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TR4/4A TR4A front floor - patch or bolt new ones on?

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tdskip

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Hi everyone. Trying to do some planning here. Thanks for the coaching while I get a plan together here.

My driver side TR4a from floor has already been patched and has some localized rust that I'm expecting to be fairly far gone.

Try to further patch and deal with the rust seems like a bad idea compared to replacing with new pans.

Never having replace TR4a pans before, they look like a bolt in replacement. Any tips or tricks to be aware of?
 
OK - after more research it looks to me like some spot welding that will need to be drilled out as well, but still looks fairly straight forward.
 
I think it's a much bigger job than that. Alignment is critical. Get the book "How to Restore Triumph TR4 & 4A" by R. Williams. He lays out the procedure, and it seems like a lot more work than what you are thinking. I haven't done it myself, but many here with TR6s have and the floorpans are the same as the 4A, as is the replacement process.
 
Hi,

Floor replacement is certainly "doable", but involves welding not bolting. It's not an overwhelming job, depending upon your welding and sheetmetal skills.

It can also be done in part, rather than replace the entire floor, depending upon where the rust is. For example, a seam can be made under the seat that will be totally hidden unless the car is up on a lift. Or, depending upon how widespread the problem is, even more limited areas can be patched, perhaps awaiting a more extensive body restoration planned for sometime the future.

There are a couple possible pitfalls:

With TR4A and later TRs, it's important that the car be sitting on the ground or otherwise supported on it's own suspension during the floor replacement process. This is because the frame flexes more than the earlier one and if the car is up on jack stands or, worse, this work is done with the body off the frame, it's very unlikely to be well aligned once it's all put back together. The floors do effect body alignment to a degree... But the inner and outer rockers are even more of a structural part, if any work is needed on them.

Be very careful welding and cutting in these areas. There are brake and fuel lines just under the floors.

Incidentally, there usually are varying amounts of rubber shims at the outrigger mountings (and often the other body mounting points) as these are used to fine-tune the fit of the doors and other exterior panels.

If you have floor rust that's localized to the center of the driver's side, that's almost certainly due to one or both master cylinders leaking at some point.

On the other hand, if the floor rust is more generalized, behind and under the seats and on both sides, it's more likely there will be some other hidden rust elsewhere too. Look in particular at the B-post, at its base on the inside. Peeling back the vinyl cover there will usually reveal rust, especially if the floors have significant amounts of rot. Removing the rear fenders gives access to the other side of the B-post. If repair is needed there, it's often easier to just trim up unrusted metal and patch the base, rather than replace the entire B-post.

Yes, Roger William's restoration book is highly recommended! Lot's of photos and detail.
 
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