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Old 07-15-2003, 08:41 AM
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jmarsey jmarsey is offline
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Location: NorCal, CA
Cobra Make, Engine: A Blue Car
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Originally posted by Richard Hudgins

Hi John,

The chassis looks very good. I am quite pleased that it was not damaged beyond repair. The black looks very good!!!!!

That chassis sure is a pain to straighten, isn't it? That is one of the drawbacks of a rigid stressed skin design, prang it and you pay the price in time and effort to get it right again. (But conversely, the initial damage in a non rigid chassis could well not be repairable in a like crash scenario.)

I bet it was a lot of fun to weld the shear panels on. The first time you do this you start wondering if you will ever finish with the stitch welds. As I am sure you found out, the stitch weld cooling process is very critical to the pre-stressing of the panels. (Dave asks if you need a job doing fab work now that you are trained?)

Also, a quick question. It appears that you have added some structure to the two rear crossmembers on the driver side. What are you planning on doing in that area? If it is a modification that you feel is needed on the chassis, please let me know and we can see about incorporating it into future chassis.

Please note: we have already added a vertical tube at the rear of the tunnel at the panel kickout to increase panel stiffness at the bend as you have done per our discussions. This is a very good addition to the strength of the chassis in mid beam loading under crash conditions..

Therefore, JBL thanks you for the R&D work, but from now on, letís try to do these tests with computer simulations as opposed to pastures and fence posts. (It is much easier on everyone involved. Particularly the test operator.)

I do not remember if we spoke about the rod ends on the right rear. I know that you said that there was no damage to the suspension, only the wheel. But you may wish to magnaflux the inner rod ends to make sure that they did not develop any cracks in the fillet between the threads and the head.

I would also look at the rear upright very carefully. Make sure that the casting did not bend any. It is a vacuum cast part and quite ductile. (Dave has plenty of these in stock if you need to replace the unit.)

Now all the above said, when are you going to get that beast out to Sears Point?


The funny thing is that the chassis did not look that bad at first. But when I took a straight edge to it I could see how bad it really was. Cutting the panels off was a total pain. As you know there's not much there with .065 wall. You're trying to carefully cut through and grind smooth a weld with out taking material off the tubing. That was the worst. Multiply by what, 100 or so?

My fabricator had the chassis on the frame machine for 2 full days. That work is tricky. It's all how you block and hold. I was such a mother-hen they finally told me to leave the shop, that I wouldn't be able to handle the sight of what they had to in order to fix the car. I was so nervous. I left and came back with my check book when done. The back cage area around the pumpkin was twisted slightly. They had the machine in the red zone trying to tweak it back. Very strong back there.

Putting the new panels on went fairly quickly. Cold weld and air. Not too bad. I think you would be very happy with the over all repair work. The panels look great, wow, just like they're suppose to.

The added structure just behind driver's side is were my roll bar will weld in. This is just for added saftey should I need to rely on this area one day. I tied the frame together, as you can see, with some box tube to beef up roll bar support.

With respect to the right-rear: I checked the rod ends which are fine. I will further check the rear upright once I get the rear all assembled. Visually it looks fine. I swept the rotor before removing and it was within .003. That was hard to believe after seeing the completely destroyed wheel.

My goal is to have car basically complete for next father's day. With a little luck. Sears has a few open track functions I can hopefully attend next year. I will take some better pics so you can see the work.

Thanks again for your support, John
NASA - Instructor - 2012 TTA Champion - We Drive Harder!
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