Monoshock rearend?

[Delman]

An open question and I am really looking for advice.
I run an Australian built Clubman-type sportscar which was based on the Herald/Spit chassis and running gear. I am not keen on the transverse rear spring (even with the various camber compensators fitted) and have been looking at the current Formula Vee cars with their 'Coil-over Monoshock' set-ups.
Does anyone have any opinions as to whether a similar set-up would be viable for my car (All up weight about 540kg)? Also, any advice on how best to calculate the optimum spring/shock combination.
Any help proffered gratefully received.

[THR]

how much movement?
what sorta spring rate? stiff?
how much wieght over that end of the car?

ive never seen it on the rear end of the car, as it makes it very stiff.

[enzo]

The Vee coilover is what we call a "Zero Roll" setup - the shock/spring has no roll resistance. If roll resistance is needed, it is done solely by an anti-roll bar.

[THR]

enzo,
im sure your right, but with no explanation to what the vee set up is, i have no idea!

[Ray Bell]

So you have a Canstel, Delman? And I assume it's purely for road use, or perhaps with a bit of Club sprint running?

I think this is an issue that's troubled many over the years. But are you attacking the real problem?

The Vees have this setup because they have swing axles, as do you. But you are speaking principally about replacing the springing medium, as far as I can see.

Often it's better to go back to basics, and in this case I'd think it interesting to see what happens if you go right back to the standard Spitfire arrangement, with the spring rate reduced appropriately to compensate for the lower weight. Take off the comensators (just unhook them for a trial run) and see what happens.

When you attack the problem from tors like this, you can work it through properly. Try to do it in concert with someone who knows the ropes with Vee technology, and worry about the springing medium only when you have to.

[Delman]

Thanks for your reply Ray. I have used the car in both Hill-climbs and Club-sprints and also in Historic regularities (They won't let me run with the 'real ' Clubman's and I would have to compete with PRBs and Frasers etc). In fact I seized the engine at Wakefield and am currently restoring the car completely, which is why I have the car in a state to contemplate this change.
Three of the seven leaves of the spring have already been taken out and the camber changes without a camber compensator have to be seen to be believed.
My reasons for looking at the monoshock route are several, and not necessarily in any priority-
i) reduction in unsprung weight.
ii) better fore-and aft control of the half shaft position (in concert with the radius arm)
iii) easier (single adjustment) control of damping rates and spring length (ride height).
iv) the Formula Vee style of suspension also incorporates a very solid threaded rod type camber compensator or droop stop which cannot be used on the standard suspension.
v) the last and very woolly idea is that it may help to lower the rear roll centre height.
I do intend to incorporate a roll-bar into the set-up eventually.
Once again, any thoughts greatly appreciated,
Chris

[Ray Bell]

Frankly, I'd stick with the leaf spring then. You won't reduce unsprung weight by very much, and you'll save on mounting problems.

Of course, the whole thing isn't before me, so I couldn't be so totally sure of how it's laid out.

One man who might help you more directly is someone who race Vees and owned a Canstel.

You didn't think that possible, did you?

Steve Wiessner. PM me right away for details. I'm going away for over a week in the morning, so don't delay.

[Delman]

Sorry Ray, don't know what pm means. Missed your communication last night, hope to catch up with you when you are back.
Chris

[Ray Bell]

There's not many S Wiessners in the Sydney phone book, look him up and give him a call. Note the spelling: Wiessner.

PM is private message.