Harrison wheel alignment

[sambo]

Thanks for all the suggestions guys. I'll try to respond in one...

Gregg - you're right, toe out encourages the car to turn more. So toe in isn't to blame here.

Krait - standard Harrison (Holden) front end with custom top A-arms. VK Commodore power rack. It's a very "quick" rack on this car. Would an underdrive pulley slow the rack down?

Rog - no I didn't sit in the car and I wouldn't have enjoyed sitting up on the hoist for 3 hrs. I'm sure it makes a difference but I'm not chasing 10ths of seconds, just after a good, stable setup.

Treeve - I might lower the tyre pressures a little to see whether it makes the steering any heavier.

Muzza - looks like I'm off to the bolt bloke on Saturday. I did ask for +6 deg caster so maybe I'll attempt that myself. I have a Longacre camber/caster gauge which I know how to use except I have trouble getting the toe right - relative to the back. Total toe amount is one thing, relative to the centre line is another (for me). Any tips?

Also Muzza, what is the effect of the roll centre being too low?

Here's a photo of the left side. The front lock nut just covers the bolt - maybe 1 thread off. I'll fix that on Saturday.

[Krait]

Originally Posted by sambo

Krait - standard Harrison (Holden) front end with custom top A-arms. VK Commodore power rack. It's a very "quick" rack on this car. Would an underdrive pulley slow the rack down?

My rack is unpowered. Thought a rack was only slowed by a ratio change, no idea of the effect of slowing the pump down.

My modded A arms and radius rods added castor as the issue was a reluctance to self centre.

[muzzza]

Sambo, Your question re roll centre goes something like this.

I mentioned the Holden sub frame is lower in a Harrison than a standard Commodore ( measure for yourself ) ..........this is equivalent to lowering a Commodore without addressing all the other suspension parameters.
Simply talk to anyone who has significantly lowered a Commodore or Skyline without addressing the other issues.......No1 problem ....Bump Steer !!
That is why the market is full of correction kits.
Raising the front roll-centre back to its correct height will increase front roll resistance, reduce suspension compression of the outside front wheel during cornering (less roll). Weight distribution is improved and camber angles don't change as much.......result better corner grip, usually less understeer and improved cornering stability.
Raising front roll centre would also improve the roll axis to make it more compatible with rear roll centre. ( will reduce pitching )
There are a stack of other complex issues involved as well.
The Cobra being a least 10% shorter wheel base than a Commodore, means we have Ackerman issues. Reduced Ackerman is fine when rear tyres are sliding across the race track ( front wheels will remain straighter - ask the drift guys ) but at lower speeds you would get better corner turn in with a little more Ackerman ( Outboard steering arms moved in )
Best solution is always a suspension setup, designed and engineered for the car where adjustments can be readily done........just ask Craig???