eddie99
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| posted on 30/8/08 at 06:48 PM |
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DeDion?
Im not a suspension expert but i have always thought that independant rear suspension would be best... Still looking at kits, some are for Dedion,
some solid rear axle and some are fully independant..
Can anyone give me an overview of the 3 differnt types and strengths and weaknesses? I also believe that you have to have solid rear axle to race but
i might be wrong.
Thanks in Advance
Eddie
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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gavin174
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| posted on 30/8/08 at 07:17 PM |
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hi eddie
i ask this question not so long ago and have read as many posts as i could find on the subject.. on all forums
and i am still confussed.
the onlt answer i can give is that eveyone has their own oppion and they all differ
i am in the process on installing a de deon
some pics in my profile.
you are more than welcome to pop round and have a look
cheers gavin
www.kwikarfracing.com.jpg)
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indykid
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| posted on 30/8/08 at 07:31 PM |
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having read a similar number of threads, i'd say the general concensus is that a perfectly designed IRS setup will be best. if you're
designing your own and aren't a suspension design guru, chances are you'll be better off with a dedion or a live axle.
dedion offers lower unsprung weight and live axle, lower overall weight.
dedion and live axles have more of a tendency to break away more progressively when pushed past the limit.
tom
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mr henderson
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| posted on 30/8/08 at 07:35 PM |
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A good starting place for the required info is wikipedia
For instance
http://en.wikipedia.org/wiki/De_Dion_tube
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eddie99
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| posted on 30/8/08 at 08:46 PM |
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I understand that its what people think, i've read lots of things of the web such as wikipedia, i just wanted to see what you guys thought, i.e
the ones who have built the types and might have compared against others, i know caterams use the dedion axle and a fair few modern cars.
Thanks for the info though, and can anyone clarify that you have to have a live axle to race?
Eddie
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Minicooper
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| posted on 30/8/08 at 09:02 PM |
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Years ago I built a Vauxhall 2 litre rwd metro, using a de dion and it was great, even though it had a fairly short wheelbase it was easy to drive the
corners, I hope that makes sense. I personally will stick with the de dion as it's easy to make and very easy to setup
Cheers
David
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Phil.J
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| posted on 30/8/08 at 09:06 PM |
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Can't understand why anyone would use a De Dion axle arrangement on a modern car, they're out of the ark (or should that be chariot).
Fit a proper independant suspension system at the build stage and you are starting with the best performance option.
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mark chandler
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| posted on 30/8/08 at 09:19 PM |
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If you are making your front suspension then making an IRS rear is not any harder.
Getting the perfect setup is of course a different matter but I would say it all depends on how much you want to make stuff or how deep your pockets
are.
I am biased as I made my own IRS rear, mostly because my donor was a 4x4 sierra which gave me a LSD diff.
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CaptainJosh
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| posted on 30/8/08 at 09:53 PM |
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I think if your building a car quickly/without allot of patience with fabrication then a De Dion is a perfect choice. Its definitely quicker to fab a
De Dion tube then 4 wishbones and 2 uprights, that is, if done correctly.
If your building a car with as little compromises as possible, use IRS.
I think in hiensite I would of chose a live axle over IRS for my first build, simply because of the amount of fabrication you have to do to get a
decent setup ( Jigs etc ). But now I've actually got an IRS setup, it was well worth it- now to see how it handles.
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oldtimer
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| posted on 30/8/08 at 10:27 PM |
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There has been sooo much opinion on this it is hard to make choises or comparisons. On my first kit I used a live axle and it seemed OK. I'm now
building one with De Dion, mainly as it was what I inherited with the part built kit. Are the weights going to be an issue for you? I have seen it
written that IRS soaks up bumps better when propery made and De Dion has less squat, particularly when applying power. I'm building now so
can't say, are there 3 semi identical locosts out there with different rears??
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mangogrooveworkshop
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| posted on 30/8/08 at 10:41 PM |
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the dedion is the best bit about my seven.Its very hard to unseat on the runways at crail but the bleeding front end is pants....no self centering at
all making it a swine to drive...thinking of doing the clever thing and selling it to get a caterham. Dedion is simple and as old as the design is it
works. less to go wrong and things to come loose.....macs met a tyre wall due to irs coming loose
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MikeRJ
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| posted on 30/8/08 at 11:14 PM |
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quote:
Originally posted by Phil.J
Can't understand why anyone would use a De Dion axle arrangement on a modern car, they're out of the ark (or should that be
chariot).
