Autox setup and results

[Daywalker]

I am finally getting around to setting up the car. I got the alignment sorted out and put on some three year old S04 Hoosiers and got to do some decent runs. Everything else is stock. Had passengers all day, which was fun. I ended up 4th Raw time and 4th Pax. Over all, not a bad day. The car will definitely be quicker with some new rubber.

If your autocrossing, I definitely recommend getting the alignment done. It makes the rear more stable. I also ran a full tank of fuel. The rear stayed planted fairly well. This was on a slow and tight course, never got out of second and never got close to redline. The car has potential at least locally.

Autox Results 4/22/07

[BlueSkyRL]

I've noticed too that the rear ends on our RLs are very squirally. My wife reminds of it everytime I squeel the tires

[TOY4TWO]

what alignment settings are you running, camber, caster, toe in / out?

Gotta get some baseline auto-x settings going

[KappaMan]

I took a look at someone's pictures of their tires after a test session (request of a friend on their... 'kappa' ), their tire probe data, bump steer measurements at their race shop, and where they were setup. This was a test session at a road course, so your actual settings may vary for autoX...

In the end, I recommended they try -2.1 front camber, -1.5 or -1.75 rear camber, .10 toe in front, 0 toe rear, front caster as high as they could get it and even, and rear caster -4.5 or -5.0 if they could get it there (they borrow the rear caster gage from their local pontiac dealership).


"parking lot checks" so far have been favorable. Local track data to follow, but they did ask I not disclose their race team name or their state/location....

The kappa seems to wear heavy on the front outside tires, more than the rear.


FWIW,HTH.

[Daywalker]

KappaMan has good advice above. Keep in mind you can get more camber up front if desired and I went with 0 toe front an rear for now. Results may vary.

[snaponbob]

After 5 events, two test and tunes, and an Evo Challenge I have learned a lot. Much translates from previous car set ups, but many things are new to deal with (full double wishbone independent suspension, power, turbo, etc.), so more has to be learned.

1) Kappas are basically engineered to understeer (GM always does this). With ANY setup on a Kappa toe IN on the front will make that worse. With almost ANY car a bit of front toe out will help turn in. The cost will be increased street tire wear, and the car will "nibble" at crowns and uneven pavement.
2) Stock alignment is .5 degree negative camber front and rear, 8 deg neg caster front and 4 deg neg rear, zero toe front and rear. Although caster is important, it will be hard to maintain it when a bunch of camber is cranked in. The rear may be impossible to retain is the GM Kappa caster gauge is not available. Front caster retention will be a function a matter of how the frame was welded up. Some people with older Kappas retained high caster numbers at 2.5 neg front camber, but most will see caster loss past 2 deg neg front camber (as I did). The critical aspect is EQUAL (or near equal) caster side to side to avoid induced pull.
3) My first alignment was 1.75 neg camber front and 1 deg neg camber rear, zero toe f/r, 7.5 neg caster front, rear unknown. IT HELPED. The understeer threshold was raised, but was still there. On Hoosier A6's set at about 40f/38r I was still killing the front tires. (Partially set up, partially driver!!)
4) Second alignment was 2.3 neg camber front, 1.5 neg camber rear, zero toe, 6.6 neg caster front, unknown rear. IT HELPED, but only "some". Same tire issues, but again at a higher threshold.
5) Installed FE2 front bar to "hook up" the front and balance the "workload" front to rear. WOW!!!!! Oh, the front end is "hooked up". At 40/38 the car was nearly undriveable. The car now felt like a drifter. I finally set the tires to 44/36 and things were much better.
6) There is room on the FE2 bar to drill another link hole forward of the stock hole, and that will stiffen the bar a little but I do not know how much. This should help balance the car some.
7) Koni single adjustables should be available in June/July. This will really allow some chassis tuning.
8) Currently I am in discussions with a fabricator in Florida for an adjustable front sway bar. (In SCCA Solo stock class only the front bar can be used for tuning. Shocks can be changed, springs can not.) Once I have the bar issue settled I will install polyurethane bushings for the bar's frame mounts.
9) Gearing SUCKS, and the car is heavy. Get this - Redline/GXP = 3050 pounds, Corvette ZO6 = 3200 pounds (yes, I know, ZO6 is an S/S car, but you get the point) C4 and C5 Vettes = ~3300 pounds, S2000 = 2750 pounds.

Upcoming changes --
1) Hawk pads (got 'em, doing them next week)
2) Konis as soon as available.
3) Modify FE2 bar.
4) If I can't get an adjustable front bar I'll extend the FE3 bar and try that.
5) My driving!!!!
6) Replace two corded A6s (next week). May change to V710s to keep from going broke.
7) Driving to Eau Claire, Wisc., Monday to have Curt Engineering fit a trailer hitch so I can tow my tires at 25 MPG instead of towing my Redline at 9 MPG.
8) Start changing the toe out at events to about 1/16th to help turn in.

