seat rail attachment to seat bottom thread repair

[AMP]

I have a question / problem. Car is a C. The rear most two 6mm threaded holes in the outboardMy question is are the threads in the seat bottom in a floating, separate part or are they in a hard part (not floating but part of the seat bottom) that I can tap into? I have looked with a mirror and tried to probe with a scribe but I cannot tell if the threaded part is floating or rigid.

Any help much appreciated!! If someone has a C seat bottom out and can look I would be very grateful before I start to attempt this repair.

[JTR70]

Wish I had the answer but your car is too new for me Ashley. I'm sure Jack, Bruce and a bunch of other guys know.

[Don C]

Ashley,
They aren't floating plates. If you look at the combined photos you'll see the tab is bent and riveted to the seat pan on it's side then bolted thru the rail. Sorry I don't have clearer views but these shots are from when I rebuilt my seats during the winter. Hope they help.

[AMP]

Thanks Don. That tells me what I needed to proceed. This afternoon I got some M7X1 screws and also M8X1 just in case. I think the stripped 6mm threaded holes that remain are close to the 7mm tap drill size and should easily clean up with the tap drill. That's what I am going to try. Will report back with, hopefully, success! Thanks again for the time to post the helpful pictures.

[JTR70]

Don, thanks for fielding these later 356 model questions!

Good luck Ashley!

[AMP]

Thought I would follow up on this repair. Hard to get a picture with a phone that shows the problem but you can kind of see the seat rail part that attaches to the seat is bent down in the back. In this case I don't think the back two screws that hold the seat rail to the seat were ever installed as they were not in the car loose and they physically could not come out of the tunnel side as there is no room. On the tunnel side the rail cannot bend down very far because of the tunnel. On the door side it can bend down a lot as there is nothing under the overhang to stop it. The seat catch riveted to the seat bottom pan relies on those two bolts for 90% of the support and the rivet maybe 10% as it's into sheet metal and off to one side.

I have had the problem virtually since I put the car back on the road and the seat back was always slanted a little to the door with limited adjustment. Might be imagining it but I seem to remember the seat problem in the early 80's when i drove this car every day.

The fix:
You cannot get the seat out of the car if this happens. It has to be at least partially repaired in the car. On the drivers side the two 6mm screw holes seemed stripped so I drilled one of them to the m7x1 tap drill and tapped it 7mm. Once I had that screw tight I was able to move the seat far enough forward to then get in the back seat and push it all the way forward to finish removing the screws and remove the seat. After that it was a quick fix to tap the other hole 7mm and straighten the two rails. The two threaded holes on the tunnel side were not damaged. The rails are soft and easily formed.
The passenger seat had the same issue but to a lesser degree. Plus all the threads were still good in the back two holes so no drilling and taping.

One nice thing, looking under the seats, the shop that did the interior did an extremely nice job even in the areas you can't possibly see with the seats in the car (except ovbiously for the back screws - but I will give him that one as an honest oversight). I wouldn't hesitate for a second to take another interior job to him.

Both seats now sit square and adjust easily.

[Don C]

Hi Ashley,
From your picture I find your seatback release different from the one on my "C". My chassis # is 220994. Both sides have the same release as the one shown in the picture below. Wondering why the change?

[AMP]

Hey Don,
Good question - I don't know.
Mine # is about 1/2 yours and it's a Reutter chassis.
Maybe they used more than one seat supplier.

[Don C]

Mine's a Karman, maybe that's the difference?
PS: Will you be going down to the Helen, Ga. gathering in Sept?

[AMP]

Yes I'm planing to go. Wanted to fix the seats so my wife can finally move the seat up to drive it. You?

Also wanted to put the bumper trim back on but might not get that done in time.

reutter eventually morphed into a seat company which is still in business. Maybe back then they were already building seats.

[Don C]

Ashley,
I'm planning on going, hope to meet some of you guys there!

[Jack Staggs]

There are at least 8 different recliners for 356, three that I have seen on C models. Progressive refinements, I guess.
I recently did a repair to a seat on a 68 Targa that had similar damage, and more as well. After I was done, I asked the customer to get in the car. The first thing that he did was place this right hand palm on the upper corner of the seat back to brace himself for entry. This put considerable weight on the seat back at that point! I could hear it groaning as he slid in to the seat. I had him do it several times before I pointed out what he was doing. He thought I was crazy for the repetition, but he complied. He hopefully has modified his entry, but I doubt it. I re- drilled the runner to allow it to hang off the back side of the perch an additional inch or so to give more support to the flimsy sheet metel seat bucket. This will not effect forward seat position. I don't know what Porsche was thinking when they designed this part that was sure to fail after only 50 years.

[AMP]

Likewise Don, glad to here you are going.

Where are you driving from?

[AMP]

It is a weak design. I like your idea to move the bottom rail back for support. Did not occur to me to do that when I had the seat out but I think it's worth going back and doing. I think the two bolts on the left side of the drivers seat in my car had been stripped for many years. I was amazed at how soft and mailable the rails are. For what they are worth I'm glad I added the modern seat belt.

There are at least 8 different recliners for 356, three that I have seen on C models. Progressive refinements, I guess.
I recently did a repair to a seat on a 68 Targa that had similar damage, and more as well. After I was done, I asked the customer to get in the car. The first thing that he did was place this right hand palm on the upper corner of the seat back to brace himself for entry. This put considerable weight on the seat back at that point! I could hear it groaning as he slid in to the seat. I had him do it several times before I pointed out what he was doing. He thought I was crazy for the repetition, but he complied. He hopefully has modified his entry, but I doubt it. I re- drilled the runner to allow it to hang off the back side of the perch an additional inch or so to give more support to the flimsy sheet metel seat bucket. This will not effect forward seat position. I don't know what Porsche was thinking when they designed this part that was sure to fail after only 50 years.

[Don C]

Ashley,
I'm from northern NJ and will be driving down with a friend from the Boston area, me in my '65C and he's driving a '63B, both coupes.
Looks like we might meet up with some Pa folks in Virginia and drive down together... can't wait!