Unfortunately, legally in the EU you are not allowed to change anything on the safety equipment.
In the case of restoration however things usually are changed, for the better even. If changes were made, usually eu countries require you to submit your vehicle for a technical check before it is allowed to enter public roads.
I dont think a self invented third seating posistion will pass such an inspection.
However, looking at Gransins tech capabilities, i have no doubt that he could make a center seat belt in a safe manner. The center seat would be the safest possibility, and very likely a police officer will not know all of these above details.
If in Finland you have to do some ( annual ) mandatory tech checks every other year or so, you may need to unbolt the " invented" centre seat belts prior to inspection....
That's unfortunately how it is, goes hand in hand with all our other strict car modification rules.. Good in some cases, bad in other cases.
But I honestly don't think the guys who does the annual inspection will have a clue, if they see that it's a clean and solid car owned by an enthusiast, they usually won't care about details like these, if they even would notice.
My recommendation on the center seatbelt didn’t involve any modifications. You just need a belt with two male ends, and you use the existing passenger receivers. The center LATCH reccomendation solved two issues. It is cheaper than a custom male belt. Latch is a heck of a lot faster and easier to install and remove (although lap belts only are pretty damn easy also). The downside is the regulation issues, and LATCH has a lower weight rating.
Anyway I think the center section is worth a shot because it is much flatter than the rear buckets. It is a bit narrow though so you need to ensure that you don’t get much lateral movement. I wouldn’t do it without tethering the top.
I want to reiterate what Markos mentioned earlier and which sounds like a great idea to me: get a short male - male belt made that can latch to the female end of each side seat. And presto: center seat belt for a car seat.
The more I think about it, that might actually be quite a clever and easy way to do it, but that would require the male - male belt to be adjustable in the middle.
I tried googling for a belt like that but didn't find any, so I guess it would have to be custom made by a belt shop? But that's not a problem as I have to get two new sets of belts for the rear anyway, and can order this at the same time.
Thanks for helping!
Congratulations Gransin on doing a magnificent job with your CSi restoration! As someone who restores cars for a living, I am absolutely blown away by your efforts.
Absolutely amazing. Well done!!!
Dan
Thank you for your kind compliment, Dan!