USA 1970 911T - the Tangerine Dream

[RobFrost]

That's a nice repair Rob!
Good to do this than spending tons on parts that may not fit.

Trust you will do a dry build on the body before paint?

In theory everything that's going back on came off so it should fit nicely - but yes, I think a dry build will be wise. In particular I need to check the repairs to the wing mounting panels position the wings well.

That's still some way off though, yet. The big welding job still remaining is the sills. They're good in the main body but are holed below the door catch. The kidney bowls on a 1970 come in two parts - vertical and horizontal. The vertical part is intact but water has run down onto the horizontal part so that will need replacing at the very least, and I'll probably replace the reinforcement at the jacking point. I can see that when jacking the car at the jacking point, the door opening changes shape slightly so I'll take extreme care to keep everything in its original shape.

[RobFrost]

Next up the corroded, reinforced bumper - cutting out the spot welds.



This bolt hole is looking a bit weak so I cut some 2mm steel reinforcement.



Repair piece where I cut the rust out.



Spot welder continues to prove invaluable.



And the repair piece.





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[RobFrost]

I peeled back the orange-sprayed gaffa tape from the nearside sill and reintroduced myself to the corrosion that developed under the aluminium trim.



After a lot of consideration I decided fortune favours the brave.



I took note of the (I assume actory original) lead in the seams and tried to avoid grinding it.





The welds were a good four inches apart on this so I decided to whip it off to see what's what a bit better.



I cut through the rear wing, remembering somebody previously saying make a note of how far it is from the inner wing.



Tentatively I'm happy with the decision. The centre sill isn't rusty at all and I was sad to cut out a lot of original good steel, but the paint was gone on the centre sill and this will mean I can get some paint on it.

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[RobFrost]

I previously thought, from peering down into the rust hole at the bottom of the slam panel, that the kidney bowl was a two part affair in this car. But I now see that the horizontal member is nothing other than the rear end of the sill (or what's left of it).



The only rust in the inner sill is those two rust holes at the base of the b pillar.

I cut that away revealing the kidney bowl, or at least the straight vertical reinforcement mine has, which I assume is standard on a 1970 car.




Cutting out the spot welds top and bottom will be a pleasure saved for another day.

I acid etched all the welding oxide off the repaired bumper, washed it and dried it with a heat gun ready for paint.



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[SeanP]

Looking good
If you haven’t seen this thread before have a read
viewtopic.php?t=28001&hilit=Sill+replacement
These areas can end up being a lot of work! You may be lucky but until you have cleaned up the entire area fully you don’t know. There are at least three layers of steel in some of those areas that add a lot of strength and rigidity to the shell.

Regards

Sean

[RobFrost]

Sadly, this top edge of the sill has spot welds both inside the recess and along the top edge, making removal a bit of a dilemma. I can't get the spot weld cutter in square enough to cut the top ones without causing any damage. One alternative is to drill them out and repair the top edge - a good few hours extra work.



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[RobFrost]

From the top I drilled out the centre of a few which weren't too close to the edge, to locate a drill from the bottom. I'll fill and smooth these holes later.



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[RobFrost]

As is customary, I have to go back a bit to find steel of full thickness. As I expected, this car has none of the rust from the inside out which 911s usually have, caused by wet thrown forwards into the kidney bowl area by the back wheels. In fact the entire area under the rear wing is free of rust.

The only spot is where it entered the holed top of the sill at the base of the door slam panel.

I think this didn't rust in New Mexico at all. I don't think this car has ever been driven in the rain, and the only rust has happened after it was exported, and caused by rain falling directly on top of the car.



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[RobFrost]

Looking good
If you haven’t seen this thread before have a read
viewtopic.php?t=28001&hilit=Sill+replacement
These areas can end up being a lot of work! You may be lucky but until you have cleaned up the entire area fully you don’t know. There are at least three layers of steel in some of those areas that add a lot of strength and rigidity to the shell.

Regards

Sean

Thanks for that Sean. I think I must have read it before because a lot of the points in there were already floating around in my head. Something I had forgotten though, was how the spot welds along the top of the centre sill often don't penetrate into the inner sill, the exact circumstance I noticed earlier today in my car. I'll be adding some welds to it before the outer sill goes on.

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[RobFrost]

As with any job on this car, hammering released a shower of sand, and opening up a the sill caused lumps to fall out.



I cut well back to clean metal and prepared with two part weld through epoxy.



I made a couple of repair pieces. Once I cut the panel I realised the original steel was a bit thicker so I made one in heavier gauge.



And painted... no time to fit today.



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[RobFrost]

As per Barry's advice I took a bit of weight off the engine with a jack before welding these in. And I kept the door on up to this point so as to be able to ensure alignment and gaps are all good.

I also added some welds to the jacking point reinforcement as per how Barry does it.



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[RobFrost]

And on with the sill removal. It's still upsetting me to cut out so much original bright steel.



I'm doing my best to not cut through, so I don't touch the intermediate sill underneath, then tear off the welds with a pry bar... Next on to grinding off all the welds.

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[arminius]

What are you using to cut your welds back with - it looks like a flap disc? Have you tried the sanding discs with a backing pad, makes for a very controlled finish. I might be mistaken but I think I’d turn the power up a bit on the MIG perhaps

[RobFrost]

I spot welded this join to add some rigidity where
the factory welds hadn't penetrated.



Do some cars have fatter kidney bowls? The Dansk sill's definitely positioned correctly at the front end, with the rear wing join precisely positioned because I photographed and marked it. It's gonna need more than a little fettling at the kidney bowl end.



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[RobFrost]

What are you using to cut your welds back with - it looks like a flap disc? Have you tried the sanding discs with a backing pad, makes for a very controlled finish. I might be mistaken but I think I’d turn the power up a bit on the MIG perhaps

Whatever you're seeing, it's most likely down to lack of talent on my part. I should've turned the welder up either side of the jacking point as the metal's thicker there.

I did this with the power on much higher than most people would use in order to guarantee good penetration to the back. Maybe what you're seeing is a consequence of 0.8mm mig wire instead of 0.6mm.

For flatting back I used the grinding disk to take away the majority then smoothed off with a belt sander, partly because of accessibility.



But the where it's not seen, the emphasis is on function over form. I'm averse to anything which would thin back the surrounding sheet steel so I'm deliberately not always getting it completely flat.

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