Woblink out-Panhard in

With the breakages that occurred during the first autocross weekend, I decided to remove the Woblink and install a simple Panhard bar. I ordered bolt on Panhard mounts for the axle and frame from Speedway Motors and they arrived this morning.

One look at the axle mount and it was clear that I had underestimated the forces involved with the lateral location of an axle, it's a serious piece of kit!

Not only does it use 3/4" thick steel but the heim joint that attaches to it is 3/4". It's also adjustable just by turning the bolt-nice!

Just take a look at the difference between the new Panhard with 3/4" rod ends (top) and the old Woblink with 5/8" rod end

I welded in this 2" square piece and diagonal brace for the adjustable Panhard mount to bolt to,

And here it is, beautiful simplicity. The kink in the bar is because I got it from a dirt tracker and in his application the bar needed a bend. Thanks to Ricky Weiss for finding me a Panhard bar when I needed one.

First autocross weekend

So, even though we actually broke the car today, I think our first autocross was a success. I drove first and the car really, really bounced around on the rough surface we use and understeered everywhere. I didn't know what was going on until I watched Briget drive, and it looked to me like the car was bouncing off the bump stops. I stiffened the rear suspension a couple of steps and went out for my second run. It was a lot better and started to go through slaloms much easier. For my 3rd run I stiffened the rear another step and also stiffened the front by one step. It was even more controlled but the rear still really bounced in a couple of places. The high speed compression was already at full soft so I adjusted it to full hard but left the low speed compression and rebound at full soft and sent Briget out on her run. Going over the first massive bump on the course, the bracket holding the short arm of the Woblink broke, allowing the rear suspension to move around-our day was done. I got the car back to the shop and took a good look at it. There was enough flex right at the end of the bracket that after Friday's track day and todays autocross, the piece failed from constant flexing. I boxed it so flex has been eliminated and we won't have that problem again. Here's a pic of the broken link:

The data from my 3rd run shows that the car was pulling .6 G at 50 mph (the only time I got on the gas in 2nd gear) and was hitting over 1 G in either direction so it has potential but I certainly was not getting the most out of it. I'm confident that it will be a lot better on a smooth surface without pivot cones. Just check out the video and you will get an idea how violent it was inside the car.  Video of first autocross event

 I was still trying to understand what the rear suspension was doing (other than breaking) so today I put zip ties on the shock shaft to see how much compression they were getting, and I aimed a camera at them. The car was really unstable under braking but was better over the big bumps.

When I got back, the zip ties were shoved up against the bump stops. I changed the high and low speed compression settings from full soft to full stiff and sent Briget out.  When Briget was on course I could see the axle moving back and forth and for a moment thought that the newly fixed bracket broke again, but that was not it. The zip ties were not up against the bump stops this time so that was positive.

 Once in the pits I tried to determine how the axle was moving back and forth and couldn't find anything at first but once I had Briget shake the car back and forth really hard, I found a fracture in a different bracket. Obviously the forces on the Woblink are greater than a typical lateral link like a Panhard or Watts because these brackets were pretty robust and were still snapping 3/16" and 1/4" solid steel plate.

   I know from trying different roll center heights at the lapping session and autocross that the car likes it set above 8" high, so I am going to remove the troublesome Woblink and install an adjustable Panhard around that height. Here is a very interesting video of the rear suspension during a run, once you stop being mesmerized by the shocks moving around, notice how much the diff is moving back and forth due to the broken Woblink.  Video of rear suspension

Dyno session with V8

Today was dyno day and things went great. A stock 5.0 makes 165 hp at the wheels so with aluminum heads and new cam I was hoping for 265 at the wheels, and that is also what a computer simulation said I would get. I got 264.8 hp @ 5307 rpm and 271.6 ft/lb @ 4839 rpm and a power curve that rises extremely smooth and linear. It showed no signs of a misfire so either the new plugs fixed it or my ram air system is so effective that it's putting the engine into a lean condition at speed. Here's video of the dyno session and a picture of the power curve.  Video of dyno session

On the track for a shakedown

I had my first shakedown test of the Pink Panther on the road course and it went very well. Nothing broke and the car has no strange handling vices but I learned some interesting things, like that the diffuser really works and you can feel the extra grip with it. The ignition would start to break up above 5000 rpm, which prevented me from exceeding 110 mph (175 kmh) on the straight. Up until that point it pulls like a freight train and once the tires are warm, I can stand on the throttle coming out of turns as long as I am in 2nd gear or higher. The rear of the car jumps going over bumps and I will try to tame that with shock tuning. Neither Briget or myself were brave enough to drive the car at even 8/10's. We both felt that the limits of the car are a lot higher than ours but we will be ready to push in Lincoln.

The rear tires rub on the inside of the wheel well but a spacer should fix that. The aluminum mesh I used in the grille does not let enough air through but the coolant temp only rose too high after 3 or 4 hard laps, and dropped as soon as I took it easy. Even when I push the car too far, it comes back fairly easily but does get twitchy above 100 mph. I attribute this to the aero on the car, I think it starts to push one end down harder than the other at high speeds. On the way home I called the guy who did my engine tune and he immediately diagnosed my problem: I have the wrong spark plugs in the car. If it clears up the misfire, that car is going to be seriously fun.

 It was a lot of fun and if we can move our hands fast enough, it should do ok at autocross. However, the pivot cones are going to be a problem but fortunately, that is only a local problem.  I only have video of my very first drive of the car and Briget's first 3 drives because the battery in my GoPro crapped out. 

Briget on the track
 Mark on track
 Drive-by