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Old 02-04-2007, 04:39 PM
  #919  
John Stranahan
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Friday Practice, Breakage Report

I had two high speed horrible crashes with the pan car yesterday. I had to hire two new drivers due to the fatalities (small ones ). I had no damage on the first crash. On the second crash, at the end of the straight. I clipped the track bumper hard making a tight entry into the sweeper. We were losing daylight. The crash broke the side tabs completely off one side of the servo. I will have to make better mounts. I have the servo taped to a wedge now that I cut out of polypropylene solid stock. It worked well during the race today. The front arms were undamaged during both of these crashes. I think this is why. I have never broken an upper pan car A-arm. This is becuase the lower one will break first and relieve the pressure. (The lower arm is much harder to break than a touring car arm because there is an upper A-arm.) The upper mount has some flex as you push the A-arm back; this also prevents breakage of the upper arm. I now have this same mount for the top and bottom arm. This is a very strong way to mount an A-arm. The single post lower arm is holding up extremely well. I could however use some more steering link clearance at full throw. The rearward screw of my mounts is a tiny bit too far back.

Saturday Race
75F traction medium

This was the first big test of the new front suspension (previously posted pic). I had new 2.40 inch diameter tires front and back for the first time on this suspension. I had raised the suspension up on one #8 Associated washer to correct for the tall tires. The car had very good manners on the straight and the sweeper. I had some understeer (push) in the infield most noticeable on the hairpins.

I removed the washers from under the suspension arms to lower the roll center. I corrected the ride height with the shock collars. This had the effect of lowering the roll center. Steering was much better. I did not have enough steering throw, though. Lap times were improved.

I turned my shocks over to give me a few degrees more travel. The smallish servo saver did not really have enough travel (because the steering link is in the back holes on the steering arm). This was causing one of the tires to quit moving at full throw. The balls in the servo saver were lined up vertically at full throw. I fixed this problem by installing a medium size Kimbrough Servo Saver (#201 I believe). Now I had enough throw and more proper Ackerman at near full throw.

The car ran its fastest laps ever, .4 seconds faster than the previous club race which had similar traction. The major change since then was the new front suspension. Previously I had run the Associated suspension with long kingpins. The car was .1 faster than its best previouly with a sugar water treated track. Tire wear is very even on the front. The rear tire wear averaged about .030 inch for 20 minutes of racing.

I can go into the straight very fast and hard now. I'll add a bit more steering for the next race. It is nice to have plenty in reserve. I very much like the adjustability and responsiveness to tuning of this front suspension.

John

Last edited by John Stranahan; 02-05-2007 at 10:26 AM.
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