Seatbelt mounting holes on transmission tunnel ???

[Mark]

My e12 has seats with the seat belt buckle built into the seat, they are from a 7 series. Ive been offered a pair of really light porsche 914 seats to put in, im reducing the weight of my e12 for track days, are there threaded mounting holes already in the transmission tunnel to attach my seat belt buckles to, the porsche ones dont have the facility to attach it to the seat itself. I think I would have to take the seats/carpet out to see, so if anybody knows please let me know,

Im originally from the Uk and as far as im aware cars have to have the mounting points built into the car shell, not into the seat itself, so this is new to me.

Many thanks,

Mark.

[alotawatts]

My US 81's do not have trans.tunnel mounts. Belt latch is on the seat rail. My 79 does have tunnel mounts for the belt latches.

[DMS]

My 78 euro does has them on the tunnel. My 79 euro doesn't.

[Mark]

So if my car does not have mounting/fixing holes on the transmission tunnel, can I drill a hole on either side and bolt my seat belt buckles to that, maybe with some big washers in there to spread the load, is that safe or would they potentially rip out in an accident, I want to be safe for sure,

Mark

[Mike W.]

So if my car does not have mounting/fixing holes on the transmission tunnel, can I drill a hole on either side and bolt my seat belt buckles to that, maybe with some big washers in there to spread the load, is that safe or would they potentially rip out in an accident, I want to be safe for sure,

Mark

Welllllll, back in the old days, before seatbelts were standard equipment, that's exactly what was done. Nowdays do that and everyone will scream about how you have a death wish. I'm sure others will disagree, but if you do it right, and I'd use something like 1/8" X 2" flat bar, say 6 or 8 inches long, not just a washer, then bolt it with a nut, preferably a locknut or use locktite, I think you would be ok. Think about it from an engineering perspective, you want to spread the potential load, and you don't want it to ever possibly pull thru, it could be your life. Without knowing how the car was constructed, what thickness where exactly and what loads it could be subjected to, overengineer it on your end.

[Mark]

I took my carpets out, I have threaded mounting points on my transmission, that made me smile. I took off all that thick rubbery sound deadening from the front floor and tranny tunnel, it weighed in at 20 lbs, with the 30 ive already taken out, thats 50 in total without much effort. My seats weigh 65 lbs each (you nearly break your back trying to lift the suckers out) so im thinking the Porsche seats ive looked at must weigh 15 each maybe, thats a saving of 100 lbs right there, with a bit more effort I can loose the equivalent of an average weight person, should make a bit of a difference. Will have to make some frames though, the Porsche footprint is smaller than the BMW, as long as my frames dont weigh 50 lbs im ok.

[Milan]

Mark what year model is your e12 ? Just curious
I'm glad yours are threaded, if they weren't i would use 1/8" or 1/4" thick backing and front plates instead of washers.

Drive Fast !!

[GripGreg]

Peeking out from my small shade tree, I would go with Mike's suggestion and add the extra strength of a bar for more bearing on the female side of your safety belt on the tunnel. You may have to roll the bar to match the curve of the tunnel at a machine shop?
My USA '80 and' 81 belt buckles are attached to the seat, not the tunnel. Wow! I guess the seat rails are that strong! Look closely at just how the rails are mounted.
Please, let us know what you end up with. This is interesting.
Good Luck,,,,,Greg

[Mark]

Milan, GripGreg,

To answer both your questions, my car is a 79 (originally from Palm Springs, but now in Canada), ive found the mounting points on the tranny tunnel which is a relief. My plan is to make simple x shaped frames that bolt on to the original floor mounting points, then bolt the Porsche seats on to the frames, and the seat belt buckles will be bolted on to the tranny mounting holes I discovered. My only concern is how my current seats are bolted on to the floor, until I remove the brackets that someone has made I cant see, im hoping the mounting points/bolts are substantial,

Mark