Wanting to modify front belt receiver so that it ‘travels’ with the seats

coupesport

coupesport

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Who’s done it? I am wanting to modify front belt receiver so that it ‘travels’ with the seats as seat is slid forward. Presently mine is anchored on the transmission tunnel and I’d like to get away from that configuration as I am presently renovating the seat belts.
VAC Motorsports caught my attention with kit pictured below.


Seems their bracket could -
1) sandwich between the seat and the rails and so ‘travel’ with seat or
2) between the floor mounting frame and bottom of seat rails for ‘non-traveling’ receiver – but in effect moved forward and off of the tunnel.

If anyone has successful experience and kit source I much appreciate your advice!
Rob

VAC mount.jpgVAC install.jpg
 
HB Chris said:
Seats mount to sliders and to floor with m6 bolts, I wouldn’t trust my belts to those bolts.
Click to expand...

Exactly! Modern cars' "travelling" shoulder harness latches are part of a well-engineered, well-tested system. They've been designed using finite element analysis and then crash tested under a variety of conditions. So yes, you can just bolt the harness receiver to the seat and hope for the best, but keep in mind that your life does depend on it.
 
My 2 cents

My concern is that E9 seats are not anchored very strongly to the floor. The rear bolts and nuts are quite small and might rip out of the seat riser structure in a big crash. The original anchor to the tunnel is much stronger and serves to keep both the occupant and the seat in place.

If you updated the seat to floor attachment and the seat base itself then I think you could easily adapt the latch part to attach to the seat frame/base ... and not decrease the level of safety.

John
 
As a crash test safety engineer i can confirm; 'bad idea' ...

I've personally witnessed a full scale crash test of a very, very cheap car. Pulled the M12 fine thread bolt right out of the floor pan, sending the passenger adult dummy right through the windshield.
Having disassembled my e9 seat rails for fresh zinc plating, i know them in fair detail. I am quite certain they dont hold.

In a crash the seat will have to carry a load of (roughly) 25 times your mass+seat mass. Say 100 kgx25 is 2500kg, or 24500 Newton, or 5500 lbs.
 
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I would think that you could install a short seat rail next to the original rail using larger bolts and somehow improvise a slider into the rail track. You could also connect the new rail to the original rail and use the same holes with larger bolts.
 
Are they call traveling because in a crash you would indeed travel with the seat?
 
I agree with Chris (and the rest). However, it may be a moot point. We will not do well in a vintage car in a serious collision...no matter how the seat belts are attached.


There is a HUGE difference in safety between the cars most of us drive daily and our vintage cars. Those ugly 1974 bumpers that we all hate started it all.

Drive safely!
 
Koopman said:
I would think that you could install a short seat rail next to the original rail using larger bolts and somehow improvise a slider into the rail track. You could also connect the new rail to the original rail and use the same holes with larger bolts.
Click to expand...
Harry, I agree.

(1) Weld in or multi-bolt in a heavy piece of steel plate (or Sngle) to strengthen the seat tower.
(2) use two high strength bolts/nuts to attach the seat rail to the strengthened seat mount tower.
(3) reinforce the metal seat bottom metal frame for the new belt attachment point. And use an appropriately big bolt, eg same size as the one currently holding it to the floor.

Seems like that would get you back to an original level of safety.

BTW: a friend was in a highway speed crash a few decades ago. It was an older/classic European sports car. It was a high speed roll and the door flew wide open after the first 360. The car did several more fast rolls during which It really was just the belt (anchored into the floor) that held him inside the car. Belts are designed with some stretch, and he said it stretched enough that he and seat were nearly outside of the door opening !! As a wizened old rally racer, he knew to crossed his arms as tight as he could across his chest, and was wearing a helmet (he was on a winter rally).

This story gave me a new appreciation for why you don’t screw around with belt mounts unless you know what you are doing.

Be safe guys. The stock seat belt isn’t THAT inconvenient.

John
 
VW has been doing this for 40 years, but their seat design is much safer. The “slider” is a female track welded to the body, and the male track IS the seat frame. The exception is the genuine recaro seats, which had the male seat track/frame bolted to the seat frame with high strength M8 hex screws.

9FC47510-BC23-4425-85D5-7EE865911478.jpeg



More pics:
 
IIRC,
BMW moved the latch onto the seat (like VW) starting w the E21 sport package. So, using those seats/belts leaves only the job of reinforcing the seat towers on the floor.
 
Follow-on question -
Those of you having the front seat belt receiver of the flexible cable structure - about how long is that assembly from its 7/16 hole to receiver end. With the front seat adjusting forward to rear about 10" and the receiver being fixed length it seems problematic.

I am working with Al on this and will followup with him.

Thanks for the knowledge share!
 
Interesting discussion. Looking at the (presumably original) seat belt mountings on my own coupe I cannot say I’d be very confident of the belt providing much protection in an accident ......
 
coupesport said:
Follow-on question -
Those of you having the front seat belt receiver of the flexible cable structure - about how long is that assembly from its 7/16 hole to receiver end. With the front seat adjusting forward to rear about 10" and the receiver being fixed length it seems problematic.

I am working with Al on this and will followup with him.

Thanks for the knowledge share!
Click to expand...
This style? 18”
 

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