Three Wheelers - Your opinions and expertise wanted!

[dave de roxby]

This newly announced 'retro' Morgan has set my mind going again. Personally, I'm not much attracted to the vintage style 3-wheeler, except as a quirky piece of history. But each to his own. If Morgan want to resurrect this design then I wish them luck.

But I would be much more interested in a truly modern interpretation of this format as a kit.

I have given this some thought over the years but always rejected it in the end, preferring to stick with four wheeled sportscars. But something is telling me to look at 3-wheelers again - 2 in front, one at the rear variety only, that is!!!!

I admit to having no direct experience of trikes - or even bikes to be honest. So can you give me the benefit of your advice and experience?

A few initial questions spring to mind:

What are are the pros and cons of fwd/rwd in this context? (3 x 3? Surely not!!??)
Does IVA apply to these?
What modern donor mechanics/engine-drive layouts are feasible?
Are they for performance or just for fun?

Gentlemen - over to you.

[dave de roxby]

slomax said:

trackerjack said:

Two wheels at the front good, two wheels at the back crap, that would sum up three wheelers

well spotted

Yep, think I came to that conclusion too DelBoy!

Thanks for all the contributions.

I'm still in a quandry regarding the behavioural differences between front and rear wheel drive in a three-wheel context. I can see that going forwards is going to be no problem so long as, if it were rwd, the rear wheel had sufficient 'grip' to handle the power.

I'm less certain of the situation in cornering. I'm sure this must have been researched and published before but I haven't seen anything myself yet. Gonna do some 'from first principles' thinking to try and get my head round this. For a rwd set-up, suppose the Grinall would give the best practical evidence. Wonder if a back-end out is easy to provoke and is it catchable? Equally, what's the situation with a fwd? Clearly, weight shift and roll are going to somewhat different to a four wheel car due to the central rear support point. All very interesting to conjure with!

[dave de roxby]

Ebo100 said:

I always liked the scorpion but preferred the T-Rex when I first saw the pictures:-
http://www.campagnamotors.com/

It's a bit pricey and maybe better suited to the Californian sunshine but I love it. This sums up everything I would like a three wheeler to be. A range of cars with maybe several different engine choices may appeal to a wider market.

Thanks for showing us that. The T-Rex looks really exiting.

[dave de roxby]

Steve_D said:

We've all seen this type of cornering before....so that will be cornering on three wheels. On a RWD 3 wheeler you would still have drive.





Steve

Yes, you're right Steve and I take your point seriously. Looking at your pics, I'm just wondering what the effect on absolute cornering ability would be of having that remaining grounded rear wheel in the middle?

[dave de roxby]

Thanks Sam 68. That's the sort of info I'm looking for.

I also remember reading that, with a three-wheeler, dodging bricks in the road requires twice the concentration!

I wish the choice of car donor parts for a fwd3 were more obvious. The rwd bike route seems to offer an easy way to a back end but maybe comes a little expensive? I don't really know - admit to having little or no bike experience. With a car-based design, from a strictly engineering layout point of view, no real problem. But when it comes to styling, less easy. Even back in the 70s/80s, attempts with the Mini (which initially seemed to offer a fairly low-slung donor package) resulted in engines sticking up far too high in front of the driver, ruining the lines. I think even the Mini-Marcos and later the Midas (to go back to 4 wheels for a moment) were cursed with this.

Anyway, I'd like to consider more current mechanicals if possible, if there are any?

[dave de roxby]

slomax said:

first generation Subaru impreza FWD version? I know that murtaya had some interesting issues with hiding the engine under the bonnet, hence the bulging nose, but I would have thought it would be a relatively flat engine package.

Could you not do something like a 7/fury idea. As in standard zetec engine with a type 9 gearbox going back to a chaft driven bike swing arm at the rear? Granted, the car engine would make it heavier, but I don't think it has been done before, probably for a good reason though!

I think weight distribution is going to be crucial, especially with a potential overall weight possibly less than a seven. The weight of driver and passenger become even more significant and weight over the driven wheel(s) is key to traction (as ever).

With a (relatively) heavy engine sitting ahead of the front axle in a very light car, the possibility of a spectacular forward somersault seems on the cards under extreme braking! Longer wheelbases with the passengers sat well back might be necessary but would compromise handling and manoeuvrability. Hmmm.

[dave de roxby]

dmulally said:

A tip I picked up from somewhere in my travels is that for optimal handling in a reverse trike, make the rear wheel the same width as the front two wheels combined.

I have a 15 inch wide wheel in the shed I want to use for a 3 wheeler build one day.