[Nemesis]

Sorry to get into the mix knowing nothing, but can these adjustments be done on a stock RL?

[snaponbob]

Originally Posted by Nemesis

Sorry to get into the mix knowing nothing, but can these adjustments be done on a stock RL?

Sure. The front and rear lower control arms have eccentrics at each pick up oint on the chassis. The FE2 sway bar is a bolt up WITH the bushings and brackets from the donor car. When the shocks come available there may be need for spring compressors.

[empirekevin]

I do not like the understeer deal. It is a real party pooper when you approach a corner and you have to drop down to speeds that my Dodge Durango can maneuver.

Snapon, I notice that this post was before the adjustable shocks and some of the springs but I was wondering what your final outcome is and what it is. Anotherword, What do you run now?

[snaponbob]

Originally Posted by empirekevin

I do not like the understeer deal. It is a real party pooper when you approach a corner and you have to drop down to speeds that my Dodge Durango can maneuver.

Snapon, I notice that this post was before the adjustable shocks and some of the springs but I was wondering what your final outcome is and what it is. Anotherword, What do you run now?

When I was at the SCCA Nationals in Topeka last week running A/S. (Thursday was NOT pretty but Friday was very good. Overall sucked. But NEXT year WILL be better.) In speaking with the Pontiac factory autocross guys they confirmed my long held suspicion that GM designs in understeer with a minor focus on liability. Also, all of GM's performace cars are being chassis tuned at the Nurburgring. Thus the results are NOT geared to autocross. But I can tell you that the GXP Z0K is very good over and above the GXP/Redline but is NOT a magic bullet. And with about a 1.5 to 2" drop, daily driving is a challenge. While at the Nationals it was clear that car set ups were all over the map. So, what have I done? Here goes -

I have absolutely no fear of sharing my set up, unlike some people. When all is said and done, the best driver most likely will win even in a borrowed car. The driver is the best mod in a race car. (And I am still working on my driver - ME.) I will first address set ups OTHER than SCCA A/Stock. All the GXP Z0K pieces will fit on and Kappa. This includes a beefed up rear frame member, spring, and sway bars. The car will be lower and stiffer than both either an FE2 or FE3 car. With a factory alignment the car will understeer at it's limit. For Street Prepared classes these pieces can be used and it's legal. Aggressive alignments and adjusting tire pressures can get under/oversteer under control. Single adjustable Koni's are MAGIC. They absolutely transform the car. By setting the rebound you can get the car to do whatever you want.
Now, SCCA A/Stock notes. Since my post in April (or whenever it was) I have changed to an FE2 front bar (legal since only the front bar can be played with in stock class) and back to the FE3. A good experiment but it failed. Pictures showed that at the limit the car was leaning too much even with the FE3 front bar and so I hoped that increased front roll stiffness (counter to conventional techniques) would control overall body lean and keep the rear camber loss at a minimum. I punched new holes in the front sway bar forward of the existing holes (thus raising roll rate of the FE3 bar) and it did help. This was pre-Koni. Tire pressure was used to adjust the handling a bit. With that success under my belt I ordered a Saner front bar that is about 40-60% stiffer than the FE3 bar. Once I got it mounted it did what I wanted - flattened out the car. It demands proper technique as terminal understeer is a bit worse, but not nearly as bad as one might suspect. The car got quicker. A couple events before the Saner showed up I finally killed my 245/35X18 Hoosier A6's and replaced them with 295/30X18's. BETTER!!!! After the Saner bar was run for a few events my Koni's showed up. I also did another alignment to 2.8 negative front with max available caster (about 6.7 degree) and left the back at 1.8. The factory rear caster is 4 degrees. Keep as much as you can, and if the shop does not have the special GM caster tool, well, you got what you get!! With the Konis installed I was able to adjust the car to do whatever I wanted. I have the Saner in the middle position, the rear shocks full stiff (and it IS stiff!!) and I trim the handling with the front shocks (which were set at 1 1/4 turns firm). Tire pressure was all the way down to 33/31 at Topeka with even temps on all tires and no excessive rollover. Caution: Topeka has low traction so be careful at you home events. At home in KC, I have been running 39-35(+/-) but with the bar, Konis and final toe settings I may be able to get away with less. Generally the higher the available traction the higher the pressures. We have more traction pads in KC. Now - to settings. Earlier someone mentioned toe IN for the front. That is the factory recommendation. Conventional autocross wisdom dictates front toe OUT for better turn. It's true, and it helps loosen up the rear. Conversely, rear toe IN helps settle a loose rear end. Well, I have been running about 1/8" toe out front with zero toe rear all year. The difference is quite noticeable no matter what else is done to the car. But it's hard on the tires on the street. So I make the adjustment when I change tires at the events. At the Nationals I played with rear toe in on the Sunday practice and liked it a lot. Thursday I ran 3/16" front toe out and 1/8" rear toe in. It was too much at both ends. Too MUCH front toe out can screw things up, and it did for me. Same in the back, and it did. Friday I set the car with 1/8" front toe out and 1/16" rear toe in and the car was great. I have two more events locally and that will be the set up. I have not run the car the same way more than twice this year, including three changes at Nationals. But I found the sweet spot - for me. Yours may be a bit different. But most Kappas are set up about 2.4-2.6 neg camber front, about 1.7 degree negative rear, and play with the tires from there. Setting the toe is fairly easy with a Longacre toe plate set (about $60). You'll need a 22mm and a 13mm wrench. If you want the method I use PM me. It's pretty easy. After the final event I will spend the $70 to re-align the car to stock for the fall and winter (all that camber is starting to show a little bit on the front tires) and set it back to "full kill" in March.

