Slingshot

[Karts of Kaos]

sounds like a cool build

 

[madprofessor]

Well, curiosity has now gotten me a look at a Polaris Slingshot. Cool, a 4-cylinder 5-speed reverse trike. That would be exhilarating and terrifying at the same time, at least with someone like me on the throttle. What are you going to power your mini version with?

 

[Functional Artist]

Well, curiosity has now gotten me a look at a Polaris Slingshot. Cool, a 4-cylinder 5-speed reverse trike. That would be exhilarating and terrifying at the same time, at least with someone like me on the throttle. What are you going to power your mini version with?

It's not just a reverse trike
...ya sit back, in it, like a go kart

To start off with, Ima gonna motivate it with a 48V 1,000W MY-1020 brushed motor
...& power it with a 48V 35AH Lithium battery pack

Then, if it's not fast enough, maybe I'll try a 60V 2,000W motor
...or if I'm brave enough, maybe even try a 72V 3,000W motor

All of 'em will mount to the same motor mount
...& can/will use the same auxiliary components (like On/Off switch, throttle etc.)

Ya just need the appropriate controller
...& proper voltage battery packs

 

[Functional Artist]

After the last dis-assembly, I laid out all of the "tail" components
...& made some notes (of the order of parts & which spacers went where)
...& took some pics too

I also, cleaned up & painted the (4) spacers, when I painted the tail

*I figured I'd give that stuff a couple of days, for the paint to "harden up good", before re-assembly

Next, I did some thinkin' about the "cock pit"

So, I measured, marked & cut some pipe
...then, measured, marked & bent some pipe
...& then, tried 'em a few different ways

 

[Functional Artist]

The rails in the bottom section are ~12" apart
...& there's gonna be ~40" from the bottom of the seat back to the pedals

The bottom rails need to turn upwards in the front

So, from a side view do we want 'em, straight up? (kinda square-ish)
...angled toward the front for a more menacing look?
...or angled toward the back? (more aerodynamic)

Then, from a front view, do we want 'em straight up?
...angle outwards, again for a more menacing look?
...or angled inwards & then, angle outwards, to kinda duplicate "some" of the front body lines of a Slingshot?

Ima thinkin, ima gonna angle 'em toward the back
...& from the front view, have 'em angle inwards then, kick back out, to kinda match the hood lines of a Slingshot

So, the "nose" should be ~12" @ the bottom
...~4-6" @ the top of the "grill"
...then, widen back up to ~12" @ the dash board

 

[Millwright]

What is the wall thickness 9f your tubing?
Can you show a picture of your bending method.
I'm impressed with the tight radius you are getting. Makes it all look very professional.

 

[Functional Artist]

What is the wall thickness 9f your tubing?
Can you show a picture of your bending method.
I'm impressed with the tight radius you are getting. Makes it all look very professional.

I use regular old 1/2" schedule 40 water pipe
...it is 7/8" Od x 5/8" Id x 1/8" thick wall

I've been bending water pipe with a HF bender for years
...got it way back, when they were only ~$69.00

I can get matching bends, in multiple pieces, by counting the strokes/pumps.
...& get pretty close to 90* bends, consistently, with 50 pumps

 

[madprofessor]

Aerodynamics look sleek, but you're going more raw than a $9500 Polaris Slingshot. Go Dennis the Menace all the way. You could even paint Flying Tigers P40 Tomahawk teeth on the front.

 

[Functional Artist]

I bent up a couple of, kinda elongated, A-frames
...& made some mounting brackets

I'm thinkin' they should go about right there

 

[Functional Artist]

I put some thought into
...where the steering wheel should go
...the steering shaft angle
...how/where the tie rods are gonna connect
...& where the pedals need to be, before determining where to mount the A-frames

Then, I built a "jig" to help "square" the frame, before "lockin' 'er all together with some "tac" welds

* Also, notice how I "temporarily" mounted the spindle brackets with a simple sheet metal screw

This, makes it real easy to "set" the castor
...& hold it there, until ya get 'er welded on good

 

[Bansil]

That is really good diy caster setter contraption...A.K.A. screw




It's very hard to be whimsical, smartazzny sarcastic with a wink involved when google goes all autocorrect....

