Born-again Italjet, with HCS, 2020

The Italjet Dragster made a surprise comeback in 2020, complete with hub centre steering. Sir Alan Cathcart got a ride on it, as seen here in MoreBikes. More here:
Myles Crowder is already putting together an FF with the earlier version of this HCS system. See here:

Photos: Kel Edge.

Born-again Italjet, with HCS, 2020

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Just out of general interest; What has any of this got to with Feet First Two wheelers? You know, seat base below 20" (500mm) Seatback capable of supporting the rider, all that stuff.

A unique, 'off the peg' HCS alternative to telescopic forks

Answer: The same reason I gave for posting the pix of the original HCS-steered F125: "Myles Crowder's project to create a lightweight FF fitted with the hub centre steering from an old F125 (see here:". In other words, for a lightweight FF, it could provide a unique, 'off the peg' HCS alternative to telescopic forks. Obviously, it's up to the FF builder to keep the seat low and the backrest substantial. PNB

A unique, 'off the peg' HCS alternative to telescopic forks



I did respond to this earlier, but the message seems to have disppeared. No matter, I just suggested that the Italjet HCS was a bit primitive and known to be short-life, and that a home-made Hossaack System was probably the best option for any lightweight FF builder.

Really, as the Italjet is just 'single-arm' rather than following Tony Foale's 'arm and wishbone'. it should be credited to it's originator and called the "Reliant" system. Or did not AV Roe do it first on one of his Monocars? Single sided that is, not like the Neracar double-sided single-arm HCS. No doubt the heritage section can put me straight.

Perdix's picture

The Primitives

I suspect that Royce hasn't read my comment, here:
my comment
where I had already called it a Reliant system. :D

Given that it will have to have passed through an amount of type approval (and in the knowledge that there's always someone ready with a lawsuit), I'm comfortable using what is a simple arm and kingpin arrangement.
Not quite sure where Royce is getting his knowledge of their failings from "known to be short-life" (with no source cited), but I've been blissfully unaware.** I would, for pretty obvious reasons, be interested in hearing about it.

Hossack systems are quite simple, but I want to minimise suspension height above the wheel (mainly for aesthetics) and that ain't something that applies to Norm's design.
As I've mentioned in the link up there ^, I could modify the Italjet arrangement to an ELFe style twin arm. But (and mine is not small) the last shattered vestiges of my common sense say "why, until you know it's needed?"

And if I do have to, it'll just be a load of old ball-joints.

**My normal state. Maybe not the blissful bit...

Italjet - Kingpin FFE

I wish people would stop calling the Italjet a HCS Front end. It is most definitely not. It has much more in common with the leading arm front suspension of the venerable Citroen 2CV. This has an inclined, fixed King Pin. The Italjet is similar and suffers significant changes of rake and trail during operation. I do like the torsion bar spring. A scaled up version could be made with a floating king Pin and top wishbone. This would be an interesting FF development.

Good stuff

I agree with Cj Russell on the Italjet issue, and he's come up with an earlier uses of Single Arm than Reliant - Citroan of course. In the 'most dangerous car ever tested' the 2CV. Unless of course A.V Roe got thetre first. Etc.

The Arm and Wisbone refered to is, as far as I know. Tony Foale's innovation, copied by Yamaha with their GTS, neatly avoiding the lock limitations of 'Double Arm' (e.g. Elf racer), with a potentially lighter wheel assembly than full Double Wishbone (e.e Voyager, Phasar, Banana. Delta et al) It needs a big wheel offset, is limited to to a single disc and does have a minor locke limitation on one side but only as bad as double sided (approx 40 degrees each side)* But it's certainly an option for a lightweight.

Turning to the points made by Pardix, I'm sorrry I didn't know you've already mentioned the Reliant connection. I was immediately interested in Italets system (after all it's works on a Reliant) and always talked to users when i encountered them. Short kingpin life was often mentioned, and, looking at it, I'm not surprised.

