Summer Project - 136" to 144" Mono Setback

[tttario]

Alright guys, did a search and couldn't find any definative answers, looking for help.

I now this is not a huge setback but will relocating the mono back to allow a 144" track have any recourse on the suspension geometry, AOA, component wear, etc.

Just looking for some pros and cons before I dig into this.

Also any pics or advice on the job (measurements, adding tunnel clearance, etc) would be greatly appreciated.

 

[Malmlof]

I´m also thinking of a setback on my Attak.

So far what I have found out:

Pros would be a better approach angle, the angle on mine is 26 degrees stock and would be 18 degrees after setback. The new Nytro 162" has this and Yamaha seems to make a big number of that.

Lower approach angle = better snow floatation / less trenching.
And if the skid is mounted lower on the tunnel the clearence for the snow would improve.

Cons would be longer "wheelbase" making the sled less "nimble" but more stable.
It will have more weight on the skis so maybe the darting would get worse?(But after riding some new ski-doos I think the Attak is steady as a train! )

The geometry should work if the setback wheels are moved back somewhere between 7.5" and 9" (less than 11.5" to compensate for the yamaha-loosening thing) from the rear arm axle. This according to Lazybastard who I think has great knowledge about the subject.
They are stock 7.5" setback on the Attak.

I´m thinking of a 16x144" with 2" lugs challenger track, but I dont know if it will stink on the trail?

I would also appreciate some advice regarding this.

Maybe this should be posted in the Apex/Attak section?

Best regards Richard Malmlöf Sweden

 

[tttario]

Alright.....looks like another summer of procrastinating has got me into fall without touching the machine...lol!

I am committed to getting this done before the trails open and need alittle help. I will be running a 1.325" Cobra with a 4-2-4 stud pattern (1.450" Gold Diggers). I know I am good to run the 1.450 with the stock clearance and tension but the future has extro's in it so I want to add the room now as I will not be running the track as tight. The goal of this project is to add floatation with the decreased angle of approach and extra footprint as well as add some traction.

So I know my setback is 4" and I am thinking of dropping the mount points 1/4"-1/2" to allow for more tunnel/track clearance. At what angle do I want my tunnel to be at when I make my measurements to relocate the mounting holes???? When the suspension has all weight off it (raised), pick up the rear of the sled and "place" it back on the ground (natural) or have someone the same weight as I am sitting on it (riding). The difference between these 3 tunnel angles changes the relocation points drastically.

From the lack of initial response I assume not too many have tackled this so I would even appreciate your $0.02 on the matter even if you disagree with the relocation.

Cheers.

 

[kinger]

Check out my post in the aftermarket suspension section that shows how to mount the ZX2, its a set of universal numbers and how to do it. I think you could follow the same process with the mono and it would get you close. There they use the ground as a reference and before you take yours apart you could get some base line measurements as it sits now and then substitiute your number for thiers and get real close.

Adding clearance in the tunnel may make it tippy but your right not a lot of people doing it so you can be the first

 

[ahicks]

I hear you on the procrastinating bit....
I've asked kinger to send the direction download to me via email (can't get it here for some reason?), but before I get that, what are your plans regarding the drivers? You want more track/stud clearance from this project - changing those will likely be required for heat exchanger clearance as well?

Alright.....looks like another summer of procrastinating has got me into fall without touching the machine...lol!

I am committed to getting this done before the trails open and need alittle help. I will be running a 1.325" Cobra with a 4-2-4 stud pattern (1.450" Gold Diggers). I know I am good to run the 1.450 with the stock clearance and tension but the future has extro's in it so I want to add the room now as I will not be running the track as tight. The goal of this project is to add floatation with the decreased angle of approach and extra footprint as well as add some traction.

So I know my setback is 4" and I am thinking of dropping the mount points 1/4"-1/2" to allow for more tunnel/track clearance. At what angle do I want my tunnel to be at when I make my measurements to relocate the mounting holes???? When the suspension has all weight off it (raised), pick up the rear of the sled and "place" it back on the ground (natural) or have someone the same weight as I am sitting on it (riding). The difference between these 3 tunnel angles changes the relocation points drastically.

From the lack of initial response I assume not too many have tackled this so I would even appreciate your $0.02 on the matter even if you disagree with the relocation.

