Handling Questions

A recent open track experience, and the pictures afterword, have shown me that my little FIA has a LOT of body roll. The car also pushes in the corners - it has way more understeer than oversteer.

Here was my setup:

Springs / Shocks: factory Unique Carrera's (don't know spring weight).

Tires: Goodyear Eagle GT II's w/23lbs of pressure.

Sway Bars: Front only.

Alignment specs: Unique factory specs

Ride Height: fairly low with no tire rub

So my questions are:

- What is a good starting point to begin making changes? Should I just start with the rear sway bar, then springs/shocks?

- What was the factory spring rate of the Carrera coil overs?

- Have any of you guys found a good spring/shock combo that gives good handling and a somewhat decent ride?

As always, any other general thoughts or input on this subject are welcome.

Here are a couple of pics from the event, where the body roll wasn't so drastic. Needless to say, it was an absolute BLAST, I'm just looking to keep improving my lap times!

http://www.clubcobra.com/photopost/d...dium/MAM21.JPG

http://www.clubcobra.com/photopost/d...dium/MAM11.JPG

Russ,
Looks like fun! Any interest in doing another track day at Hallett (Tulsa) on October 12? We have a group heading over there and we'd love for you to join.

Russ- Cobras were always able to overcome any natural understeer tendencies with the throttle. Your enclosed pictures certainly don't look bad but I don't know how fast or how close to the limit you were when these were taken. Rear sway bar would help too without having so much effect as stiffer springs on normal street ride.

Phil Souza

Quote:

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Originally Posted by nolastyankee

Russ,
Looks like fun! Any interest in doing another track day at Hallett (Tulsa) on October 12? We have a group heading over there and we'd love for you to join.

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Brian:
I think I have an open track event already scheduled with the local Porsche club at Heartland Park Topeka that weekend, but I'll double check. I really want to drive Hallett though....

Quote:

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Originally Posted by souzape

Russ- Cobras were always able to overcome any natural understeer tendencies with the throttle. Your enclosed pictures certainly don't look bad but I don't know how fast or how close to the limit you were when these were taken. Rear sway bar would help too without having so much effect as stiffer springs on normal street ride.

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Phil:
Thanks for the input on the sway bar. I agree that I will probably try that first.

The pictures were taken early in the day, before I really started pushing it. I'll post some others that are a better example. I tried correcting the understeer by giving it more throttle, but that put me into a four-wheel drift with the car still heading towards the outside of the corner. There are just so many factors in trying to figure out how to get the front tires to get more grip and eliminate some of the push.

I'm not a road racer, but 23 psig in those tires seems low to me. I run 26 in my FIA for normal street driving and would think 30+ would be required for the track.

Russ- Dennis has a good point. You might try running your rear tires up a little....try 28-30 lbs and see what happens. Modern street tires (your Goodyears) are probably better than the comp tires from the '60s. Just remember that radials can be very non-linear when they break away as compared to the old bias tires. Don't get too aggressive in corners where there are trees.

Phil

Stiffer springs and the rear sway bar will help. I hope that Naumoff would chime in because he mentioned some excellent times that he turned in while autocrossing his car with Clay on the Gasholes forum. If I remember correctly he was only a second off of Clay's Elise and that was with BFG tires!
I think Naumoff also ran that event with the spring rubbers in place to set the spring rate. He may be onto something with the use of these instead of trying different shocks and springs until you find the correct combonation. I'm sure you could call Pro Shock or Afco and tell the what your current spring is and the stiffness of the inserts and come up with a good spring rate for your car.
Good luck, It is nice to see you enjoying the car.

Justin

Hallett is a great place to try out some of these mods...Biiiiig runoff areas and no trees!

My good friend tested the spacious runoffs last fall when he melted down a brake caliper and boiled the fluid going into the hairpin.... No damage other than the brake, rotor, and pride.

Russ,
Your car actually does'nt look bad in the turns shown.
I have the factory front and rear sway bars and, from my track experience, I find the roll is still more than I care for.
On the other hand while the roll restraint feels "soft", once the suspension transitions to the outside the car seems to handle just fine. If you install the rear bar mount it in urethane bushings. Swap out the front bushings at the same time.

