ALFAGTV6.COM

[Duk]

I also asked about rear RC on another forum I'm a member of and found this to be very helpful:

"The front part of the chassis is forced to hinge on the front RC, and the rear part is forced to hinge on the rear RC. If the chassis is rigid, it will be forced to hinge on the axis that connects both RCs , that axis is called the roll axis.

The position of the roll axis relative to the cars CG tells a lot about the cornering power of the car; it predicts how the car will react when taking a turn.

If the roll axis is angled down towards the front, (Rear Roll Centre Higher than the Front RC) the front will roll deeper into its suspension travel than the rear, giving the car a 'nose down' attitude in the corner. Because the rear roll moment is small relative to the front, the rear won't roll very far; hence the chassis will stay close to ride height. Note that with a car with very little negative suspension travel (droop) the chassis will drop more efficiently when the car leans over.
With the nose of the car low and the back up high, a bigger percentage of the cars weight will be supported by the front tires, more tire pressure means more grip, so the car will have a lot of grip in the front, making it oversteer.

A roll axis that is angled down towards the rear will promote understeer.

Remember that the position of the roll centers is a dynamic condition, so the roll axis can actually tilt when the car goes through bumps or takes a corner, so it's possible for a car to understeer when entering the corner, when chassis roll is less pronounced, and oversteer in the middle of the corner because the front RC has dropped down a lot.
In terms of car handling, this means that the end with highest RC has the most grip initially, when turning in, or exiting the corner, and that the end with the lowest RC when the chassis is rolled will have the most grip in the middle of the corner.

A very high roll center in the front will make the car turn in very aggressively, but understeer in the middle of the corner. It's nice if you like an aggressive car you can 'throw' into the corners, but I doubt it's the fastest way round the track.

Conversely, if the rear roll center is set very high, the car will turn in very gently, and possibly oversteer after that."

[Carter Hendricks]

I would rather use a Alfa 6 hub like everyone uses here. Check this pic out. Look carefully

Dooley told me to use Alfa 6 uprights a long time ago. I thought I'd seen photos of them somewhere [where???] but exactly how are they different? Is the spindle height higher or is the difference above the spindle? I maintained an Alfa 6 for a long, long time and I remember that the front wheel bearings were larger [rear pad sizes were larger, too].

--Carter

[GTV27]

Thanks Duk - they were the diagrams I was thinking of. Also that explanation corellates with my understanding in terms of result, but not in terms of process (which may not matter so much anyhow).

Applying the low front high rear RC scenario, that theory says that this puts more weight on the front wheels as the car rolls, which gives them more grip relative to the rear and hence promotes oversteer (if I read it correctly).

My take on that scenario is that the low front roll centre will allow the front end to roll more easily than the rear and therefore the rear will resist proportionately more of the roll thereby depriving the rear tyres of some grip and leading to oversteer. This is an extension of the basic weight transfer theory where a tyre can only cope with so much and you get to choose how you use it up.

In terms of the dynamic changes, I had thought about it but not in the terms you've described (ie as to how it could contribute to initial grip on turn then less grip at mid corner as the car rolls (sounds very familiar).

Anyway - lots more to think about there