Yes, the business of wheel and tyre selection seems important, also depending on which wheels are driven and steering/braking requirements.

I guess for a rwd 'reverse' trike, relatively skinny front wheels and tyres might be appropriate with something larger at the back for traction. For fwd, maybe more similar sized tyres would work although, from a styling point of view, a larger rear wheel diameter could 'look' right?

But then, there is roll to consider. As Sam 68 has said, roll will be essentially dependent on front suspension design with the rear wheel contact patch acting as a pivot point. If a large potential degree of roll is involved (as, for instance, with a 2CV based front suspension with leading arms) then maybe a motor-cycle type rear tyre would be best?

Then again, with a wishbone type front, roll could be controlled (or even designed out, although that in itself could lead to problems!) and maybe a wider car type rear tyre used.

Some years ago, Onyx produced a quirky Metro based 'sort-of' trike with two rear wheels set very close together (by swapping positions of the left/right rear trailing arms!) to exploit some UK regulation stating that so long as the two rear wheels were close together (maybe 12 inches between centre lines??) they would count as one and the vehicle would fall under trike construction rules. I think the idea quickly fell by the wayside but it raised interesting possibilities! Not sure if this regulation even applies now.

Edited by dave de roxby on Monday 28th February 07:16

Edited by dave de roxby on Monday 28th February 11:44

[dave de roxby]

slomax said:

originally the lomax was of this design too! The two rear swing arms just pointed inwardsand the rear wheels closely set together. This was abandoned though, I think due to classification and tax/licensing.

One arm was shortened and the other lengthened between the hub and the elbow by lomax so the rear wheel was central.

Thanks for that - I didn't know! I wonder if that reg still applies. Maybe Onyx would know? Not sure if it would add or detract from handling? Maybe best forgotten.

Anyway, after much thought, I've decided to concentrate on a fwd design with a fabricated, rather than bike-sourced rear swing-arm. Still puzzling over a donor, particularly engine and box. I'm not after mega performance but something using readily available parts - a cheap but jazzy runabout. Will keep the thinking cap on!

[dave de roxby]

mikeveal said:

I have a Malone Skunk. They're now calling it an F1000.
The sub 300Kg Skunk was based on a 900cc Fazer. It's spaceframe was made with tubing a couple of guages lighter than the production skunks. It was also clad in Dural rather than aluminium.
My car is currently tipping the scales at around 350Kg, with a 2003 Yamaha R1.

If you are considering driving, building or buying a trike, of any sort (1F2R can corner as well as 2F1R, it's just harder to get right) you really need to read and understand this document.
http://www.rqriley.com/3-wheel.htm

Finally, I don't know if anyone has responded to your question about IVA. Trikes under 450Kg are tested under the MSVA scheme - not as stringent as SVA or IVA.

Thanks for this Mike - all good stuff. Your Skunk sounds awsome!

And thanks Italo for your links - the Venom inspires me most. Must admit, I'm looking at bike donors again.

Edited by dave de roxby on Friday 11th March 19:10

[dave de roxby]

On another thread re bike engines:

slomax said:
There is a 2cv floating around somewhere with a BMW GS1200 engine and it goes like stink.

Dave de Roxby said:
Hi Slomax, In connection with our deliberations on trike designs, do you know what gearbox this 2CV uses? Is it the original Citroen or something more special. I've been having thoughts about using a BMW flat twin in a fwd format but am stuck for a suitable transaxle unless I design something myself. Have considered the old Alfasud/145 but they are not that prolific and Audi seems a tad heavy.

Is there another modern, lightweight transaxle you can think of that could be used with a bike engine, approx 100/120 bhp?

Edited by dave de roxby on Saturday 2nd April 10:59

[dave de roxby]

slomax said:

Dave,
I have answered on the other thread too, but what about a vw box as used in the blackjack zero?

Thanks Old Boy,

To understand what I'm getting at, you have to get into my mind set.

As you already know, I am a frustrated, would-be car designer who is hoping to make one last lunge into the kit car world as my swan-song! Wish I could have done it earlier but life took me in a huge round circuit. Mining in Africa, property developement, recruitment, classic cars, motor trade, bleedin' women, it goes on and on. But that's all water under the bridge now. However, I have picked up loads of 'transferable skills' along the way, consultant engineer, managing director of various companies etc etc so not exactly a complete fool! And I do believe I have talents in aesthetic design - but I have to put my money where my mouth is!