Probably more relevent is the note about 'height over the wheel', one of the major advantages of 'non-fork' systems. I focussed on this feature with early designs (001) cautious about high side area at the front. However, later aerodyamic research showed that a relativey high 'leading edge', provided it has suitable separatiuon features (e.g. FJ, Monliner et al), gives the lowest drag, frontal download, and Indifference. This implies more space over the wheel is available. Not enough for telecopics, the 2010 Cmax cockpit is compromised by it's stock forks but enough for a Hossack System, especially on a small wheel. It also allows twin brakes and use of the stock wheel.

Then there's Ball Joints. Ordinary automotive Ball joints are ideal. Cheap, hopelessly over-engineered for the loads, and with more engular range than anything else. OK, too big, a bit heavy. Life is hard.

If you buy the right makes (e.g. Quinton Hazel, FIrst Line but not Delphi) you can squeeze the crimped cap in a vice, over a socket to support the edge of the crimp, untill the pin just rotates freely. Perfect. As sreering joints these will last at least thirty years. The Loaded 'Bottom Ball joint' in a Voyager HCS maybe only ten. (MGF, £10)

*It turns out that it's not the wheel that limits steering lock on HCS. It's quite easy to get close to 50 degrees each side in the wheel but if there's a top wishbone it will have a base of some width. By forty degrees of lock the track rod/s at full lock will have closesd towards the steering axis to the point where clearing that wishbone base mount becomes a consideration. I've never bothered to find the practical limit, FJs 38 degrees in ample for it's wheelbase but I doubt if more than 45 degrees is practical with a meaningful wishbone base.

Blah etc. Friday night drink beer.

Perdix's picture

such a bind

"By forty degrees of lock the track rod/s at full lock will have closesd towards the steering axis to the point where clearing that wishbone base mount becomes a consideration."

I'm probably misunderstanding the statement (confused is quite a normal state for me), but isn't that why the Bebe Jebus gave us asymmetry?
Instead of: △
we can use: ◺
to clear the way for drag links?

I'm being thick, aren't I?



I would imagine that a mass produced Italjet front end is much easier to source and cheaper than a specially built HCS. If ultimate performance is not an issue, then I can see why this would be a better choice. The rake and trail could also easily be changed by using an offset key, or similar engineering technique in the front end of the leading arm.

Tech, tech.

Never met your Bebe Jebus but understand your very good point. There's no obvious suspension reason why the top wishbone should be symetrical. At the rear it makes a top wishbone feasible on a single sided rear end (e.g.C-Evo)

But at the front it assumes a single track rod, connecting the upright of the HCS (Foale/DifazioTait/Creasey) to the chassis-mounted 'transverse arm', pivoting at the same angle (of rake) as the upright, that the hand control is attatched to. This is certainly feasible, the Quasar and various other FFs, with remote steering, also used a single track rod. However it is immediately apparant (in theory and practice) that coupled track rods are far stiffer and more precise for steering than one. It also transpires. due to the dumb design, that water tends to get into the bearing housing that the Voyager Transverse Arm rotates on and in one case this resulted in the bearing disintergrating, without having ay effect on the steering. Coupling eliminates any loads on the the pivots and allows the lightest possible components - Although I'm still stuck using Metro track rods ends.

This is turn calls for a symetrical top wishbone. And hence the eventual conflict between the width of that wishbone base and the paired track rods at their minimum width.

'Course, this is just one design development path. Feel encouraged to come up with something better!

Turning to Martin's point the availability of Italjet and other systems (Voyager HCS still available...), It seems to me you either throw something together (Mk1 Cmax, nine days) and have fun, without bothering about details. Or you build something to the specification you've established. In which case you'll want it to last long enough to develop and enjoy that experience. How long is that? Three years? Five years? Ten? Thirty three? The average life of a PTW, last time I Looked was 3.6 years. It's a good idea to look at durability.

But I guess it's all relative. As a hobby that can be afforded it doesn't really matter. One could even build a better single arm/king pin and still use the Italjet wheel.