[EVMAC70]

They normally sit higher as they sit astride the backbone of the vehicle
In a side by side trike they sit inside the "box" and a lot lower
I did a fair amount of concept work before settling on a four wheeled machine for my design
I simply could not make a sensible three wheeler as small as the four wheeler!
Which was NOT what I was expecting

Only true if you have a back bone, monocoque doesn't have to have a back bone, the mini floor pan doesn't and a space frame doesn't need a back bone either

 

[EVMAC70]

The tandem-seating approach works to reduce frontal area (especially with front wheels with cycle fenders), but makes little difference to roll in turns, and no difference to roll in a steady-state turn. It also forces the vehicle to be quite long (because the entire rear suspension and rear wheel must be entirely behind the rear occupant), unless the rear occupant's legs straddle the driver like on a motorcycle or snowmobile.

I agree but if you are seated centrally as a reverse trike is all about symmetry and proper weight distribution surely its less like to lift a little on one front wheel when cornering hard and hence less likely to lose traction and we are talking electric so oodles of torque all of the time

 

[Ed Gray]

Hello All,
I live 25 miles NE of Pittsburgh and I am looking for someone capable of automotive grade welding
to construct a space frame to fit a mini subframe into.
I know its cheaper to buy a reverse trike frame and adapt but there are no appropriate basic kits
in existence that seat tandem let alone could be adapted to take the mini front subframe.
Any suggestions would be welcome,
Thank You & a Happy New Year to the Forum

I recommend looking for a drag racer or stock car racer. They are constantly integrating tube frames with modern unibody frames. First step would be to find a performance parts shop and either go (iffy these days) or call and see if you can get suggestions.

 

[EVMAC70]

Hi Mac,
I agree with your tandem approach, keeping driver and passenger on centreline, to minimize roll on bends. 40 years ago I started on a mini front end trike to be driven by a Vespa 150 cc engine. That old type mini subframe is heavy, but gives you so much mechanically in one piece. I was fortunate in having a Power Station welder to hand. Sorry to say my project got overtaken by events.
Two trikes by the same name but not manufacture in England were the Skorpian, or Scorpian.
The original built and tested was suggested as a track day machine, single seater monocock construction and driven by a Suzuki 750 or 1000 motorcycle engine.The other made it to limited production nicely done bodywork, but side by side seating, driven by a 750 K series motorcycle BMW engine.
Maybe some ideas.
I would like to do a similar ev project, but now the wrong side of 75, with health issues!
I would think a good welder would be easy to find. I have a friend only the wrong side of the pond!
Good luck with it. Joe

HI Jo, Thank You, I myself turned 50 last year so I want to the get this project underway, I am considering building a very simple wooden mockup (a traingular bucket) out of plywood simply to join the subframe and rear trailing arm / wheel brake assembly together and a true sense of space in the vehicle before putting some more serious money into this.

 

[EVMAC70]

I recommend looking for a drag racer or stock car racer. They are constantly integrating tube frames with modern unibody frames. First step would be to find a performance parts shop and either go (iffy these days) or call and see if you can get suggestions.

HI Ed, Thanks for the tip, I have looked at space frames that could be modified and just the other day came across some drag racer frames, I looked at sandrail frames too

 

[EVMAC70]

Hey I’m in Pittsburgh. I just finished my first EV conversion- tesla large drive unit into a Mercedes 300cd 1980. I did all my own custom welding for motor mounts and frame reinforcement. Depending how involved and what you are looking for I may be able to help. Send me an email- Vegthesystem at gmail

HI Wigman, Thanks for the offer, sounds like you may be able to assist me with motor mounts and welding of various tabs and securing brackets once I get a frame made up. I will keep you in mind sir, where r u at in Pittsburgh I live in Lower Burrell and my partner Anita lives in Bloomfield

 

[brian_]

Why do the driver and passenger have to sit higher ? in a tandem seated vehicle ?

They don't. It's just that common examples of tandem-seating vehicles have the occupants sitting up high to straddle a structure, to straddle an engine or track, or just to perch in a posture that allows them to lean into the turn.

