Need a little help figuring something out

[Ron Sutton]

Hi Lance,



It is cool to see how much progress you have made with your car at the track. I remember when you posted this in April ...

Car drove a LOT better today, part I'm certain was due to straightening everything with rear suspension out..the rest was the tires. I usually finish about 60-70th out of 100 cars or so in raw time...38th out of 97 cars today!!

Now, with a little work & very little budget, you have improved your car from a pushing mess ... rear tires bouncing ... to a flatter running, neutral handling, smoother "AutoX racer" that is faster, fun to drive & impressing people at the track.

Well, yesterday's event was a whole different story with the new setup.

Here were my times for the day:

Heat 1
#1 53.123 (hit a cone on the inside of first sweeper, was surprised how well it turned)
#2 52.438
#3 52.307
#4 50.260 (last one that was going to count, so I stepped it up)

Heat 2
#1 50.232
#2 49.820
#3 49.553
#4 50.123 (over drove the corner after the last straight, wheel hopped under braking and dirttracked the corner)

Here are the posted raw time results

http://www.kcrscca.org/results/solo/...vent11_raw.htm

Officially I finished 25th out of 100 drivers. Had my 49.553 counted I would have finished 18th.

Check out the list of cars I finished ahead of! A LOT of those cars are considered "autocross" type cars and a bunch of them were running on some sort of racing compound tire as well. This was done with my 3700 pound 1985 Sport Luxury Monte Carlo with a full interior including AC! Nothing better in my book than beating them at their own game.

I'll let Ron talk about the changes we've made and how they've affected the car from his perspective...I LOVE them and think it can only get better. It's unbelievable the grip this car has now, even with the problems it still has which we will continue to correct upon.

Not sure that it makes any difference but I was up into the mid 60 mph range at the end of all 3 straight stretches on that course. It was really giving the low horsepower cars fits...most of them were shifting 6 times or more during a run.

You should have seen the grin on my face get bigger and bigger as I walked the course for the first time...and then after each run.

Let's recap what you did for anyone following along:

1. Mapped the roll center & corrected a RC migration problem
2. Raised car 1" to increase front travel with spring adjusters
3. Installed larger front sway bar ... kept same 575# springs
4. Installed stiffer rear springs from 125# to 225# ... kept same rear sway bar
5. Installed DSE LCA's to add caster
6. Modified LCA holes to get a little more caster
7. Increased caster from 5.5° to 7.5° (Better but still about 1.0° -1.5° less than optimum)

Now ... with the higher travel front end & bigger sway bar ... the car is working the front tires much better. The caster is helping keep the contact patch much better. This is one of the keys to taking the bad push out of the car that you had ... and why the corner speeds are up. You can not make a car go faster the front tires have grip. The videos show you still need that extra 1.0° -1.5° of caster. Winter project maybe ?

The stiffer rear springs are keeping the rear tires planted better ... no hop ... plus helping to keep the rear roll angle in line with what the front is doing ... while helping to keep the inside front tire planted better. As you know, I worked out the spring & sway bar combo for the correct FLLD & RLLD. Anyone following along ... the calcs showed the rear spring rate needed to be 207#. I asked Lance if wanted to err on the tight/pushy side or the free/loose side ... and he choose the free/loose side ... which is why we went with 225# rear springs.

Lance, if after you dial in the new shocks ... you find the car is still a bit on the free side ... you can always go to 200# rears to tighten it up. You may find in the early Spring & Fall when the weather is cooler ... and the track has less grip ... the 200# rear springs may be the hot ticket. Then put the 225#s back in for warmer weather.

The one LCA hole that was off ... causing the RC to migrate to the side made the car handle much differently left & right. Correcting that made the car handle more consistently & predictably. One cool thing is you learned how all that stuff worked .. and learned that you can correct & affect your geometry.

What's next:
Replace those 5 year old Edelbrock street shocks with adjustable ridetech shocks with special valving. I worked with Britt & Herb at ridetech to develop some AutoX valving. They utilize digressive valving on the rebound side of the front shocks ... with much stiffer low speed rebound valving to better hold the front end down through the roll through zone of the corner ... then release and extend as normal on corner exit. After you get them on your hot rod ... test & tune is next ... then another AutoX event.

It has been a lot of fun working with you ... and it has been very rewarding to see your car's handling & track performance improve so much. Of course there can always be more. That just depends on how hardcore you get in search of performance.