Finally found a 69 240z, #51 Time to finish a 30 year multiple owner restoration.

[dspillman]

1 minute ago, Namerow said:

Does anyone have a picture of how the roof and rear quarter panels come together when the latter is replaced.  Failing that, maybe just a detail shot of the relevant area of the rear quarter panel.  There has to be a weld somewhere!

I would appreciate that as well….

[CanTechZ]

7 hours ago, Namerow said:

Does anyone have a picture of how the roof and rear quarter panels come together when the latter is replaced.  Failing that, maybe just a detail shot of the relevant area of the rear quarter panel.  There has to be a weld somewhere!

Here are a few pics from the early eighties when I had my rear quarters replaced. Sorry that they don't show more detail. The left side was actually done about a year before the right, as someone lightly backed into me and due to the existing shoddy bondo repair, a pile of rusty bits was left on the ground similar to the second pic, during the more complete resto. At the time of the incident I didn't have the funds to do the full resto.

The left side was cut back to the factory joint but on the right side it is cut further down, I'm not sure why? Or if it was cut more later in the repair process?  Anyways you can see a little of the detail. I wish I had taken more closeup pictures back then.

Edited April 25 by CanTechZ

[dspillman]

7 minutes ago, CanTechZ said:

Here are a few pics from the early eighties when I had my rear quarters 

Agghh, it’s like a horror show….

[HS30-H]

Here's a right-hand front pillar joint without the lead loading (blasted and etch primed). Spotwelds visible:

[HS30-H]

...and here's a right-hand rear quarter roof/quarter joint with rear quarter panel removed (spotwelds drilled out), blasted and etch-primed:

It's a complicated joint - the meeting point of roof outer panel, roof rear crossmember/hatch hinge mount/roof longitudinal rail/rear quarter. Perhaps not surprising that it required lead-loading.

[dspillman]

Thank you Allen… windshields pillars are looking good, thankfully…  dip,or blast will tell the tale.

 

[Zed Head]

Filling, fixing, loading, flexing.  Is everyone talking about the same thing?  Lead is a soft metal used to fill defects in metal bodywork.  It is generally considered to be better than plastic bodyfillers.  But it has no significant structural effect.

The discussion about the C pillar seems less about how the seam was "connected" but more about the dimensions of the strut.  The C pillar, apparently, was designed to be the weak link in the box shape of the chassis.  Designed to give before the A pillar did, so the windshield area would not be affected.  Since it was designed to flex, using lead as the filler of the seam makes sense since lead is a soft flexible metal.  That might not have come through in the discussion with Mr. Matsuo.  

Today's "Bondo" might have the flexibility to serve the same purpose as the lead did.  But neither of them will affect the stiffness of the pillar's metal.  They're just fillers.

https://www.motortrend.com/how-to/mopp-0101-how-to-do-lead-bodywork/

[dspillman]

  Having to shout squirrel every 30 minutes or so, when distracted by items not noticed before, or perceived body and fender support changes in production methods like this welded joint between ….some changes through the years….

Hls30-00051  first pair welding exhibits “Green car”

Hls30-00740….”blue car”

Hls30-03496…. “Primer”

Hs30- 10324…..”red”

quite a difference in weld patterns.

 

[HS30-H]

57 minutes ago, Zed Head said:

The discussion about the C pillar seems less about how the seam was "connected" but more about the dimensions of the strut.  The C pillar, apparently, was designed to be the weak link in the box shape of the chassis.  Designed to give before the A pillar did, so the windshield area would not be affected.  Since it was designed to flex, using lead as the filler of the seam makes sense since lead is a soft flexible metal.  That might not have come through in the discussion with Mr. Matsuo.  

Since the screen pillars ('A') and rear quarter/roof joint ('C') are both finished with lead-loading, any hypothesis of them being "designed to flex" (I would say more likely 'expected to flex'...) would have to apply to both, no?

I'm struggling to think of any other cosmetically-observable area on the bodyshells of these cars which is similarly 'filled' before paint. Nissan Shatai didn't bother to pretty up the joint between the rear quarter panels and the lower rear apron (spotwelds nicely visible and always a pleasure to see...) and I can't think of any other points on the body where - all opening panels closed - filling/joint disguising before paint was necessary.

If I'm right, those lead-loaded joints are the only cosmetically-enhanced/filled-before-paint joints on the whole car. The 'designed to flex' thing seems like an answer looking for a question.  

 

[Zed Head]

On 4/21/2024 at 3:28 PM, Mark Maras said:

At the Atlanta Z-CON, Charles and I talked with Matsuo-San when that question came up. As I recall he said that joint was intended to flex. The consequence of a stiff C-pillar was the A-pillar flexing instead with the possibility of a windshield popping out.

It follows from Mr. Matsuo's comments.

 

p.s. It shouldn't be overlooked that many of the things you see on a car are there for ease and speed of production.  Not performance.  

p.s. 2 - those welds look terrible.  I wonder if they got better along the way to the 280Z bodies.  It would be interesting to see some later welds.

.

Edited April 25 by Zed Head

[Mark Maras]

 I've never had a good look at that seam but I vaguely remember Matsuo-San talking about the welded seam options. Butt or flush lap seams would be too stiff so they opted to bend both sides 90 degrees (or possibly a standing seam joint) to join the two parts. @Patcon Charles, do you remember that part of the conversation?

[Zed Head]

dspillman, if you want to refocus on your restore goal just say so.  This is an interesting aside though.

I found a 77 seam.  It doesn't look much better than the 240Z's.  Maybe a little bit smoother.  Still just a fairly crude stitch weld.  

https://youtu.be/uN8ca_KFVcw?feature=shared&t=415