Irs (Independent Rear Suspension) In 205

[foreigner 0]

Getting back to my very lightly crashed 205 and thinking about putting on the road.

 

I know that rear beam is in need of update ( £300 ), I thought about IRS which I saw on very few projects here.

 

So ..

Any opinions?

Any experience?

 

 

 

 

Please sensible stuff.

[welshpug 1,626]

it already is IRS

[foreigner 0]

come on mate you know what I mean?

 

I thought it's considered semi-irs

[dcc 855]

Do you mean turreted rear arches for using suspension like on the front?

[foreigner 0]

Yes , exactly that.

[jackherer 543]

come on mate you know what I mean?

 

I thought it's considered semi-irs

 

It is fully independent.

[dcc 855]

many people have had this done, but either by a specialist or they have spent weeks measuring testing and refabricating what they have tried. a name which springs to mind is colin satchel.

[Batfink 201]

A number of us have run turreted rear suspension for a few years. I personally found with a soft rear setup the car was very stable at high speed even in the wet. Ultimately its probably not a faster setup like for like compared with uprated torsion bars, but it allows an element of ease of adjustability.

[stu8v 68 1 Cars]

http://www.hh-ms.com/hhms-independant-suspension.php

[foreigner 0]

It is fully independent.

 

we could discuss that for months so I am going to agree with you. But only after you answer this : If one of the side is faulty and the other one isn't , wouldn't the faulty one directly affect the good one?

 

 

A number of us have run turreted rear suspension for a few years. I personally found with a soft rear setup the car was very stable at high speed even in the wet. Ultimately its probably not a faster setup like for like compared with uprated torsion bars, but it allows an element of ease of adjustability.

 

That 's the reason I am after it again as you remember me looking at your brothers car about 5 years ago.

I like the freedom of adjustment without taking the beam apart and buying expensive bars. Eesay adjustment , can you imagine?

The only reason against retaining beam and turreting is the beam.

Edited August 7, 2011 by foreigner

[dcc 855]

foreigner as they are on the same chassis, i would argue that on any suspension setup a failure of any sorts would 'directly' impact the other.

 

If you are worried about failure, you must be running some MASSIVE G-Forces in dem cornaz y0!

[foreigner 0]

http://www.hh-ms.com/hhms-independant-suspension.php

 

Good site, pretty expensive too.

 

thanx, good info.

 

any companies doing it for 205 ?

[foreigner 0]

foreigner as they are on the same chassis, i would argue that on any suspension setup a failure of any sorts would 'directly' impact the other.

 

If you are worried about failure, you must be running some MASSIVE G-Forces in dem cornaz y0!

 

again, you are right too, i must have somthing against the beam.

[welshpug 1,626]

Good site, pretty expensive too.

 

thanx, good info.

 

any companies doing it for 205 ?

 

yeah

 

http://www.hh-ms.com/hhms-independant-suspension.php

[foreigner 0]

yeah

 

http://www.hh-ms.com/hhms-independant-suspension.php

 

ok, got it, read through it again.

 

However that one is with lots of alterations.

 

Is there a bolt on kit? ok I hear it again, there is some welding needed to be done , ok, I accept that. Just wondering if anyone managed to make a kit for 205/309.

[Rippthrough 98]

we could discuss that for months so I am going to agree with you.

 

 

There's nothing to discuss

It's fully independent, if you take the ARB out, cycling the suspension through it's range of travel on one side will not cause the other side to also cycle.

 

It's a torsion bar system not a torsion beam.

 

 

Whether you like it or not is another matter!

Edited August 7, 2011 by Rippthrough

[Anthony 1,000]

As has already been said, the standard 205 rear beam setup is fully independent.

 

There's two areas where the standard setup is lacking and where I suspect you're getting a bit confused. Firstly, the standard damper positioning/setup gives a rubbish damper movement ratio, and means that you have to run very stiff dampers (and the problems that brings with it) to get a sensible damping rate at the wheel. This is where the turreted rear setup as offered by Colin Satchel makes a massive improvement, as that gives something around 1:1 damping ratio.

 

Secondly, the standard beam doesn't change camber as it goes through its range of motion, so unless you have a fair amount of static negative camber and/or very stiff bars, you're going to end up with positive camber on the back when you're mid-corner. The front suspension isn't a whole lot better from this point of view though thanks to the limitations of Macpherson struts, and it's even worse on a car that's been lowered considerably.

 

Cars with something like double-wishbones on the rear tend to be much better as standard on both of the above fronts, but crucially, they're no more "independent" than the standard torsion bar beam on a 205 is.

[Cameron 16]

Give me a few months and I'll have my design for a double wishbone rear subframe finished. I'll charge you a lot more than the £3,500 kit though..

