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So I've read reports of the BC steering lighter than the 137s & 129s. And after my little demo ride despite the conditions & TS skis I came away convinced Doo did something different with the 9Ts to reduce steering effort. When it comes to the BC at first I thought it was just the weight difference (35 lbs or so) between the SHOT and C-Motion. But all that weight savings is out back, not over the skis. The heaviest part of ES is the battery which is now located behind the seat. Then I thought maybe it's the BC specific spindles. I remembered some guy selling MPS or Mechanical Power Steering for Yamahas. A quick Google search brought up his web site and the MPS is achieved by simply extending the distance between the tie rod & spindle via a lever for more mechanical advantage. I then went to Doo's site to zoom in on the BC spindles but I couldn't see any difference with the naked eye that would explain the BC steering lighter. So I turned to the parts site. If you pull up the BC 850's steering you can see it doesn't have a rack. You can also see that the steering post has a throw to it and a linkage at the bottom which give it mechanical advantage. If you pull up the Renegades or MXZs the X & XRS (rack equipped) models have pretty much a straight steering post & no linkage (lever at the bottom of the post). Then look at the TNTs & Adrenalines, they have a throw & linkage just like the BC. If you check out the 900 Turbos both the Adrenaline / Enduro & the X / XRS models come with a throw & a linkage even though the X / XRS Turbos have the rack just like the 2 strokes. So there you have it. If you want a lighter steering 2S G4 buy a BC or a TNT or an Adrenaline. This is for 2019 & prior models, I know Doo is nixing the rack on the X so maybe the 2020 X will have the same steering set-up as the older TNTs & Adrenalines? Anybody have any back-to-back same day same condition seat time between a similar set-up (ski / carbide combo) MXZ TNT 850 vs say a MXZ X or XRS 850 or Renegade Adrenaline 850 vs a Renegade X or XRS 850 to confirm my thoughts ???
 

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I personally feel its more about how they are set up. All of my new sleds from the factory, steered very easy until I added carbide and made adjustments to them, to handle the way I wanted them too. Although my current 2016 Blizzard rails corners and I feel it has the lightest steering of any sled I have ever owned. Rode a G4 2019 900T last season and it had light steering and railed. We normally ride 200+ and some times 300+ mile days, range in age from 45 to 65 and no issues with heavy steering (all Doos). I have had the opportunity to do several demo rides over the years and found them difficult at best to get a good feel for how a sled will ride and handle for me personally, I have found the set up all over the board from too stiff to, too soft. What I take away from Demo Rides is how I feel sitting and standing on the sled, everything else is unknown until I take delivery and put miles on it and set it up the way I like it to handle. The BC has a non Coupled Skid compared to the other sleds and that can make a huge difference.
 

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Discussion Starter · #5 ·
I wish your theory was correct but imo there is no late model skidoo that steers easy for my old bones
Yeah, a quick check of my 09 and 2012 on the Doo parts site shot my theory all to heck. Any mechanical geniuses on here??? Where's Daag when you need him...LOL
 

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I have written on the Gen 4 MXZ X and XRS rack steering vs the TNT non rack steering often and I have swapped sleds many times on the same day between rack and non rack steering. For old guys probably any one over about mid 50's - I am in my mid 70's they will notice you can ride longer without tiring on the rack steering sleds. They have more leverage and don't turn as sharply as the non rack sleds. You get much less kick back from wooped out mogoled trails with the rack steering. A few years back, Jamie (A7M266D) put the rack steering off a 600RS on his XS sled and I followed suit and did the same thing on one of my XP's and saw a similar improvement in effort and reduced feed back.

That said, the reason your Back Country steers lighter probably has to do with the uncoupled rear skid. and the fact that it tends to lift the skis out of the snow on accels. And Bar549 is also correct, it is also mixed up in how you set up your sled.. if you go light on the spring pressure on the skis and heavy on the center (front kid spring) your sled will steer lighter too.. won't turn as tightly as there is less pressure on the carbides. But it will tend to feel lighter.

