three wheel car

I don't think this will be legal as a motorcycle in WA. http://apps.leg.wa.gov/rcw/default.aspx?cite=46.04.330

I spent some time researching designing and building my own reverse trike (for my own use) but found that I would have to register it as a car, so I decided just to build a car and have started on one of kb58's Midlanas.

Alan Cesar wrote: It takes two to tango, and your tone in the latter part of this thread is not appreciated. You're all complicit, and I've had enough of your smartass nonsense. Don't make me come back in here.

Thanks...and sorry. I'll be nice.

yep...apologies for my outburst...Icecube was wrong, today is not a good day

Nice research, 3wheeler. You went to Amazon and cherry-picked the worst reviews you could find of a book I wrote 7 years ago. That must have taken a long time to do and certainly gave you a deep understanding. Yes, I started with a frame that someone else originally welded together. Then I reengineered the stuff that didn't work, increased the chassis rigidity, fixed the suspension geometry - then spent a few years fine-tuning it and making more changes. The end result was a homebuilt car that GRM - this magazine - liked better than an $80k Ariel Atom. That was years ago, I've been building fast cars ever since. And I'm not the most accomplished person here, not by far.

Anyhow, there's my background. Or part of it, anyhow. Now, a polite suggestion.

If you want to know how to post to a forum like this, go read the Exocet "reveal" thread. It's an intelligent discussion on both sides. Warren engaged the audience and was able to give well-reasoned answers to his questions - because he'd thought of those answers and he was able to communicate at the same level as the folks asking the questions. That's important, you need to judge your audience. It also has some great information on frame design for strength, crash behavior and ease of manufacturing as a bonus.

Anyhow, I won't get in the way of this particular thread anymore. If you want to get in touch with me for anything, my email is keith@flyinmiata.com. Good luck with your business.

Keith Tanner wrote: Nice research, 3wheeler. You went to Amazon and cherry-picked the worst reviews you could find of a book I wrote 7 years ago. That must have taken a long time to do and certainly gave you a deep understanding. Yes, I started with a frame that someone else originally welded together. Then I reengineered the stuff that didn't work, increased the chassis rigidity, fixed the suspension geometry - then spent a few years fine-tuning it and making more changes. The end result was a homebuilt car that GRM - this magazine - liked better than an $80k Ariel Atom. That was years ago, I've been building fast cars ever since. And I'm not the most accomplished person here, not by far. Anyhow, there's my background. Or part of it, anyhow. Now, a polite suggestion. If you want to know how to post to a forum like this, go read the Exocet "reveal" thread. It's an intelligent discussion on both sides. Warren engaged the audience and was able to give well-reasoned answers to his questions - because he'd thought of those answers and he was able to communicate at the same level as the folks asking the questions. That's important, you need to judge your audience. It also has some great information on frame design for strength, crash behavior and ease of manufacturing as a bonus. Anyhow, I won't get in the way of this particular thread anymore. If you want to get in touch with me for anything, my email is keith@flyinmiata.com. Good luck with your business.

There Only Be One Leader The Rest Is Followers. I'm not here to follow anyone or win a popularity contest. At the same time I'm not here to put down some of the great people who commented on my post. Yes some of you are great even after all the crap you gave me here:-) And Keith I have no doubts in my mind that you are great expert but that was not the point I was trying to make when I posted some of the comments you had on your book. No one is perfect and you don't have to try hard or bash someone to get your point across. Some of the comments was completely inappropriate and doesn't belong here. I will be definitely in touch with you and large number of other people who actually like my work when I get to actual production frame which would be completely different.

Back on all three

Mr. go3wheeler,

I think you're taking criticism of your design very personally when you should be more objective. The thread started taking a negative turn when you took objective concerns about the frame as personal attacks. As soon as you started fighting back against the legitimate concerns, well, that's when the focus moved towards the designer rather than the design.

When I brought the Exocet redesign to this board, I expected and welcomed a lot of critiques, concerns, ideas, and full-on-dismissals. If you read the threads, you'll see I did my best to improve the car based on this feedback without making enemies. The experience has been overwhelmingly positive, and I think it was due to a positive attitude and the ability to be objective about it, rather than the quality of the product.

GRM has a wealth of engineers, fabricators, and racers with a formidable collection of skills and experience. If you revisit many build threads on here, you'll find that every project thread is full of critiques and ideas. That's kind of the point of a forum. Simple "LOOK WHAT I DID" posts are boring.