Cheers.

 

[kinger]

ahicks - do a right click and save as on the download button in the previous post. I just clicked it and got a blank screen when i click save as and put it on my desktop it worked perfect.

 

[ahicks]

<<<At what angle do I want my tunnel to be at when I make my measurements to relocate the mounting holes???? When the suspension has all weight off it (raised), pick up the rear of the sled and "place" it back on the ground (natural) or have someone the same weight as I am sitting on it (riding). The difference between these 3 tunnel angles changes the relocation points drastically.>>>

After reading the universal mounting directions (twice!), they don't do a very good job of something you're asking about here, and that something I think is the absolute key on a project like this - the place most guys get in trouble. That's taking front end ride height into account when setting the front skid mounting height within the tunnel - or, as you put it, setting up the angle the tunnel runs at.

Here's what I wrote when kinger asked about lowering his skid for increased clearance:

If the sled is handling well now, I would get the (unloaded!)height dimension of the front end prior to modifying or changing anything. Then figure out a way to support it securely at that same height so you can dink around with the back end without it falling down or changing. Maybe somewhere in the area of the lower front a-arm mount?

From there, I'm not familiar with how the ZX mounts. But if it were a Poo/Cat/Doo suspension, I would measure from the ground up to both the front and rear mounting points, with the sled unloaded, and prior to any work, with the front end blocked. (as it turns out the ZX is not much different)

Then I'd drop/pull the suspension, lift the back up the amount you want, hold it there, and measure the front mounting point to see how far it moved. That's the distance you'll want to drop it for the amount you've lifted the back to stay "in sync" front/middle/rear.

Blocking the front end prior to doing any of this is critical. If you skip that step, there is no doubt you'll end up with your front skid mounted too high.

Does that answer your concern regarding the angle of the tunnel?

 

[tttario]

I hear you on the procrastinating bit....
I've asked kinger to send the direction download to me via email (can't get it here for some reason?), but before I get that, what are your plans regarding the drivers? You want more track/stud clearance from this project - changing those will likely be required for heat exchanger clearance as well?

Alright.....looks like another summer of procrastinating has got me into fall without touching the machine...lol!

I am committed to getting this done before the trails open and need alittle help. I will be running a 1.325" Cobra with a 4-2-4 stud pattern (1.450" Gold Diggers). I know I am good to run the 1.450 with the stock clearance and tension but the future has extro's in it so I want to add the room now as I will not be running the track as tight. The goal of this project is to add floatation with the decreased angle of approach and extra footprint as well as add some traction.

So I know my setback is 4" and I am thinking of dropping the mount points 1/4"-1/2" to allow for more tunnel/track clearance. At what angle do I want my tunnel to be at when I make my measurements to relocate the mounting holes???? When the suspension has all weight off it (raised), pick up the rear of the sled and "place" it back on the ground (natural) or have someone the same weight as I am sitting on it (riding). The difference between these 3 tunnel angles changes the relocation points drastically.

From the lack of initial response I assume not too many have tackled this so I would even appreciate your $0.02 on the matter even if you disagree with the relocation.

Cheers.

I only plan on running a max 1.450" stud on my tracks and I am pretty sure there are alot of people on here doing that already. My only concern was with the longer studs guys are scraping the exhaust shield slightly so I am trying to mediate that issue as I will most likely be running looser that stock tension once the extro's go in. I'll be running stock diameter extro's and there is enough clearance for the front heat exchanger, I believe.

 

[tttario]

<<<At what angle do I want my tunnel to be at when I make my measurements to relocate the mounting holes???? When the suspension has all weight off it (raised), pick up the rear of the sled and "place" it back on the ground (natural) or have someone the same weight as I am sitting on it (riding). The difference between these 3 tunnel angles changes the relocation points drastically.>>>

After reading the universal mounting directions (twice!), they don't do a very good job of something you're asking about here, and that something I think is the absolute key on a project like this - the place most guys get in trouble. That's taking front end ride height into account when setting the front skid mounting height within the tunnel - or, as you put it, setting up the angle the tunnel runs at.

