My buddy just picked up an older FC chassis that looks like it sustained a pretty good engine explosion at one time based on a damaged frame rail. It's only about a 15" section that needs to be replaced. Very simple fix, but not sure what kind of red flags may come up upon chassis inspection. Only going to be a 10 second drag car for now, but needs to be safe! Obviously the repair needs to be sleeved and rosette welded (as well as butt welded)..but how much sleeve should be inside each tube? I've heard answers like 1.5 to 2 x's the O.D. of the tube being repaired. Any input would be apreciated! Thanks!
Its probably chrome moly tubing, so you know it needs to be tig welded only. Use a mild steel rod, like ER70S3.
There is only one way to get the correct answer, go to NHRA rule book. Just Google it and the current one comes up in PDF form. Once you read the chassis repair section if you have any questions call your local Tec Inspector. Anything else is just guess work or possibly out dated information. If you are a racer, you know rules change on a yearly baisis just to keep us jumping for there inertainment. The Wizzard
Three inches either side of the junction will do the trick. Rosettes should be 1/2" from the ends of the sleeves. This is the standard for sleeving the top rail under the front roll cage hoop so it should suffice for the repair that you are proposing. In that application the rosette should be a minimum of .25" diameter. If you are only doing one frame rail all you have to figure out now is how to get the sleeves in place. PM me with a phone number and I will explain how. Roo Roo
Also, it is a good idea to leave an inspection hole near each end of the sleeve so the inspector can see how much sleeving is in there.
Roo is right on the money. Another common trick to get some extra weld surface is to "baloney slice" the ends of the tubes at a 45deg angle. A little trickier to line everything up; but when you get to that level, you're not doing things the easy way.
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