I'm drawing up plans for a super light weight 3 wheeled single seater. 200 - 250kg target weight. I've been told that a cinquecento steering rack is the best for the job and a process of thought has led me to think, why not use the fiat's front upright and ARB and brakes and wheels and eventually, the master cylinder and pedal box. All cheap, chearful and bolt right in from the donor.

The fiat master cylinder comes with a servo built in, which I won't need for such a light weight vehicle. Can it be dismantled to remove the servo bit and use the remainder?

yes you can as far as i know but you will need to build a new push rod.

why not use it anyway. it will be well fun with the servo. :O)

good luck.

Weird coincidence, I've been working on a 3 wheel (tadpole/reverse) single seater trike along the lines of the Hudson Freespirit over the last couple of nights. Though I'm still at the very high level concept stage.
Are you going FWD or RWD? BEC or CEC?
Presumably BEC RWD from the target weight.

Personally I'd get a BMC4020 master cylinder, from brakesint it's only about £17+VAT and designed for un-servoed operation. (From a Fiat124)


[Edited on 27/5/10 by iank]

Will the pedal feel ok as the m/c I assume would be a larger bore size than non servo.

Iank, thanks for the tip on the MC. Do you have any sketches of your 3 wheeler ideas? Mine will be scooter engined, so rear drive. I'm told front engined FWD is the best layout but I already have the scooter drive train.

To get that weight, there'll be virtually no bodywork. I'm thinking of a space frame of 12mm tubes in a geodesic arrangement with something like tent fabric over it to keep some of the weather out.

Only sketch I have is a very basic 1st cut drawing for packaging to get an idea of size/layout. I want it to be low and short but may have gone too far with the first cut. Triangulation isn't even started yet before anyone mentions the distinct lack of triangles




Current thinking is FWD but I need a small, low, lightweight engine gearbox with a cable change gearbox tunable up to 100-120bhp ish which should be plenty at my 330kg target weight.

Possibly BEC if I can find something that connects easily to a diff (Quaif make the idea box of tricks but as usual they want a kidney or two for it). There's not a lot of room but I know an R1 with chain driven diff can be squeezed into a mini front subframe so maybe that's the right route but chain length will be very short which isn't ideal.

I figured you'd be avoiding bodywork on your project but your fabric/frame idea is fascinating (from what I remember there was something East German that used a similar fabric idea).

East German car was the Velorex and was actually Czechoslovakian
http://www.absoluteastronomy.com/topics/Velorex

[Edited on 27/5/10 by iank]

Interesting idea you have there. You'll need a very low engine if you want to recline that far back.

I've seen pictures of the velorex before. I'm thinking more like Thi s with tube lengths of about 200mm. The gap might be small enough to keep out the MSVA tester's sphere, which will be a bonus.

Why is FWD considered the choice for weight? Surely a 600cc bike engine and rear suspension would be the lightest most integrated solution? The only issue I can see with my idea is your feet become the crumple zone essentially.

quote:

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Originally posted by alistairolsen
Why is FWD considered the choice for weight? Surely a 600cc bike engine and rear suspension would be the lightest most integrated solution? The only issue I can see with my idea is your feet become the crumple zone essentially.

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Ian, for FWD it is possible to use a FJR1400. The gearbox output shaft runs across the engine and from what I know (very little) can be adapted to provide an output. No diff though....

I seem to remember a thread somewhere with one being used BEC style for AWD.

interesting reading! 3 wheelers aren't something Ive ever looked at.

Its probably far too heavy but the layout of a merc a class would lend itself to this!

quote:

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Originally posted by coozer
Ian, for FWD it is possible to use a FJR1400. The gearbox output shaft runs across the engine and from what I know (very little) can be adapted to provide an output. No diff though....

I seem to remember a thread somewhere with one being used BEC style for AWD.

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