If I trail ride my Gen4 uncoupled Summit X (non rack steering) with my buds on MXZ X and XRS (with rack steering) on a tight rough trail it tends to tire me out. And I swap with one of their X's even a renegade and steering is much easier on my arms, I can survive the rest of the day. So I recently bought the rack steering from a Gen 4 MXZ X from Rene and Mike on here and my Gen 4 Summit X it will have the extra weight of the rack steering on it next year but I will enjoy it more.

Ha ha what you young bucks have to look forward too. It is hard to maintain body strength as you age.. and once you cross into the 70's you really notice it, but if I look back I suspect you start loosing muscle mass in your later 50's and it continues as you age into your later 60's and I have really noticed it in my 70's You start paying for all of the fun and broken bones you had in your younger years with arthritis. Anyway, in your 20's thru you mid 50's you probably wont notice the difference in steering efforts. But there is a reason they put the rack steering back in the 600RS race sleds back in 2015 I think it was, because like mountain riders, racers don't like adding weight but it made them less tiring to ride on snow cross tracks and it is also easier to hold a line in the moguls... even the young strong snow cross racer's benefited.

We could get into Ackerman, anti Ackerman vs Parallel steering, but it is easier to keep that out of the discussion. Suffice it to say, old guys, smaller women and younger riders will appreciate the rack steering sleds at the end of the day. It is leverage and geometery. But you can confuse the issue with the way you set up your sleds. Pull the skid strap down, put a lot of ski spring pressure and lighten the center skid spring to rail corners and only hydraulic or electric power steering will help you.
 

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Discussion Starter · #9 ·
The back country models steer easier because of the drop chain case there is less weight on the front end with how the skid geometry is.
I thought the dropped chain case on mtn sleds was just for the attack angle of the track to help them get up on top of the pow easier? How would a less steep track angle effect steering effort?
 

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Discussion Starter · #10 ·
Wow, I see it now. The FTS looks way longer on the BC. The dropped chain case was probably just to " maintain " track angle...LOL Holy weight transfer Batman... Ok, so now what the heck did Doo do different with the Wide Body???
 

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So I've read reports of the BC steering lighter than the 137s & 129s. And after my little demo ride despite the conditions & TS skis I came away convinced Doo did something different with the 9Ts to reduce steering effort. When it comes to the BC at first I thought it was just the weight difference (35 lbs or so) between the SHOT and C-Motion. But all that weight savings is out back, not over the skis. The heaviest part of ES is the battery which is now located behind the seat. Then I thought maybe it's the BC specific spindles. I remembered some guy selling MPS or Mechanical Power Steering for Yamahas. A quick Google search brought up his web site and the MPS is achieved by simply extending the distance between the tie rod & spindle via a lever for more mechanical advantage. I then went to Doo's site to zoom in on the BC spindles but I couldn't see any difference with the naked eye that would explain the BC steering lighter. So I turned to the parts site. If you pull up the BC 850's steering you can see it doesn't have a rack. You can also see that the steering post has a throw to it and a linkage at the bottom which give it mechanical advantage. If you pull up the Renegades or MXZs the X & XRS (rack equipped) models have pretty much a straight steering post & no linkage (lever at the bottom of the post). Then look at the TNTs & Adrenalines, they have a throw & linkage just like the BC. If you check out the 900 Turbos both the Adrenaline / Enduro & the X / XRS models come with a throw & a linkage even though the X / XRS Turbos have the rack just like the 2 strokes. So there you have it. If you want a lighter steering 2S G4 buy a BC or a TNT or an Adrenaline. This is for 2019 & prior models, I know Doo is nixing the rack on the X so maybe the 2020 X will have the same steering set-up as the older TNTs & Adrenalines? Anybody have any back-to-back same day same condition seat time between a similar set-up (ski / carbide combo) MXZ TNT 850 vs say a MXZ X or XRS 850 or Renegade Adrenaline 850 vs a Renegade X or XRS 850 to confirm my thoughts ???
I didn't read the start of this thread.. your first thoughts..