They normally sit higher as they sit astride the backbone of the vehicle
In a side by side trike they sit inside the "box" and a lot lower

But there's no reason that they can't sit inside the box in tandem... as they have in many vehicles, including the Modulo in my earlier example.

I did a fair amount of concept work before settling on a four wheeled machine for my design
I simply could not make a sensible three wheeler as small as the four wheeler!
Which was NOT what I was expecting

That's exactly what I would expect. Most three-wheelers exist for two reasons:

• to use cheaply available components from motorcycles (front suspension in the case of two wheels in the back, powertrain and rear suspension in the case of two wheels in front)
• to avoid regulations and taxes which apply to four-wheeled vehicles.

If neither of these apply to a project, going with three wheels might be an amusing challenge but likely makes no functional sense.

A three-wheel configuration can be used for a body configuration with low frontal area (like an aircraft fuselage with a pair of wheels sticking out of one end), only if the seating is solo or tandem... which I believe is Mac's intention. Unfortunately, the Mini's front end is a relative barn door stuck in front, so the body can only be narrow in the upper portion.

 

[brian_]

Hello Brian, Not sure what your point is, i will explain:
Elio 110" WB to 66.8 TW = ratio of 1.16467
Mini 80" WB to 47.5" TW = ratio of 1.68
so both in terms of ratio of TW to WB will almost be the same.

When you stretch the wheelbase of the Mini to fit in a rear passenger despite the centrally located rear wheel and suspension, without increasing the front track width, the ratio will change.

Also, because tadpole trikes inherently suffer from understeer resulting from doing all the lateral load transfer at the front, they need wide front track compared to the height of their centre of mass... and so if the Mini-based three-wheeler keeps the Mini track, it need to be very low.

When you have a passenger you must accept that the vehicle dynamics will change and live with it, the only countermeasure you can take is have a very wide rear wheel for more sideways grip when cornering but even that is trade off between the grip of the tire vs the weight per square inch on the tire.

That looks like a recipe for excessive understeer to me.

Now to the single rear wheel, if you look closely at a mini wheel base and where the trailing arm attaches it is possible by sliding the down a little and toward the driver seat to maintain the wheelbase but you do of course reduce the legroom and this may result in legs akimbo for the passenger.

It's not like the Mini is a limousine to start with, so this really means that you do need to stretch the wheelbase to maintain an adequate rear seat, or resort to the passenger's legs straddling the driver. There's a reason that both three-wheeler designs using Mini front ends (including the bodywork at least back to the windshield), which have at least roughly Mini wheelbase, give up on the rear seat; of course, they have side-by-side seating so they can accommodate two without a rear seat.

The Vanderhall Edison is a well engineering and all electric front wheel drive revere trike and a really tasty package but it is not enclosed so no good for PA and with that flat front I doubt its CD is very good.

I don't think aerodynamics are of any importance to that design. I think it's a toy for people who like the idea of a Morgan trike but can't stand to actually drive one. I only listed it as an example of the same general configuration (tadpole, front drive, transverse powertrain) as this project.

 

[brian_]

... I have looked at space frames that could be modified and just the other day came across some drag racer frames, I looked at sandrail frames too

I hope that by "modify", you mean copy some of the design features in a structure that you build from scratch to suit your needs. Drag racing rails and sand rails won't suit the Mini front end, or the tandem seating, so almost none of the original frame would remain after modification. Sand rails are called "rails" because they are long, but they are normally too wide, being designed for side-by-side seating.

 

[brian_]

I recommend looking for a drag racer or stock car racer. They are constantly integrating tube frames with modern unibody frames. First step would be to find a performance parts shop and either go (iffy these days) or call and see if you can get suggestions.

Okay, but Mac's project doesn't logically use any of the Mini unibody.