PM me for details on acquiring Konis for cheap. I know a guy that knows a guy sort of thing. Now, here is a bonus with the Konis. GXP Z0K springs set the GXP about 1.5" lower. But so do the Konis on a non Z0K GXP or Redline. Why? Konis are low pressure gas and the Bilstiens are higher pressure!!! I had my car car parked behind a Z0K converted GXP on Sunday and a lot of people were looking under my car for the Z0K parts. Why? It sat JUST LIKE a GXP Z0K. Surprised the hell out of ME!!!!

So, there you. I am not saying that my set up is THE set up, but most of it is fairly common. Just like the S2000's seem to have settled into similar set ups, Kappas will eventually find their "happy spot". The big money is tires, but for less than one set of R-comps you can get a Saner or Pontiac GXP Z0K front bar, a set of Konis, and a half dozen alignments. The toe adjustments can be down track side. Air is free. And Evolution Schools can make all the money work better.

[empirekevin]

Originally Posted by snaponbob

All the GXP Z0K pieces will fit on and Kappa. This includes a beefed up rear frame member, spring, and sway bars. The car will be lower and stiffer than both either an FE2 or FE3 car. With a factory alignment the car will understeer at it's limit. For Street Prepared classes these pieces can be used and it's legal. Aggressive alignments and adjusting tire pressures can get under/oversteer under control. Single adjustable Koni's are MAGIC. They absolutely transform the car. By setting the rebound you can get the car to do whatever you want.

Although fine tuning all aspects of the suspension are needed to perfect your car for autocross, which of these statments are true to fix the understeer issue?

1. Koni's are all you need.
2. A aggressive alignment is all you need.
3. A good set of swaybars are all you need.
4. You need it all son if you want to dance with the devil.

[snaponbob]

Originally Posted by empirekevin

Although fine tuning all aspects of the suspension are needed to perfect your car for autocross, which of these statments are true to fix the understeer issue?

1. Koni's are all you need.
2. A aggressive alignment is all you need.
3. A good set of swaybars are all you need.
4. You need it all son if you want to dance with the devil.

Ummmmmmm #4 with one caveat; in stock classes only the front bar can be changed. So, a Saner or GM Z0K front bar for about $225-$250 plus shocks for about $600 (yup, that's what I paid). An alignment for about $70-75 and you are set except for tires. The REAL trick is getting all to the event. I have a custome made hitch so I hawl a cheap trailer with the race rubber and a cargo box with all my "stuff" for the event. At 70 mph I loose about 3 mpg.

Hey, I just noticed you are in NW Arkansas. We have events Oct. 21, 28, and Nov 4. You are about 3 hours from KC. Why not come on up?

[empirekevin]

Maybe so. Is there a web page with the info on it?

[snaponbob]

Originally Posted by empirekevin

Maybe so. Is there a web page with the info on it?

Yup. http://www.kcrscca.org/ Then click on the schedule link. It will have everything for KC, Topeka, and Salina. If you need directions PM me.

[kwayne]

New to autocross (have only done it twice, on stock tires) so pardon my ignorance
1) what is in the Z0k GXP pkg?
2) sway bars-FE2, FE3, Saner? bushings, what is stock urethane or rubber? Can bushings alone make a difference like in offroad trucks?
3) tires: can a rim height increase of less than 3mm really make that much of a difference?
245x.35=85.75mm
295x.30=88.50mm
I was under the impression that a shorter stiffer sidewall was preferred?
4) tire pressures: is it better to have higher pressure in the steering wheels or driving wheels? and at what ratio difference in PSI?
Thanx from all us newbies.

