sgraber
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| posted on 10/1/04 at 06:23 PM |
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Nik Link ARB
While we are on the subject of interesting Suspension designs (And I didn't want to dilute the Dax thread...) here is a link to the
Radical Motorsport Nik Link Anti Roll Bar. A most interesting ARB.
I'd like to hear your comments about it.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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pbura
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| posted on 11/1/04 at 08:50 PM |
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Quote from the designer:
"I haven’t yet found a satisfactory mathematical way to assess the bar precisely, but by varying the tube diameter and wall thickness, combined
with a lot of testing with three drivers, good feed back and a variety of bars we are building up more and more knowledge all the time."
No engineer here, but doesn't it seem reasonable that it should be possible to calculate how much the bar would deflect given a certain amount
of force? Maybe that curve in one end mucks up the math.
I must be missing something, because I can't see how the bar could not be heat treated, seeing as it acts as a spring. Anyone got an
explanation?
Quite a neat piece of gear, actually. If the roll stiffness could be estimated in advance so as to avoid all the experimentation described in the
article, it could be practical for a Locost. Set up with one bar and maybe change it out if it wasn't exactly what was wanted.
All in all, I'd probably go for the safe bet, a standard ARB with adjustable end links, such as this one from another thread:
[img]http://www.locostbuilders.co.uk/viewthread.php?action=attachment&tid=6859&pid=51677[/img]
WTF? BB code for images not working? Chris W?
[Edited on 11/1/04 by pbura]
Pete
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JoelP
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| posted on 12/1/04 at 12:20 AM |
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though there is a good chance im wrong, ive done that before. Isnt it meant to be <> rather than []? 
<img>http://www.locostbuilders.co.uk/viewthread.php?action=attachment&tid=6859&pid=51677</img>
hope that works or im gonna look well daft...
ah well nothing new there...
[img]http://www.locostbuilders.co.uk/viewthread.php?action=attachment&tid=6859&pid=51677[/img]
seems you're right about <> anyway!
use the icon for inserting an image, then it doesnt matter about bb stuff!!!!
[Edited on 12/1/04 by JoelP]
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JoelP
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| posted on 12/1/04 at 12:22 AM |
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i give up...
doesnt work anyway!!!!!
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sgraber
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| posted on 12/1/04 at 02:22 AM |
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That's very unusual. Usually the properties for the image point to the absolute location of the file. But in this case, it points to a php
reference to the file.
Maybe ChrisW. can explain why the image properties (right-click on image) doesn't show the image absolute location anymore. I think it used
to... [confused]me[/confused]
Graber
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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GTAddict
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| posted on 12/1/04 at 12:54 PM |
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Back to the topic!
It looks a teeny bit complex to me... plus you have to swap and change whole bars instead of adjusting... and it looks as if finding a specific
setting is a case for trial and error, rather than getting your calculator out and selecting a bar thickness.
In one of Staniforth's books (Race car suspension?) there is an antiroll bar with adjustable links which uses a similar concept. The bar itself
is conventional, but the links are flat bars which can be rotated along their length. If the bars are 'vertical' then they are
stiff, and impart maximum torsional displacement to the roll bar. However, if they are angled 'horizontal', then they themselves flex and
impart less torsion to the bar. I'm sure the math gets a bit squirrelly inbetween angles, but the simple result is a roll bar which can be
'softened' substantially away from the chosen torsion in the bar.
Mark.
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Spyderman
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| posted on 12/1/04 at 02:37 PM |
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quote:
Originally posted by sgraber
While we are on the subject of interesting Suspension designs (And I didn't want to dilute the Dax thread...) here is a link to the
Radical Motorsport Nik Link Anti Roll Bar. A most interesting ARB.
I'd like to hear your comments about it.
That is an interesting way of increasing coil/damper travel. I would hate to work out the coil rate though as it would still be falling rate and those
pivots look to be different. It would be bad enough if both sides were identical!
I can see how it is difficult to calculate the ARB rate, because in a left turn the ARB is trying to be straightened and in a right hand turn is being
bent more.
As you are all aware it is far easier to bend steel than straighten it
I'm not really sure it would work! The most difficult thing would be making both sides react the same way. Unless that is the purpose of
it!
I'm all for the standard approach to ARB's as at least you can adjust them on the car.
The flat bar that GTAddict mentions seems simple by comparison.
Terry
Spyderman
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Alan B
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| posted on 12/1/04 at 02:51 PM |
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Following and agreeing with Mark.....I can't believe is not mathematically modelable, but I do believe it is very difficult...so this would make
them difficult use in certain applications....
Imagine F1 guys says I need "X" roll stiffness...erm...well OK, this our best shot.....Hmmmm can't see that working very well
Stop press:..
Just read Terry's input..sums up nicely some of my concerns too...
Can't deny it's simple and clever though...
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kb58
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| posted on 12/1/04 at 04:03 PM |
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We also know the goal is to keep things simple - as in, no ARB at all. This keeps our hard-fought IRS setups independent.
At least in theory... which is where this bar seems to be at the moment... I'll go off and mumble to myself some more now....
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ProjectLMP
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| posted on 13/1/04 at 01:56 AM |
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As far as I am aware, the Radical system is rising rate, that is one of its virtues.
The flat blade type rollbars are not perfect. Unless the outer end is supported they can flutter creating a situation called rock roll which can feel
strange to the driver. Also they are not linear in adjustment which can make them hard to adjust. However, they do seem to be the in trend at the
moment for a lot of race cars.
Home of the Astronomicalcost Mid engined LMP project
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Tudor (Ted) Miron
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| posted on 13/1/04 at 12:17 PM |
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I allways liked the way Radical is expressing his cars and it's sistems. Good sales job!
How ever my personal opinion (which means that it's more likely wrong than right) is this sistem simply doesn't do all those 8 jobs they
mentioning in their pamflet. At list no better than any other.
As fo blade type bars they are used in racing for decades. They do have some drowbacks - just as Paul mentioned. Depending on blade thickness (t),
relation to main bar torsional stifness it's adjustment range can get bigger or smaller. It also may be more or less linear. To simplify: the
thinner the blade the samller the workable adjustable range. Usually all available linear range is no more than 30 deg. But than you have two blades
to work with. That linear range can be big enough to have a very stiff bar and virtually no bar in case of rain.
On the mathematics point - we just dreamed up a little program to calculate blade type bars resultant stiffness - how about that?
Unlike that super innovative Nik sistem good old blade bars give you solutions for very compact neat sistems when in use with push/pull (T bar for
example). Any practical motion ratio and virtually infinite choice of rising/falling or linear rate.
Oh! forgot to say - I especially liked their statement that Nik sistem made 50GBP damper work as 250GBP damper - that was a good one
Cheers
Ted
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