by Ron Barrette in the May 1993 RootesReview:
Many Tiger owners who have cars that have spent most of their days in the Northern tier states will have cars with some degree of rust in the area of the “X” frame pass-thru. Although not a critical problem yet, I feel eventually even the West coast cars will develop some deterioration in this area. The problem in this area can be directly related to the deterioration of an exhaust system with the hot and cold causing condensation. Until recently, it has been repaired by time consuming home fabrication methods.
The first thing you should do before diving into the project is to examine the extent of your problem. To make a proper examination, that particular section of the exhaust should be removed. Once removed, all undercoating should be scraped away within an inch or two of the welded perimeter of the pass-thru. Using a coarse wire brush and electric drill, wire brush the same area. At this point, you should be able to determine whether replacement is necessary. Replacement is recommended if:
- Flared section of pas-thru is missing or falling apart.
- Any rust holes through the pass-thru.
- Upon inspection inside the “X” frame visual signs of rust appear.
If it is determined that replacement is necessary, purchase an “X” frame repair kit, consisting of the sheet metal forms to cover the “X” frame. Once you have the parts, removal of the old pass-thru is the next step. I found a disk grinder the easiest way to remove the old part, grinding flat over the weld and using caution so
as not to damage the “X” frame. Once you get through the weld, you should be able to pry the old parts off. This sounds a lot easier than it really is because the originals are welded around the whole perimeter. At this point do another rust inspection. If your “X” frame is damaged from rust, now is the time to replace that section of the “X” frame. The original sheet metal used in this area is 16 gauge, but to eliminate any
future problems a heavier gauge could be used.
Be sure if you replace any of this sheet metal it conforms closely with the factory dimensions as the pass-thru repair kits are precision made to fit the original frame. Also, before removal of rusty sheet metal be sure to take measurements from either side along the “X” frame to insure that the replacement pass-thru is positioned in the same place as the original thus allowing the exhaust pipe to pass through freely.
At this point, the “X” frame exposed, if no major deterioration appears, wire brush the “X” frame again in the area that the pass-thru had covered and whatever you can reach inside the holes in the frame. Now is the time to apply your preferred method of rust retardation on both the internal and external section of the “X”
frame. I usually use an acid etching primer and a coat of paint but other methods are acceptable.
If all of the above conditions have been met, we are ready to install the repair kit. If the “X” frame itself has been patched use your measurements and, if not, use the tell tale weld marks to position your pass-thru’s and weld the perimeter preferably using a wire feed welder. When the welding is complete, cover the entire area with a rubberized undercoating; and you should have no problems in that area for many years.