This statement " If you want a lighter steering 2S G4 buy a BC or a TNT or an Adrenaline." is totally wrong.

They have less leverage and lack the straight through movement to both spindles on the non rack steering Gen4 TNT and Adrenaline sleds. The effort is higher on these sleds but they do turn sharper. You will be less tired after riding the MXZ X and XRS at the end of the day. No question. I usually finish the day on one of my younger buds X or XRS if we are riding trails. Ha ha.. I might not get home if left to the non rack steering Gen4.

And as mentioned in my previous note, I am putting the rack steering out of a Gen 4 X on my Gen 4 summit because I am a really old guy that still likes to ride. As previously mentioned steering efforts get messed up in how guys and gals set their sleds up. Your back country like my summit tends to life the skis on accel due to skid geometery.. and that gives you the false sense of light steering.

When I am doing the swap, I will measure the lever arms on the spindles and the steering column and give you those numbers. The advantage will be to the rack set up. It is why they turn less sharply.... vs the non rack which turns more sharply or tighter radius.
 

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I thought the dropped chain case on mtn sleds was just for the attack angle of the track to help them get up on top of the pow easier? How would a less steep track angle effect steering effort?
The greater the attack angle, the greater the force from the track that pushes the sled up on top of snow vs forward.

Dropping of the chaincase is for clearance. While it does the opposite to what is needed for off-trail, the geometry is adjusted to gain the desired attack angle.
 

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Discussion Starter · #13 ·
^^^ I would think a sharper angle would act more like a snow plow versus a more gradual angle that would help the sled get up on top of the surface of the pow???
 

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^^^ I would think a sharper angle would act more like a snow plow versus a more gradual angle that would help the sled get up on top of the surface of the pow???
I agree with you on this one.... the shallower angle ...between the drive wheels and the bottom of the skid.. the easier it is to get up on the snow...
 

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Yeah, a quick check of my 09 and 2012 on the Doo parts site shot my theory all to heck. Any mechanical geniuses on here??? Where's Daag when you need him...LOL
Ncapster, you tend to start good topics that make us think lol I'll do the best I can with a Markup to show what I see, but you might me surprised that I'm not seeing any REV-olutionary tech. I can easily argue that it is moving the G4 forward the many steps back the G2 took a decade ago in 2008.

Note that the following two paragraphs refers to the Rack Steering System on the Rev Gen 1 (G1).

The G1 REV/RT has a pretty elaborate Rack comprising of a Track Rod and two Idler Arms connected to the Frame via a Plate. The Track Rod connects both Tie Rods, and a Link connects the Track Rod to the Steering Arm.

The Idler Arms are called as such since they don't have any direct linkage between the Steering Shaft Plate and Tie Rods. It's not much different in the mechanism, but it helps to distinguish the Rack system on the G1 from the G4 which has a Drag Rod that links the Steering Shaft Plate (aka Pitman Arm) to the Bellcrank Steering Arm.

When comparing the Rack on a G4 to a G4 without rack that uses only a Steering Arm, then there is a big difference. But I don't see much difference with the G1. The biggest difference I see with the G4 Rack is when the steering is straight the G4 makes a right angle between the Link and Swivel Arm, whereas the G1 has the Link offset to the Track Rod by roughly 5 degrees. In other words the G1 doesn't push the Track Rod straight, but rather on a slight angle. It would be like pushing a stuck car from the side vs the rear. I doubt it makes a noticeable difference especially when compared to the difference the suspension setup makes, but everything counts on longer rides.

Also note that BRP doesn't sell the G4 Twin Bellcrank Rack steering system as easier to steer than the G4 Tripod Steering System.

