1968 was a special year for 911s-Tru6 decklid grille finding

[Shaun @ Tru6]

As the only person in the world who restores 65 to 73 decklid grilles, I thought I knew everything about them. It's somewhat commonly known that 68, like 69, was a transition year for 911s. Early 68s got the sought after aluminum case and later moved to magnesium cases during the production year. Similarly, early 68's got the 65-67 decklid and grille which were switched to the decklid style we know through '89 but with a new 3-bar grille, therefore also missing 4 grille-mounting tabs in the opening.

Owners, oddly enough, used the grille to close the decklid. The soft aluminum extrusions bent very easily and became unsightly so the grille and special decklid only lasted the latter part of 68 production and 69 years before going to a 5 bar grille with 4 extra mounting tabs for the 2 extra bars for 70 to 73. Plastic grilles maintained the 8 bolt mounting style through 89.

I have received a lot of grilles for restoration over the years and now and again will get an amateur rebuild in. I have gotten in quite a few 3-bar grilles recently, one from a known low mileage original car. It was in great shape but didn't have the dome head rivets I've seen, and made, on all other grilles. These were countersunk rivets into and flush with the bar surface. Checking carefully many of my own and other customer grilles, I found the same, also dome style, and am confident that Porsche started this new style of grille for 68 cars using countersunk rivets and then went to the dome head style rivets for 69 and later. I am totally chuffed at finding this little quirk in early 911 production.

[masraum]

so do you have flush rivets to replace those with?

[Shaun @ Tru6]

I will have to make them in a similar way that I make the dome style rivets Steve.

[masraum]

Originally Posted by Shaun @ Tru6

I will have to make them in a similar way that I make the dome style rivets Steve.

I knew you'd have an answer of some sort. Cool! Shaun "no half measures" B!

[Tim Hancock]

Why not just buy flat or dome rivets?

https://www.aircraftspruce.com/catalog/hapages/solidalumrivets.php

[Shaun @ Tru6]

Tim, I get long shank domed rivets from McMaster Carr and cut them down to the correct diameter and dome height as original. Then I have to cut the shank to the right length with a chopsaw and jig to get perfect rounded sets on the bottom of the bars. I am sure I will have to do the same for these little countersunk rivets.

[Rot 911]

I really admire how meticulous you are in your restoration work.

[pwd72s]

Are you mentoring anybody, or is your knowledge doomed to pass with you?

[onewhippedpuppy]

That’s pretty cool Shaun. Always interesting finding a bit of unique history.

[Tim Hancock]

I have thousands of aircraft rivets in all sorts of sizes.

FWIW...

McMaster Carr c'sink rivets are probably only offered in 78 degree aluminum.
Where as AN426 "countersunk" rivets have a 100 degree head angle.

AN470 "domed" head rivets have a head diameter that is 2x the shank diameter (with dome height about half the shank diameter).
McMaster Carr offers "low profile" domed head rivets in similar head dimensions.
McMaster Carr's standard aluminum domed head rivets have smaller head diameter and taller head protrusions.

Your pictures of your installed dome rivets "appear" to have the same head profile as the AN470 aircraft rivets.

Only mentioning this because it seems like extra work having to re-machine rivet heads when you could buy an 1/8 lb bag of long rivets then simply have to only cut them to length before setting them.

[Targa68]

How much to restore this early 1968 Porsche 911 grill?

[masraum]

Originally Posted by Targa68

How much to restore this early 1968 Porsche 911 grill?

[Baz]

Interesting technical details, Shaun - thanks for sharing!

My '73 Italian delivery 911T......this must be the plastic version Porsche switched to....



You can see the fastener layout in this pic of the ductail it had when I bought it.

Fortunately the seller still had the original engine lid, which I put back on.

[70SATMan]

Great!

Now I have to dig the three bar gill out of my storage to take a look at the rivets.

[LWJ]

And every time someone mentions 1968 911 I mentally go back to the polo? red L that I passed on in 1989. Dammit.

