De Deon versus IRS?

[Guest]

I'm interested to know how my westy SeiW compares to the caterhams and dax's with the de deon setup?  Interested specifically for track use, and how the different characteristics behave.  Which is the 'best' ?

*lights touch paper and stands back*

[JeffC]

I should have an answer for you on Monday if the weather is favourable  

dunno if I dare link this  

forum for heritage  

[Bob Green]

De Dion is far superior given the correct set up.

[Matt Seabrook]

[tex]

iasked this same question at dax last week - my old car was irs - they dont do IRS anymore because of the issues with undulating roads making the car feel skitty - they only make de dion because of it

[Matt Seabrook]

Unless I am missing something I cant think of a single high performance car designed in the last 20 years that had a De Dion axle. Quite a few with IRS though

[Guest]

Irs is ultimately better , but takes longer to set up correctly in amature hands . carl drive a caterham and see how you find it , it suits some styles of driving and the chassis feels totally different .

You need to be very good and very consistant though to say on any given day which is best , and everything else needs to be equal ..... comparing apples to apples etc.

in sumary ,there is and there isn't an answer to your question.

[iiyama]

I gotta say that I know nothing about suspension or setting it up! However logic dictates to me that IRS has to be better then De dion for track purposes given that it makes the car adjustable on all four corners. This is of course on the understanding that the suspension is easily adjustable;the end user knows how to get the best from it and has the equipment to set it accuratly.

On the road I guess its a bit of a compromise but surely would give a better ride quality then De dion?

As for the Dax comment, my personal view on this is that Dax couldnt be arsed with it! Surely if its 'skittish' it comes down to set up again??  And while I would not expect a road user to crawl under the car to make a suspension change every time he/she wanted to use the car, there must be an 'average' setting that is more then adequate for road use. Or maybe Im over simplifying???

[stephenh]

Surely all other things being equal (which they rarely are) de dion tubes tend to result in more unsprung weight?

[stu999]

Not sure that there is *a best* Carl, regardless of what the IRS supporters may try and tell you. Individual cars/setups/drivers will shine on some tracks, and not others. As always, it is finding the best compromise that suits you.

My car has a dedion axle, which was originally supplied to me by Dax, and subsequently adapted to fit my own chassis design. It was *the best* choice for me, but not (at the time anyway) chosen for ultimate handling ability, but rather simplicity of build, and the ability to use standard bolt-on Ford components.

In the real world, I have always been amazed at how much grip/cornering ability my car has compared to other seven style cars. Yes, there are cars that do go round corners faster, but they are few and far between, and the ones that do are almost always dedicated trackday/racers. Bearing in mind that this is a car I made in a corner of an old farm building, I think at least some of the credit can be given to the choice of de dion

[Bananaman]

Unless I am missing something I cant think of a single high performance car designed in the last 20 years that had a De Dion axle. Quite a few with IRS though

There are a few Yank ones with truck axles.........      

[Norman Verona]

Series 1 Lotus 7's had solid and IRS rear axles. The De Dion came later.

I've often thought about making a subframe to bolt on the diff mountings and the upper and lower chassis rail on which to mount wishbones and create my own IRS.

But then I can't fault the handling, when I set it up correctly, so what's the point.

[zoso]

As has been said each system has it's pros and cons.

IRS requires a longer structural area to the chassis, as the suspension mounts further rearward.  So load paths get longer, making the chassis more complex, and possibly heavier.  However it allows full control over the wheel motion, or as close as possible, which may be worth the penalty (usually is in my experience).

De-dion often mounts most of the suspension in front of the axle, allowing shorter structural area, load paths etc.  So the chassis can be lighter (possibly).  However increased unsprung weight, and limitations to wheel motion control are the trade offs.  Some de-dion set ups get passive rear wheel steer, which some people like.

IRS makes the most sense to me.  Though on a smooth race track/hill/sprint with equal car specs there really shouldn't be too much difference between the two... and I think that shows in the real world...

[Blatman]

If De Dion was *best* Caterham would not have bothered to develop an IRS chassis, would they?

Given a blank sheet of paper, you would not design a performance car with De Dion.

I'm with Matt Seabrook on this one...

[Guest]

If De Dion was *best* Caterham would not have bothered to develop an IRS chassis, would they?

Given a blank sheet of paper, you would not design a performance car with De Dion.

I'm with Matt Seabrook on this one...

So it's CSR (with it's wide body and IRS) versus Superlight with it's narrow body and De Dion.  Does this mean that you don't like any caterhams?