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First Autocross of 2009
The autocross season got off to a soggy start on the Triple Skid Pad at Summit Point. The NCC had their first points event of the season on Saturday. I’m running a street-tire class in the BMW this year. The rain meant I had a good chance of scoring well.
I was fastest most of the morning session and ended up fourth in my class. The three ahead of me all ran in the afternoon when it was dryer. The course was partially under water. The surface is new and slick. The run off areas are muddy and deep.
NCC BMW CCA HPDE Summit Point 3.17.09
No, that’s not a vintage photo from 20 years ago. That’s from this past weekend at Summit Point. It was time for the annual Spring HPDE on the main circuit. It was a weekend of a number of firsts for me. First time out on R-comps; first time for this car; and first time on the track driving a rear-wheel drive car.
[The sound quality is poor. If you have a fast connection, click the HD button to get better picture quality once it starts playing.] The video doesn’t convey the sense of speed down the front straight. I was just touching on 120 before the braking zone. There may have been a bit more in the car, but since it’s more than 20 years old and has over 215,000 miles on it, I didn’t want to have to buy a new engine, so I didn’t push it. Since it’s so much quieter than the MINI, I often ran it out to 7,000 RPMs on the straight from turn 9 to 10 before I got my rhythm down.
The car was much more like the MINI than I thought it would be. They are similar in weight and braking characteristics, thought the MINI brakes have more bite. It is very neutral in handling like the MINI, but no where near the amount of torque. You have to get on the power much sooner in corners and are rewarded with trailing throttle oversteer. Toward the end of Sunday, I felt as comfortable diving it into an apex as I did the MINI.
Here are a couple of things to remember for next time on the main circuit in this car.
- Between 2 and 3 don’t follow the edge of the track. Line up in the middle toward the gap in the tire wall, wait for the dip after the access road to turn in and use the camber on the inside.
- Tap the brakes right after the crest before 4 to settle the car, turn in, and full gas through the apex. Brake straight into 5.
- As soon as possible, get back on the gas in 5 to counteract the understeer. Go wide to keep up speed into 6. Position in 6 isn’t as important as a good set up to apex 7.
- Between 7 and 8 starts steady throttle to max gas at apex of 9. Try to get the shift into 4th gear before 9. Don’t early apex 9. (See M3 photo below.)
- Move the brake point for 10 back a bit. Key off of power lines. Brake less, carry more speed into corner, full gas through the apex. There is plenty of room to track out. An extra 3 MPH at exit is worth 10 MPH at the end of the straight. Remember to adjust brake zone into 1 with that in mind.
- Try to separate end of braking from turn-in in your mind as you adjust. Work on one thing at a time. If you can get on the gas before the apex, then your speed at turn-in isn’t high enough.
Stealth Ready for Shakedown
With more than 24 hours to spare, I finally finished the F-22 for the first track outing of the year. Since I was running out of time, I had Dan Martin’s shop finish the front suspension and fix the cam gear seal.
I’m really impressed with the Bavauto springs. The ride height is aggressive but not slammed. The ride is firmer but not harsh. I’m looking forward to getting it on the track and seeing if I still need to upgrade the sway bars. Compare the ride height to the 20 year-old stock set-up.
I also had them install the IE front strut bar as well. The bar looks really slick in basic black.
Now all I need are some go-fast stickers…
Stealth Springs into Spring
Thanks to the break in weather, I was able to start the suspension work this past weekend. The photo above shows the difference in size between the stock rear spring and the Bavauto spring.
Shorter springs require shorter shocks. This photo shows a comparison of the Bilstein HD shock with the Sport Shock.
This photo shows the stock spring prior to removal. Changing springs and shocks on the rear is fairly simple.
- With the car on jackstands, remove the wheels, and support the differential with a floor jack.
- Lower the exhaust by disconnecting the two rear brackets and the rubber hangar. Support the exhaust in the lowered position.
- Remove the bolt from the differential housing that mounts the differential to the subframe. Slowly lower the jack. This will take the pressure off of your axle shafts. You may have to disconnect your speedometer sensor if the wire is too short to drop.
- Remove the nuts that hold the swaybar to the trailing arm. Use another jack to support the trailing arm and disconnect the shock at the base. Disconnect the shock from inside of the trunk, but don’t let it fall. Remove the shock.
- Press down on the trailing arm. If your springs are really worn out, you may be able to remove them by hand. I didn’t have that luck so use a spring compressor to carefully remove them.
- Replace spring pads and reinstall new spring. Jack up the trailing arm a bit to hold it in place.
- Install the shock from inside the trunk. Now is a good time to replace the gasket under the shock mount. Think about adding reinforcing plates or a strut bar at the same time.
- Reattach the lower shock bolt. Tighten all bolts to torque specifications.
- Repeat for other side.
- Raise the differential and reattach bolt. Torque to specification.
- Attach swaybar bolts and wheels. Remember to torque the lugs.
- Attach exhaust hangar and brackets.
The photo above shows the new springs installed. Notice the difference in height by the gap at the top.
I also added the strut bar. I even changed out the brake calipers while I had everything available.
This final picture shows everything put back together with the new RA1s and Konig wheels.
Compare that to the off-roader height from before the change.
The final change was the addition of a new lip spoiler. It’s actually not the right one for this car, but with the lowered ride height and shallower design, it has a better chance of remaining attached after multiple autocross cone-crunches. Notice the ride height in the front. That will come down when the front springs are changed out.
Stealth Enters the Home Stretch
I had some time on my hands the other night, went out to the garage, and much to my surprise, there’s nothing left on my punch-list to do on the BMW. Sure there’s plenty left to do — just not much I can do myself. The new suspension components have started to arrive. Once the new brake calipers get here, I’ll throw on the rear springs and shocks and take it down to Dan Martin to install the front struts/springs; fix the leaky cam gear seal, and flush the brakes. The first CCA track weekend is in less than 3 weeks. I should be in a good position to base-line the car. I won’t do the full Spec E30 suspension right away. I’d rather get some seat-time and understand how the car handles with only minor changes before going with a full race set-up.
