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Kirkham Motorsports

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Old 11-03-2012, 01:29 AM
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Thanks for the compliments -

I have been able to drive the car three more times. The first time we added 8 clicks of dampening into the shocks (they were set at zero) and it was a major improvement. We had a dry day and took it down Skyline drive to Cornelius Pass and then looped back to Portland using HW 30 along the Columbia river. It was a major improvement, but with a full fuel tank and 400 lbs of passengers it still proved a little soft at the rear. We put it back on the stands and and added 2 clicks to the front (10) and 4 clicks to the back (12) and started working on ride height.

We dropped the front until the front lower control arms were parallel with the floor. I have been unable to find any info on E.R.A. design goals with respect to the suspension e.g. where are the optimal roll centers based on control arm inclination. Once we were parallel to the floor I stopped dropping the front.

The stance just did not look right from old pictures (which is probably not right since we are not running leafs) so I decided to pick the rear up 1 turn.

There was a window in the rain Wednesday night and we pulled it out and took it for a run through the Terwilliger turns on I5 headed north. This is down hill and we got to run it thru the corners at 70 with much,much,much improvement. It tracked the corners very well and for the first time I felt like I knew where it was and where it was going except the turn in was amazingly quick (perhaps needing more castor). We put it back on the stands and lifted the rear another full rotation.

It rained Wednesday night which knocked a lot of leaves on the ground. With the new ride height we headed out to German town road around noon. It was not raining, but it was very wet with wet leaves on the road. German town rises from the river I would guess 1000 to 1500 feet in around a mile + with switchbacks in the 180+ deg range. I chose this route because it was uphill and I wanted to get an idea of the swing weight of the car. I never even got around the first corner. I cut the speed going in and threw the car just hard enough for centrifugal to have its way (25 mph ?) and I was immediately sideways and not able to recover. Got it all straightened out and was much more respectful with the rest of the climb - big; round, and smooth transitions. The slightest boost in throttle and I could feel it spin.

We found a way back down to the river with a descent which included lots of switch backs. I still tried to drive it with some kind of rhythm, but was very much on edge. Still - I was still able to get it to transition, but not where centrifugal was going to stomp me.

From there we ran it 50 miles on freeway around the city - 80mph - 2000 rpm - with the windows on we could easily converse and it was very smooth.

I do not understand the roll center on the Jag suspension. I assume it is at ground level with the lower arms parallel. I think I have a couple of degrees of inclination (higher at inner pivot) in the rear lower control arms at the present ride height ( have not measured). It does handle much better with the rear chassis higher than the front.

Do you guy's run the rear arms parallel?

The way it sits looks great - feels stable - but needs an alignment around these settings. I don't want to waste my money if there is a more optimal starting setup. The build manual only relates to chassis height from the floor which negates control arm inclination. Maybe it is toleranced that well.

I was able to weigh it - with a full fuel tank -

2580 => with me 2740

Distribution

51R 49L => with me 49L 51R

Fore Aft

49F 51R

Painted the pipes but bumping off the rev limiter cooked it.



Upgraded Throttle Linkage



Swapped the Edelbrock 750 for 650 Speed Demon -



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