[zeaken]

What would you guys think of if some one made a 4 wheel conversion to turn it into a poor mans ktm x bow?

The car is already incredibly wide and with a long wheel base for its oal and weight. Adding that fourth wheel would probably add the needed traction and control that would boost this things performance to play with cars by the likes of lotus and boxsters for a fraction of the price point.

Would any of you consider it as an option for your slingshot?

 

[Bigfoot21075]

You would be re-engineering the ENTIRE vehicle. Not to mention you turn it into a car, it will not longer be a motorcycle. At that point I would assume it needs to be registered as a reconstructed vehicle and suffer through that entire process. I say just enjoy it for what it is..... They will develop upgrades for this design. It probably is already a great handler and is more performance capable than 99% of the peoples driving ability to use such capabilities.

 

[zeaken]

I do not believe it would make the transition to car by adding a wheel legally speaking but perhaps some one more informed can answer that question as I do believe their was one 4 wheel motorcycle that was made in the us.

I personally just want more rear wheel traction, spinning the wheel through the first three gears tells me I need more rubber in the back.

 

[Bigfoot21075]

I do not believe it would make the transition to car by adding a wheel legally speaking but perhaps some one more informed can answer that question as I do believe their was one 4 wheel motorcycle that was made in the us.

I personally just want more rear wheel traction, spinning the wheel through the first three gears tells me I need more rubber in the back.

Well, to be exact about it at least in Maryland (this will vary state to state of course with specifics refining basic Federal Guidelines) according to Transportation Code of Maryland Article 15 Section 136, subsection a;
(a) “Motorcycle” means a motor vehicle that:
(1) Has motive power;
(2) Has a seat or saddle for the use of the rider;
(3) Is designed to travel:
(i) On not more than three wheels in contact with the ground; and
(ii) At speeds exceeding 35 miles per hour; and
(4) Is of a type required to comply with all motor vehicle safety standards applicable to motorcycles under federal law.
(b) A detachable sidecar is an accessory to and not a part of a motorcycle.

 

[jdskycaster]

I have to agree. There are already options out there if you want to go four wheels and an open top. Granted the price of entry may seem initally higher but by the time you make all of the necessary changes to this vehicle you would most likely be better served with an Atom, Vette, Mustang, modified miata, etc.....

 

[WTFover]

I can't speak to the legality aspects of it, but adding a real rear end setup to this system appears do-able, although somewhat advanced fabrication. Remove the right angle drive/swingarm/belt setup. Create a subframe that attaches to the chassis that is triangulated and stiff. Install a standard style automotive driveshaft running to an IRS style rear center section, such as the aluminum 8.8 out of the T-bird or explorer (light, strong, easily obtainable and large aftermarket support for gears and diff). Create rear A-arm or trailing arm suspension, or possibly utilize existing suspension components, to complete the package. Lots of work, but totally doable with the proper tools and know how.

 

[NDV]

I have to agree. There are already options out there if you want to go four wheels and an open top. Granted the price of entry may seem initally higher but by the time you make all of the necessary changes to this vehicle you would most likely be better served with an Atom, Vette, Mustang, modified miata, etc.....

Or an Exocet (which is an MX5 at it's heart).

 

[NDV]

I can't speak to the legality aspects of it, but adding a real rear end setup to this system appears do-able, although somewhat advanced fabrication. Remove the right angle drive/swingarm/belt setup. Create a subframe that attaches to the chassis that is triangulated and stiff. Install a standard style automotive driveshaft running to an IRS style rear center section, such as the aluminum 8.8 out of the T-bird or explorer (light, strong, easily obtainable and large aftermarket support for gears and diff). Create rear A-arm or trailing arm suspension, or possibly utilize existing suspension components, to complete the package. Lots of work, but totally doable with the proper tools and know how.

And 8.8 centers are HUGE!

