BO15 Cyrus the Virus

[OddJob]

Tank looking goooood ! Hmmm, cobra look.... how 'bout "Hood Rat". **waits 10 seconds**

 

[Psychographic]

With the top piece ready, it was time to get to fabricating the rest of it.

First was the base. I used a tube slightly larger than the top of the Schwinn. This will allow me to use a tire tube as an insulator when I bolt it in place. I found the center and wrapped the tin around it to make my tunnel. Then I marked my bends, and lined up a length of 3/4" angle iron on the marks, and clamped it in a vise along with two pair of Vice Grips on the ends. Using two pair of duck bill Vice Grips, I started bending as far as I could, then finished with a hammer.

Next I drilled a hole towards the bottom of the top piece and plug welded them together. After that I tacked a brace toward the front to set my height and make sure it was level.

A template was made for the back side pieces, and amazingly it fit both sides almost perfectly.
So they got tacked in place.

Now came the hard part, figuring out what shape to trim the bottom plate so the front side pieces can be made and fit. After a little cutting and grinding, I have one side that fits close enough to make a template. Once I had it cut, I hammered the compound curves into it using the lawn as a lead shot bag and a ball peen hammer. This is as far as I can go without an extra pair of hands to hold the metal tight enough to tack it together.

 

[Captain Awesome]

You going to tab mount it or use bungs from the underside?

 

[kingfish254]

That Cobra tank is awesome!!!!!!

It really makes me want to go out and sweep a leg!!!

 

[Psychographic]

I'm impatient, I figured a way to hold the panels to finish the initial tacking process.

For my first attempt to build a tank, I think it came out OK. It's symmetrical, and fits the bike well, at least I think it does.

Next I will tack all the connecting edges of the panels and regrind them to be sure it's solid. Then I will figure out how to finish off the back of the tank so it somewhat blends into the top tube.

 

[Psychographic]

You going to tab mount it or use bungs from the underside?

Right now I'm thinking of using rivnuts on the bottom of the top tube and straps across the bottom of the tank, The straps will have a hole for a bolt to go into the rivnut.

Tank looking goooood ! Hmmm, cobra look.... how 'bout "Hood Rat". **waits 10 seconds**

Thanks, but you know I don't build rats!

 

[kingfish254]

That tank is a work of art! Looks incredible!

 

[Psychographic]

For those interested in the dimensions of Cyrus:

Overall length- 75"
Axle to axle length- 56"
Rear track width- 37.5"
Seat height- 13"
Crank center height- 8"
Top of handlebars 36.5"

 

[Psychographic]

I finished fabricating the back of the tank. Using about a half inch piece of the tubing I used to bend the tunnel, I cut a slice into it, flattened the sides, stretched it to fit over the top tube, then made two filler pieces, and formed it to go from a square edge to round. It finishes it off nicely.

 

[metalchewy]

Great work on that tank, I love it. The Frenched-in base gives a nice transition to the top tube.

....

 

[Psychographic]

That tank is a work of art! Looks incredible!

Great work on that tank, I love it. The Frenched-in base gives a nice transition to the top tube.

Thanks guys!

The more I look at it, the more I wish I had put a curve into the rear side pieces. As this was my first time building a tank, I wanted to keep it simple. To be honest, I was hesitant to post pics of the build of the tank as I really didn't think I could pull this off.

 

[MattiThundrrr]

Yeah, a concave curve on the side panels would flow nicely. More "cobra-ey"

 

[SkyknightJohn]

For a first attempt at a tank, you nailed it! You can always use what you learned to make another “more perfect to your vision,” but there is NOTHING wrong with this one.

 

[kingfish254]

Thanks guys!

The more I look at it, the more I wish I had put a curve into the rear side pieces. As this was my first time building a tank, I wanted to keep it simple. To be honest, I was hesitant to post pics of the build of the tank as I really didn't think I could pull this off.

You are right. Toss this one aside to my address and do a proper one with curved sides.

 

[horsefarmer]

Very unique and cool! It's like you created a new type of vehicle.

 

[Brian macumber]

Killer work on the tank and trike.

 

[Psychographic]

I tack welded all the edges of the tank, then ground them down. After looking at the bottom of it, I realized I don't have the room for the mounting straps I originally planned. The plan now is to drill two holes through the frame and mount rivnuts to the tunnel of the tank. I might weld tubes through the frame holes so not to weaken it. I'm not sure if that is necessary.

I also stopped at the machine shop and had the remaining bit of weld turned down from welding the drive bushing to the axle. Also, a notch cut in the freewheel hub so the flange bearing fits flush for the brake rotor, and had the stub on the drive side turned down to 1/2". When I got home I was able to use my new tap and die set to thread the stub to fit a 1/2"-20 nut.

With it all assembled I am able to mark the non drive side so that can be cut and turned down to 1/2" and then that will be threaded for a nut also.

 

[OddJob]

It will be interesting to see how this turns out. I'm still trying to visualize it in my mind, but my traditional bicycle brake / drive train mounting images keep blocking it out.

 

[Psychographic]

It's really not hard to understand. Instead of a mounting the caliper(s) to the seat or chain stays, mine mount to the axle housing. So in both instances, the calipers are rigidly mounted.

On a normal bike the rotor mounts to the wheel hubs, and spin with the hub/wheel. My rotors are also mounted to the hubs and spin with the hub/wheel.

 

[Psychographic]

The noodles are glued in place using JB Weld. I roughed up the end of the noodle with some 36 grit paper to give it some tooth. I've got silver braided brake lines coming, along with some cable guides and stops. I wish the lines could be symmetrical, but with the calipers facing different directions, it wasn't meant to be.

For @OddJob, I've tested the freewheel side brake, and other than the rotor being out of round, it works perfect! Will it have enough stopping power with me on it, considering I'll have two more brakes, I think it will. I guess we'll know soon.