Howdy. I just purchased a 67" 400 /4-speed convertible. Discovered that (a) RH/LH rear passenger floor pans and (b) LH front driver side pan are rusted through. Also discovered that (c) transmission tunnel was cut up on the sides and then poorly patched (reason unknown). Interestingly the underside of pan is in great shape (original paint, no rust) and support braces, trunk and back seat are also solid. Photos attached.

So, question is; "do I patch the three sections of floor pan and the transmission tunnel - or just replace the full pan?" I am inclined to replace entire pan as my initial take is that the labor to do multiple patches will be about the same as just replacing the entire pan. I understand that replacing the entire pan requires additional planning, measurement, temporary bracing, removing seat bases, etc. but I think the end result will be better.

And, should I decide to replace the entire pan, what brand replacement panel should I go with - Sherman, Dynacon, Goodmark, Other? I want proper gauge steel, inclusion of support panels for Convertible and want to avoid having to buy and assemble all the various components. And I'll just cut off the back seat pan.

I am willing to pay more for higher quality replacement panel with the proper supports included to reduce labor time /costs.Will be paying professional shop to do the work as I do not have the cutting tools nor welding equipment - so labor matters as I am in the Bay Area and body shop rates are high here.

Any guidance on patch existing vs. full pan replacement and replacement product will be appreciated.

I have replaced my full floor pan, rear inner/outer rear whelksells
Brackets, braces etc etc

It's a lot of work. Need an excellent welder.

Patching maybe a better option. Depends where they are rusted

Rusted at panel weld connections, plug
Welds you probably have to go with full pan

Need pics first beforre I comment more

I had very little rust on drivers side, and I patched...but in your case..I think I`d recommend replacing....maybe piece meal, not full pan

Have a look at the thread I started years ago in regards to the floor pan. I'm going to try and update the thread with pics of what was done to fix my floor pan.

In the meantime, have a look underneath the car at the pinch welds. Verts have extra bracing. Are the joints expanded with rust? Mine were and that was the major issue with my floor pan. The actual flat floor part was in excellent condition. The flat part is patch-able, the pinch welds can't really be patched.

Had similar on my passenger side.
Patched it...worked out fine.

Helpful input. If I had just one or two pans to patch then patching would be the obvious choice. I have however three (possibly four) pan sections and a transmission tunnel to patch or replace - thus I am struggling with the LOE for multiple patches vs. replacement of the entire floor pan (excluding the section under back seat and in trunk).

The cost of materials is roughly the same for both approaches - and feedback from two restoration shops that I consulted with is that the labor costs should be roughly the same as well give or take a few hours to deal with unexpected issues.

So, the deciding factors then become the expected labor cost differential (which could be est. $500) and the resulting stability and longevity of the cars floor. I may just need to get the car up on a lift and cut into the floor a bit before I can make definitive decision in which path to take.

Any input on parts brand? I assume that there are differences in the suppliers of panels.

Have you stripped the car completely?
Are you going to send it in for media blasting before you do floor?
Blasting the car body will expose all the issues with your car.
I find it hard to believe you don't have other issues.
Best you know up front what is required so you
Lessen the possibly of budget creep.

Here is my thread on the floor pan.

https://firstgenfirebird.org/forums...;Main=32566&Number=278177#Post278177

I used Dynacorn and did both sides. (you can buy the whole pan, just the sides, or each of the four seat areas) They fit well. Dealing with the front seat mounts was the most difficult part. Getting those off the old floor pans was a PITA.

I thought you didn't want to go through all this work? Soon you'll be doing a full trunk pan, firewall, wheel wells, frame... Oh where will it ever end?