 

[madprofessor]

You said you're going to weld the caster angle in, but I wonder..............Wouldn't this be a good opportunity to make a caster swivel more permanent (than the screw) and weld in an adjuster bolt for later adjustments? You're already in the adjustable phase of what could become a permanent and possibly useful attachment. I have no science to base this on, but just have a feeling that the trike even in the reverse configuration would lend itself to a slightly different set of adjustments for caster, camber, toe, etc. than a common 4-wheel configuration.

 

[Functional Artist]

You said you're going to weld the caster angle in, but I wonder..............Wouldn't this be a good opportunity to make a caster swivel more permanent (than the screw) and weld in an adjuster bolt for later adjustments? You're already in the adjustable phase of what could become a permanent and possibly useful attachment. I have no science to base this on, but just have a feeling that the trike even in the reverse configuration would lend itself to a slightly different set of adjustments for caster, camber, toe, etc. than a common 4-wheel configuration.

Yup, an adjustable castor bolt could be installed
...but, from what I understand, setting the castor angle a few degrees (usually ~8* - 10*) toward the back, just aids the steering in "auto-centering"
...ta help ya go straight & it not drive all "squirrely" (technical term)

So, the more degrees ya set 'er back
...the faster & harder it wants to "auto-center" or "self-center"

*Think like a house door mounted in a crooked frame
Because it's on a bit of an angle (the castor set a few degrees back) it doesn't want to stay open
...& just keeps wanting to swing shut (auto-center)

 

[Functional Artist]

After extensive contemplation, I went ahead & tac welded the A-frames in place

 

[Functional Artist]

Now that we have all of this steering stuff, kind of established

Lets move on to another section

Ima thinkin' something along the lines of a side bar, seatback support, "tail topper"

So, I started off with an 84" piece of pipe
...marked it (8) times, on each end, at 3" intervals
...& right in the middle at 42"

Then, I put 'er in the bender
...& did (5) pumps at each of the 3" marks
...then, lined 'er up with the center mark
...& drew 'er together, until the ends were ~12" apart (it took (70) pumps)

 

[Functional Artist]

Before we could establish where that piece goes
...we gotta get the "tail" attached

So, I made up a couple of "hinge" mounts
...& used a piece of pipe (cut to the appropriate size)
...& some threaded rod

This helps align 'em
...& hold 'em the proper distance apart, for welding (without actually using that purrty "tail")

 

[Functional Artist]

I'm tryin' to use the "side bar, seatback support, tail topper" to kinda, "mimic the look" of a Slingshot
...by connecting it, to the lower frame rails, right around, the front edge of the seat
...& having the "rear point" end, just above the rear wheel

* Like, in my "reference pic"

I added a "cross bar"
...to use as an upper seatback support/mount
...which also, should be able to be used for the upper, rear shock mount, too

 

[madprofessor]

Blew by at 45 mph, but caught a look at a real Slingshot this morning outside the old Yamaha shop, gloss black with some neon green accents, very wicked looking. They're a little longer and bigger than I had thought, pretty hefty piece of machinery, what % scale would you guess you're building?

 

[Functional Artist]

Blew by at 45 mph, but caught a look at a real Slingshot this morning outside the old Yamaha shop, gloss black with some neon green accents, very wicked looking. They're a little longer and bigger than I had thought, pretty hefty piece of machinery, what % scale would you guess you're building?

Um...go cart size LOL

IDK really, my goals were to use go kart parts (cause, I already had most of 'em)
...make it big enough, for a 6' guy to sit in & drive, comfortably
...& kinda look like/resemble a Slingshot

I did some checkin' for ya,
I found that a full size 2022 Polaris Slingshot has a wheelbase of 105"
...& a track width of 69"

My mini-Slingshot will have a wheelbase of ~56"
...& a track width of ~36" (it's 30" from king pin to king pin)

So, it looks to be ~2:1
...but, that doesn't seem right

 

[Functional Artist]

I aligned a coil-over shock in between the swing arm
...& the "side bar, seatback support, tail topper"
...makin' sure it was centered, on both pieces
...& then, welded the brackets in place

Next, after makin sure the motor "cleared" everything (mainly the seat back) at max travel, I cut, bent & welded in (2) "rear body bars"

These 'rear body bars" should help triangulate & strengthen the "side bar, seatback support, tail topper"
...& also, kinda represent the rear body curve/lines, as in the pic)