A discussion about safe chassis repairs, welding, fitting and finishing Options

[rick 918-S]

I try to check the resto threads and titles that have to do with chassis repairs and welding. I have been playing at and learning about auto repair, auto body and welding since the age of 12. I am self taught and learned enough in my youth by watching others and practicing what I learned to eventually open a collision/resto shop. In my hay day I had 6 full time guys, a computerized office, a Celette in the shop and all the headaches that go with it for 18 years.

I have been out of the industry now for 20+ years. But over that time I have still worked to hone my skills. I'm not posting all this to boast. I just want you to know when you read the following where I gained my knowledge and why I suggest this method of repair.

I have read many threads and see the same questions asked as guys learn how to go about repairing the projects they start. I have seen some threads started and questions asked after things went too far south that recovery was not possible. I hope to help some of you from making that error.

I have to say I see the most inventive and industrious guy on this forum. Lots of knowledge here. I've see cars repaired that other non 914 guys would have scrapped. Nice repairs too.

Here is where I wanted to start. The right rail and jack post. The easiest and hardest part of the chassis to repair. Here is a link to a repair I did on a factory 6 I did for Ben.

http://www.914world.com/bbs2/index.php?sho...26585&st=60

I wanted to expand a little more on why I did what I did.

Specially when it comes to the double layer. I installed a double layer in the rail on Ben's 6 when I did the rail repair. This serves two functions. One, less important but functionally as important is heat transfer. This will allow the single outer layer to transfer weld heat into the thicker two layers slowing the transfer and help reduce warping and shrinking.

The second and most important reason in a unit body car is structural. When your talking about trying to butt weld a rail section and count on your weld to carry a vertical, horizontal and angular flexion you will very likely not succeed. By adding the stiffener or backer you ensure the joint is safe.

One word of caution though. The ribs on the outer panel serve two functions. One is strength the other is weakness. Strength in the stamped design, but a designed weakness as a crush zone to allow the chassis a place to give and absorb energy in a collision. The energy transfer passes around you instead of into you. You will not want to bridge these or eliminate them. They serve a function.

I hope this helps others just getting started with a new project and others that are in the midst.

[rick 918-S]

Other than changing the physics of the car in a pedestrian crash I would say there is no real negative effect. Possibly with a 40 year old chassis it could actually make it safer. You be the judge. I'm not going to comment on modifying the chassis beyond my earlier statement about Brad's kit. It is my opinion that a chassis stiffener that passed the weak place (the jack post) just makes the most sense. Although Mark Engman was an engineering genius. I was fortunate enough to sit with Mark once and listen to him talk about the zero steer riding mower design he was working on. Impressive. There are plenty of guys on the forum that build race chassis' and can comment on chassis stiffening and the pros and cons of roll cages in street cars. I'll leave that to others.