Today I started to work under the car (change rear shocks).
During pre-exam of the work/area, I noticed that the rear torque box on passenger side had started to degrade from rust. I had seen something last year, while I was jacking the car up from the back, but did not pay enough attention I guess…
Anyway, here is what I got after poking:
Is this critical?
How quickly does it need to be repaired?
Can the car be driven in the mean time?
Is there a method that does not involve welding?
What concerns me is that this is most likely not an isolated area. I would be probing the entire underside very carefully as this is your frame so to speak. Not having a roof makes it crucial to have good structural integrity on the bottom side.
Also looks like the DS inner rocker was replaced (poorly) previously. Cannot speak to the PS as no supplied photo shows the inner to outer rocker pinch weld.
When I purchased the car, I poked it in various places and then my mechanic did the same when it was on the lift. We both found it to be not bad at all given this is an eastern Canada car!
But yes Don, I had the exact same fear as you after seeing rear torque boxes in this condition, so I just went to probe it meticulously all over again. Surprisingly, it is not too bad i.e. as expected most of the undercoating is flaking off with surface rust + some crusty areas, but nothing soft. Frame, chassis, panels, fire apron, shock towers, engine supports, front torque boxes, ect… are still thick and solid (except 2 shorts sections about 1-2" long x ¼" wide on the driver side rear well and lower trunk panel, both at/near junction with quarter panel).
You are correct. This was done around 1995 by the original owner. It certainly does not look stock and in addition, it is probably thinner than original, but this car being just a driver, all it needs is to be solid and safe.
Knowing this, how would you answer my original questions?
Is this critical? Yes especially on the convert.
How quickly does it need to be repaired? Not going to fall apart tomorrow, but get it fix before it causes other damage that will need repaired.
Can the car be driven in the mean time? That up to you but, I wouldn’t be doing hard launches and fast cornering flexing the body.
Is there a method that does not involve welding? NO, need a patch from a donor car or make your own repairs with metal plate. Make sure you cut all the rust out. Might be a repair patch for a Mustang that would work. That’s a Don question.
Any repair will need welding. If you’re not concerned with remaining 100% stock, you can weld in some sub frame connectors to make the frame stronger than stock, but I’m in the same boat as Don. I would be concerned about the rest of the underside also…
Subframe connectors won’t help. This is the part that locates the rear axle, so it’s critical in the strict sense of the word.
I’d say this car needs probably both sides done to be safe. And probably when you get into it you’ll see more stuff that is rusted that needs work. But this is minimum safety stuff. The thinner materials aren’t up to engineering specs for Ford, so even if it’s just a driver it’s still not up to spec for that.
I say fix both sides. All four locations probably need work.
Thank you all for advice.
Probing all sides of boxes from the openings in the rust seem to indicate that only the bottom plate of the driver side box would be rotted. Same on passenger side, except that portion of the bottom frame rail adjacent to the box is also rotted. So the plan is open both boxes and see what’s really going on in there.
The garage where this is going to happen is only 2 miles away from home, so I am confident I can drive up there (since I drove the whole summer in this condition before I knew), but this will definitely get fixed before the next season. Will post updates.
Ok there we go. Work started yesterday, passenger side first.
Damages looked kind on minor from the top side (floor) but actually was not as good from the underside. Apparently still manageable though.
This side should be finished tomorrow. I hope the other side won’t be as bad… that stuff makes me nervous.
The “rust specialist” encouraged me when he said he has seen much worse cases and that my car looks pretty straight, but he also confirmed that I should take action to stop/slow it down in inner frame, rockers and floor pans.
Another thing to consider is finding out where the moisture got in to begin with. I imagine the top leaked at some point, and puddled there. Probably fixed now, but worth a look see up in those rear quarters.