[Shaun @ Tru6]

Originally Posted by Rot 911

I really admire how meticulous you are in your restoration work.

Thank you Kurt, it's a terrible disease but I love it.

Originally Posted by pwd72s

Are you mentoring anybody, or is your knowledge doomed to pass with you?

I am not Paul, over the 10 years of Tru6 I've burned enough money training people that I could have bought a perfect 993 and been further ahead. This post, or a restoration series thread on Technical, will be it. I was interviewed for an article in 000 years ago but this tidbit obviously wouldn't be in there. Another that I learned afterwards is that for 68.5 through 71 grilles, Porsche mounted the ribs on the top bars, anodized that as one piece, then dropped rivets in the bars, masked the ribs and painted the bars black. Then assembled the grille with black anodized mesh and raw, not anodized bottom bars, setting the rivets.

Originally Posted by onewhippedpuppy

That’s pretty cool Shaun. Always interesting finding a bit of unique history.

I really live for this kind of stuff, learning how Porsche built their early cars.

[Shaun @ Tru6]

Originally Posted by Tim Hancock

I have thousands of aircraft rivets in all sorts of sizes.

FWIW...

McMaster Carr c'sink rivets are probably only offered in 78 degree aluminum.
Where as AN426 "countersunk" rivets have a 100 degree head angle.

AN470 "domed" head rivets have a head diameter that is 2x the shank diameter (with dome height about half the shank diameter).
McMaster Carr offers "low profile" domed head rivets in similar head dimensions.
McMaster Carr's standard aluminum domed head rivets have smaller head diameter and taller head protrusions.

Your pictures of your installed dome rivets "appear" to have the same head profile as the AN470 aircraft rivets.

Only mentioning this because it seems like extra work having to re-machine rivet heads when you could buy an 1/8 lb bag of long rivets then simply have to only cut them to length before setting them.

Thanks Tim, I use McMaster but also Hanson Rivet for rivets, Hanson for attaching the chrome vent window catch to the anodized "nike" that holds the tilt window. Also the steel buttresses to the vent window horizontal on all frames and copper rivets for targa vent window frame tips. Recently had to make every single rivet, something like 12 of them for BMW 2002 vent frames. The whole contraption is riveted togther, pretty low brow compared to 65-68 911.

Years ago after a massive search and several orders later, I discovered that 1. No one carried metric rivets and 2. Some SAE rivets were close but not close enough. I'm down to 3 minutes per rivet carving them up on the lathe, the chop saw to length is 30 seconds being careful. I can live with that. I almost had 500 custom made to spec in Poland in 2018 for what I recall was a reasonable price but never got them done. That would be the way to go. While I have a lot of grilles to restore, just going to keep making them by hand.

[Shaun @ Tru6]

Originally Posted by Targa68

How much to restore this early 1968 Porsche 911 grill?

Those are $3K. Making the brass rivets and setting them is terribly fun. I make new rods, all new washers, bright nickel plate new steel cap nuts, the original aluminum ones are no longer available.

[Shaun @ Tru6]

Originally Posted by Baz

Interesting technical details, Shaun - thanks for sharing!

My '73 Italian delivery 911T......this must be the plastic version Porsche switched to....



You can see the fastener layout in this pic of the ductail it had when I bought it.

Fortunately the seller still had the original engine lid, which I put back on.

Baz, 72 and 73 are all aluminum, all black anodized. For 70 and 71 bright grilles, Porsche used zinc plated steel mounting bolts captive between the bars. But you can't run steel in an anodizing tank (unless it's been masked) so Porsche assembled the entire grille with aluminum captive bolts. These grilles are the most difficult to get right and if even the smallest flaw occurs, you have to strip it and pray you can create a proper surface condition for the right tone of black. Black anodized grilles are soul crushing. I need to do one for a very special '72 ST rallye car and am dreading it. 74 was the first year of the plastic grille.