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2012 AK sled build

It's looking good. Your fabrication skills are impressive. Thanks for sharing.
 

Stock ski bushings


Alternative Impact Ti bushings


.138 lb loss. It's rediculous, but I wanted a couple Ti parts on my sled just for fun and these are actually cheaper than stock.
 
I put the motor back in and subframe on as I'm going to start relocating my steering tomorrow. Going to get as close to stock as possible so I have a sled that actually handles well and isn't awkward. I might add some weight with the u-joint but eliminating the bent tie rods & bump steer will be worth it.

In the meantime, my buddies were kind enough to point out that I don't use the front 30% of my seat when I sit on it.

So...


Ignore the blue pen line


Race seat. Covering it tomorrow.


Don't need the front support anymore or the 3rd bolt


The battery is going to be relocated in front of the gas tank so I'll cut out the old battery bracket which should be at least .25 lbs


And I'll lose about 60% of the wiring, so approx .22 lbs


Slowly closing on sub 420 lbs.
 
So the steering has been a pain to say the least. To start off, I won't get the same angle on the steering arm as factory, but I can at least get the post in the same centerline so the steering arm swing will be close. As in the picture, it puts the front of my steering post at about the front of the rear a-arm mount.



I really didn't want to run a u-joint as it makes the post angle steeper at the steering arm and adds considerable weight. So I threw out that idea pretty quick. Luckily before spending $50 on a Borgeson lightweight u-joint.

Back to the drawing board I started over by putting a nice size dent in my charge tube (for post clearance) and changed out the Vibrant silicone couplings for shorter pieces of regular silicone hose. This got the charge tube against the throttle bodies and the post far enough back that the steering block was in the same position as last year. Good, but not good enough.


Good bit of weight lost




So then I thought I'd buy some 2" 5052 tubing and oval it out in a press to get even more clearance. Good in theory but not much more clearance and the .035 (all I could find locally) was proving rather difficult to weld. Scrapped that idea 3 hrs after spending $55 on 3 feet of it.


So after wasting the last couple days figuring out every way I didn't want to do it, I decided I'd just build a new boxed charge tube. The volume will be the same as 2" tubing but since I can follow the angle of the post, I'm able to move the post nearly all the way back against the hoop. This is as good as the steering is going to get. I made a mock charge tube out of .032 to check clearance. Finished one will be .080.



New position vs old


I'm waiting on some material to come in the mail so it will be a few days befor I finish the steering and charge tube.
 
I really like this build! Nice to see someone who tailor fits his snowmobile to his own needs. Spare no details! I would like to do a build like this some day too.
 
I've been waiting on some tubing that finally came in so I worked on my steering a bit. Tried to get the lower post mount as light as possible. I did away with the heavy bearing setup I was previously running for a factory plastic pro block. The 1/2" square tube will get welded in between the rear upper a-arm mounts.

Started by welding 9/16 x .035 round tubes (had to special order the 9/16) to the 1/2 x .035 square tube.


Once the tubes were welded I cut them down and welded thin 5/16-24 jam nuts on top. This allows me to run short bolts instead of the the factory Polaris spacers and through bolting the blocks.


The finished parts



Old


And the new. The 1/2 square tube is a little long so it'll end up a touch lighter, but overall I'm pretty happy with another half a pound lost at this stage in the build.
 
Caleb:
Good to see your still working on the beast!!! I can't wait to see the final weight. A turbo 4 stroke way sub 400???? WOW

Struggling with the same steering issue as I redo the front end of my Nytro...now on its 2nd year....LOL. Trying to use a straight steering post that is quite a bit steeper than stock with the OFT relocate. Middle cylinder is always the issue but I think I can use a different inlet rubber/K&N combo to get mine to fit (it's a NA engine) . I like your charge tube idea. I kept thinking "turbulence" with the charge tube being that tight to the inlet header however this is a turbo which will definitely push the air through so shouldn't effect power. Post if you notice any change in throttle response.

On the steering /bump steer side, the one thing that I've figured out is that vertical position of the ball joint in relation to stock is critical. You want to place the ball in the ball joint as close as possible to its original vertical position. Front to back is not as critical, in fact having your steering rods perpendicular to your spindles also reduces steering effort and helps bump steer a bit, but nothing compared to vertical. Think mm's here because there isn't much to play with before steering gets wonky.

Awesome bud.

