ProNytro V2

Kennyspec · Aug 27, 2014

First build thread can be found here:

http://www.ty4stroke.com/threads/another-pro-nytro.116477/

Version two will be a tube chassis mounted to the pro rmk bulkhead. a lot of this idea has came from jskattum606's propex build. Planning on using the stock clutches and getting custom jackshaft and driveshaft from http://www.industrialjigandfixture.com/ and building a belt drive setup instead of a chaincase.

I think the biggest problem with the nytro is the high center of gravity. so far I have a drawing in cad and the top of the new fuel tank is lower than the top of the nytro tunnel!!!! Should be a drastic improvement. Keeping the stock location of the driveshaft relative to the suspension mounting points of my cat float skid.

First I had to build a table to get the sled up on and take some measurments.

Then transferred into cad and came up with this:

White lines are the old tunnel, green the new tunnel. hoping to make a fuel tank that is only about 5" tall and keep the center of gravity low.

Now drawn in Bend Tech.

so far most of the tube is 1" .065 wich is probably overkill. Currently weighs 38lbs according to bend tech. changing the tunnel to 3/4" .035 takes the chassis down to 22 lbs.

Wheel House Motorsports · Aug 27, 2014

1" 065 is stupid overkill for anything outside of motor mounts, around motor, and stuff 065 is nice, but for just bracing and stringers, 5/8 035 works killer. adds a lot of strength and almost no weight. also, doing 1" down the tunnel sides makes the thing super fat and it kinda makes it feel bow legged.

On the note of top heavy, dont go overboard on dropping mass, realize, for a mountain sled, you want the thing to be easy to get on edge and hang there, the lower you put the center of gravity, the harder it is to roll over and stay on edge with. Tall and skinny can get a little wild on the trail but makes backcountry riding a freakin hoot. low mass means you can haul *** down the trail and not roll over, but your gonna be tired from trying to roll that bugger over in the woods all day.

Kennyspec · Aug 27, 2014

Thanks for the input!!. I have used a bit of chromo in my first build. all 1" .065 lol I didn't really know how strong this stuff was compared to mild.

Do you think that tunnel stringers in 3/4" .035 will be enough? changing the tunnel braces from 5/8 to 3/4 only added .3 of a lb so I may just make the entire tunnel in 3\4 .035 just to keep it all the same. I may have to use 1" .065 for the hoops around the clutch and belt drive area as that is as thin as my bender can handle without kinking. its a jd2 model 3. What material do you use for the running boards? 3/4 .035 once again?

Looking at bend tech (awesome program) the tunnel and boards all in 3/4 .035 get me down to 24.6lbs

I see what you are saying about having a high center of gravity and rolling the sled over. But what about when the sled is sitting at a angle with the left ski downhill and the right ski uphill. the sled is going to want to topple over to the left side, When I had my nytro in the mountins it seemed really hard to pull the downward ski up in the air and get it to lean into the mountain and carve back uphill. I think even with relocating the fuel tank lower the c.o.g. will still be a fair bit higher than most sleds, espically with the mid mount turbo. :face-icon-small-sho

Wheel House Motorsports · Aug 27, 2014

first tube chassis we did the whole tunnel out of 3/4 .035. We actually put another sled on the tunnel and rode out. 2 people and a sled on it and rode home. its as strong as the design allows it to be.

another reason i love the smaller diameter stuff is it bends a ton nicer, 3/4 .035 was never able to go past 60 without a full kink, it would wrinkle a hair past 45. 5/8 does about 10 more * before same results, big thin stuff sucks to bend. all of ours are/were done with just a hand conduit bender.

Also, your stock nytro was a tank and had so many geometrical issues its hard to even consider the cog the issue. im not saying mount the motor above the bars, but dont try and drag it on the ground either. building a well rounded sled so you can always get it around with a quick blip and pull on the bars.

sportsterdanne · Aug 28, 2014

Nice ! I will follow this.

jskattum606 · Aug 28, 2014

I recognize those CADs from somewhere?......
oh yeah! that info was floating around in my head a few months back:face-icon-small-coo

looks good man!
for the tunnel, I did the bottom tube and the bottom tube and the outer running board out of 3/4 .035. The rest is all 5/8 .035.
The front is a mix of all sorts of stuff. The upper pyramid is 1" .035
Go wild though and learn for my mistakes this is my 4th chassis and by far the best

sportsterdanne · Aug 29, 2014

I can see how a higher COG will make it easier to flip to one side but when throwing it from side to side a low COG must be better ?

Im not even done with my current build and i already have plans for a new sled spinning around in my head....
some interesting stuff that i really would like to try out.

