Friday, April 20, 2018

Rear Seat Belts in Mini Estates

What to do about rear seatbelts? In the UK, car manufacturers weren't required to fit rear seatbelts until 1986.  Sadly manufacture of all estate variants ended in 1980, so the UK factory never needed to solve the problem for us.

Lap belt catch mounted through wheel arch.
Lap belts in a Clubman Estate
Its not too hard to retro-fit lap seat belts. Most jurisdictions allow a metal spreader plate fitted with a standard 7/16 UNF captive nut to be used under the floor, or in the wheel arch. To anchor the two ends of the belts. Here are some pictures I stole from the old Clubman Estate Register forum.

The wheel arch is structurally strong, but too low to mount a shoulder sash
Also the fuel tank  is right there in my Traveller.
The bigger challenge is if you want a lap/sash belt. Lap/ sash belts are far safer, something I learned in my short career as a Mini Moke crash test dummy. The problem in the back of a Traveller is the lack of places to solidly attach the shoulder strap. The attachment point needs to be structurally solid and at the correct height relative to the passenger's shoulders.  Pictured here is another example of a Clubman Estate, this one fitted with a sash belt. In my opinion this belt is mounted much too low to be safe. When an adult is seated in the back seat their shoulder will be several inches higher than the seatback. In a collision, the belt will pull down and loosen. Its difficult to find any hard data on the correct height but generally between 4 inches below shoulder height to level with shoulder height seems to be accepted.

Here are two more examples. Both have the reel mounted at a better height. However I have serious doubts about the strength of that section of the seat rest that these are attached to. The red one seems to be reasonably well reinforced, as well as being a few inches higher, but the black one is ugly and the bar which runs right across to the other side will obstruct the load area when the seat is folded down.

As mentioned previously the UK factory never needed to solve the problem, but the Australian factory did. The Australian factory never put an estate version into production, but they did experiment with a couple of prototypes. The green clubman estate in these photos was one of apparently two prototypes developed in the mid '80s as an experiment. Unfortunately the only pictures I have were taken from a gumtree ad when the one survivor was sold a few years back. There are a couple more photos in "The Mini Experience"magazine, but they are under copyright.
These pictures show that the the shoulder sash is attached in the rear corners of the roof, each side of the doors. There is a rigid 'droplink' mounted to the body above the side windows at the top and in the seat rest at the bottom. The droplink has a smooth loop that the seatbelt passes through. These keep the sash at a good shoulder height.

On the face of it this looks like a good solution. I imagine that a metal bracket must be welded into the upper rear corners of the body to provide a mounting point, but that wpuld be a very strong part of the body. The droplinks have comparatively little force on them becasue the belt just slides through, so they should be more than strong enough.

If I was going to fit lap sash belts, I think that's what I'd work toward. The mounting points should be able to be hidden under the trim in those areas comparatively easily. Choosing belts that complement the trim (not dirty black and flouro orange) would help.

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