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Cortex Koni review

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Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
My race buddy and I both have the Cortex extreme coil over setup with the Konis and race springs with 600# front and 400# rear. I thought I would try to give a write up on the difference they made. Still a rooky to the race world so excuse the terms etc!

1)First thing you notice is how solid the suspension feels compared to P springs, stock Boss shocks. Firmer but more controlled with little problem doing double duty on the street. Set the ride height to pass some speed bumps and parking spots. What a relief!

2) Changing ride height is very simple and can be done at the track easily while changing wheels. Front Konis are quick and simple to adjust. Take care with the rears since they have to be adjusted with the coil overs out of the car.

3) It was my first time with the coil overs so I did very little adjusting. First two session I kept the nannies on and had lots of braking problems and it felt like the car was trying to take over the driving. very uncomfortable as the computer freaked out! With everything turned off the car was much better and quicker. It was controllable at the limit, giving more confidence to push harder. Even when you over cook things the recovery was quick and agile. Will have to set my sights higher as the car is just easier to drive.

My buddies GT has had more time with the same coilovers and runs in a different category with R7s. Fine tuning his car was great. With the LCAs in the lowest position for traction the car was getting light in the rear on a steep down hill section under braking. By lowering the rear of the car another cm you can fine tune the angle of the LCA and the car improved right away. The GT runs with out a rear bar.

Next time out we should have the cars corner balanced and ride height set quite a bit lower. Got the bump steer kit ready to go.

This has been the single most expensive change to our cars but we both agreed that the Cortex kit brought the car to a new level and, apart from tires, was the most important change we have done to the car. So far very happy. I will try to put some videos up of the two cars at work later
 
To control rear lift under braking (especially downhill) you want to slow down (or stiffen) the rebound on the rear dampers. But never make the rebound in the rear more than 2 or 3 clicks away from the front bump setting or the car will be very out of balance front to back. Only make max 2 clicks adjustment before testing. And only do one end at a time. Slow process but the best method.

I've found best ride height is with about .5" rake in the rear. Aids turn in.
 
Nice review and glad to see you liked the improved control. I'm hoping to be dealing with this in just over a week, as soon as the SA JRI's arrive at CorteX.
 

Mad Hatter

Gotta go Faster
5,237
4,227
Santiago, Chile
Its hard to give a definitive answer on lap times. I think I am driving a little differently now then I did about 4 months ago on the same track. Previously I had a best of 1:13.8 and I got it down to 1:13.6, But I added a Dynatech drive shaft and my Nitto 555 RII tires have no tread pattern at all any more (expecting cords any lap now). Its also first time out on Cortex kit.

To get the car on the track I left it about 1cm taller in the front and 1.5cm in the rear. I left it at the same height for the track (it was hot and had to get it back on the truck at the end of the day, that and all the tire change.... ya, lazy).

Next time out will leave it on the ground and see what its like. I feel pretty comfortable that I can drop my times down another second or so. Will be switching to 295/30-18 Dunlop DZ03 in March. I guess a 25" diameter wheel will reduce the bump steer a bit!!
 

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