Yes there is room in the tunnel for the Schroth backing plates
hgere's the pilot for mine


I'd use the GT3 sub mounts, I've torn off the plates under the car

 

When I laid out my belts, I think the 305 mm mark ended up close to the diamond above the arrow below where the forward legs of the transmission mount are in a 993, these are not in the 964 (at least early chassis 964 like RS). I decided to drill through the double thick plate for my belts.

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I changed Bill's image to make it a bit more clear what was going on for the tunnel seat belt mount #3. The page is copied from the 964 factory service manual's body book in the section "Conversion of Body in White to RS"

 

Bill, would that be the BK R-9035 piece ?
Pricey option but if this can both eliminate drilling the pan as well as a safer option....I'll go this route.
Thanks CupCar for the illustrative clarity. This is something you definitely want to "measure twice/drill once" so the visual helps.

 

No it would be the factory GT3 part 996.521.933.90 they were ~$55 when I bought them, the are a perfect match for the RS tunnel side 3 point mount 964.521.065.00 and the 3mm 999.025.231.03 washers that go w/ it to keep things leveled, the submount, washers and mount are all sanwiched between the sliders and the sidemounts



As I recall I put my harness mount further back so that it wouldn't interfere w/ the trans stabilizers that mount where the reinforcing is another influencing factor is where you run the seat, w/ my long legs it has to be as far back as it can go

 

Just FYI, I won't be using any sliders (direct bolt on to tracks) since I'm the only driver, does this alter this application ?
So I would remove the clips at the end of the Schroth sub belts and just wrap them around the GT3 sub bar (as your pic illustrates) ? Sorry for all the questions, just want to order the right stuff.

 

It's best to have the mount close to and just below and behind the seat hole, because it gives a fairer fetch and more adjustment on the dead end of the harness.

If you are bolting to the floor then you sandwich them between the floor and the sidemounts

you would also need a 3 bar slider for each sub, ~$3 ea.

On mine I drilled on the passenger side and used the GT bar on the driver side, I have brushed the through hole ones off on the turtles at WGI so will need to redo the passenger side w/ the spare GT3 bar that I have.

In addition, to drill the drivers side you have to relocate all the electronics located there, the Motronic brain is easy but the big connectors are a RPITA to relocate, the GT3 bar eliminates any need to relocate parts or connections( at least on mine w/ sliders)

The nice thing about floor mounts is the extra headroom, but it sure is convenient to move the seat up to get access to the rear areas

 

A tip on moving the big connectors under the seat around is to unwrap the wiring harness to move things around, then retape it back up with with the OEM Tesa brand gaffer's tape, or use hockey stick tape or another brand of gaffer's tape if you want the OEM look. Otherwise any electrical tape will do, I like 3M.

 

S2K 993 has very illustrative avatar, I think I am in the picture.

 

Excellent, thanks Bill. Answered all my questions. Now I can order with confidence.
In my case, no sliders will give me the headroom I need (6'3) so its worth the limited back seat area access. My only issue might be egress, since I'm considering a halo drivers seat with non removable (996) steering wheel. Need to be able to exit quick should the need arise.

 

I wonder about this. You may want to mock something up to insure that in and egress will work for you.

Without a removable steering wheel (and sliders perhaps), you may be VERY limited. In an emergency situation, this could become critical.

 

I put a QR on my wheel, it has the extra benefit of getting the wheel closer to my body(that's a good thing)

 

This is still a street car so I want to keep the OEM wheel w/air bag. I have one set of Recaro sliders, so once I compile everything I will test fit to see if these allow for enough head room.

 

It'll be interesting to see how much headroom you end up w/

 

Ok, started to tackle this project today. Removed the trans tunnel cover & as I see it, the only place to mount the reinforcement pad is at the flat spot in Bill V.'s pic above. Using CupCars location, the trans bracket would interfere. However, Bill V.'s pilot hole location is considerably aft of the 305mm mark; is this acceptable ? Also, what's the best way to punch a hole from under the car (limited space in there) thru the steel ?

 

it works for me, w/ the seat all the way back
You want, the control inside the side hole



The further forward the more inside it will be but this is fine, the strap runs w/o intereference and there is still a lot of adjustment at the clip

As you can see there is room for both the 3 point receptacle and the harness strap