For the terminology, what BRP refers to a Pitman Arm I refer to a Tripod Plate as mentioned in an International Research Journal of Engineering and Technology (IRJET). Click here for the research paper.

New for 2017 Exclusively on Gen4 REV platform sleds, the RAS 3 further refines the RAS 2 geometry for more precise handling, especially in extreme bumps and in deep snow. MXZ and Renegade X models also feature a new rack steering system (vs. a Pitman arm) that further sharpens precision in bumps.

Click here for pictures of the G4 Tripod Steering Mechanism.

G4 Twin Bellcrank Rack Steering Mechanism

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Ncapster, you and Roamer7 tend to start good topics that make us thing lol I'll do the best I can with a Markup to show what I see, but you might me surprised that I'm not seeing any REV-olutionary tech. I can easily argue that it is moving the G4 forward the many steps back the G2 took a decade ago in 2008.

Note that the following two paragraphs refers to the Steering Rack System on the Rev Gen 1 (G1).

The G1 REV/RT has a pretty elaborate Rack comprising of a Track Rod and two Idler Arms (aka Swivel Arms) connected to the Frame via a Plate. The Track Rod connects both Tie Rods, and a Link connects the Track Rod to the Steering Arm.

The Idler Arms are called as such since they don't have any direct linkage between the Steering Arm and the Tie Rods. This part is important to distinguish the Rack system on the G1 to the G4, because the Tie Rods are connected to what we would normally call Idler Arms. Since they are no longer idle on the G4 we can refer to them as Swivel Arms.

When comparing the Rack on a G4 to a G4 without rack that uses only a Steering Arm, then there is a big difference. But I don't see much difference with the G1. The biggest difference I see with the G4 Rack is when the steering is straight the G4 makes a right angle between the Link and Swivel Arm, whereas the G1 has the Link offset to the Track Rod by roughly 5 degrees. In other words the G1 doesn't push the Track Rod straight, but rather on a slight angle. It would be like pushing a stuck car from the side vs the rear. I doubt it makes a noticeable difference especially when compared to the difference the suspension setup makes, but everything counts on longer rides.

Also note that BRP doesn't sell the G4 Steering Rack System as easier to steer than a non Rack system or one from the G1. I believe this would be difficult to prove.

For the terminology, BRP refers to a Pitman Arm, while in both systems I call it a Steering Arm since the Arm is welded to the Steering Post.

New for 2017 Exclusively on Gen4 REV platform sleds, the RAS 3 further refines the RAS 2 geometry for more precise handling, especially in extreme bumps and in deep snow. MXZ and Renegade X models also feature a new rack steering system (vs. a Pitman arm) that further sharpens precision in bumps.

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Rack steering 850 - JPG.jpg
The effort difference is easy to prove. The key difference for effort is the distance from the center of the steering column to the center of the hole on the what you call the steering arm vs the length of the lever on the spindle arm from the center of the tie rod bolt hole to an imaginary line through the two steering pivots on the spindle. The distance on the steering arm of the mxz X and XRS will be shorter than the one on the one on the TNT. It is why the TNT turns tighter than than the MXZ X and XRS and why the steering is easier on the MXZ X and XRS. Simple leverage. I believe the spindle steering arms have common length. I will measure those distances when I change out the steering on my G4 summit and install the MXZ X steering in it. Will probably be towards the end of the summer. The better tracking comes from the linkage and the radius of the various arms throught the turning motion.

I am thinking of making my own steering arm and moving the bolt hole even closer to the center line of the steering shaft to make it even easier steering. Why Ski-Doo doesn't break down and offer an electric power steering system for us older riders I don't know.

Maybe they think we won't pay for it and the cost of developing and tooling is too great for the returns.. But there are getting to be a lot of us older riders who played hard and broke bones and joints in our younger years who would really appreciate it now.
 

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^^^ I would think a sharper angle would act more like a snow plow versus a more gradual angle that would help the sled get up on top of the surface of the pow???
The snow plow is a good example. Which position will better push the snow?
 