[engine killer 5]

Secondly, the standard beam doesn't change camber as it goes through its range of motion, so unless you have a fair amount of static negative camber and/or very stiff bars, you're going to end up with positive camber on the back when you're mid-corner. The front suspension isn't a whole lot better from this point of view though thanks to the limitations of Macpherson struts, and it's even worse on a car that's been lowered considerably.

 

Hi Anthony, would you mind explain a bit more why the car will end up with positive camber on the back when mid-cornering? is it just because the car rolls?

 

A roll-centre-kit will improve the lowered car with MacPherson strut issue. I have a few failed roll centre kits and now I am working on a strengthened hub carrier welded with some webs to support the extension, hope it will work.

[Anthony 1,000]

Hi Anthony, would you mind explain a bit more why the car will end up with positive camber on the back when mid-cornering? is it just because the car rolls?

Yes, basically

 

 

Because the rear doesn't gain any additional negative camber as it loads up, it doesn't make much bodyroll to make the rear wheel have positive camber in relation to the road. The picture above of my old 205 Mi16 shows the issue nicely - running standard 309 GTi rear arms (0.5 degrees negative camber) but the amount of bodyroll means that it's effectively positive camber on the rear wheel, which isn't good particularly when coupled with soft-sidewall road tyres.

 

To overcome that, you either need more static negative camber (to make the wheel more upright when cornering) or stiffer rear suspension (to limit the amount of roll)

 

I'm sure someone like Cameron or Rippthrough would be able to describe in far more detail than I can though

[foreigner 0]

Give me a few months and I'll have my design for a double wishbone rear subframe finished. I'll charge you a lot more than the £3,500 kit though..

 

 

Great.

I'll take your word for it.

 

Spec: double wishbone rear suspension unit for 205/309, bolt on unit , no welding to the chassis, welding and cutting of bodywork optional.

 

Time schedule: let me know.

 

Can you let me know the delivery time and date.

 

Finally I found someone for the job or not?

[foreigner 0]

As has already been said, the standard 205 rear beam setup is fully independent.

 

There's two areas where the standard setup is lacking and where I suspect you're getting a bit confused. Firstly, the standard damper positioning/setup gives a rubbish damper movement ratio, and means that you have to run very stiff dampers (and the problems that brings with it) to get a sensible damping rate at the wheel. This is where the turreted rear setup as offered by Colin Satchel makes a massive improvement, as that gives something around 1:1 damping ratio.

 

Secondly, the standard beam doesn't change camber as it goes through its range of motion, so unless you have a fair amount of static negative camber and/or very stiff bars, you're going to end up with positive camber on the back when you're mid-corner. The front suspension isn't a whole lot better from this point of view though thanks to the limitations of Macpherson struts, and it's even worse on a car that's been lowered considerably.

 

Cars with something like double-wishbones on the rear tend to be much better as standard on both of the above fronts, but crucially, they're no more "independent" than the standard torsion bar beam on a 205 is.

 

Thanx Anthony.

 

I am just looking for different option to what is already fitted.

There is not much to be confused about when talking about the beam. |The beam fullfil it's main objective - bigger boot space - but still give great service.

I'll leave the beam for you to work with since you are much better at it.

 

 

 

 

 

 

I was more interested in the form of front setup at the back - like that blue 4x4 (everybody remember that one - right?).

 

 

 

 

So now.

 

Anyone with front suspension setup at the back speak up or forever hold your peace.

 

Just really interested if it make a great/big/small/little/neglible difference.

 

 

If you don't have experience with this setup, please only technical advice no jokers.

Edited August 8, 2011 by foreigner

[Cameron 16]

Great.

I'll take your word for it.

 

Spec: double wishbone rear suspension unit for 205/309, bolt on unit , no welding to the chassis, welding and cutting of bodywork optional.

 

Time schedule: let me know.

 

Can you let me know the delivery time and date.

 

Finally I found someone for the job or not?

 

Yep, bolt-on unit at the rear, bolt & weld-on unit at the front is the aim.. It's being designed to require as little custom fabrication as possible, although some "light relieving" of the inner wheel arch will be needed to clear the upper wishbones. The major issue will be it's 1500mm track width, which means you'll need some wide-arch extensions - either a Dimma kit or some of the 4" extensions in the group buys section.. not the end of the world though!

 

If you're serious about it, I'm aiming to finish the design in October / November, then make the parts over winter. I wouldn't be keen on selling anything until I've proven it to be durable, unless it was under the express understanding that I would accept no liability for prototype failures. (It's not that I don't have confidence in my design, you just never know what people will do!)

 

Don't expect it to come in for £300 though.. I haven't even considered the price yet but it wouldn't be cheap. It won't be extortionate, mind, considering what's on offer.

[Batfink 201]

make it race only Cameron. Saves you that public liability insurance risk .....probably.

[Cameron 16]

Yeah not going to be intended for road use, mainly as it'd be totally overkill! But yeah, good point.