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What's Your Problem? - Tech Questions

Jeff Smith Answers Some Of Our Readers' Questions

Rust Never Sleeps
Scott Jordan, Columbus Junction, IA: I recently acquired a '71 Nova that was about fenderwell deep in a pasture. The car is relatively sound with the floorpans and the front frame among the pieces that are OK. However, the driver-side rear framerail is rusted clear through behind the shackle, thus causing the bumper mount to rust out as well, and now the bumper is falling off. How hard is it to replace a framerail like this? Will I need a full rail installed and then also have to have a piece fabbed up that ties both sides into each other? I ask this because I can't find a shop that supplies the piece that includes the bumper mounts. I'm capable of doing most repairs, however I have never had a body off a car and would rather not try to do it either. What are my options, and where do I look for parts? I live in Iowa, so the selection of people doing major projects like this are few and far between. Any help would be great!

Jeff Smith: We talked to Craig Hopkins at Goodmark Installation Center (Goodmark, the sheetmetal restoration company) about saving older musclecars from the ruthless ravages of rust. Hopkins had some great suggestions that can save your Nova, Scott. First of all, a Nova is not a full-frame car like a Chevelle or an Impala. The Nova uses a removable subframe in the front, but the rear "frame" is really a unibody design where the rear framerail is integrated into the sheetmetal floorpan that supports the rear of the car. This repair will require some cutting and welding, so grab your cutoff wheel and MIG welder and follow along.

First, you will have to find a donor car because you are correct that no one makes replacement framerails for these unibody cars. As far as we know, Nova rear subframes from '68 through '74 are all the same, so look for a car that has a nice framerail in the area you need. If you really want to use new material, we know that Detroit Speed offers new framerail sections as part of a minitub kit. You might be able to talk them out of some material, but double-check the size before you buy. Or, if you have access to a sheetmetal supply company, it's possible you might be able to find a section of rectangular tubing close to the size you need, and then it could be sectioned and welded to fit.

Assuming you use a donor-car frame piece, this rail section will have to be removed. The best way to do that is with a cutoff wheel and an air-operated die grinder. Short of that, you might get by using an electric Sawzall with a metal blade. Cut a much longer section than you need to replace, with at least 2 to 3 inches ahead of where you intend to splice the new rail in place. This will give you room to trim.

Next, support your car with jackstands and remove the rear bumper, gas tank, and complete rear-axle assembly. Before cutting the old section out of the car, Hopkins suggests making multiple triangulated measurements to establish the precise location of the old framerail so the new rail will replace it accurately.

Here's where we test your fabrication skills. Hopkins recommends building a sleeve that will fit inside both the new rail from the donor car and the end of the existing rail in your car. This sleeve needs to be 2 inches long and can be made out of a portion of the donor framerail or out of new sheetmetal. If you are using a portion of original framerail, it will require sectioning the rail down the middle in both directions (vertically and horizontally) to make it smaller so it fits tightly inside both ends of the framerail splice with roughly a 1-inch overlap. Once the sleeve is constructed, drill a hole in the top of the old framerail that will be intersected by the sleeve. This will serve as a plug-weld connection. If it is not possible on top of the rail, the next best place would be the bottom. This plug-weld will maintain proper position on the sleeve and serve to improve the strength of the repair. Don't weld yet, however.

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