Better ask Caterham why they continued using it for so long then!
People choose it for the reasons stated in here, it works very well and there's far less scope for screwing things up than designing your own
IRS. It's also a easy retrofit to a live axle chassis.
How many IRS designs keep the camber of both wheels under full control with body roll? Apart from the very complex Dax system, I can't think of
any others. Live axle and de-dion lose out in single wheel bump where IRS has an advantage.
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Phil.J
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| posted on 31/8/08 at 08:16 PM |
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Thats why so many race cars use it then including all single seaters (NOT!).
If you have any serious performance pretentions then do it properly from the start, use a good independent set-up.
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gavin174
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| posted on 31/8/08 at 08:25 PM |
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sorry phil
are you building a single seater race car..or a road going two seater..
if we had the money i am sure we would
all employ formula 1 technology in our
builds
but if funds dont allow we have to make
the best of what we have got!!!!!!!!
[Edited on 31/8/08 by gavin174]
http://www.essexkitcarclub.com
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Minicooper
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| posted on 31/8/08 at 11:54 PM |
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quote:
Originally posted by Phil.J
Thats why so many race cars use it then including all single seaters (NOT!).
If you have any serious performance pretentions then do it properly from the start, use a good independent set-up.
Give it a try, you may like it
David
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flak monkey
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| posted on 1/9/08 at 06:46 AM |
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Its is very easy to get the design of IRS very wrong and you end up with a car that handles very poorly indeed. Some of the IRS back ends in sevens
are very poorly designed so that they fit in the given space. If you have the know how to design a good IRS set up then by all means do so, if not,
you could be very disappointed.
For road use and home building de dion is ideal.
Its also actually the lowest weight of all 3 designs, but not the lowest unsprung weight (IRS does win out there).
Its each to their own really. A seven with a live axle will out handle pretty much any other road going vehicle. Most people wouldnt be able to drive
to the limit of the car anyway.
Phil.J you seem to have a very high opinion of yourself, perhaps you could design a good IRS back end for a seven to share with everyone if you know
it all?
David
Sera
http://www.motosera.com
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procomp
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| posted on 1/9/08 at 07:19 AM |
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Hi
I spot the OP Eddie is asking about racing. Is this for the LOCOST CHAMPIONSHIP. If it is you MUST use the escort live axle setup.
If it is for racing in an other championship you can regulations dependent do what suits you.
But general rule in that for bumpy roads IRS will give a better ride but handling as others have said will depend upon the desighn. Look at how many
manufacturers have made a mess off it. Although that dose not mean it cant be done properly and made to handle. Just needs some understanding of what
is needed to gain good geometry.
De dion is a compromise between the live axle and IRS. Generally used by KIT manufacturers due to donor live axle units becoming harder to get hold
of. It gives less unsprung weight compared to the live axle but is heavier overall by 20kg-30kg dependant on desighn. But can be used to incorporate
anti squat unlike an IRS system.
For simple track use the live axle is the way for a basic seven type. It is the lightest overall setup and can have all the antisquat incorporated in
to it's desighn. You can still have the camber and tracking set up by manipulating the axle.
It's only real down side is it's unsprung weight but by choosing dampers with the right valving and springs of the right poundage this
problem is not a problem anymore.
Cheers Matt
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MikeRJ
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| posted on 1/9/08 at 07:24 AM |
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quote:
Originally posted by Phil.J
Thats why so many race cars use it then including all single seaters (NOT!).
Ever heard of the 750MC Locost series? They aren't exactly slow around the bends.
You are right in that for the best compromise (and it always is) for handling under all conditions some kind of well designed and well constructed IRS
system would be the best, but a de-dion or live axle gets you most of the way there for a fraction of the complexity.
quote:
Originally posted by Phil.J
Can't understand why anyone would use a De Dion axle arrangement on a modern car
The locost isn't modern though, it's a replica of a replica of a 50 year old car.
[Edited on 1/9/08 by MikeRJ]
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procomp
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| posted on 1/9/08 at 07:48 AM |
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Hi
never mind the Locost championship with a live axle. What about the Mallocks.
They have done the lot and what has the MK35 still got in the back of it after 50 years of continued redesigning. Yep an escort axle  .
Cheers Matt
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