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I have spent countless hours setting up my XP, XS, G4 sleds. There are many attributes of the Doo sleds relating to steering that are great. They go where you point the bars. In the north east, this is good when you are riding mountain/woods trails. But the effort to steer the sleds is noticable. Hop on a Axys Poo, and be amazed at how the front end reacts to imput without extra effort. The rest of the sled is nothing special. But as far as steering goes, nod to Poo. FWIW, I have a torn rotator cuff. I will ride up to 300 miles in a day, 200 in VT.
 

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The effort difference is easy to prove. The key difference for effort is the distance from the center of the steering column to the center of the hole on the what you call the steering arm vs the length of the lever on the spindle arm from the center of the tie rod bolt hole to an imaginary line through the two steering pivots on the spindle. The distance on the steering arm of the mxz X and XRS will be shorter than the one on the one on the TNT. It is why the TNT turns tighter than than the MXZ X and XRS and why the steering is easier. Simple leverage. I believe the spindle steering arms have common length. I will measure those distances when I change out the steering on my G4 summit and install the MXZ X steering in it. Will probably be towards the end of the summer. The better tracking comes from the linkage and the radius of the various arms throught the turning motion.
We are getting into Geometry and Physics... sounds like fun. Actually it is fun if you can use two sleds to compare. I think the biggest challenge would be trying to remember the formulas and math.... It would be easier to compare the travel of the steering vs skis at difference positions to give an idea of the leverage. I think it would take resistance on the skis and steering with hook type scales to evaluate the system as a whole. Assuming it is easier, by how much? 2%, 5%, 15%? I find 12 model years without a rack is strange. Did BRP realize that it made very little difference and decided to cut cost? Or was a lack of space with the G2 and G3? Why was is standard prior to 2008 and now a specialized option on the G4?
 

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Ncapster, I think that you will enjoy this video that explains the Torque Arm Angle. Note at 2m50s it also mentions the effects of the Limiter Strap.

I later added a picture of the Track Approach Angle to show the effects of the limiter strap. Note that in both cases a longer Limiter Strap is used for Off-Trail Deep Snow.

Torque Arm Angle

Given good traction from the snow:

- Shorter Limiter Strap = Shallow/Less Angle = Faster Acceleration for Trails.

- Longer Limiter Strap = Steeper/Higher Angle = More traction for Off-Trail Deep Snow.


Track Approach Angle

- Shorter Limiter Strap = Shallow/Less Angle = More ski pressure for more positive steering on the Trails.

- Longer Limiter Strap = Steeper/Higher Angle = Better handling in Off-Trail Deep Snow.

From the Arctic Cat 2013 M series updates (click here) we can see that lowering the arm mounting location in the tunnel will help the sled to roll up and out of the snow better. Since this change lowers the skid, it also increases the Approach Angle.

- Steeper/Higher Track Approach Angle = Better rolling up and out of Off-Trail Deep Snow.

https://www.scooterforum.no/index.php?threads/ski-doos-new-remote-adustable-systems-improve-handling.40175/

Two years ago, BRP introduced the adjustable limiter strap for tMotion rear suspensions as a quick, easy way to adjust deep snow handling on Summit and Freeride snowmobiles. This year, the concept has evolved into a remotely controlled system (product #860201496) for even easier operation.

Riders can now quickly adjust their ride between a playfully light and agile setup and a more connected setup, where the track approach angle gets much more gradual and the skis don't lift as easily. A dial-like switch is mounted on the handlebar riser, so riders can now change positions by twisting this knob, rather than reaching down by their feet to flip a lever.

The kit should also prove popular with the crossover crowd, as it also fits the new cMotion rear suspension on the 2018 Backcountry models. A rider can easily move the strap to the shorter position for more positive steering on the trail, or to the longer position for better handling in off-trail deep snow.

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