DDK - Die Deutschen Klassiker

Hi All,

Something I have never quite figured out. Should the B post panel gap on a 911 be tapered?

For example

[*]4 to 5 mm at top of B posts in paint (5 mm to 6mm in bare metal)
[*]3mm at bottom of b post in paint, before curve in paint (4mm in bare metal)

I have seen it in genuine factory Porsche pictures, but I cannot conclude if they have been designed like that or if there is body sag.... I did read one of Barry's comments "about 90 percent of 911's he had worked on had rear end sag", so maybe that is the case. I have seen it quite pronounced on targas.

(See thread here viewtopic.php?t=40853

I've attached some pictures. Some show doors with a taper, some with no taper, and some with the slightest of tapers. Almost all of these cars have been painted. In one of them, a poster on PPF, is absolutely adament that the B post must have taper, as is chat GPT....but actually I have not ever read about the taper in the factory manual or another book like the haynes restoration manual or bentley manual or etc....maybe its there and I missed it.

The reason I ask....is I have one door (the white one in the picture) which does not have any taper....i have bare metalled, it, and there is no sign of any filler (i.e "fixing the taper when the car was last painted"....so I can only conlclude that either this is how it left the factory or there is something else going on, like the rear end body sag, which Barry mentioned that 90% of porsche 911's have.

Any thoughts? Anyone got a factory 911 that has never ever been painted, with or without B post taper?

Note....9 pictures in total, so check out this post and the next 2 under it.

more pics

final pics

Personal thought:
I doubt the shells in the 70/80's were made as well as an AUDI/BMW etc of today.
Would not surprise me if some cars were 'parallel' and some tapered.

Shims are quite thick, about 1mm each iirc so the adjustment available was quite course. In the same period, BMC cars were set using wood blocks and brute force.

911hillclimber wrote: ↑Wed Dec 31, 2025 1:38 pm Personal thought:
I doubt the shells in the 70/80's were made as well as an AUDI/BMW etc of today.
Would not surprise me if some cars were 'parallel' and some tapered.

Shims are quite thick, about 1mm each iirc so the adjustment available was quite course. In the same period, BMC cars were set using wood blocks and brute force.

Indeed. That could explain it. I will leave the debate to run for some time. While I will be dialing in my gaps some more I have some time before my rear quarter panels need to come off and either go back on or new ones fitted so on that basis I dont need to finalise my personal b post gaps anytime soon.

In the meantime I would especially interested in seeingb the b gaps on either a bona fide low mileage never been painted mid 70s 911 or one that has been perfectly set on a cellette bench without the b posts off.

The factory workshop manual makes no reference to tapered gaps only 3 to 4 mm

Finally I would be especially interested if collectively we can reach a decision which either agrees or disagrees with the PPF poster whom is insistent on a taper. Only because I like to live in a world of fact.

If we decide that tapered gaps are always indictive or body sag then next portion of this thread will be devoted to some more about that discussion