What I am trying to create are a couple of cleverly designed cars which could be a commercial success in the difficult world of the specialist car industry (Steffan - I've listened but wont be put off!). My main focus is on a mid engined roadster, already well defined. But I also find myself fascinated by three-wheelers of the 'reverse trike' genre (ie 2 wheels in front and probably fwd). Perhaps this might be the best start? Smaller, less physically to produce?

Whatever, I am determined that my designs/prototypes must be capable of being 'productionised' and therefore must utilise relatively modern and available components. When I started this design adventure in the late 60's, Ford 105E engines and reversed VW Beetle gearboxes seemed the way. But hell, we're in 2011 and I want to use something more up to date. The four wheeled roadster is not a problem. I've forgotten my Alfasud ideas (although I've got a shed full of parts!) and I see Audi or perhaps Subaru as the way forward.

But for the trike, I'm still scratching my head. I've actually got great respect for the 2CV but need something more up to date. So 2CV and Beetle gearboxes are out. There will be an answer!

[dave de roxby]

fuoriserie said:

Dave,

Nardi created sportscar specials just after the end of WWII using BMW 750cc boxer engines.....

Jeez Italo! And I was born 3 weeks before Hitler blew his head off! Thanks for that! I shall digest.

So basic thinking has stood still for 65 years!! Seriously, with our continuing fuel crisis, I think there is another opportunity for an economical commuter/shopper/fun vehicle which might well be a trike.

I saw a report the other day that all petrol/diesel vehicles could be banned by 2050 - we'd better get a move on!

[dave de roxby]

fuoriserie said:

I totally agree with you..., and if you like an alternative engine to the BMW Boxer, I've been looking at this, thatm I'm sure you're aware of:

http://www.ural-motorcycles.com/

The engines have a period look and sound like one....

Thanks once again Italo. We do seem to have similar ideas.

Let's face it, within twenty-five years, electric or hydrogen powered vehicles are almost cerainly going to be the norm. Undoubtedley, the big manufacturers will have developed new small efficient power units by then, together with new compact transmission systems. Whether the kit-car industry or specialist designer will even have a role to play is debatable. More advanced technology, costs and legislation may put paid to us. I hope not, although I'll probably be pushing up daisies by then in any case!

So I sense there is one last golden window of opportunity for specialist vehicle designers/manufacturers.

If we're talking performance machines, then there are plenty of options in terms of power-plants and transmissions already available. After many years dithering, I have decided on an Audi n/s mid engined set up for my little 4 wheel roadster. It's the obvious choice if I'm going to produce these in small numbers. It's not going to break any new ground engineering-wise but I hope it has something to say stylistically.

But I'm still fascinated in designing something really petite, probably a three-wheel design, not necessarily designed for out and out performance but as a down-to-basics, useable-on-a-daily-basis fun/shopping/commuter vehicle. To be a commercial success, I think it needs to be fresh and modern rather than retro. And it will need proper weather equipment and heating but no fancy extras. I'm sure I know what the thing would basically look like. But the choice of engine/transmission is less certain.

It's even been on my mind to design my own engine/transaxle. I know this might sound a bit too ambitious and I'm not thinking about a total blank sheet of paper here. The BMW flat twin appeals in some ways but I'd need to connect it with an existing transaxle which would probably be too heavy really for the application (unless I go for rear wheel drive via the BMW bike system). Air cooling has its pros and cons too. I've even toyed with designing my own flat twin block and crank (can't be that hard or expensive for a small engine) and utilise a pair of water-cooled bike barrels with 4-valve, ohc technology linked to a specially designed lightweight transaxle casing, but using existing internals. If such a thing were available, I could see it being saleable to all manner of producers. (I don't know of anything similar which is readily available in our part of the world??)

Don't want to speak too soon but my house sale looks to be going through at long last! So hope to have the finance to start turning some of these dreams into reality within a couple of months. About f*****g time!

[dave de roxby]

dmulally said:

Another question...

What about using a small transaxle out the front driving the front wheels? The Beetle or Imp transaxle for example the correct way round. The gear change would be good fun but not impossible and it would need to be a very short engine or you would be sitting too far back. It might cut down on faffing about with a rear wheel drive setup and perhaps help with traction with two driven wheels.

These are all valid ideas. The Hudson Free Spirit used to use the early 4 cyl Renault 5 engine and box in exactly this configuration. For one offs, Beetle or Imp transaxles could be used. But if I'm going to produce something which is going to sell in sufficient numbers to make it commercially viable, I think I need something more modern and readily available. Trouble is, I can't seem to find anything (so far) off the shelf which suits (there may well be something, needs more research) which is why I'm considering trying to find a clever but not too expensive way to cobble up something myself. There already could be something Japanezy which would work - but unlikely to be readily available in Europe, I fear.

