I am experiencing with my Cox a bit to find the best suspension setup before I get it on a racetrack.

I have improved the handling quite a bit with strenghtening the rear steering arm fixing rod's picpup point - it was flexing badly. Replacing the outter balljoit with rose joint was also a good idea. I have also reduced the bump steer effect to as minimal as I can get max 0.3-0.5mm on the whole susp. travell.

The car now handles acceptable, but it is still not perfect.

The straight line stability is only good up to 70-75mph. above this when I step off the throttle, it becomes quite sensitive to road bumps and crosswind.
Plus the car still has a tendency for oversteering especialy at speed. Maybe only the LSD-effect? It is not uncontrollable, but still anoying

Any ideas?

Can you list your settings

Front
ride height to top of sill at front
Camber
Castor
Toe on each wheel
Tyre pressure

Rear
ride height to top of sill at rear
Camber
Toe each wheel
Tyre pressure
method of rear toe lock, from memory you use the reverse a arm?

It is possible to get some stability, on my car at castle combe this weekend just gone I was hitting 119 Mph up to Avon rise before hitting the brakes and the car was stable, I did not have the balls to keep it planted any longer as avon rise/quarry have a reputation of destroying cars. That was as far as I was willing to push mine.

Sounds like you are doing some good work on the bump steer, have you checked the rear is good too? is your steering rack mounted onto the subframe or front bulkhead?

Neil

Front.

Ride height: 290mms
Camber: -1degree
Castor: 3.5degree
Toe-in: 1mm each side
Tyre pressure: 1.5bars

Rear.
Ride height: 300mms
Camber: -1.5degree
Castor: ? Used to make wheelbase equal down to 1mm
Toe-in: 1mm each side
Tyre pressure: 1.8bars

At the rear I use normal mini suspension arms with poly bushes. The steering arm is merto type (longer). The steering is locked with an adjustable bar, rose joint each end. The bump steer is corrected to the same amout as on the front.
The rack is attached to the subframe.
I

Increasing the rear toe in may help.

Try increasing it in increments of 0.5mm until you find a setting you like.

I wil try that. What's the maximum You would go?

Next questions from me

Wheel size,
tyre size
and where are you measuring the toe from the wheel rim?

Also does it feel like the rear or front is instable,

I have some ideas already.

Neil

Wheel size: 10x6
Tyre size: 165/70 r10

I have measured the toe-in at the outter diameter of the wheel.

I plan to check my measurements at a garage with a laser-guided tool.

At speed, the front feels instabile, and at fast corners, the rear

On my car I found that 1.5 mm toe in each side was all I needed but I would imagine that if you used more than 2.0mm each side you would start to notice it in the increased tyre wear.

Soo...

I have converted to rear steering rod to rose joint, plus gave it 1.5mms each side. It nearly eliminated the oversteer. Soo I have raised the front steering arm a bit (3mms) to give some slight bump-understeer. It was just an idea, but it worked suprisingly well! Now the car is very precictable in the corners. The grip is quite massive.

Unfortunatly I still lack straight line stability...

Open for ideas...

West?...

Been busy but, quick answer this evening is

Need to work out what 1mm toe in on a 13 inch wheel is on a 10 inch wheel

I was thinking more Castor, From memory when I set my car up I am running 5-5.5 Degrees of castor, which is on a larger diameter tire combination.

I would be very tempted to put more castor on,

Do you have a picture of your rear toe lock improvements

Neil

Thanks!

Sorry. I am not good enough to put in a pic .

Here is the link:

http://picasaweb.google.hu/fmela1/Verda ... 4060255698

http://picasaweb.google.hu/fmela1/Verda ... 7893012802

In my (limited) experience the straight line instability comes from the rear end.

Have you checked for rear bump steer / toe change as the suspension compresses and extends?

I have corrected the bump steer on the rear to virtualy zero. I have a very limited on the left, but it is below 0.2mms on the whole suspenion travell.

Today I have made an experiment: I have put a plain steel wheel on, and attached a long iron pipe to it (maybe 4 feet long). I have checked the suspenson for free move.

I have nearly no clue on what kind of forces can be at the suspension on the road, but using that long shaft, I could turn the wheel in-out some 3-4mms. Half that amout was possible with limited strenght, the rest if I forced it. The movement came from different sounces. I think it is normal. nothing looked to have free play. The two sides are the same.

I will try to give the car 2mms/side on the rear.