 

[brian_]

I agree but if you are seated centrally as a reverse trike is all about symmetry and proper weight distribution surely its less like to lift a little on one front wheel when cornering hard and hence less likely to lose traction and we are talking electric so oodles of torque all of the time

It is true that a side-by-side vehicle - especially one which is very light and especially a three-wheeler - is better turning one way than the other when only one side is occupied. There is also the appeal to many of central driver seating, just for the different perspective given the driver. This is one reason that the McLaren F1 has central driver seating.

 

[gregpdmt]

The problem I see is the steering rack. I went and looked at one and noticed that the rack input shaft is way over to the left and then leans way to the left. I just don't see being able to move the steering column to the center and go around the motor to get to the output shaft of the column. Just some things I,ve learned to look at thru the years of cross breeding car parts.

 

[EVMAC70]

When you stretch the wheelbase of the Mini to fit in a rear passenger despite the centrally located rear wheel and suspension, without increasing the front track width, the ratio will change.

Also, because tadpole trikes inherently suffer from understeer resulting from doing all the lateral load transfer at the front, they need wide front track compared to the height of their centre of mass... and so if the Mini-based three-wheeler keeps the Mini track, it need to be very low.


That looks like a recipe for excessive understeer to me.


It's not like the Mini is a limousine to start with, so this really means that you do need to stretch the wheelbase to maintain an adequate rear seat, or resort to the passenger's legs straddling the driver. There's a reason that both three-wheeler designs using Mini front ends (including the bodywork at least back to the windshield), which have at least roughly Mini wheelbase, give up on the rear seat; of course, they have side-by-side seating so they can accommodate two without a rear seat.


I don't think aerodynamics are of any importance to that design. I think it's a toy for people who like the idea of a Morgan trike but can't stand to actually drive one. I only listed it as an example of the same general configuration (tadpole, front drive, transverse powertrain) as this project.

HI Brian, thank you for insights and opinions please see below:
(1) This will mostly be a daily driver to work and back with a long drive every other weekend to run some much loved trail
(2) 90% of the time it will only be me in the vehicle
(3) Range will be around 140miles with me in it and probably 120 to 125 with a passenger
(4) Journey time or time in the back seat for a passenger wont not be long due to needing to stop to charge
(5) Due to all of the above I will not be stretching the wheelbase
(6) Rear seat will be used mostly for an overnight bag, shopping etc with cargo net employed
(7) I am under no illusions that no one will want to spend a long time in the back
(8) Motor and reduction gear with speed Drive will come from Swindon powertrain with the motor and reduction mounted into the bottom of the front subframe, this is not a cheap solution but its about as perfect as it get and is specifically engineered to drop right into the mni subframe with only welding of a few tabs necessary and comes with the necessary hardware to connect right up to the driveshafts
(9) 26 batteries will sit just above the lower frame of the front subframe and 12 more batteries will be just the other side of the bulkhead split into 2 packs of 6 either side of the driver seat.
(10) This essentially means the top of the battery box in the front will only be 12" above axle height and the top of the the batt box in the drivers cabin only 12" above axle
(11) in the subframe the mini usually has around 420lbs of weight with engine, coolant, battery radiator etc...... the motor and reduction gear weigh 110lbs yes really and the motor packs a whopping 107HP. Batteries in front weight in at 26 x 8.4lbs = 218lbs so that 328lbs, by the time you add coolant radiator, speed drive and chargers it models to the same weight within the subframe.
(12) Placing the 12 batteries which weigh 100lbs in the front of the drivers cabin adds to my 200lb frame to be equivalent to 2 people sitting in the front which again matches what the front subframe and it components were built to handle
(13) As the steering rack for the mini mounts behind subframe changing to a centrally tapped steering rack is not too problematic

Q. Do you think its better to have another 6" wide tire at the rear or go to something like a 10" wide tire ? I guess I am really asking do you know how much wider than the original tire a tire needs to be to provide better sideways grip that a narrower tire, I would think there is a 'deadband' where its not beneficial to reduce the pressure per square inch of the tire to the road until you get enough rubber to increase the grip where its better than the original tire, is there a rule of thumb ?

