RP Saloon Sill & Floor Repairs

[Chris KC]

Some time in the coming year I need to address rot in the floor of my RP.
In all honesty I have yet to make a comprehensive assessment, but I can confirm there are areas where the road is visible below. 
I think it more than likely that the cills/ sills will need repair or replacement. 
Probably rear arches too.

My question is, simply, can anyone point me to any helpful how-to's, write-ups, or even Youtube videos which go into the nitty-gritty of saloon floor repairs? I've made a basic search but didn't come up with much. I'm hoping to harvest as much wisdom as I can before embarking on the project.

Failing that, does anyone have any helpful experience to share?

Specific areas of interest:
1. Can this be done on the chassis? I'd very much prefer piecemeal repair in situ over a body-off, new floor approach, whatever the shortcomings. 
2. How to maintain door opening shape and dimensions (is it really necessary to weld in braces?)
3. ...and how to avoid locking in distortions which might have been better corrected beforehand (e.g. door droop).

Any thoughts welcomed - thanks in advance.

[Dave Mann]

I have a friend faced with a similar problem on an RN, he jacked the car into it's correct shape then welded the doors in place while he replaced the sills. he never explained how he got into the body to do that.

[Chris KC]

Thanks Dave, that's very much the kind of thing which is of interest. 

It might be a mistake to weld up the floor and then hope to correct the door openings afterwards...

One side at a time perhaps? I think it would take some bravery to have both sills off at once.

[Peter Naulls]

Having rebuilt a couple of Minis many years ago I was advised to repair the A posts first, then hang the doors before replacing the sills. This means you can keep an eye on the door alignment at each stage. I imagine the same principle would work for a Seven. Make sure your screen stays flat too - the friend who rebuilt our Ruby years ago found it difficult to get the doors hanging right without the screen pillars going out of line with each other. I have seen one or two disasters where bodies have been repaired in isolation only to find that none of the panels fit afterwards.

[Goldnrust]

I can't comment specifically on the 7, as I've not had to do any major welding on mine (yet?!), but from from experience of other cars I think you'll be fine to do the repairs with the body on the chassis, it might actually help.

As mentioned above, keeping the body in shape when you cut out the floors and sills is the challenge and having the body still bolted to the chassis (presuming the chassis is straight!) can help with that. The obvious downside is the inconvenience of having to to work around the chassis, making access difficult at times. With the 7 chassis being so simple I doubt it will be much of a problem.

I would recommend buying some steel box section, can be small 20-25mm, and temporarily welding that across the door openings, and anywhere else that helps hold the body in shape before you star cutting the rot out. Whilst it can still be awkward to manoeuvre yourself in and out of the car, it's easier than having the doors welded shut!

I appreciate why you'd not want to add bracing, it can seem daunting the first time, but it only needs a few tack welds which are easily cut off afterwards and the confidence you'll have that the body stays in shape is well worth it.

Fixing previous distortions is again somewhere bracing can help. You need to make sure your door hinges and window frames are all in good condition themselves first, straightened anything that looks twisted etc, even if that makes the doors not sit quite right to the current shape of the body. Then using a mixture of standing back and eye balling it and taking measurements you can try to identify if theres any twisting or mis-shaping of the body. Then you can force the body into shape, normally using a jack to push or ratchet straps to pull, and weld your braces in with the body in this corrected position. You'll find that when the floors and sills have been cut out and replaced and you cut out the bracing, then the body will not hold it's new shape nicely.

As an example of this, when I did the floors and sills on my '65 Fiat 500, the drivers door had dropped so I used a jack to push the top of the A pillar forward to lift the door into place, and then welded bracing in to hold its shape. The finished car has a nice door fit.