[snaponbob]

Originally Posted by kwayne

New to autocross (have only done it twice, on stock tires) so pardon my ignorance
1) what is in the Z0k GXP pkg?
2) sway bars-FE2, FE3, Saner? bushings, what is stock urethane or rubber? Can bushings alone make a difference like in offroad trucks?
3) tires: can a rim height increase of less than 3mm really make that much of a difference?
245x.35=85.75mm
295x.30=88.50mm
I was under the impression that a shorter stiffer sidewall was preferred?
4) tire pressures: is it better to have higher pressure in the steering wheels or driving wheels? and at what ratio difference in PSI?
Thanx from all us newbies.

Hoo boy --- here we go!!
1) There are two versions of the Kappa platform - Pontiac Solstice and Saturn Sky. Each has a "base" version in the 2.4 FI (port injected fuel injection engine) and the base (FE2) suspension. However, Pontiac has an "sport" version of the 2.4 with option code Z0K. Saturn does not. The GXP is a bare bones Solstice with no upgrades except the Z0K package which includes posi, ABS, and the same FE3 suspension on the turbo Kappas except the front springs are shorted than stock. The turbo Kappas are the Solstice GXP and Saturn Sky Redline. This car has the newest Ecotec engine (2.0 direct injected) and turbocharger. The GXP/RL both have the regular FE3 suspension which is firmer shocks, springs, sway bars. Recently Pontiac rolled out a Z0K suspension package for the GXP, but again not available for Redlines. This package has different springs, sway bars and a replacement rear frame member. Again this is a "club sport" version. And it is about 1.5" lower. And it's pretty stiff.
2) FE2 and FE3 refers to GM parts codes for factory assembly. As above the FE2 and FE3 packages are model specific, although completed interchangeable across all Kappa versions. I think that the FE3 bushings may be firmer rubber than the FE2, but not sure. Polyurethane bushings are a WONDERFUL thing to have for off road or dedicated sport use on road cars. But they can hammer you senseless on a newer street car. I have them everywhere on a Triumph TR8 and they do tighten up what is otherwise a very loose car. The Kappas are very stout, stiff cars and poly bushings might not be a good idea except for a dedicated track car that gets trailered. A Saner sway bar is an aftermarket adjustable sway bar made by Saner Fabrication in Florida.
3) For purposes of properly addressing this question, the rim is the metal thingy and the tire is the rubber doodad that goes on the metal thingy. The example you gave was the 245/35X18 vs. the 295/30X18. The interior diameter is the rim diameter, the first number is the "section" WIDTH, and the middle number is the aspect ratio (section vs. the measured difference of rim diameter and overall tire diameter. The larger the FIRST number they wider the tire. The small the middle number the "shorter" the sidewall. Low aspect ratio tires tend to have firmer ride because they flex less, which is an advantage in hard driving. The 295 you cited is taller than the 245 (despite a shorter side wall) because although it is the same rim application, it is a bigger tire overall. If it were a 295/35, it would be larger in o/a diameter because of the aspect ratio I explained. Confused yet? I wouldn't recommend anything less than a 40 series on the Kappas for a) overall ride quality, and b) taller sidewalls are better at protecting the rims from curbs and chuckholes. Short stiffer sidewalls are GREAT for racing. Oh, and they LOOK good, too.
4) Tire pressures. I think GM hit the 10 ring when they recommended 29 psi front and rear for the Goodyears. Any less and the car gets "mushy" (high tech term there, huh?), and much more and the handling and ride get "edgy". Also, excessive are pressure for road use may crown the tread and increase wear. For racing purposes just erase the previous two sentences. If you want to start a free for all, just drop a case of beer in a room full of race car/autocross drivers and ask what proper tire pressure should be for XYZ track/course. . Then GET OUT. There were at least 10 entries in Kappas in A/Stock at the Nationals last week. Not only was there not a consensus of tire SIZE (let alone brand) but if any two cars were running the same pressures it was a coincidence. It is a matter of "feel". Street and track are very different, so the tire demands are different. I have run anywhere from 43/39 (earlier alignments and 245/35x18 Hoosiers) all the way down to 33/31 (more aggressive alignment and 295/30X18 Hoosiers) at the last day of Nationals. It just "depends". Loose rule of thumb for autocross is lower traction = lower pressures and greater traction = higher pressures.

So. now that your hair may be on fire, I certainly hope some of that helped.

[snaponbob]

PS, don't ask about shocks until I have had a chance to nap and recuperate!!!!!

[SkySoldier]

Originally Posted by snaponbob

PS, don't ask about shocks until I have had a chance to nap and recuperate!!!!!

Ok. Nap's over. When I was running my FS Camaro, I ran with 1/4" wheel spacers. I'm thinking about using them on the Sky (yes, longer bolts are required), and I was wondering if you are using them with yours?

Also, how much better would you rate the Koni shocks over the stock?

Thanks in advance!