bi22le
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| posted on 18/12/15 at 08:21 AM |
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one for the pro chassis engineers / designers - Striker ARB
Hi all.
Follow some summer time reading on chassis design i am still considering building an ARB for my striker but I am going down a different route.
Ill make it in car adjustable using the blade method. I am also going to connect it to the top of the coil overs.
One question i have is regarding th benefits of where to connect it. One of my books states that when connecting to the wheel the ARB should be as
close to the lower ball joint as possible. Contradicting this many F1 cars as well as others mount theirs inboard often where i have said, on the
shock side of a bell pivot or shock top.
Assuming there is no movement in the suspension system what are the benefits of mounting it low down close to the hub? Is it just a case of packaging
the ARB and allowing maximum distances for ARB leverage and torsion forces?
Any other advice and help you want to chuck in, chuck away!!
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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mark chandler
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| posted on 18/12/15 at 08:32 AM |
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You need to be looking for greatest movement, also some pretty hard mountings as most cars the wheels will have moved an inch just taking up slack in
the ARB.
As an ARB is really a straight Spring I would try and keep it long as you do not have access to F1 materials, all which points as getting as near as
possible to the lower ball joint.
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daniel mason
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| posted on 18/12/15 at 08:40 AM |
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With regards to f1- everything is done for packaging reasons to keep the airflow where they want it!
Contact ash mason on uphillracers.hes specifically designed various for the Westfield he ran and are supposedly excellent!
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nick205
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| posted on 18/12/15 at 09:16 AM |
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Do RAW not offer an ARB designed for the Striker?
Could be a good start if the design work has already been done!
ETA...the 205 GTI has front and rear ARBs. The rear is designed to work within the constraints of the torsion bar rear suspension set up. The front
is mounted on the front subframe and connected to the front shocks with ball jointed rods. It's effectively a straight spring acting across the
front wheels held in place with hard rubber mounting bushes.
[Edited on 18/12/15 by nick205]
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Volvorsport
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| posted on 18/12/15 at 09:51 AM |
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Front or rear?
I would be tempted by a Caterham one first.
www.dbsmotorsport.co.uk
getting dirty under a bus
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peter030371
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| posted on 18/12/15 at 11:45 AM |
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I assume you are aware of this old topic? Stylus/Fury/Striker etc
ARB
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Camber Dave
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| posted on 18/12/15 at 01:05 PM |
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The prime purpose of an Antiroll bar is to transfer weight to the outer, loaded, wheel.
This increases the proportion of the total weight transfer on to that wheel.
The increase in load increases the slip angle and thrust the tyre delivers.
By selecting the correct length, lever arm length and diameter of the bar combined with the existing – or revised spring rates the car can be designed
to have a prearranged amount of Understeer or Oversteer. This is when a car is said to be balanced in a corner.
Obviously acceleration transfers weight to the rear so this needs to be allowed for in the calculations.
The ARB also incidentally reduces roll to improves the wheel camber change.
An off the shelf aftermarket or homemade bar to one end of the car will reduce Roll but will also change the balance.
A short, thin and light bar inboard can have the same effect (on weight transfer and roll) as one 3 times the diameter and the full width of the car,
depending on where the drop links act on the dampers, rockers or wishbone.
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theprisioner
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| posted on 18/12/15 at 04:35 PM |
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Can't be that much different to a J15, made a fantastic difference see:
http://sylvabuild.blogspot.co.uk/2014/11/anti-roll-bars-arb.html
http://sylvabuild.blogspot.com/
http://austin7special.blogspot.co.uk/
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daniel mason
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| posted on 18/12/15 at 05:03 PM |
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I actually much prefered my old radical with the rear ARB removed. Always ran with a front ARB,but not rear!
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britishtrident
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| posted on 18/12/15 at 07:12 PM |
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The main use of an adjustable arb is to allow quick simple adjustment of the front-rear balance of the handling by altering the roll couple
distribution
The best and simplest place to mount the wishbone end of a front arb is on to use special extended bolts on the lower damper mounting.
The further out board the mounting the better.
On a front engine rear drive car arb is always a good idea because it allows the front suspension wheel rate (ie spring rate) to be reduced relative
to the rear while maintaining the front-rear oversteer-understeer balance.
By allowing the use of softer front springs the car will stay more level front to rear crossing bumps, ie ir reduces the bucking bronco effect as
first the front then the rear wheel cross bump.
It is a common mistake to use too stiff a bar on a light car, the classic example was a Robin Hood model that used the standard Sierra ARB, the bar
was so unsuitable it completely removed any independant suspension movement of the front wheels.
With suspension on a home build following current F1 practice usually isn't a good idea F1 cars are all about downfore several tons of down
force and reducing drag, most of an F1 cars suspension is in the tyre side walls. There is probably more to learn from the suspension used on a 1960s
or 1970s F1 car than the current generation.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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bi22le
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| posted on 18/12/15 at 08:05 PM |
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Thanks for all of your replies.
I don't have my notes to hand but IIRC my plan is to stiffen up the rear, fit ARB on the front and reduce spring rate. This is all to dial out
the current under steer I am suffering (although I predict may make non-LSD traction at the rear worse).
I am happy with my tyre pressures and adjustment on my shocks, I have already played with these. The car is also full geo set up.
So, to answer questions \ points raised;
F1 materials are not available but CAD FEA and a testing lab is. Im pretty certain I can design some 4mm steel bar to provide the flex I need. I
understand they are very sensitive to air flow, packaging, COG and many other things, I watch as much behind the scenes F1 stuff as I can. The books I
have actually reference 1970's F1 and Nascars so along our chassis design lines and tech!!
ARB is on the front.
I also feel my suspicions are correct. Full width to outer edges of wishbone are due to maximise leverage \ distance travelled. The obvious game
changer here for me is the fact I have INBOARD suspension at approx. 1:1 allow almost as much movement under the bonnet as out of it. By creating a
very rigid cross bar and single link, the other link can be the flex bar providing the torsion spring effect. Mounts wound have to be very HD but
again, I have a sneaky light weight plan for that. . .
Not sure if RAW do one, ill check.
Peter030371 you deserve a special mention. I have not seen this, although I have googled this type of thing to death. Ill have a good read of that in
a min.
Thanks for all the other inputs. Ill update you when there is progress. I al half hoping to have something for my 2016 track day season, between
decorating, studying and being a dad of a toddler, I am probably looking more like 2026!!
Any other thoughts \ ideas welcome.
Track days ARE the best thing since sliced bread, until I get a supercharger that is!
Please read my ring story:
http://www.locostbuilders.co.uk/forum/13/viewthread.php?tid=139152&page=1
Me doing a sub 56sec lap around Brands Indy. I need a geo set up! http://www.youtube.com/watch?v=EHksfvIGB3I
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adithorp
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| posted on 19/12/15 at 12:21 AM |
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I've got one on my Fury. Not F1 tech... but it is Dellara IndyCar tech...
https://www.youtube.com/watch?v=gL52K9WGzoI&index=66&list=UUkqX3uMKLeoBRZz5bypNzjQ
Gives from no effect to very stiff and all adjustment from the dash on the fly. Works really well. Great when you get a rain shower at one end of a
track and dry on the rest.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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