Double locker or single locker sport seats

[Scott A]

I was just working on a pair of 72, single locker sport seats.
I would like to ask some questions.
Can you make a single locker into a double locker?

(It appeared that most of the pivot anchors were welded in place for the double linkage)


Is it a good idea to make doubles out of singles?


(As I understand it, the double locker was for safety, to keep the seat from flying forward on a crash.
The seats are so heavy, they must really throw themselves forward.
I doubt the single tooth can handle an impact)

Are the linkage parts available?

Certainly, you would need another toothed rail, that part seems easy.

[gled49]

I have a set of 72 sport seats also with all the mounting welded in place, but no operational hardware. 72 shows L&R outer seat rails. 73 shows one X 2 outer rail. The 73 outer rail has elongated mounting holes that are covered by the double washer for adjusting and synchronizing the double locker. Good luck finding the hardware.

[911MRP]

I have a set of 72 sport seats also with all the mounting welded in place, but no operational hardware. 72 shows L&R outer seat rails. 73 shows one X 2 outer rail. The 73 outer rail has elongated mounting holes that are covered by the double washer for adjusting and synchronizing the double locker. Good luck finding the hardware.

I’m interested by the question. I have a feeling there a thread somewhere discussing the detail of how this feature evolved from around 72: some sports seats in 72 without pivot , some sports seats like the OP got the welded pivot only, then the seats got the complete fitting ? IIRC there are comment(s) in the workshop manual giving dates that suggested happened on sports seats on a particular date across all markets but wonder if in reality this rolled out same date in all country markets? Porsche quite frugal and could envisage the seats in supply chain got used up in some markets after the nom in all date if perhaps region or country hadn't got it under as strong safety ( regulatory) focus as perhaps USA?
Steve

[recarno]

double locker were introduced worldwide at the same time. In total there were three series of heavy brackets over the years. Between series 2 and the third series (double locker) there was a transition period in which different individual parts of the double locker were already installed.

I wouldn't bother converting from series two to three. I think this is quite time-consuming and why?

I wouldn't have any concerns about safety. The first Recaro brackets for 911 (1966/67) didn't even have ONE lock. The seat was simply held on the bracket by its own weight. You didn't have to loosen anything to fold the seat forward. Everyone survived too ;-)

Hope I could help a bit.

regards uwe

[911MRP]

While the factory documentation seems somewhat clear* empirical data from forum members cars would be nice to see. What evidence is there of the evolution of those with the welded pivot and those with the full double mechanism. Even if prvenance is a muddied over 5 decades where seats have been swapped, replaced or restored would be interesting to see examples in that particular period from Sept 72 through to the say March of 73. I understand the Sport seat locking mechanism was further revised in the spring of 73 to make mechanism more precise?

Any more examples with ink date stamps underneath ( I’ve only seen a few) would be particularly interesting!

Steve
*There is some inconsistency in what the factory wrote in period … roughly six weeks difference in date said to be introduced in these two separate notes in the factory workshop manual pages on my shelf. One is the so called rest of world and one is USA version of the manual:

[frederik]

I wouldn't have any concerns about safety. The first Recaro brackets for 911 (1966/67) didn't even have ONE lock. The seat was simply held on the bracket by its own weight. You didn't have to loosen anything to fold the seat forward. Everyone survived too ;-)

Interesting, I would think that a loose seat would add at most 10 kg to the weight going forward, added to the 75 kg for the driver. The (three-point) seatbelt should be able to keep that in place. Still better if the seat stays fixed of course.

The sport seats in my '70 S are on the COA but also have double lockers, so that is an interesting riddle.

[recarno]

Double locker brackets definitely didn't exist in 1970. Unfortunately not original in this respect. But of course it doesn't harm the function.

regards uwe

[Scott A]

From what I remember, from my days designing for crash testing…
If you are holding a 10 pound child in your lap in a 30 mph crash, effectively that child feels like 300 pounds being pulled away, and nobody could hold that.

It all depends how quickly you stop.

The seats are over 50 and would be essentially 1500+ pounds of force.

There is a crash calculator on the internet.

[911MRP]

It isn’t the speed that kills you it’s the sudden lack of it

[frederik]

Yeah now that I think of it again, that weight of the seat pushing forward would squash you between the seat and belt. Happy with my non-original double locker I suppose.