i was going to do a fully independant rear suspension setup on my locost but my brother seems to think that the de dion setup will get the power down better and make it handle better because the wheels will be flat on the ground at all times. what are peoples opinions??? Im using a sierra LSD off a xr4 with disks. thanks.
Which way's the wind blowing...?
In an ideal world with flat, smooth road surfaces (or a track) then a well designed De Dion set-up has the potential to offer better handling.
In real world UK road driving a well designed IRS set-up should give a better ride and road holding.
From what I've seen/read it appears that it might be easier to design a good De Dion set-up than IRS - that's my take on it.
From discussions/observations at hill climbs, I reckon that a live axle (or a de dion) will put the power down better off the line, however as the car
experiences body roll through corners (and subsequent geometry changes), the independant set up potentially offers more options if there is enough
adjustability and the design is good to start with.
As with most things, whichever way you go it will be a compromise
If the DeDion setup was better suspension the F1 boys will use it.
They have the best flat tracks of the world too.
Watch out for the TRUST LINE on a DeDion. The car will always go in that direction!. [Shake it! baby]
But for a normal use, it is a solution.
Regards,
Cobra289
Suspension questions are no fun any more since Rorty/Syd left!!!
Whichever you use, Z20let Corsa, it'll be great. I've never heard anyone say: I've built a De Dion/IRS/Live Axle Locost and it handles
crap!
Cheers,
James
quote:
Originally posted by Cobra289
Watch out for the TRUST LINE on a DeDion. The car will always go in that direction!. [Shake it! baby]
Cobra289
quote:
Originally posted by Ivan
quote:
Originally posted by Cobra289
Watch out for the TRUST LINE on a DeDion. The car will always go in that direction!. [Shake it! baby]
Cobra289
What is the "TRUST LINE" - have never seen this term before.
I think you guys are talking about the THRUST line. The imamaginary line along which the rear wheels "push" (or thrust) the car forwards.
Not difficult to imagine the result if this line is well off centre.
quote:
Originally posted by MikeCapon
I think you guys are talking about the THRUST line. The imamaginary line along which the rear wheels "push" (or thrust) the car forwards.
Not difficult to imagine the result if this line is well off centre.
I dont think that for normal road, and the occasional track day, that you can beat IRS. De dion is fine if the road is flat, but for normal, (read bumpy), english roads a well set up IRS can't be beaten. Just my oppinion. Cheers Ray
IRS everytime given the choice. Much lighter and infinitely more tunable.
MUCH lighter????
Interesting statement.
How do you figure that?
For de-dion you've got the bar running left to right which increases your unsprung weight - but you haven't got all the associated boxing of
the back of the car to hold the trailing arms.
I won't argue it may be lighter - and i won't argue it may be heavier. But MUCH lighter seems a contentious statement to me.
If someone can weight an original MK IRS and Live axle chassis then add on the IRS or my (previous) de-dion weights we'll have some interesting
facts.
(note i'm not suggesting comparing a standard MK chassis as its different to the book - perhaps the good comparison would be a Aries / Stuart
Taylor race vs road chassis)
Also infinitely more tunable also equals infinitely harder to set up and much more likely to muck up.
[Edited on 25/2/09 by MikeR]
quote:
Originally posted by MikeR
For de-dion you've got the bar running left to right which increases your unsprung weight - but you haven't got all the associated boxing of the back of the car to hold the trailing arms....
I would say that the de-dion is definately heavier than the IRS system. You have almost the same set up as for IRS, (in the way of tubing), plus that bloody great steel tube that holds the wheels on. Just my opinion. Cheers Ray
You need to put a box around the diff. This should be braced to take the forces of the IRS suspension - its got to mount somewhere. This isn't
present on de-dion.
You need 10 tubes to make up the rear suspension on IRS, only 4 on de-dion + panhard. I'd guess that the total of the 10 tubes would be a smidgen
greater than the 4 + panhard on de-dion.
So its down to does the de-dion tube weigh more or less than the bracketing for the IRS suspension mounts. Hence my comment about it not being MUCH
lighter - just perhaps a little BUT far easier to set up the geometry.
Hi guy's,
It doesn't matter witch one is heavier, this just a advertising item.
The important thing is that you get a good handling and that you choose the axle that suit your needs.
Suppose that it is 5 Kg heavier what happens when the driver is 20 Kg lighter than you????
So this kind of discussion about the weight is not relevant.
Take as an example the McPherson suspension, every one that goes into the design get into troubles and a lot of problems to verify all the theories
and methods of suspension design, but well this type [McPherson] is a well proved suspension that no ones can clarify why?
Regards,
Cobra289
quote:
Originally posted by Cobra289
So this kind of discussion about the weight is not relevant...
quote:
Originally posted by SPYDER
quote:
Originally posted by Cobra289
So this kind of discussion about the weight is not relevant...
If Colin Chapman were alive today he'd be turning in his grave!!
The consideration of weight, in particularly unsprung, is surely of primary consideration.
I was always led to believe that a live axle setup was the lightest, although I have never seen any figures. It does, however, also have the greatest unsprung weight.
I dare say the difference in lap times between the various setups may be minimal, but the difference in ride quality on the road may be more noticeable.
A lightweight De Dion setup, with ally cross tube and arms or a billet CNC cross member may be the best compromise.
Not exactly "locost" though.
"Locost" option has to be live axle.
But as Mike R said "Also infinitely more tunable also equals infinitely harder to set up and much more likely to muck up."
Unless you are thinking about weight ALL the time it would be easy to compromise a little bit here, a little bit there, then suddenly it adds up to 30 kilos.
Conversely, saving the EXTRA litle bit here and there will add up too.
Geoff.
[Edited on 26/2/09 by SPYDER]
Let's say you're car is 40 kgs heavier due to engine, suspension or you're carrying a lot of doughnuts. That represents about 10 BHP
more that you'll need to push it around. Big bloody deal. Don't eat so many chips that week if that is the concern.
[Edited on 27/2/09 by RK]
quote:
Originally posted by RK
Let's say you're car is 40 kgs heavier due to engine, suspension or you're carrying a lot of doughnuts. That represents about 10 BHP more that you'll need to push it around. Big bloody deal. Don't eat so many chips that week if that is the concern.
[Edited on 27/2/09 by RK]