maybe they are trying to get rid of the difficulty that the magazines and others were having in putting the XP on its side compared to the other brands.

BING, BING, BING We have a winner and once again it is mountainhorse.

Caution: I'm about to piss XP riders off.

There has been a fairly large number of people, not just magazine riders, who have complained about the XP's handling, especially with longer tracks and bigger riders. Take an otherwise fairly skilled rider and put him (or her) on a 163 XP, point them down an off camber hill and ask them to cut it around in to a sidehill. 9 out of 10 won't be able to do it.

XP lovers have always said that this was bull crap. "You just need to learn to ride it". Well apparantly the factory agreed for 2010. They lengthened the front torque arm 1" to push the front of the skid down 1". This allows for easier "pivot" so that you can turn the thing.

I spent a bunch of time on the 2010 XP comparing it to an '09 and it does make a difference. Not enough in my opinion, you still can't turn it on it's side nearly as easy as the Cat or Polaris and it's only slightly better than the heavy Nytro. But it is noticeably better than the '09.

BUT, the side affect of pushing the front of the rear suspension down is that you increase approach angle. In their marketing spin they say that doesn't adversely affect the XPs performance. I can't comment, the snow we rode it in didn't present any challenge to any of the sleds.

But that's why they did it, they were trying to improve the off camber and sidehilling performance.

sled_guy
 
T
May 25, 2008
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Oroville Washington
Well, I have always said that the xp isnt a stellar performer in hard snow sidehilling. I dont even enjoy riding hard snow so I simply DO NOT care. As for soft snow performance, mine has never been beaten...but thats just mine. Skidoo went the wrong direction in a few key areas in 2010, for that reason I will keep my 08. Adding weight and increasing approach angle in a mountain chassis??? WTF.
 
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skidoo_guy

Well-known member
Nov 26, 2007
1,280
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Bismarck, ND
Between my Rev and my XP the Rev is way more predictable on turning it on it's side and I need that predictablity in the trees. On the XP sometimes I just don't know if I am going to be able to get it pulled up fast enough and hold it when I am going slow through the trees. I was going to try tilting the steering post back but didn't go out to ride after I thought of that. I can carve it no problem when sitting and that is why I think I need to move back. But I am also thinking of trying the new A-arm and shock in my 08 next year.
 
S
Feb 21, 2009
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16 wide

It seems to be the track rides like a log when sidehilling etc..I would be more worried about the clutches.All the guy's in our group can't get them to rev out without clutch work.And then there is the belt thing..OMI
 
H
Dec 11, 2007
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Valley Boy
It seems to be the track rides like a log when sidehilling etc..I would be more worried about the clutches.All the guy's in our group can't get them to rev out without clutch work.And then there is the belt thing..OMI

I bought an 05 800 159" Rev brand new in 2005 and rode the heck out of it up here in Alaska. I love that sled. I just bought a 2009 XP 800 163" and rode the heck out of it this season.

Without a doubt, the Rev is the hands down winner for ease of operation and predictability in any terrain. I just really learned how to ride my XP at the end of the season. In the powder it handles very well, I can carve and climb and jump with ease. Down hill powder turns are another story on the XP. They are tough to execute because if you put your feet in the footwells your weight is too far forward and the centralized mass wants to keep going down the hill so it fights you to roll it over on a downward slope. Truly, that is my only complain about how the sled handles.
 
B
Nov 27, 2007
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Rovaniemi, Finland
I agree 100% what highlife is saying. Driver is too far forward and it causes issues when going downhill. When heading straight forward uphill I think XP may be the best sled? But if you need to drive slower, watch some trees etc... then it's a bull with own mind.

This improve may be good but I'm more bashing doo because of the drive line. How that big company can't fix one simple drive line? Here in Finland breaking belts is a huge problem. That problem has been years and factory has done nothing to it. People who buy new BRP around here need to tear new sled apart and recalibrate whole drive line again by them self. That costs a lot and needs a lot experience to do. If you don't do it, you need to buy new belt every 100-200km. That sucks big time.

What if you buy a new car and first thing to do is tear it apart and fix the gear box? No sense at all.

Second astonishment:
Why they changed the track? I think that old track was awesome for hillclimbing etc.
 

Anylizer

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Lifetime Membership
May 17, 2005
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Top 'O the Great Basin... almost
You keyboard supertuners kill me !!!!! This is what limit straps are for. In the 08-09 Xp with the straps all the way out there is still too much ski pressure for a fun trail/ cross over ride. So if they drop the front arm for lighter ski pressure and a better, more fun to ride sled "GREAT" if you want the flatter attack angle and better hillclimb performance....... PULL THE LIMITERS UP!!!:eek::eek::eek:
 
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LRD

Well-known member
Mar 27, 2002
572
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When I built my XP mtn sled out of a TNT I put Yami app Floats on the skis .5 " shorter which raised the skis (dropped the front end) 1" which essentially does the same thing as dropping the front skid arm but without making the attack angle steeper. Also have a front end about 50 lbs lighter than a stock 800 which also puts higher % of the sleds weight under the front arm for nice pivot action either side to side or end for end.

I built my sled for a much lower polar moment of inertia than a stock XP. Here is what polar moment of inertia is for those that don't know. Take a barbell 36" long with 15 lbs on each end and grab in center and rotate in circle = high polar moment of inertia. Put both 15 lb weights in center with room to grab bar and rotate again = low polar moment of inertia. Other examples, mid engine formula I vehicle has the most radical low polar moment of inertia and a F350 diesel would be one of the highest.

Good Luck
 
P

portgrinder

Well-known member
Nov 26, 2007
1,161
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Edmonton
There comes a point, where if the front of your skid is sucked up too high there will be too much weight on your skis. What will those skis look like going through the snow.....they will tilt up. There is a balance. Where is it? I don't have a clue

Probably doesnt help that 70% of the people that 'sled' in the mountains don't know how to ride in the mountains, so they think it handles bad.
 
T
May 25, 2008
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Oroville Washington
Probably doesnt help that 70% of the people that 'sled' in the mountains don't know how to ride in the mountains, so they think it handles bad.

Exactly. IMO the XP is the single best handling, most flickable snowmobile in the mountains. It rips on the Rev, Dragon, M and Yammies just are not even close. If you ride a sled hard in the mountains, it will become apparent how much better the XP is. Learn to ride it, yes it is a little different. Once you learn to ride it, it is far better. For two reasons. One, the rider is placed on the sled where he has greater leverage and control over the front of the machine. Second, the machine is a significant amount lighter than anything else.

As for downhill powder turns, I guess Borchers and the rest of the Slednecks crew figured out a way didnt they??

So, for all you keyboard hotrodders out there, how in the heck is a lighter machine that the rider has more control over not a superior piece of iron in the mountains?? It just doesnt make sense. ADJUST the dam thing if you dont like the feel of it for you, but more likely you need to get off you azz, go learn how to ride, and quit causing Skidoo to build a better trail sled out of there mountain chassis. Buy a friggen MXZ if you want to run trials, leave our mountain platform alone!!

Rant over for now

Jake
 
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