Steering Rack Options - quicker ratio

[Fullchat289]

Experts:

What options do I have to improve driveability on the auto-X course? Seems I'm putting in a whole load of wheel when it comes to the turny bits.. I need to get closer to the FFRs next season, so winter upgrade planning is in full swing. For cost reasons (need to budget for tires/dampers/springs, too), I don't want to go PS and would rather stay manual for now. Is it possible to use a quicker ratio PS rack using it manually and upgrade to PS down the line? Too many questions?

Help, my turbo'd subaru family sedan is quicker than this car around the local auto-x right now in basic ERA trim..this has got to stop.

This thread is specifically about a question relating to a quicker ratio rack, but my car's spec includes:
- Comp Brakes
- ERA Rear
- Single adjustable Spax
- ERA sways front and rear

- Allen.

[Tom Wells]

Fullchat289,

The way I see it, you have two options: do the PS now, or do some serious upper body workouts

Tom

[Excaliber]

Indeed, running Auto X makes PS a worthy consideration.

[RICK LAKE]

Fullchat289 Allen first off forget about trying to outurn an allwheel drive car. I have 2 kids that live behind my house, 1 has a WRX car with hoosier tires, the other is an EVO car with the same tires. WRX puts out 580hp at the wheels. The evo is in the low 500's. BHoth have spent 20K plus for custom differentials(Quieffs) the spelling may be wrong but the lockup of all tires works and a special transfercase with a different internal setup. They both run between 1-3 seconds faster than my cobra with 550 hp.
We had one run at one of the last R&G in St.Loius 2 -3 years ago and ran times as fast as the striker cars. Car pulled 1.2 g's on the course with a G-Force meter in the car.
If you want to get serious about autocrossing, you need to find the rules out and what class you want to run in. Most places are a 200 wear on tires, exhaust under 100 dbs. rollbar, any motor or trans combo. This is for street class.
I don't know what springs you are running but something in the 500-550 lbs rating to start. Either a custom set of shocks or used the double adjustable QA1 shocks. power steering a must. Talk to Bob at ERA about building a car with P/S. Mine had it done at ERA years ago.
Racing seat fron Kirkley to keep your body in location and not be fight the car and your weight sliding around in the car. Go to a couple of driver schools and then polish your new skills. Check the weights on all 4 corners, with yiour weight in the drivers seat. Thrust angle of the car. wheel alignment. Bumpsteer. making sure the front tires turn correctly
. The other big thing is the drive train, power output from the motor, matching ratios of the trans and reaend to keep the max power going to the ground. This is a good start. Rick Lake

[smallblockhead]

Allen, I don't know how much experience you have with autocross, but the guys that have the best times in autocross are the ones that keep the front wheels the straightest. Power steering isn't necessarily required. After my first 6-10 events, I was also convinced I needed PS. What I have discovered after now having 35-40 events under my belt is that I don't turn the wheel as much, and I am steering more with the brakes and throttle. There are things you can do with your current set-up (very similar to mine) that will help. You probably have a lot of understeer in the slower turns, try adjusting the rear sway (anti-roll bar) a little stiffer and trail braking to get the rear end out a little. Turn early with big arcs, not late with small radius turns. If you are just starting out with autocross, I think it's best just to leave the car alone for a year or so, and learn driving without adding too many other variables. The one exception to that is to get some sticky tires. No matter what, as I'm sure you have seen, autocross in an ERA FIA is an absolute blast!

[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

[Excaliber]

Toe out does make it easier to turn in quickly and is the primary cause of instability at higher speeds. With toe out the car likes to "dart" from one side to other with less input from the steering wheel. Works well for Auto X, wears out the tires big time!! Down right scary on the street, I've tried it a couple of times. Very impressive results, great if it's a dedicated tow it to the track kind of car, but don't drive it on the street.

[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.

[Fullchat289]

Thanks again, everyone. Really appreciate the responses.

- Allen.

[ERA Chas]

As I belabored in your 'hardtop' thread, lowering the car 2" will radically improve the transient handling.

[Fullchat289]

Chas:

I appreciate your input, too. I just haven't gotten to it yet, but it's on the punch list.

- Allen.

[ERA Chas]

Thanks for the reply.