rally car geometry


D

dave benson

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Jul 24, 2008
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401
hi almost finished my build of my tarmac rallycar for club uk tarmac events

http://www.ek9.org/forum/builds-projects/30144-ej9-rally-car.html

setup is avo coilovers, 3 way adjustable, ride height adjustable, energy suspension bushes, skunk 2 front camber arms, mfactory rear camber arms

expectations are class wins !

can anyone list standard ek9 geometry figures, camber toe etc and any advice on modifying these to get it handling

also running ek9 rack/subframe front roll bar and dc2 itr rear roll bar

cheers
 
Hi, for tarmac rallies I would set the front camber to about 1,5-2,5 degrees negative, the rear to 1-2 degrees negative. As for the camber You will have to check the tire temp straight after training or so at the inside/outisde middle and have a look how Your tires wear off.

A good thing in FWD cars is to advance caster aswell. It aint easy in the 6 gen CIvic as You have no traction rods but a lower triangle shaped wishbone which determines the position of the wheel. But You can swap Your upper wishbones left for right wchich will give You a bit better caster. DO the caster thing before adjusting camber as it affects camber when cornering (thats the advantage)

I would also toe out the front a bit (1-2degrees) for better turn-in and the rear at the beggining to 0. Than toe in at the rear will shift the car towards understeer and stabilise the rear while toe out at the rear will make it more oversteer. This should be done aswell before adjusting camber.
 
Arv said:
A good thing in FWD cars is to advance caster aswell. It aint easy in the 6 gen CIvic as You have no traction rods but a lower triangle shaped wishbone which determines the position of the wheel. But You can swap Your upper wishbones left for right wchich will give You a bit better caster. DO the caster thing before adjusting camber as it affects camber when cornering (thats the advantage)
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Not on the EK chassis you can't as the arms are symmetrical. This only works for the EG/DC chassis as their arms are assymetrical.

Keep an eye on those Skunk2 camber arms, I would check them after every stage as I wouldn't be confident in them holding up to rally abuse!
 
Incorrect Kozy

The EK upper arms, albeit minimal, but they ARE offset slightly :nice:
 
Balls, I have no idea if I specified the right one when I replaced one for MOT then. :(
 
dave benson said:
so are the skunk arms sided ?

it's news to me as well !

any more advice ?

thanks
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They would have to be if they are keeping standard castor angle +1deg ish , max castor ive seen on a ek was 3deg with a top/lower arm kit.

castor ultimately is king over camber although running large camber can have near as good affects.

For the rally car geo. Id run -1.0-1.5deg camber all round , start with a good base geo. first. Obviously your castor isnt adjustable yet.
As for toe again 0 all round for high speed courses and maybe increase toe out on the rear on smaller courses or as you get more used to the extra rotation.

I hopefully maybe putting together a custom front geo. set for an ek civic with +4deg. castor arms / new track rod ends etc.
 
Arv said:
How do You do that Mate?:naughty:
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Modified SPC arms , concentric bushes and modified track rod ends from another car should reduce bumpsteer :nice: +4degs minimum , should nearly get 5-6degs. max
 
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