Steering Rack Options - quicker ratio

[Fullchat289]

SBH:

This is my third season. It's a local, well organized club. We run index based on whp/weight/tire composition. Trouble is, I've run three different cars this year, and only two events in the ERA. It's just plain hard to drive in comparison. However, I agree and can appreciate what you are saying. I was going to leave my BFGs on the car just to achieve a level of balance with the car in it's basic trim save for some shock dampning and rear sway adjustment, so it's nice to know my line of thought is parallel with yours.

Rick:

As always, I appreciate your technical input. To be honest, it will be a while before I can prepare my car to the level you describe, but it's good to save the information you relay for future reference.

Perhaps the best recipe is more seat time.

BTW, what Castor settings are you guys running?? I looked in the manual the other evening and noted ERA specifies around 4.5 degrees. After looking at my latest alignment sheet, it appears I'm running a skoche less than 2 degrees....would moving to 4 or so help with my turn-in and applied steering effort??

Thanks,

- Allen.

[smallblockhead]

Allen,
I'm using the ERA recommended 4.5 degrees caster, I haven't played with the caster at all. Less caster, as I understand it, will do two things: it actually makes it easier to turn the wheel at slow speed, but it reduces high speed stability in a straight line (twitchy steering).

I think that caster also adds negative camber to the outside wheel in a turn, which is a good thing for autocross. I run as much static negative camber as I can with the stock ERA front suspension, which works out to be about -0.8 degrees, and have used -1.5 degrees in the rear.

I've set a very small toe-in up front, and zero toe in back. Some recommend slight toe out for autocross for improved turn-in, I have not tried it.
Gary

[strictlypersonl]

Originally Posted by Fullchat289

SBH:

...

BTW, what Caster settings are you guys running?? I looked in the manual the other evening and noted ERA specifies around 4.5 degrees. After looking at my latest alignment sheet, it appears I'm running a skoche less than 2 degrees....would moving to 4 or so help with my turn-in and applied steering effort??

Thanks,

- Allen.

You should correct your caster to close to the recommended spec. Bump steer is dependent on the height of the steering arm, which changes with the amount of caster. The rack height was configured with the stock caster.

More caster will make the steering more self-centering and a little heavier, but you can counter that effect by running a bit of toe-out, up to 1/8". The turn-in will be much better, but the car will wander in a straight line.

*Note that the pivot shaft for the front upper control arm has a slight offset. If you need more negative camber with the recommended caster, rotate the shaft 180 degrees in the control arm.