The feedback on all these build threads can be harnessed to improve the design/execution. Even more important may be the relationships you can build on this site with like-minded individuals that want to get involved. Getting into ego-battles is not going to make anything better. I think you have an opportunity to wipe the slate clean here, you just need to be more receptive and objective about the design. Like you said, no one is perfect, and everything can be improved.

What is the designed front RC height, VSAL, Sprung Frequency and Roll stiffness? Also I'm not sure if your steering rack is installed in that picture but are you concerned about Bumpsteer?

In reply to nocones:

I think that's out of scope of this project. As long as there isn't a huge jacking moment, it'll be fine for its purpose as a runabout. Based on the track width and driver position, you'd only be able to get about 0.7g-0.8g of lateral force before lifting a tire.

go3wheeler, if you can get me wheelbase, track width, cg position (or corner weights), and an estimate of cg height, I can run my stability analysis script for you on that thing. Bonus points on any sort of suspension geometry measurements. All I need is a drawing of the pickup points and contact patch positions from the front view and the side. Part of my senior thesis at Georgia Tech was stability analysis of three wheeled vehicles for the World Solar Challenge. This could help you a lot, as I could tell you how to set it up to slide before tipping, even with adjustments as simple as static ride heights. I could also tell you how to set up your braking system with that info, too.

I was wondering what ride vs roll ratio they have selected. 3 wheeled vehicles can get away with things that 4 wheeled vehicles can't in this area so I was just interested. The picture does not paint a flattering picture of suspension geometry (bumpsteer and roll center height) so I wanted to give him the chance to provide what should be very accessible number to a vehicle designer regardless of how mild the performance envelope will be before I reacted to what I am seeing. Understanding that the ride height is probably no where near final.

In reply to nocones:

Do bear in mind that, for the most part, the car is a high output 3 wheeled golf cart. One can make do with a lot of odd things with something like that.

and not that there is anything wrong with that, as there is an entire class of transportation that are defined by those kind of rules, speed limits, non highway accessable, etc. As it stands, this car would not be legal on most freeways, as most of them have lower displacement limits on motorcycles.

If I were going to ask a question- I would look at the set up and note that it's pretty close to an intended ride height right now. Yes, I know the target is 450lb, but it does not look like it's anywhere near that. Then add a 150lb passenger, and all of a sudden, the front springs are bound.

The front suspension is an area where I would copy or use the front end of a 4x4 cycle. that would give you a good geometry (suspension, steering, etc) and brakes. No point in trying to reinvent a good idea.

Are those EMPI Volkswagen "coil overs"? If so those are intended to be used in addition to the stock VW torsion bar suspension, and even then have a very bad reputation. I looked into using them on my project, but dismissed them after a bit of research.

bgkast wrote: Are those EMPI Volkswagen "coil overs"? If so those are intended to be used in addition to the stock VW torsion bar suspension, and even then have a very bad reputation. I looked into using them on my project, but dismissed them after a bit of research.

If they are they are (and they appear to be) they are beyond crap. The damping function of the shock will hold out for maybe 1000 miles in most applications, maybe slightly longer in something of this weight.

Rear view

So, go3wheeler, are you planning on having larger engine options and other upgrades down the line? Seeing that rear shot, this thing would look pretty cool with a fat rear tire and a bigger engine.

Warren v wrote: GRM has a wealth of engineers, fabricators, and racers with a formidable collection of skills and experience. If you revisit many build threads on here, you'll find that every project thread is full of critiques and ideas. That's kind of the point of a forum. [....] The feedback on all these build threads can be harnessed to improve the design/execution. Even more important may be the relationships you can build on this site with like-minded individuals that want to get involved.

I don't have much to add except that every word of this is true. The amount of support and advice you can get on this forum is amazing. Look at the bracket that nocones just mocked up for me:
http://grassrootsmotorsports.com/forum/off-topic-discussion/learn-me-mounting-brake-pedalmc/72366/page1/

Double_Wishbone wrote: So, go3wheeler, are you planning on having larger engine options and other upgrades down the line? Seeing that rear shot, this thing would look pretty cool with a fat rear tire and a bigger engine.

Yes, it looks even better in person. Should be fun sculpting some sleek body over it. I'm planning number of power options including battery powered plug in with electric motor. The whole concept is simple run around inexpensive three wheeler with little attitude. Speed is not what I'm after. So I'm not sure if I want to go with much larger engine and faster than 55 MPH.

You need to check the load those rear bearings can take. The housings are cast, and with the all the weight from the motor, rider, body, and suspension you may have a problem. The wheel is intrinsically unsafe by having all that weight, and force being supported by the bearing. You may want to put the bearing on the bottom side of the swing arm. FWIW this is the internet!

I've got a question..

