Nikolai
TY 4 Stroke God
I cut out the long tubes, unbolted the rear suspension mounts from the jig and lifted the back just to see how much flex there was in the lower 1” tube by itself and there was a lot.
I sat staring at this thing for a few days trying to come up with a strong way to build the tunnel that’s not ugly and truth be told I couldn’t. If tubing wasn’t outrageously expensive and I had more free time I would completely redo it from steering hoop back but it needs to get on the snow so I left it as is.
I had quite a bit of 1x1/2 .035 left so I started by adding tubes to the side. Tack welded and unbolted the suspension mounts again and they took 95% of the flex out. With the rear unbolted I could push up on the bumper and lift the entire jig and table. OD side to side is 16.5” so not super wide and I kept them below where the tunnel will taper in at the top. Standing on it with boots it feels totally fine.
Then I added 2 more 3/4 x .035 tubes. They are the height of the tunnel skin and brought them in at the hoop staying inside of the bent part of the tunnel so my legs don’t hit them. I will add 1 cross tube to support the header, and some tubing to support the turbo. The fuel tank will rest on top and bolt to the tubes and hoop to add rigidity to frame. I may add some bracing on the sides to triangulate a little but not sure at this point.
Having a tall tunnel to keep the header below makes things a little awkward. I’m going to ride it at is and if I hate it down the road and want to change the design it’s not the end of the world to do so.
Good part is that there’s only about 13 lbs of tubing from behind the steering hoop for the tunnel and with the added tubes the skin will not need to be structural at all and I will save a lot of weight there. I’m going to skin the top with .040 7075 aluminum since the header is close, and the sides will be a couple layers of carbon fiber, just rigid enough to hold up and keep snow out. Complete tunnel should come in well under 20 lbs. It might be ugly but at least it will be light.
If I built another tube frame I would build the entire front half including the steering hoop and do the tunnel last. Live and learn.
I sat staring at this thing for a few days trying to come up with a strong way to build the tunnel that’s not ugly and truth be told I couldn’t. If tubing wasn’t outrageously expensive and I had more free time I would completely redo it from steering hoop back but it needs to get on the snow so I left it as is.
I had quite a bit of 1x1/2 .035 left so I started by adding tubes to the side. Tack welded and unbolted the suspension mounts again and they took 95% of the flex out. With the rear unbolted I could push up on the bumper and lift the entire jig and table. OD side to side is 16.5” so not super wide and I kept them below where the tunnel will taper in at the top. Standing on it with boots it feels totally fine.
Then I added 2 more 3/4 x .035 tubes. They are the height of the tunnel skin and brought them in at the hoop staying inside of the bent part of the tunnel so my legs don’t hit them. I will add 1 cross tube to support the header, and some tubing to support the turbo. The fuel tank will rest on top and bolt to the tubes and hoop to add rigidity to frame. I may add some bracing on the sides to triangulate a little but not sure at this point.
Having a tall tunnel to keep the header below makes things a little awkward. I’m going to ride it at is and if I hate it down the road and want to change the design it’s not the end of the world to do so.
Good part is that there’s only about 13 lbs of tubing from behind the steering hoop for the tunnel and with the added tubes the skin will not need to be structural at all and I will save a lot of weight there. I’m going to skin the top with .040 7075 aluminum since the header is close, and the sides will be a couple layers of carbon fiber, just rigid enough to hold up and keep snow out. Complete tunnel should come in well under 20 lbs. It might be ugly but at least it will be light.
If I built another tube frame I would build the entire front half including the steering hoop and do the tunnel last. Live and learn.
Nikolai
TY 4 Stroke God
Was going to run header support this way
The above doesn’t add much strength to the overall frame so I ran a diagonal tube centered between the two header mount holes. Will weld tabs to the tube for the header bolts.
And ran one more to triangulate it. I couldn’t get it all the way to the back corner due to header height and exhaust in the way. I could have brought it further forward on the tunnel but I wanted the other one to stay centered in the header mount. It is what it is
Those tubes will provide a good structure for my gas tank to bolt too. I’m thinking if I make the base of the gas tank go to the edges of the tube I wouldn’t even need to have a tunnel skin below it.
I don’t know how close an aluminum fuel tank could safely be to the header? Any guesses? 1”? 1.5”? 2”? Bad idea regardless?
The above doesn’t add much strength to the overall frame so I ran a diagonal tube centered between the two header mount holes. Will weld tabs to the tube for the header bolts.
And ran one more to triangulate it. I couldn’t get it all the way to the back corner due to header height and exhaust in the way. I could have brought it further forward on the tunnel but I wanted the other one to stay centered in the header mount. It is what it is
Those tubes will provide a good structure for my gas tank to bolt too. I’m thinking if I make the base of the gas tank go to the edges of the tube I wouldn’t even need to have a tunnel skin below it.
I don’t know how close an aluminum fuel tank could safely be to the header? Any guesses? 1”? 1.5”? 2”? Bad idea regardless?
