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Ive got a bottle that Jim gave me so will get some gas and do it properly i rekon. How are you at welding Murran?

Ive taken a couple of pics this morning but cant upload em till i get home later - But this is where the crack is

The earth strap connection will be in the way so may have to grind it off. The metal will need bending slightly around the underneath of the chassis tunnel to do it properly and i guess this means the front sub frame will have to be removed.
There looks to be 2 layers or so of metal where ive wire brushed all the shit away, it does'nt seem hollow like the majority of the tunnel. Is there a block where the earth connection is attatched to ?

Gutted!

Edit - Just found this pic of Robs project on Retro Rides

This looks like what i need to be doing!? Would i cut the metal out and butt joint a panel in or would i get away with just overlapping some metal on ??

Trying to neatly butt weld in a precise patch will be a PITA and probably doomed to fail. Slap an oversize patch over the hole, just make sure you prep the hole properly.

On the slug I had a hole in the underside of the NSF chassis rail about where the second patch is on Robs pic, maybe a bit further. I found a piece of U shaped steel that was just the right size lying about in the workshop, ground the hole out thoroughly then drilled lots of holes in the repair plate over the sides/bottom where it would be on top of metal. Hammered it into position - it really was a fantastically lucky find of the perfect sized piece, fitted on exactly. Then I plug welded in all of the drill holes before running a seam around the edges. The repair is undoubtedly stronger then the original.

Well this is what im dealing with. There's another patch in the same place as robs on mine too but its only just started to go so will just prep and paint it up. Should last a few years.
Am off to buy some shit tomora for the welder, didnt get chance today. Will this be an mot fail unless its properly seam welded?

Being told on the welding forums that its deffo not a job for a beginner. They say i need to cut outer and inner skin, drop sub-frame and weld in some angles. Wish i'd have left it mucky and never discovered it

I think they are being a bit OTT, although that's the 100% correct way to do it. Murran knows about rusty E21's - see what he says when he comes. Personally I'd just grind all the grot out and plate it.

I'm not a welding god, in fact i've only welded a handful of times so very much a novice but why not do it once and do it right. Plating, IMO is a bit of bodge, a temporary fix. It’s one of those repairs that will repair some time down the line, maybe not when the car is in your ownership, but if it's worth going to the trouble of plating it then its worth taking an extra hour and cutting it out and welding in new. If you're not confident on doing it then get a mobile welder over to do it for you. You don't need to fully remove the subframe, you just need to drop it from the chassis so you can get at it properly. A mobile welder will not take long to cut out the rot, bend some steel plate to the correct size etc and weld it in and grind it back. Then you just need to zinc prime it, stone chip it, and paint it the wax oil the chassis.

At least once you've done it, you'll be able to kick back happy that you've done a proper repair that will last as long as the car does.

How much roughly would something like this cost with a mobile welder d'you rekon ?? Already stretching the budget with the engine swap and renting out this workshop

the idea is that when your finished the repair looks as close to original as you possibly can you'll be much happier with it when your finished.

make your patch first i.e. fold it and shape it, then trim it to a nice mangable size with a 1mm disc in a small grinder make your edges and corners SQUARE where possible it will be a much neater job.

offer your patch up to the body and scribe around it.

cut out the bad bit to the scribed mark and clean the edges up with the grinder an 80 grit flap disc is ideal for cleaning and finishing.

set your welder up and tack your patch into place.

i find when welding a car body that rather than trying to get a big run of weld going its better to just tack in the center each time so, keep splitting the gap between two other tacks if you can understand. and build your weld up gradually. if you were doing a patch on the outside of the car sat the middle of a quarter panel and where worrying about warpage you could blow the weld with an airline just after you have welded it to take the heat out of it it helps alot.

buff the welding down with your 80g flap disc and paint.

if ou were really fussy get an aerosol of weld thru primer and paint the inside of every thing before you weld it.

make it as easy as you can for yourself if you think the subframe is in the way drop it down.

Im just concerned as it seems to be a double layer. Would you try and cut the outer-out, then the inner? Or would you just cut the whole thing out ?

this is the problem, that area is double skinned. that inner skin is the strength for the subframe mountings and chassis rails. youve got a hole in the outer skin. personally id cut a nice square hole bigger than the hole youve already got. but ONLY in this outer skin! then id try to clean that corrosion up on the inner skin and get some corrosion resistant paint in there as best as possible. cut a patch to let in (rather than plating over it.) and weld it in.
afterwards though you need to somehow get some waxoil in the chassis leg otherwise you'll be doing it all again in a couple of years.

I dinitrolled my chassis legs today. Stick the probe in from the holes in the rail under the car, feed the tube forwards and it goes right the way through to the front if your probe is long enough. When I do the insides of the sills I'm going to inject some more into the very front of the chassis legs just to be safe.

Note to anyone contemplating spraying waxoil/dinitrol via an extension tube on a shutz gun to do cavity wax, ensure you have secured the hose with a jubilee clip so it doesn't pop off mid squirt. Also ensure that you fill the cavities first before spraying black stuff all over the underside of the car, turn the pressure on your regulator down a bit so the top doesn't pop off the can and wear a hat for the rest of the day in case you wander under the car.

If anyone forgets to follow these tips, a big bottle of turps is a handy thing to have in the bathroom to wash your hair which has a slab of dinitrol setting on top of it, your face/neck/arms which are covered, and to soak your clothes in to dissolve some of the lumps.

Sad thing is I had similar problems last time and knew what to do - just forgot!

howve you got on dave?

No go so far on the welding mate
Gonner have to get someone in otherwise its just gonna drag on

i think in my car i cut both layers out and relaced it with one bit of 3mm plate it was 100% very easy too.

you can get wax from the renault dealer its called "ixell hollow section protective wax" its brilliant stuff their seam sealer is great stuff too pity their cars are sh*t lol

i'll get a part number for it not dear at all far superior to original waxoyl

Cool, do you just srpay it in through one of the round hole jobbies in the chassis tunnel ?
Im going to just weld a patch over mine like Rob did a while ago. When im more confident in welding I may attempt to start cutting sections out. Would a 1.5mm thick or there abouts patch work ok ?