Kennyspec · Sep 29, 2014

not much done to the sled lately. was just thinking of what to do a belt drive or a chaincase. If I do go with a belt drive there is the problems of having all one off parts, and no reverse. The only way to get reverse is buying a apex chaincase as it has a mechanical reverse. I also thought of getting a nytro right side bulkhead plate and cutting the moulded chaincase out of it and mounting it to my aluminum bulkhead side plate. then I can at least use all the internals from my current nytro. thoughts\?

Norway · Sep 30, 2014

sportsterdanne said:
I can see how a higher COG will make it easier to flip to one side but when throwing it from side to side a low COG must be better ?

Well, I see his point as a question of where do you move the COG when you sidehill?

If your COG was impossibly low, down between the skiis, then you would have to flip the sled 90 degrees before the weight stopped pulling the sled down planted again.

Higher COG means you don't have to hang way out there for the balance to be over the ski you ride on (COG of you + sled is above lower ski).

Yes? No?

Something like that anyway.

sportsterdanne · Sep 30, 2014

I would ditch the reverse and go all in with a belt drive on such a custom build.
Apex and Nytro chaincase seems to handle massive horsepower and thats good but the distance between driveshafts is to short in my opinion. If you mount the track drivers lower for better track angle like most newer sleds the secondary shaft gets placed inside the tunnel.

Kennyspec said:
not much done to the sled lately. was just thinking of what to do a belt drive or a chaincase. If I do go with a belt drive there is the problems of having all one off parts, and no reverse. The only way to get reverse is buying a apex chaincase as it has a mechanical reverse. I also thought of getting a nytro right side bulkhead plate and cutting the moulded chaincase out of it and mounting it to my aluminum bulkhead side plate. then I can at least use all the internals from my current nytro. thoughts\?

Kennyspec · Sep 30, 2014

the sled is going to be used about 95% in the flatlands. maybe a week in the mountains every second year. It seems stupid to build a 156x2.5 for flatland riding, buy why not.... I don't care if I can do 120mph. The sled is backed off of a trailer, loaded on a truck, reversing on the trail quite a bit....so I don't know if the extra 10lbs in weight savings is worth losing the reverse. I was planning on cutting the chaincase out of the nytro bulkhead and welding it to a flat alum plate for the side of my new bulkhead. so while I am at it I guess I could always cut it in half and end up with 9" or 10" or whatever I want for shaft centers.

Kennyspec · Oct 1, 2014

did a little editing of the frame.
blue is 3/4 .035
green 3/4 .065 (just to bend without kinking)
black 1" .035

total weight is 25.5 lbs

Kennyspec · Oct 1, 2014

also drew up this version of the chassis

Kennyspec · Oct 5, 2014

Tubing, 3/4" die and a notcher is ordered and on the way!!

Kennyspec · Oct 8, 2014

Tube showed up today.

On a side note, my cousin asked me to make him a laptop stand for his DJ equipment, the mixer goes on the bottom and the laptop is on the top. I drew it in Bendtech. The frame is 1" .065 all one piece. A total of 8 bends and most of the bends weren't a simple 90* and the "rotation" of the pipe wasn't 90* each bend either, the top has a 10* tilt to it to be able to see the keyboard on the laptop better. The measurments I got from bendtech was bang on. as I did the last bend the frame was within 1/8" from closing! I believe the most bends I have in one length of tubing on the sled is 2 or 3 so building this chassis should be no problem!

CDK · Oct 8, 2014

Cool! Snap a pic of the tools you're using, for reference. I love home fab work.

Kennyspec · Oct 8, 2014

In the two pics u can kind of see the bender. It's a JD2 model 3. Also planning on buying a JD2 notch master for all the tube notching I will have to do. Currently I notch my tubes in a old atlas lathe with a little clamping device I have for it. Miller syncrowave 200 for the tig work. I will take some pics later on once I start building this thing.

jskattum606 · Oct 9, 2014

Looking good! Should work well
I would add one more rung into your running boards so they are not spaced out as much. Don't want you to get your foot stuck in one of the hole. Around 3.5 OC for the rungs

Kennyspec · Oct 9, 2014

Ya I may just do that. I was going to grab my snow boot and measure off of it to make sure I can't get it stuck lol. But 3.5 sounds like a good number. That 3/4" .035 sure seems weak, but I am sure it will be fine once all braced up in a truss configuration.

Kennyspec · Oct 9, 2014

did a bit on the sled today. got the front tube cut and one of the lower stringers for the tunnel done.

doesn't look like much yet.

the "biggest" notch 80* turned out awesome with the printed notch wrappers from bend tech.

LOOK AT THAT FIT UP!!!

ProNytro V2

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