Non-IRS version:

 

[WTFover]

I'm sure there will be other options out there, possibly the miata diff, but the 8.8 is the one I am most familiar with, and isn't really that big. It's nothing compared to a Dana 60, Ford 9", etc, which would be way overkill for something like this. That rear end family is also extremely popular in general so pretty much any gear ratio, various types of locking/torque biasing differentials are available, as well as stub shafts for 930CV's. They are also stacked up like cordwood at every one of the U-pull-It yards around here. I am all ears for any other alternatives if you know of some.

 

[Noah Katz]

Not worth all of the effort it would take.

There's no chassis structure there to support rear suspension; it would be less effort to start from scratch.

 

[Mike P]

Doesn't sound like a great idea so you go first

 

[Otter]

Hardest part would be getting it re licensed.
( in the middle of getting a 'rebuilt from salvage' title nightmare now :-(( and that is easy compared to doing a 4 wheel SS.

 

[3wheeledrollercoaster]

Yeah I'm thinking making it a 4 wheel would be to much of a headache.
There are some other options out there that are tube frame and use
The Miata for a donor car. I would go that route for 4 wheels.

 

[Jimbo Jones]

Physically, there are a bunch of Harley trike conversion kits that also say they can custom fit to your bike with full rear IRS if you want. if you provide them your rear cog, they can build it to your frame. There's one on ebay for $7k, and comes with brakes!

It doesn't address how rigid it will be, but I'm sure a good crafts worker can work in a rear stabilizer and an extra cross member. Heck to simplify things, you can even even get rid of the slingshot propshaft to belt-drive assembly and replace it with a rear diff.

Can anyone comment on registration issues? I would assume when you purchase it, and the dealer licenses it, the DMV registration will say Motorcycle (at least in CA), assuming all these modifications are made after you purchase the "motorcycle" or 3-wheel cycle. What happens if the highway patrol pulls you over, your regsitration says motorcycle, but you obviously have 4 wheels?

If you want to register it as a 4-wheeler, do you have to meet current crash safety standards like a regular car, like bumpers, airbags, windshield, SMOG, etc?

 

[Tango]

Perhaps if you can register it as a kit car you can get away from airbags, windshield wipers, etc. Kit car laws also vary state to state though.

I agree with others that there are kits out there already that fulfill that fantasy and can be relatively cheap (Exocet).

 

[SlingshotJoe]

Sorry, but why would you buy a three wheeled motorcycle and then convert it to 4 wheels? Sort of defeats the whole idea/purpose. As someone else mentioned, buy a sports car. Hell, you can get a used Boxster, Z4, or Miata for a lot less.

 

[Mike P]

He wants to answer a question no one asked.... : /

 

[Otter]

Sorry, but why would you buy a three wheeled motorcycle and then convert it to 4 wheels? Sort of defeats the whole idea/purpose. As someone else mentioned, buy a sports car. Hell, you can get a used Boxster, Z4, or Miata for a lot less.

I bought the SS because I couldn't buy an X-Bow. I only wish US laws allowed a 4 wheel version of the SS. My Z3 just isn't the same thing. I feel every pound of every machine I own. Lighter is better.

 

[NDV]

Not worth all of the effort it would take.

There's no chassis structure there to support rear suspension; it would be less effort to start from scratch.

Not that I have an interest in doing it but my thought was more like a racing ATV. They don't have much out the back in the way of framing either but shoving the axle through the swingarm seems "plausible" along with updating the suspension to take on the extra weight etc.

Again, no interest myself but I've kookier things done. Just search for VW trikes. Makes me wish for the days of the Spanish Inquisition and hot pokers to the eyes again. Thems things ugly.

 

[Okierider]

If anything what would be most plausible would be to offset the existing rear drive and mount a second rear wheel on the opposite side. It would have a gap between tires only wide enough for the belt drive. Would look like the SRT Viper bike rearend but with wide tires. Still the roll or
torsional strain would kill it.