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.

[slomax]

Where to begin-

obviously there are different layouts. Front engined rear wheel drive:

these tend to be older style ones with an exposed engine (usually 2 cylinder) engine up front. These include jzr, morgan, triking etc etc.

I also believe that the Malone f1000 is also front engined. This may be along the lines you were thinking.

Then there are mid engined rear drive where basically the bike has been bolted onto the backe of a front car section chassis from the yolk back. Here we are looking at grinnall, rayvolution, MEV tR1ke etc etc.

And then there are the front wheel drive cars. Most of the ones I have seen have had exposed 2 cylinder engines. The blackjack zero and avion, lomax, BRA etc etc. There have been a few fwd cars where the engine is covered, the Hudson Spirit and DRK immediately spring to mind. These were both Renault 5 based. I have also seen one or two mini based specials too.

As for what's best, it's mostly down to personal preference I would say. Mid engined rear drive seems the easiest as you get all your drive train in one neat package good to go from a single bike donor. Sure, you have to source hubs, steering componants and what not, but they are relatively easy to het hold of. One small problem though is the lack of reverse on bike based kits.

The other easy possibility is take the front drive assembly from a standard car and put it in a car with a modified rear motorcycle swing arm as a trailing braked wheel. The problem people have found with doing this though is the assembly is very wide, meaning the bodywork has to be tall and wide, making it look ungainly and ugly. This is the reason why most of these cars thend to have good looking air cooled engines with the engines exposed take a good look at the VW beetle powered blackjack.

As per getting them on the road they have to go through an MSVA, which is for light vehicles and trikes (iirc). It is not a stringent as an IVA but is still pretty cromprehensive. It's also a fair bit cheaper. But I haven't looked into it in a lot of detail as I have never needed to.

[fuoriserie]

Slomax has given a very good explanation, so will just add that I'm also looking into starting a new Design build in 2011....,

Maybe after Stoneleigh who knows...I've got the design ready but need the chassis and various components to start the project...

Just to get an idea here is a Morgan inspired 3wheeler with a Harley engine that should sound pretty similar to the new Morgan three wheeler.

http://www.youtube.com/watch?v=k7Cf8rHcyl0&fea...

Edited by fuoriserie on Friday 25th February 13:02

[trackerjack]

Grinnal Scorpion....................ACE.

[fuoriserie]

trackerjack said:

Grinnal Scorpion....................ACE.

I like it also...

[trackerjack]

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

[slomax]

trackerjack said:

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

well spotted

[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!

[Ebo100]

fuoriserie said:

I like it also...

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.

[Steve_D]

dave de roxby said:

.....I'm less certain of the situation in cornering........

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

[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?

[XanderH]

slomax said:

And then there are the front wheel drive cars. Most of the ones I have seen have had exposed 2 cylinder engines. The blackjack zero...

Not always, certainly not the original version!

[seansverige]

You could be a bit cheeky and see if you can get a test drive of MEV's tR1ke

http://www.youtube.com/watch?v=sfaNVup27Z0

Love the 'sleazy listening' soundtrack: all it needs is some bad acting and a handlebar moustache "hello, I've come to repair your kitcar..."

Or there's always the Rayvolution

Call me a wuss if you like, but the Harley trike Italo posted looked scary - he seemed to be sitting on it rather than in it; I'd feel safer on a motorbike.

In terms of outright grip, IIRC some research I dug up as part of a student project, a reverse trike can ultimately generate more lateral g than a four wheel design (but I think you end up with a very short, wide trike - which brings it's own problems... ). My research was pre-internet - it might have been an SAE paper; a little googling might turn up some research papers on the subject which might contain some useful data.

[Sam_68]

dave de roxby said:

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?

Three wheelers are an interesting case when it comes to cornering. Obviously, all the roll resistance is at the front, so you can't use relative front:rear roll stiffness to tune the handling as you can on a normal car.

Steve_D's photographs (all front wheel drive) rather neatly demonstrate that most FWD cars have roll axis and relative front:rear spring/ARB rates arranges so that they unload (and ultimately lift) an undriven rear wheel. If he'd posted photos of a bunch of RWD cars like Mk. II Escorts or Porsche 911s, you'd have seen the opposite - undriven front wheel being lifted.

With a three wheeler, you don't get a choice. In extremis, the car will always lift the inside wheel at the two-wheeled end, as it tries to overturn around an axis between the contact patch of the single wheel and the outside wheel at the two-wheeled end.

There is a school of thought that says FWD three wheelers (assuming 2 wheels at the front) are safer, because if you use an open diff, they will spin off the power through the unloaded wheel as it starts to lift in a corner - effectively acting as a crude form of DSC, preventing you driving through the corner any harder.

Then, of course, there's the issue that with a driven rear wheel on (for example) country lanes, your driven wheel is spending most of its time in the centre of the carriageway where 'normal' cars haven't cleared a path through the loose chippings, leaves and horse st, so that already over-worked rear tye spends even more time scrabbling for grip...

[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?

[slomax]

Sam_68 said:

There is a school of thought that says FWD three wheelers (assuming 2 wheels at the front) are safer, because if you use an open diff, they will spin off the power through the unloaded wheel as it starts to lift in a corner - effectively acting as a crude form of DSC, preventing you driving through the corner any harder.

it's a really satisfying feeling when you do this in the lomax! Childish I know, but still...

-I know not all balckjack Zeros have 2 cylinder engines. But the guzzi seems to be the preferred option as it is a lot lighter and IMO, looks better than the vw block too! And gives plenty enough power for the weight.

As regards to drive choice it really depends on what you are after. If you want a really really fast 3 wheeler then rear drive is probably the best, you are always going to be limited by front drive/steering/diff complications. but I imagine that they can be very excitable and just not feel as secure and planted as a front drive car as you will always have that thing at the back of your mind that thinks really carefully about the quantity of throttle you apply as you exit a corner, especially with a big excitable bike engine.

Of course, you will get to know the car, but the ferocious power, especially considering how light they are, may bite you occassionally. Maybe it's just me being pathetic though.

[slomax]

dave de roxby said:

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

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!

[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.

[slomax]

Dave- the VW powered blackjack seems to manage okay with the lump foward of the axle. I can't imaging that a vw lump is particularly light, but this is only a presumption, I may be wrong.

The malone f1000 claims a weight of under 300kgs, which seems a little optimistic to me. I don't even thing you could build a tR1ke for under 300kgs and there Is a lot less material in one of those.... Who knows...

I still thing that you could use the front section of a seven chassis with a motorbike shaft driven swing arm at the back. Technically it's a mid engined layout so it should be okay in terms of weight distribution. This obviously gives builders much more choice in terms of engine. Zetec, pinto, k series, motorbikes etc etc.