Here's what I wrote when kinger asked about lowering his skid for increased clearance:

If the sled is handling well now, I would get the (unloaded!)height dimension of the front end prior to modifying or changing anything. Then figure out a way to support it securely at that same height so you can dink around with the back end without it falling down or changing. Maybe somewhere in the area of the lower front a-arm mount?

From there, I'm not familiar with how the ZX mounts. But if it were a Poo/Cat/Doo suspension, I would measure from the ground up to both the front and rear mounting points, with the sled unloaded, and prior to any work, with the front end blocked. (as it turns out the ZX is not much different)

Then I'd drop/pull the suspension, lift the back up the amount you want, hold it there, and measure the front mounting point to see how far it moved. That's the distance you'll want to drop it for the amount you've lifted the back to stay "in sync" front/middle/rear.

Blocking the front end prior to doing any of this is critical. If you skip that step, there is no doubt you'll end up with your front skid mounted too high.

Does that answer your concern regarding the angle of the tunnel?

Yes it does. To be honest, I never though about unloading the front suspension and blocking it, makes absolute sense though.

I'll have to read the instructions a couple times as well.

Thanks Guys!!!

 

[tttario]

OK, just finished reading the ZX2 install instructions and it looks like all measurements are taken with the top of the tunnel parallel to the floor. I would assume this would be close to the same level as blocking the front end and raising (unloading) the rear skid as ahicks has mentioned.

Just posting the instruction download so it is in this thread.

 

[kinger]

In those instructions where it says to double check the front hoel position before drilling, take all teh measurements from your current skid including the line from the driveshaft to the rear hole etc, and then you know the dimensions, then simply recalculate the "B" dimension for your added clearance you want and "A" dimension for your set back and see where that puts your mount points.

 

[ahicks]

<<<I only plan on running a max 1.450" stud on my tracks and I am pretty sure there are alot of people on here doing that already. My only concern was with the longer studs guys are scraping the exhaust shield slightly so I am trying to mediate that issue as I will most likely be running looser that stock tension once the extro's go in. I'll be running stock diameter extro's and there is enough clearance for the front heat exchanger, I believe. >>>

My concern for the heat exchanger clearance may be unfounded for the reasons you mention - but - you say you want to run the track looser, and you'll be running extro's. Thinking both factors are going to cost you some heat exchanger clearance. That track is going to want to climb up those extro cogs big time if the track is loose enough to let it, if not while accelerating, then when you apply the brakes. Just a heads up, OK? Keep an eye on it? If you hear ANYTHING when on the brakes those first few test runs - look here first.

Regarding "top of the tunnel level" - check your sled before doing any work on it? If it's level, great. If not, compensate. That'll accomplish about the same as what I suggested earlier?

Consider for a second that your tunnel is level now. Now raise the rear up a couple inches "for additional clearance". Not level any more right? My point is those directions do not take that change into consideration.....

Edit: Second thought. The "universal" instructions are regarding a fully coupled skid. You can adjust that coupling easily to compensate for the front mounting point height. A little more conventional skid design can't compensate for that so easily.... it NEEDS to be right from the get go.

FWIW -Al

 

[tttario]

Thanks Al and Kinger, this is very much appreciated!

With respect to the loose track, I understand. I am talking about slightly looser than Yamaha's "piano string" tension spec. I would not be looking for excessive sag in the track if picked up but just a slight bit looser to free up some friction. I have always perferred a tighter track as opposed to a looser one. But I will definitely keep this in mind for testing, thanks.

First, I think I am going to do the normal 4" setback with the top of the tunnel level. I also think I am going to use the top of the tunnel opposed to floor to take my measurements from. Even a slight variation in floor surface from one side to the other could cause a slight tilt in the skid and added strain to certain skid components. Measure, re-measure, etc. With the tunnel perfectly level it will make it easier to get everything square and properly setback and offset.

Once I get the new holes marked I will move them straight down 1/4" for my added clearance.

What would one use for new mounting plates. Aluminum, mild steel, SS???? Thickness that would not be to thick????

 

[kinger]

1/4" or thicker alumin works if you dont have that much space your stuck with SS or steel in 1/8"

 

[ahicks]

I have no clue how to grade aluminum, but I can tell you I'm using some pretty stiff 3/16" aluminum stock for the rear reinforcement plates on the ProX conversion. I suppose metal would work, obviously much heavier though.