If you're after simplicity and fuel efficiency, why did you use a knockoff of a Honda GX engine?

They're not exactly an efficient, modern piece of engineering.

Why not use a donor motorcycle for power, cut the back half off and have a well designed suspension unit and powertrain all in one go.

Even 30+ year old motorcycles are more efficient than that engine.

Using one of my old Honda CX500's as an example, you get around 50hp and 50mpg from a 500cc engine.

Your engine is 420cc, makes 16hp and undoubtedly far less torque, probably with the same or a bit less fuel burnt.

You can scare up running CX's for under $500 and occasionally for free.

With the CX/GL layout, you could buck the frame off just in front of the radiator/engine hanger and tie in a frame in front of the four rear engine mounts to have a very strong structure.

This would also give you a donor VIN and allow you to register it as a homebuilt motorcycle.

Shawn

Was this your prototype?

http://www.youtube.com/watch?v=KSGIl90Hrno

Trans_Maro wrote: I've got a question.. If you're after simplicity and fuel efficiency, why did you use a knockoff of a Honda GX engine? They're not exactly an efficient, modern piece of engineering. Why not use a donor motorcycle for power, cut the back half off and have a well designed suspension unit and powertrain all in one go. Even 30+ year old motorcycles are more efficient than that engine. Using one of my old Honda CX500's as an example, you get around 50hp and 50mpg from a 500cc engine. Your engine is 420cc, makes 16hp and undoubtedly far less torque, probably with the same or a bit less fuel burnt. You can scare up running CX's for under $500 and occasionally for free. With the CX/GL layout, you could buck the frame off just in front of the radiator/engine hanger and tie in a frame in front of the four rear engine mounts to have a very strong structure. This would also give you a donor VIN and allow you to register it as a homebuilt motorcycle. Shawn

Awesome idea! This seems to answer a lot of questions that have been raised.

clownkiller wrote: You need to check the load those rear bearings can take. The housings are cast, and with the all the weight from the motor, rider, body, and suspension you may have a problem. The wheel is intrinsically unsafe by having all that weight, and force being supported by the bearing. You may want to put the bearing on the bottom side of the swing arm. FWIW this is the internet!

These bearings are huge and rated for 17000 pounds but I hate how they look and they have limited adjustability. I would love to mount them under swing arm but it would put the whole swing arm higher by 6 inches. The engine is weight about 63 pounds and I want to keep it as low as possible to the ground. It should work fine for now as it sits but I would have to comeback and redesign how the bearings are mounted. In the future it will be side mounted bracket with flange bearing. This way it will have more adjustment with chain tensioner at the end and have clean look to it.

I work doing conveyors, industrial machines ect, we never load them like that. Glad to hear there is a redesign for that. Make sure the wheels are DOT approved too, you got the tires!

Trans_Maro wrote: I've got a question.. If you're after simplicity and fuel efficiency, why did you use a knockoff of a Honda GX engine? They're not exactly an efficient, modern piece of engineering. Why not use a donor motorcycle for power, cut the back half off and have a well designed suspension unit and powertrain all in one go. Even 30+ year old motorcycles are more efficient than that engine. Using one of my old Honda CX500's as an example, you get around 50hp and 50mpg from a 500cc engine. Your engine is 420cc, makes 16hp and undoubtedly far less torque, probably with the same or a bit less fuel burnt. You can scare up running CX's for under $500 and occasionally for free. With the CX/GL layout, you could buck the frame off just in front of the radiator/engine hanger and tie in a frame in front of the four rear engine mounts to have a very strong structure. This would also give you a donor VIN and allow you to register it as a homebuilt motorcycle. Shawn

I agree, 420cc knock off engine is not as efficient design as I would like and makes only 16 horsepower but it is good starting point and available everywhere brand new under $300. I want to make this a clean enjoyable built for average guy who doesn't have a lot of skill, tools or time to look for suitable engine. There is few more lighter water cooled motorcycle engines available with 20 horsepower and reverse gear for around $750 on Ebay that I'm thinking to try as well. Any motorcycle engine will do wonders to this three wheeler. I'm sure some one with a lot more knowledge can easily fit a larger one but it will be up to owner to decide.

go3wheeler wrote: I want to make this a clean enjoyable built for average guy who doesn't have a lot of skill, tools or time to look for suitable engine.

This is what using a bike donor would solve.

The engineering in the rear half of the car would be done for you.

Just square it up and weld it in.

You might need to play with the spring rates in the shocks, build your own exhaust, have some longer cables made and build a shift linkage. Really not any harder than building the chassis from a pile of tubes.

Shawn