-Geary

Thanks to everyone for all the advice. I will definitely try adjusting tire pressures my next time out, and I will probably start with the addition of the rear sway bar and urethane bushings before messing with the springs and shocks.

Another addition will be a more substantial seat. Even with the Simpson belts snugged down as tight as possible, I was still being tossed around quite a bit in the turns. Sliding around in the stock seat means you have to hold yourself in while trying to drive at the same time. Quite challenging!

I think I'm going to try one of those short-backed Kirkey vintage style seats.

Quote:

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Originally Posted by Justin Upchurch

Stiffer springs and the rear sway bar will help. I hope that Naumoff would chime in because he mentioned some excellent times that he turned in while autocrossing his car with Clay on the Gasholes forum. If I remember correctly he was only a second off of Clay's Elise and that was with BFG tires!
I think Naumoff also ran that event with the spring rubbers in place to set the spring rate. He may be onto something with the use of these instead of trying different shocks and springs until you find the correct combonation. I'm sure you could call Pro Shock or Afco and tell the what your current spring is and the stiffness of the inserts and come up with a good spring rate for your car.
Good luck, It is nice to see you enjoying the car.

Justin

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Justin is correct. Naumoff does have a good set-up. When an SCCA National Solo Champion drove his Unique, he shaved about 5 more seconds off those times, and he was very impressed with the car. He had only driven the FFR with solid rear axle, and he felt the IRS made it a different animal and very capable car.

Naumoff and I were both Solo rookies. I was overdriving the Elise, because it has so much grip, I kept forgetting to brake, so I spent the entire day driving longer lines and missing the proper apexes. Sometimes you have to go slow to go fast, and I haven't gotten that yet.:)

Hey Phil........it was about time........jeez I waited forever!!!!!;)

I went to Pocono (North Track) Speedway, PA - last month.
I'm running a Unique Motors 427SC with a Southern 427 S.O. stroked engine.
The best thing I've done to help with the handling is buy and run new tires. Alan/Maurice suggested Hooiser Street TD's. They are unbelievable comparing them to my street tires (B.F.Goodrick Radial TA's). Hooiser man reccomends 20-22 pounds cold, after warmup laps they should be 26-28 lbs. They are a bias belted tire, you feel the track wonderfully. It's my experience that radials hold on until they just snap, bias belted warn you all the way until they break off.
My opinion - change your tires to race tires if you want to race safely.

Russ,

I used the rubber spring spacer and cut them to fit. Took out 1 1/2 coils out of the 300# spring.(factory Unique)
I have a rear and front sway bar.

I set my front end up to these specs.

1.5* neg. camber
3.5* pos. caster
1/16th toe in
(These specs are Tom Motorsports in Las Vegas) and he seems to like 700# up front and 600# springs in the rear.

Rear set at .5* neg camber.
40 PSI in the street tires for the auto cross school(the rules)

Steering is very responsive. and I had little roll. The spacers let you play with the spring rate some before buying new springs. It can probably get you close. You don't want to take to many coils out of the spring as it will make the spring to short and you might get coil binding.
I might put one more spacer in and my slicks for the Auto X this Sunday.
I have to count my active coils and calculate the new spring rate.

1st pic is in the middle of a hair pin turn.
2nd is accelerating out of the hair pin turn
3rd is last gate of the slolom going into a 90* right hand turn
The course was short and tight. I felt the car did great for a first timer.
This is the instructor driving and he is pushing the car pretty hard.

Russ - Check this out as a point of reference!
CSX3011
-Geary

Geary,
The driver looks very relaxed even in that hard turn. Do you know who it is?

Tony - I don't know who the driver is. This image is from the Ken Miles/Dan Gurney era. It should not be difficult to track down the information. I'll try to check it out.
-Geary

Russ,

I agree with the comment that your tire pressure in front sounds a bit low. For competition, I run Hoosier Street TDs, and I run 25 lbs front (hot) and 27 lbs rear (hot). Tire pressure makes a HUGE difference in handling. Too high or too low and the tires just wash out. Of course, different tires and cars require different tire pressures (for example, in my C6 Vette with R compound Pirellis, I run 38 front, 36 rear). A good investment is a pyrometer (the kind you stick into the tire). I've got a basic one from Longacre that runs about $100. It's about the only way (other than a lot of trial and error) to find your optimum tire pressure.