Newbie MX5 repair.

[Jelly_Sheffield]

Thanks to everyone for their valuable tips. So I'm not gonna try and do it inside the container...as recommended. It turns out there is a slightly more experience colleague at work who is willing (with a bit of cash and beers) to show me and he also has a full workshop. So probably the best way..
This weekend I took out the carpets and inspected the rust holes from.inside and they could be a lot worse..

Honestly, I'd kill for that level of access after some of the stuff I've done in the last year: Trafic, Hilux, and Landrover

I wasn't appreciably more experienced than you when I started.

The Trafic in particular has taught (is teaching) me a lot, and you can see in all of those threads that sometimes getting stuff in correctly but looking dog rough, then grinding back and if necessary re-welding is the best course of action.

Like I say...I'm a complete novice!

The plug welds look fine, and you've obviously found a joggle tool, but for the area's you're doing you are required to butt-weld the patches as per section 10 of appendix A of the MOT test manual.

Knowing the MX5, I would be tempted to get them all in solidly from above, then grind the back side of the weld flush (on the outside) to prevent rust traps before you paint it.

Working from the inside you would be as well just cutting the patches to fit, and using butt-weld clamps to hold them whilst you weld.

If you had to weld it from the outside I would be tempted to joggle the patches or body, plug weld in position firmly, then weld out the seam fully as a lap-fillet along the joggle, which also makes burning through a lot less likely.

For doing that a one-sided clamping solution like Cleco Clamps is a godsend.

That way you can get it all clamped in correctly, then one by one remove a clamp and plug weld through the hole you used for it till it's in solidly.

The photo's of how I did the outer cill on the Trafic will probably make that description make a bit more sense.

 

[Nederlands]

Like I say...I'm a complete novice!

Looks good.
But as bij @Jelly you should butweld
Try that to before doing it on the car

 

[johnik]

good luck, seems like you are not going to give up, i had 2 NA,s and loved them so i have skin in the game as it were.
another piece of advice if you want it, have someone doing fire watch and some wet bath towels laying around, they stop the fire and also smoke.

 

[Misterg]

It could be a lot worse...

Very sorry to say but I think that’s quite bad.

The rear floor and front foot well holes are where there are multiple layers of metal and rust has got in between them. This means you have 2 or 3 layers to repair, and may need to cut away good metal to get access.

I’ve just repaired the front footwell for much less damage (just a few pinholes from the top, but thick rust in the overlap joint underneath) and it was possible to work with the carpet propped out of the way, but it was a real pain.

Outside before (what you can’t see is the thick rust packed into the seam lower centre of photo):

Cut away the overlapping panels (from inside). Luckily the front footwell panel wasn’t really rusted, just some light pitting that cleaned up with a spot blaster - it looks like yours is)

Repair the floor

Then repair the end of the front apron/torque box panel:

I also had a small hole in the floor at the rear. I needed to cut away the rear outrigger(?) and repair them both.

The only thing visible from above was the hole by the green arrow. The red circle is what needed to be cut away to clear the rust.

The rear sills had been professionally repaired on mine before I bought it, so I thought that everything would be OK there, but it wasn’t:

7 repair sections needed!

The front jacking points are also complicated structures with lots of overlapping layers. Repairs to these need to be fabricated.

(The front apron/torque box panel is available from mx5 restorer though)

I’m not trying to put you off, but I am trying to get you to take a critical look over the whole car. Yes, there are repair panels available, and pretty much anything can be saved, but the cost very quickly exceeds the cost of buying one in better condition (whatever the welder’s skills).

Check the condition of the panel that joins the sills to the floor pan. If that’s gone, it is a very big job.

Good luck