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MEV Eco-Exo Trike Front Suspension
scootz - 24/11/11 at 07:22 PM

Can someone who knows their suspension onions have a wee look at this reverse-trikes front suspension design and tell me what they think.

I'm not really bothered about the minor detail of the MEV set-up, just a general critique of such a double-supported upright design.

Ta muchly!







designer - 24/11/11 at 07:30 PM

It's cheap to make.


phelpsa - 24/11/11 at 07:41 PM

Virtually zero camber compensation but I guess it doesn't matter if you're running bike tyres!

[Edited on 24-11-11 by phelpsa]


scootz - 24/11/11 at 07:50 PM

quote:
Originally posted by phelpsa
Virtually zero camber compensation...


Would switching to adjustable top and bottom rose-joints take care of that?


Mad Dave - 24/11/11 at 07:57 PM

Supporting the wheel spindle at both ends is fine only if it can be made rigid enough. The MEV setup doesn't look like it's up to the job. Bend a similar tube, maybe 25mm diameter 180 degrees and you can easily flex the ends with your bare hands

[Edited on 24/11/11 by Mad Dave]


scootz - 24/11/11 at 08:04 PM

Cheers Dave. Could anyone hazard an (educated) guess at what metal types / dimensions would be required to eliminate such issues?

(assuming a 275kg vehicle weight).


Mad Dave - 24/11/11 at 08:11 PM

Take a look at the diameter of motorcycle forks. Also look at the way the wheel spindle is held at the bottom of the forks. Its not just a thin 3mm thick strip of steel its more like a bore of 20-25mm and a length of 40mm or so. That stops the forks from going skew

[Edited on 24/11/11 by Mad Dave]


daniel mason - 24/11/11 at 08:39 PM

How come it runs bike tyres up front anyway? Will a standard double wishbone with ford hub and car wheels/ tyres not be more suited?


nick205 - 24/11/11 at 09:36 PM

quote:
Originally posted by Mad Dave
Take a look at the diameter of motorcycle forks. Also look at the way the wheel spindle is held at the bottom of the forks. Its not just a thin 3mm thick strip of steel its more like a bore of 20-25mm and a length of 40mm or so. That stops the forks from going skew

[Edited on 24/11/11 by Mad Dave]


Spot on, the front axle itself creates a lot of the rigidity be being very well supported either side. A quick look at MTB forks over the years shows how they've been developed with bigger diameter stanchions and legs and moved from 10mm QR spindles up to 20+mm through axles with substantial clamps on the lower legs, maybe 20-30mm wide pinched with 2 bolts.

I can't see the benefit of the MEV setup myself; it's light and inexpensive, but if you're going to the trouble of double wishbones suspension why not fabricate a proper single sided upright and benefit from larger car tyre contact patches.

Have you looked MK Engineering's fabricated uprights for the single seater he did a few years back (can't remember the name of it). Might be worth speaking to him to see what he could do for you.


scootz - 24/11/11 at 09:44 PM

Thanks for the comments guys.

I'm looking at a few possibilities for the front end. One thought is to make a traditional upright utilising the stub-axle and rear wheel from a single-sided bike swingarm. The other is an upright similar to the MEV design pictured running a front wheel with the rotors attached on both sides and 4 bike calipers (one either side).


dlatch - 24/11/11 at 11:25 PM

never seen the Mev stuff before but i think it will be plenty strong enough interesting use of parts readily available too
it literally is a 3 wheel motorbike.
what i would really like to see is the whole thing counter leaning over in the corners to make use of the bike tyres


jonno - 24/11/11 at 11:51 PM

I think the trouble with the Eco-Exo setup is that it uses the Suzuki Burgman scooter as a main doner vehicle (front wheel spindle off a Burgman 125 is only 12mm !!).. im sure its fine for the eco-exo but on your beast ?

What does the MEV Tr1ke use on the front end ?


jonno - 25/11/11 at 12:06 AM

Done some google searches for the Tr1ke...





Might be worth giving a call to MEV ?


sat351 - 7/12/11 at 11:31 AM

Some Great points made,

But really it comes down to what you are trying to build ie, power / weight etc,,,

Our setup is perfect for the Eco-Exo, and its 32mm tube x 2mm wall and belive me once the spindle is bolted up there isnt any flex which is down to the tight U bend and the fact the front end is reasonably light,

As pointed out we could upgrade to uprights and hubs etc but unless you start mounting powerful engines its pretty pointless,,

Scott

[Edited on 7/12/11 by sat351]


Peteff - 11/6/13 at 10:08 AM

It needs a seat on the back, a back rest and some footpegs so you can carry a pillion Great looking project, 650 Burger vans pull well so it should hold it's own.

[Edited on 11/6/13 by Peteff]


ray.h. - 11/6/13 at 08:33 PM

its certainly an unusual set up but for lightness and suitable strength I think its more than man enough for the job. ive been researching other hub options for a light weight single seater and they seem either very expensive or hard to come by. its just another mans solution to an age old problem.
if it was any heavier I would say then look for car uprights but I think its inventive innovative and practical.


paulf - 11/6/13 at 09:06 PM

Its a nice simple set up but I have always questioned the use of industrial rod ends for the bottom pivot point , they are taking the full front end weight in a sideways direction and in my experience they are not very good for that type of use on a machine let alone a vehicles front suspension.
Paul


ray.h. - 11/6/13 at 09:22 PM

good point paulf. my brother uses these sort of things in his industry and says you need to be carefull which ones to use. some are almost indestructible while others fail regularly. I must admit on such a critical component quality and suitability is everything.
he also told me some have very limited spherical movement so you mustn't exceed its limits.


Andy S - 11/6/13 at 09:34 PM

What wheel bearings get used in the Eco trike stock bike bearings will not like axial loads for long which is why most trikes go for a car type stubs with taper rollers.


ray.h. - 11/6/13 at 09:43 PM

I can see many of the down sides of using motorcycle components that are designed principaly to take vertical forces and asking them to take lateral forces and I think it goes back to the weight of the vehicle. 250 kg seems acceptable. many larger trikes run 150 bhp through the back wheel and weigh over 600 kg and still run stock bike rear wheels and bearings. now that's scary.