Is the live axel on a lightweight car going to make it inherently twitchy on bump roads?

I've driven three Locosts and found them almost underivable on less than perfect country roads.

Did I just have three badly setup cars or is this part of the live axel unsprung weight issue?
I don't minda crashy ride, but this felt nervous and not in anyway planted.

Would irs solve this? Not had a chance to drive one with irs yet.
Thanks

The unsprung weight of a live axle will always be noticeable to some degree - you'll never totally overcome the characteristic live axle 'hop' if you hit a bump mid-corner - and yes, a well set-up IRS will always be better for road use than an equally well set-up live axle - but it certainly shouldn't be 'undriveable' on less than perfect tarmac... just a matter of backing off to a sensible pace.

There is a current fashion for fitting springs and setting dampers far too stiff 'because race car', which ruins the behaviour for road use, though, so it's possible that the cars you've driven all suffered from this.

But if you're expecting to barrel down poorly-surfaced country lanes as quickly as you could in a good, modern hot hatchback you'll probably be disappointed in even an IRS Seven-type car - the ratio of sprung:unsprung starts to tell, no matter how good your springing and damping is.

To be honest it was even in a straight line. Seemed as if the springs were far far too stiff, almost rigid.

Maybe it was a combination of not being used to these cars and a bad setup..

Ultra wide very low profile tyres don't help either.

Let me give you my experience with a Cobra kit. It wasn't a Locost, but the reference points will help out.

We began with the live axle and we were never satisfied with the handling because it would bounce all over the road on rough roads and any sort of imperfection in the track caused it to step out.

We dropped in the IRS from the 99 Mustang track car and it was as if we had a totally different car. IT WAS PLANTED EVERYWHERE!

The ride was somewhat smoother as well. I would never use a live axle again.

Plenty of Cateringvans and early Westfields running live axles to very good effect......

Could be they needed resetting after welding brackets on as well.

Yes these cars did have 15inch rims.

The suspension on these cars is very old-fashioned, so I fitted old-fashioned tyres - 185/70 R13 - as the high sidewall contributes towards softening the suspension (I believe).
However, I'm dreading the time when I need to replace them, as all I can find are 'cheap-and-nasties' or super-expensive.

My car runs a live axle and isn't at all twitchy. In fact it is very comfy and predictable. I would be looking at the setup!

Soft 250lb front springs - Soft 150lb rear springs - shocks set soft on zero..
A021'r Yoko 185.70.13 - 15psi
Narrow body Locost - Live Axle - 2.0 Zetec - 0-60 maybe 5 sec - Top 130+
Had a very spirited drive in wales with a shiny Porsche - he gave up

One usually thinks hard springs - hard shocks - low tyres - hard camber ..
I've found the opposite works for me ...

And you might even go softer than that, if you wanted!

Different chassis (though similar leverage ratios - it was one of the outboard suspension versions), and a light car, but I used to run my Crossflow engined, live-axle Sylva Phoenix on 180lb front and 130lb rear springs, with 185/60x13 tyres, for road use.

It certainly wasn't undriveable.

I never experimented further than that, but it never bottomed out (even 2-up and with me - all 17 stone of me - driving), so no reason to believe that I couldn't have gone a lower still on the spring rates.

Very different car, but to show how much fashions have changed: the original Lotus Eleven (and remember it was Colin Chapman who came up with the 'soft springs, firm dampers' dictum) used to run 125lb front and 65lb rear!