clib

has anyone ever heard this before..........

I am considering a roll bar and 6pt harness in my 993. I currently have the 996 GT3 seats installed. This would be for DE use, not racing events.
Talked to my shop and they were getting set to order from shroth distributor. Distributor told shop that they didn't think it would be wise to put a 6pt harness into the 993 that utilizes the GT3 seat mounted inboard lapbelt point. They said the floor pan that the seat mounts to in a 993 is not adequate for safely installing belts directly to the seat, and recommended a separate direct floor mount install of the lap belt.
I am going to call the distributor directly tomorrow to understand where this comes from. I have never read or seen anything like this before.
Curious if anyone else understand where this is from or has seen anything similar on the 993?

thanks
b

Bill Verburg

These are the factory instructions for mounting 6 pts



the tunnel side lap mount looks like this


a good alternative to drilling the floor for subs is the GT3 sub mount
drilled


GT3 sub mount


Schroth sells the pad eyes and backing plates

clib

thank you bill

jhg41977

Bill, where did you find that info? Just curious, I just finished mounting my harnesses, this would have saved me some time!

Bill Verburg

one of the shop manuals, I forget whether 964 or 993

IamSMC

Bill V, I think clib's question is whether or not its safe to use the inboard mount point on the GT3 seat itself for the lap belt in relation to strength of the 993 chassis seat mounting points, not how to install 6 point harnesses specifically

If I remember correctly, the inboard mount point is part of the GT3 seat bracket and not the seat itself

It appears the schroth distributor is advising its not safe, though they manufacture a specific GT3 seat harness

clib, are you ordering the schroth "regular" harnesses or GT3 seat specific harnesses?

http://www.schrothracing.com/competition/profi/profi-II

clib

Thanks for the clarification IamSMC. Inquiring on both really, and appreciate the where to anchor instructions.

But yes, the overall question was of safety in DE car of mounting lap belt to GT3 seat bracket is question. The inquiring to distributor was for either really, probably not the GT3 specific set up as that is for shorter shoulder straps for a rollbar.

Doing some more research and talking to HMS (schroth distributor) and from Bill's diagram, its clear the basic 993 floor pan is not the same as the 996 or the 993RS. That was their concern - it was not necessarily designed to sustain the forces of the seat mount, subbelts and lapbelt system to the 4 seat/floor mounting points. Now it may be fine for DE experience but that is a different discussion I guess

b

Bill Verburg

HMS consulted on my belts too. The 993 and 993RS tubs are exactly the same and 964 is not too different forward of the rear suspension, 996 is a whole different thing, I'm ok w/ the 3 point belt attaching to the seat mount but want something sturdier for the 6 pt.

Here's a mock up of the RS tunnel side attachment for the 3 point belt & GT3 sub mount. I used 993 rear receptacles through the side holes because the side bolsters on these seats are too high to go outside the seat. PP is just on the edge of being too high, but can be made to work outside w/ some fiddling

IamSMC

So 3 pt vs 6 pt on the inboard side was just a preference on your part, but I'm wondering if Porsche designed the inboard mount to withstand forces beyond the 3 pt system through the seat mount points?

As for RS/GT2 with PP, what was available from factory beyond the 3 pt system?

If Schroth believes there are possible issues with strength of harness mount points in conjunction with seat mount points, then companies like Brey Krause should be disclosing same.
http://www.bkauto.com/category_s/220.htm

And your solution for using the rear receptacles is excellent, when I used the front receptacles, there always appeared a concern with the height of the front receptacle in conjunction to the GT3 seat

Bill Verburg

All 964,993,996,997 w/ factory installed 5/6 pt harnesses and race shells use the through the floor/tunnel mounts for the harnesses and where also equipped w/ 3 pts use the RS or GT3 seat mounts

IamSMC

Bill, are you club racing your 993?

Bill Verburg

No, just built as close as possible to Cup specs

clib

helpful clarifications, thanks. I had same concerns with the GT3 seats and the tunnel side receptacle being too high. I even checked on the 996 board and apparently that is the way they also come from porsche, so I am guessing it is safe and tested, but to me it seems high.
Bill is that what you used, a rear receptacle belt? it looks like it would be ideal.

clib

and for clarification, I don't know what Schroth thinks directly. The technical person at HMS (derek) was really very helpful in understanding his concerns and he knows the cars and the technical aspects really well. This was all a relative surprise to me as I'd seen a lot 993 threads on installing harness to the tunnel side seat bracket. I have discovered that its very hard to to safety upgrades piecemeal and less than full hog can be less safe.
So now I just have to decide if I just continue as is awhile longer with a more purely street car or commit to making more car more track worthy.

IamSMC

clib: didn't I tell you it's a very slippery slope...yet fun altogether...