 

[EVMAC70]

When you stretch the wheelbase of the Mini to fit in a rear passenger despite the centrally located rear wheel and suspension, without increasing the front track width, the ratio will change.

Also, because tadpole trikes inherently suffer from understeer resulting from doing all the lateral load transfer at the front, they need wide front track compared to the height of their centre of mass... and so if the Mini-based three-wheeler keeps the Mini track, it need to be very low.


That looks like a recipe for excessive understeer to me.


It's not like the Mini is a limousine to start with, so this really means that you do need to stretch the wheelbase to maintain an adequate rear seat, or resort to the passenger's legs straddling the driver. There's a reason that both three-wheeler designs using Mini front ends (including the bodywork at least back to the windshield), which have at least roughly Mini wheelbase, give up on the rear seat; of course, they have side-by-side seating so they can accommodate two without a rear seat.


I don't think aerodynamics are of any importance to that design. I think it's a toy for people who like the idea of a Morgan trike but can't stand to actually drive one. I only listed it as an example of the same general configuration (tadpole, front drive, transverse powertrain) as this project.

Agreed with that trike its about the retro styling and in my view I think they got it right for what it is, as for Morgan's they look good but I do not wish to own one and this is coming from a Brit

 

[EVMAC70]

The problem I see is the steering rack. I went and looked at one and noticed that the rack input shaft is way over to the left and then leans way to the left. I just don't see being able to move the steering column to the center and go around the motor to get to the output shaft of the column. Just some things I,ve learned to look at thru the years of cross breeding car parts.

As the steering rack for the mini mounts behind the subframe changing to a centrally tapped steering rack is not too problematic

 

[EVMAC70]

I hope that by "modify", you mean copy some of the design features in a structure that you build from scratch to suit your needs. Drag racing rails and sand rails won't suit the Mini front end, or the tandem seating, so almost none of the original frame would remain after modification. Sand rails are called "rails" because they are long, but they are normally too wide, being designed for side-by-side seating.

I was really looking for spaceframes that utilize front subframes and have no upper structure above the level of top of the dash effectively a bucket between front subframe & rear wheel assembly but all of them are too wide and I need mine to taper back into a triangle

 

[EVMAC70]

Okay, but Mac's project doesn't logically use any of the Mini unibody.

May be the bulkhead and a modified floorpan but I'm not sure its worth it, I guess the bulkhead at least provides immediate separation from the engine bay but can that be easily married to a space frame chassis ? probably easier just have all space frame with front and back bolting on and use aluminum panels either side of the frame at the bulkhead with expanding foam inbetween, therr again the bulkhead makes the construction of whatever goes behind that much easier as now you need literally only need a triangular box, Thoughts anyone ?

 

[TT-Man]

Hi, I like the tandom approach on a front wheel triketrike. The driver, as i have suggested is on the centre line AND without a central spine can be seated just as low as the side by side. The great majority of journeys are solo so optimal. Yes trikes are a compromise, and the occsional passenger would be seated close (very) to the driver legs either side, feet forward motor cycle style. And yes they are longer than a 4 wheelr. But hey! Vive la difference! Joe

 

[wigman]

I’m in Braddock. Let me know when you are on that stage of the process.

 

[brian_]

May be the bulkhead and a modified floorpan but I'm not sure its worth it, I guess the bulkhead at least provides immediate separation from the engine bay but can that be easily married to a space frame chassis ?

Since the Mini firewall (front bulkhead) is much wider than required, I don't see it as being useful for this vehicle.

probably easier just have all space frame with front and back bolting on and use aluminum panels either side of the frame at the bulkhead with expanding foam inbetween, therr again the bulkhead makes the construction of whatever goes behind that much easier as now you need literally only need a triangular box, Thoughts anyone ?

This makes more sense, although I don't see the need for a sandwich. Just run a metal (steel or aluminum) panel across in front of the frame that you build (which is just barely be the width of the subframe), and insulate the rear side of it with the sheet material sold for this purpose.