HP. said:

Isn't it trailing arms, rather than torsion beam?

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A torsion beam has to have trailing arms in order for it to work.

Van Diemen said:

I don't disagree with a lot of that, but my argument was simplified to working with what you have available rather than re-engineering roll bar into the solution (which is of course preferable). I would maintain that by playing with spring rates it would be possible to make a better 'real world' setup than the stock offering, even without RARB.

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Well no doubt a good spring/damper setup would improve things, but i think you could get a better overall balance with the addition of a rear ARB.

Also it wouldn't be incredibly difficult to engineer the car to take a rear ARB.

So i really do think it would be preferable to engineer a rear ARB as the benefits are obvious i guess.

trackdayqueen said:

A torsion beam has to have trailing arms in order for it to work.

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Isn't torsion beams what the Peugeot 205 etc. have, where the twisting action (hence torsion) along the beam provide the springing effect? They don't have rear coil springs like Pandas.

HP. said:

Isn't torsion beams what the Peugeot 205 etc. have, where the twisting action (hence torsion) along the beam provide the springing effect? They don't have rear coil springs like Pandas.

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That is correct.

I guess we could argue the details of the correct way of describing the rear suspension setup, or maybe we could actually debate the whole Rear ARB thing which is a bit more interesting i think.

The ride is pretty poor. The worst I have had in nearly 20 cars owned. Its a shame, it is the ONLY reason I may change the car when its three years old.

Unless of course, i could retro fit something to help.. As discused.

I'd hang on to see if the Cobra people come up with some shorter bump stops - looks like the ones from the Panda Sporting can be cut down easily to fit otherwise.

HP. said:

Isn't torsion beams what the Peugeot 205 etc. have, where the twisting action (hence torsion) along the beam provide the springing effect? They don't have rear coil springs like Pandas.

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Two similar names; two different things.

The Panda (All except the 4x4) uses a torsion beam (and many other small cars, eg VW Polo - where it was first introduced). This has a trailing arm at either side, with coils providing the springing. The arms are linked to each other near the pivoting end by a section of metal bar (looks like a bit of angle iron). This provides a degree of interconnection, and as such provides the function of an anti-roll bar. Its also true to say that this set up is not truly 'independent' rear suspension.

The Pug (and many other small French cars, eg Saxo, Renault 5 etc) uses torsion bars. There's a trailing arm at either side, but no 'spring' as such. instead, each arm is attached to a round rod, which is fixed to the body at the opposite side to the arm. This twists as the arm moves, providing a torsion spring. One result of this set up is that the wheelbase is different down one side of the car than the other, to allow the bars to fit side by side. Because there's no interconnection of the trailing arms in this arrangement (so it is truly independent rear suspension), either you get massive body roll (like on older Renaults), or an anti-roll bar is needed, linking the two trailing arms together.

Here endeth today's lesson (from a previous Mk 1 Polo and many Renaults driver, as it happens)

Herts Hillhopper said:

Two similar names; two different things.

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Later: just found this page in Wikipedia. http://en.wikipedia.org/wiki/Twist-beam_rear_suspension (or torsion beam suspension if you prefer)
Note under 'advantages', 'no need for separate sway bar' (the American name for antiroll bar). There's a link to a photo too at the bottom of the page.
Pete

The standard Panda torsion beam (in effect an anti roll bar) could probably be stiffened in some way. but ARBs usually reduce grip because they lift the opposite wheel off the road.

Standard springs with posh shocks (adjustable compression and rebound damping) will do a better job.

The 100hp's suspension is no harder than a lot of much newer stuff these days, have a go in a corsa vxr for instance, for me the worst things are sunken inspection covers on the road and broken surfaces as these really do jar the suspension badly but it is what it is really, combination of hard/short springs with 45 section rubber is never going to be compliant.. there is a rear arb available from DNA racing in Italy that some on the Italian facebook page have fitted but i don't what the results were.

The Fiat 500 or Ford Ka II rear axle will physically fit under a Panda but the track is 50mm wider. It has an ARB built into the cross beam and 30% softer springs.

The issue on the 100bhp will be wheel arch clearance on its lowered ride height and fat tyres. You might need special springs to get the correct ride height. Simply cutting a spring will increase its spring rate by the percentage of material cut away. Chop a 10" spring to 8" and you increase the spring rate by 20%.

For a couple of hundred quid you could try one and see how it works. If its too much hassle just resell the axle.