OTM
 
Glad to see your getting time to work on your incredible build. Keep up the work & amazing craftsmanship as always!
Your creating your own front steering & I can't even fix the icing issue in my tunnel with the Push turbo! LOL
 
On the steering /bump steer side, the one thing that I've figured out is that vertical position of the ball joint in relation to stock is critical. You want to place the ball in the ball joint as close as possible to its original vertical position. Front to back is not as critical, in fact having your steering rods perpendicular to your spindles also reduces steering effort and helps bump steer a bit, but nothing compared to vertical. Think mm's here because there isn't much to play with before steering gets wonky.
Click to expand...

Just so I'm clear, when you are talking the vertical position of the ball joint, are you referring to the inner tie rod end? My goal was to have the inner tie rod end in the same position as factory. The swing in the steering arm won't be identical, but I'm pretty sure I can get it dang close.

I appreciate the help, the steering on these is a pain.

It won't be under 400 lbs. Running the numbers Im thinking 415-418 dry. This is with a 40 lb or so 155 Pro skid I have coming. I won't spend the money on floats or Ti parts (metal lathe is the next toy), but you can get a pro skid under 33 lbs.

If I end up doing a full tube chassis with a belt drive sub 400 lbs is obtainable for sure.
 
Nikolai said:
Just so I'm clear, when you are talking the vertical position of the ball joint, are you referring to the inner tie rod end? My goal was to have the inner tie rod end in the same position as factory. The swing in the steering arm won't be identical, but I'm pretty sure I can get it dang close.
Click to expand...

Exactly. The inner steering ball joint. Try to get its vertical position (center of the ball) as close to stock as possible. I did a full mock up of the Skinz 39" front end in CAD and then rolled the A-arms through their full suspension movement. I was totally surprised how good the bump steer was on the Nytro....pretty much non existent when riding bumps in a straight line... but I was also surprised how sensitive the bump steer is to the vertical position of the inner ball joint.

On CAD, the best vertical location gave me a ball at 26.6 mm above the lower a-arm bolt centerline +/- 2.0 mm MAX and when I measured mine, it was like 27.5 so pretty close. Also had the center to center horizontal spacing of ball joints on steering post arm at 32mm's. If I remember right your build used all the stock suspension mounting positions on the spindle and your subframe so your measurements should be similar.

Don't worry too much about steering post angle or swing. If anything a steeper steering post is actually better for bump steer as it gets the steering post angle closer to being parallel to the caster angle of your spindles.

Hopefully that helps get you in the ball park.

Mike
 
Awesome information, huge thanks! I'm printing your post off now to keep on the bench.

I'm sure my previous front end geometry was off by quite a bit, my steering arm was pretty high above the a-arm mounts and I had to run spacers on top of the spindle mounts to raise the outer tie rod ends. My tie rods each had two bends in them. All reasons why I'm trying to correct it now.

Here's some old pics of how it was.




 
Last edited:
Caleb:

Are u using 2008 or 2010+ spindles??? I'm looking at the picture and thinking maybe 2008?? That would be a problem as mine is a 2011 and the spindles are WAY different where the steering arm attaches....which would throw off the spec's I sent you.....great :(

Maybe before you butcher the front end, I can try to recreate your front end in CAD, to see where you need to put your steering arms to minimize bump steer. I have half of it on cad (the a-arms and 2010 spindle) so it wouldn't take too long. It won't be bang on because I don't have your "rest position" and shock stroke, but I can get pretty close.

I don't know if it can be improved, but it's not a big deal to check to see how good or bad it is.

I'll need 2 measurements assuming your A-Arm mounts are basically stock:
1. The distance the inner ball (center of ball) is above the center line of the lower a-arm bolt center line
2. The distance the outer ball (center of ball) is above the spindle steering mounting plate.

I have a 2008 spindle here, so just let me know which one you are using and I'll put that one into CAD.

Fun eh.....lol

Mike
 
Interesting that the spindles are different where the tie rod ends mount, because I don't think Yamaha ever made changes to steering arm or its subframe mount. That would suggest the spindle should be the only difference correct?

I'm not interested in keeping my steering the way it was if that's what you are implying. I want to go back to straight tie rods and get everything behind the rear a-arm 3/4 vertical tubes.

I'm sending you a PM here shortly.
 
Charge tube parts showed up today. Because I'm only running 1" long pieces of silicone hose, I wanted narrow clamps.

I ended up ordering Oetiker Series 167 clamps. They are only 7 mm wide, cinch down extremely tight, and weigh nothing. They aren't reusable but I had to order a package of 100 off Amazon anyway. Oetiker part# 16700066. These are the correct size for 2" ID silicone hose only. 1.75" ID require a smaller clamp I'm still trying to source.


Width difference


The three factory clamps with the three hose clamps I was using.


Six Oetiker clamps


Old charge tube hoses & clamps together


New hoses and clamps together.
 
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