[dave de roxby]

slomax said:

I'm currently in the process of designing a very simple, tiny vehicle that is intended to be a 2016 Invacar with a view for potential mass sales to non disabled customers too. Packaging a 3 wheel vehicle is very tricky for the dimensions i have set myself and have decided to go with a 4 wheel vehicle. Currently working on packaging different power trains into the space.

Basic dimensions are 2.3m long, 1.5m wide and 1.4m tall with a view for 1 person+ wheelchair. If a wheelchair is not required by the user then there is enough room (just) for a second seat, although i doubt a 97.5th percentile dutch male would fit comfortably in it.

This really sounds an interesting challenge! I think one answer could be in designing a special wheelchair in the first place which could maybe lower and/or recline before entry to the chariot! Trouble is, disabled people obviously don't all come in the same shapes and sizes. And maybe a non-standard wheelchair would not be allowed in your design brief anyway?

Best of luck!

[dave de roxby]

slomax said:

it had a sliding door on each side with a single seat that could slide from side to side. The occupant transfered themselves from thier chair to the seat. They then folded the wheelchair and slid the car seat to the opposite side of the vehicle where they could then put the folded wheelchair.

these are the original information sheets about the Invacar-

http://www.virtualgaz.com/update%20apr01/invacar1....

http://www.virtualgaz.com/update%20apr01/invacar2....

I wouldn't have said a modern copy is the right term, but its certainly heavily influenced. I have not decided on many things yet, so its still very much a work in progress...

Having looked at the links and thought about it carefully, my gut feeling is still that, in an ideal world, there are actually two inter-linked design challenges to be addressed here - the chariot and the chair. And if time and money were no object, I'd be starting with the chair! Re-designing one without the other would be such a missed opportunity.

But I know the mission you are tasked with may not accommodate this.

[dave de roxby]

stig mills said:

I had a very serious look at golf car engines, they use 2 cyl eco engines in a very compact layout with CVT as shown. Take off the gov and they shift too. Ideal for a lightweight single person commute. They have drum brakes and a mech reverse gear on the trans. There are always lots for sale that are 3 years old ex hire for around £6-£800.
The track width could be considered too narrow but it is fairly easy to alter and complete the layout with a single front wheel/headstock from a scooter.

Very interesting. I hadn't thought of these before. Thanks Stiggy! Wonder if it would be possible to adapt the final drive to independant? Needs a closer look.

[dave de roxby]

fuoriserie said:

stig mills said:

I had a very serious look at golf car engines, they use 2 cyl eco engines in a very compact layout with CVT as shown. Take off the gov and they shift too. Ideal for a lightweight single person commute. They have drum brakes and a mech reverse gear on the trans. There are always lots for sale that are 3 years old ex hire for around £6-£800.
The track width could be considered too narrow but it is fairly easy to alter and complete the layout with a single front wheel/headstock from a scooter.

It is a good idea and perfect for a four wheeler too:

http://www.brenhamyamaha.com/g-max_4-pass_gas_2007...

But no suspension (apparently?) unless the whole engine and subframe go up and down, pivoted at the front??
I dunno! Maybe it's totally solid, relying on bush compliance?? Fine for a 5mph golf-cart I suppose.

I know a new, clean sheet design for small engine/transaxle would be prohibitively expensive but I'm thinking a re-design/adaptation of some existing engineering might be possible??

[dave de roxby]

stig mills said:

golf cars tend to have coil overs in each corner. Some have leaf springs

Thanks, I must have a proper look. Can't quite work out from the photo how the axle is attached but the package certainly looks to have applications for other small vehicles.

However, I've come to the conclusion that what I am actually seeking for my three wheeler design is a more modern interpretation of the 2CV! BMW flat twin + Audi transaxle perhaps but I'm open to suggestions. I don't rule out a bit of re-engineering to get what I want.

Edited by dave de roxby on Saturday 23 April 17:15

[dave de roxby]

stig mills said:

You could always stick one of these in

Hey mate! What's that from? Looks interesting. Ah, I see it now!! The answer to my earlier question re the golf cart final drive!

Let me say thanks again. I know there must be some existing technology out there to suit my design aspirations. But it is difficult for one guy to be aware of it all. Thank goodness for the internet and helpful guys like you! Cheers Mate.

Edited by dave de roxby on Tuesday 26th April 09:34

Wonder what the performance parameters are? Is it petrol or diesel, by the way? I can see applications in a small commuter buggy ..??!!

Edited by dave de roxby on Tuesday 26th April 09:39