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anti roll bar on a swing-axle
goodall - 18/3/07 at 07:39 PM

is this safe to do as i could see it perhaps improving the system

is there any god way to improve swing axles other than ripping them out all together and replacing it with irs

britishtrident - 18/3/07 at 08:25 PM

Anti-roll bar will generally make a swing axle more unstable -- I can only think of one exception to this the case where a swing axle is used on the front of a rear engined, rear wheel drive car.

Swing axles come in many different types, generally the trick is to get the centre pivot point (roll centre) as low as possible and use a little neghative camber.
The roll stiffness should also be kept low -- it can be reduced further by using a Z bar or "camber compensator" spring which is really the exact opposite in function to an anti-roll bar.

britishtrident - 18/3/07 at 08:28 PM

Just to add the best example of good swing axle deignss are found on "fintail" Mercedes of the 1960s

Ivan - 18/3/07 at 09:03 PM

If by swing axle you mean something like a VW Beetle one, then what you possibly need is a Z bar - this limits jacking and isn't anti-roll.

goodall - 18/3/07 at 09:15 PM

this is for a spitfire

just thinking all the possible ways of making the suspension better with out removing it totally, but i mite just design a fully independent system

how does a Z bar work?

Chippy - 18/3/07 at 11:56 PM

Want some advise mate, bin the thing and fit a decent IRS set up. There are firms out there that make kits to do this. Despite comments made, the swing axle was never really any good, any car fitted with one, that was half good, would have been vastly improved by fitting a good IRS. Having owned a Spitfire many years ago, can say that cornering hard and having one of the wheels tuck under, just make sure your wearing brown trousers. Just me opinion, for what its worth. Regards, Ray

britishtrident - 19/3/07 at 08:17 AM

quote:
Originally posted by goodall
this is for a spitfire

just thinking all the possible ways of making the suspension better with out removing it totally, but i mite just design a fully independent system

how does a Z bar work?


Z bars or compensator Springs reduce roll stiffness at the end with the swing axle.

First question what mark of Spitfire ? The suspension was revised on later marks (mk4 onwards), to lower the rear, reduce the roll stiffness and introduce some negative camber, the changes weren't enormous but made a big difference to the the handling.

The fully IRS suspension mods from the GT6 marks 2 & 3 can be applied to the Spitfire but because the design was a comprimise modifcation of the swing axle parts the results aren't any better than MK4 Spitfire. rear end.

http://members.cox.net/spitlist/CamberCompensator.html
http://members.aol.com/herald948/cc/

If you have a Mk3 or earlier Spifire eith mod your existing setup to the Mk4 (-- minimum of new parts required) or fit a compensator spring as above.

If you have Mk4 probably very little can be, the IRS from the later G6 marks won't give a noticeable improvement in handling,

[Edited on 19/3/07 by britishtrident]

goodall - 19/3/07 at 09:29 PM

emm, its the later model

rite just rebuild the car over the summer as standard and just accept the car the way she is, cause doing to much would lower the value of the car it being a cassic