1" is fine with a shield for sure.
kinger
VIP Member
All good things, I like those diagonals, even though you missed the nodes in the corner you added a lot of torsional rigidity which is what you needed. You only need a 1/2" air gap with a proper shield. Look at a dimpled heat shield and use carbon fiber to make a crude shield as Carbon doesn't conduct heat and you will be fine.
Lastly the idea of using the tank for a tunnel skin is great and gives you easy access down the road by just unbolting the tank. Also with a rear mount you can boil the fuel under there so having it exposed to snow will really help prevent that. I really wish I had a space to jig up and work on my own tube frame tunnel. Looks like its good creative fun. I view my job from down here in Iowa for you is to keep you motivated and not get into analysis paralysis
Get it on snow and you will want to make a bunch of changes anyway so no need belaboring them now. Looking great!
Lastly the idea of using the tank for a tunnel skin is great and gives you easy access down the road by just unbolting the tank. Also with a rear mount you can boil the fuel under there so having it exposed to snow will really help prevent that. I really wish I had a space to jig up and work on my own tube frame tunnel. Looks like its good creative fun. I view my job from down here in Iowa for you is to keep you motivated and not get into analysis paralysis
Get it on snow and you will want to make a bunch of changes anyway so no need belaboring them now. Looking great!
Nikolai
TY 4 Stroke God
Analysis paralysis is real, fallen victim to it many times on this build. I keep telling myself I can put the frame back in the jig anytime down the road and make changes.
I was thinking the same thing on the fuel tank. If I didn’t have to run a skin below I would have easy access to the header. I’ll put something flat on top of the tubes and measure the clearance to the header in a few spots.
I was thinking the same thing on the fuel tank. If I didn’t have to run a skin below I would have easy access to the header. I’ll put something flat on top of the tubes and measure the clearance to the header in a few spots.
I closed both my Phazer and Viper holes in tunnel fully with shields which I keep a eye on. 24000mi on Viper and about same on Phazer. Never a issue.
Nikolai
TY 4 Stroke God
What I would like to is set the fuel tank on the frame tubing and not use any additional shielding. Shielding around the turbo and the flex joints but underneath the fuel tank itself it would be the open frame tubing. I’ll cut out a cardboard template and measure clearance.
Nikolai
TY 4 Stroke God
Welded the tops of the 3/4 tubes. Will work on the 1” steering hoop tubes tomorrow.
Since I’m on a roll adding weight to the frame I went ahead and made an “X” with 1/2 .035 square tube to strengthen the back. Will also give me something to set a gas can on and secure the u-cooler too. This stuff is light, only 0.17 lbs a foot. Total weight for the X was 0.76 lbs.
Since I’m on a roll adding weight to the frame I went ahead and made an “X” with 1/2 .035 square tube to strengthen the back. Will also give me something to set a gas can on and secure the u-cooler too. This stuff is light, only 0.17 lbs a foot. Total weight for the X was 0.76 lbs.
I hate to say this but you are going to get alot of ice buildup on those frame rails. Top of tunnel with exhaust under it needs to be perfectly flat or ice will stick. Running the exhaust on top the tunnel would be much better or if enough room for track clearance enclosing that tunnel under the exhaust would be ideal. Ice is going to negate most of the weight savings otherwise.
Nikolai
TY 4 Stroke God
I’ll skin the top in between the header and frame tubes with .040 aluminum as originally planned then. Might do a small piece of aluminum directly over the header due to the heat and then carbon fiber for the rest of the top to minimize snow buildup.
Last edited:
74Nitro
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- 2019 Sidewinder LTX
Agreed, I rode a Nytro for years and as much as I thought the rear exhaust was unique, it wasn't without problems, ice build up being the biggest.
Glad you're going to skin in between.
Having said that, the Winders do have have some open exposure underneath the exhaust manifold.
Glad you're going to skin in between.
Having said that, the Winders do have have some open exposure underneath the exhaust manifold.
Nikolai
TY 4 Stroke God
Trade offs with everything and snow buildup in the Nytro did get really bad at times. I wanted to keep the rear mount turbo to have the weight in back, that’s an easy 15 lbs or more(turbo, header, charge tube ect) behind the rider vs in front by the motor. I want the front end of this sled to feel as light as possible riding it.
I need to see what kind of heat carbon fiber can handle for prolonged periods of time. Thinking if I cut the aluminum to be slightly wider than the header then the rest could be CF.
I need to see what kind of heat carbon fiber can handle for prolonged periods of time. Thinking if I cut the aluminum to be slightly wider than the header then the rest could be CF.
Carbon Fibre I bet would work better than aluminum since it wont transfer heat like aluminum. There must be some types that take heat. My SRX had a piece of carbon fibre between the pads and stainless backing plate. Best brakes I ever felt on a sled.
Nikolai
TY 4 Stroke God
I appreciate the help/input. I’ll do some research on CF and temps. Aluminum is terrible for snow buildup so the least amount needed(if at all) the better.
kinger
VIP Member
I was going to skim my tunnel with glossy carbon fiber sheets, and use airplane rivets that you smash like a mushroom so they don’t give the snow anything to stick too. I’m mid mount though so no heat back there besides coolant.
