Help! Corbeau seats in Z4? Also, I don't understand seat mounting options too well.

[intoflatlines]

Originally Posted by Beedub

looking forward to the harness pics :-)

Here ya go. Thanks to fellow Z driver Robin for fabricating this for me.

Remember, this setup is not safe for street or track or any kind of collision. Dangerous and illegal!

This is the fabricated piece. It is constructed of some square steel tubing and some flat pieces of steel. The square tubing section is horizontal and goes behind the roll hoop covers. At the ends of the tubing, there are steel pieces cut/bent/welded to match the contour of the roll hoop cover to help distribute the forward load.

There are vertical steel pieces that are welded to the middle of the square tube. These serve to separate the two harness straps. The bottom vertical section allows the whole piece to rest nicely on the plastic interior panel behind the roll hoop. The top vertical section is to prevent the part from rising up. At the ends of each vertical sections there are horizontal steel pieces welded on to match the contours of the body panel/roll hoop. On the surfaces that touch the car (lateral "paddles", bottom horizontal piece, top horizontal piece) there is some rubbery/plastic material that I adhered to the steel, to help even out the load and to prevent scratches on the plastic parts.

The top vertical section I don't think does anything other than to separate the harness straps. All of the force on the piece is pulling forward and down, I can't think of a situation where the piece would be pulled up as to do this, you'd basically have to grab the straps between the seat and the roll hoop and pull up.

The piece, dismounted:



In position behind the roll hoop:



Straps mounted (I did not snug the hardware up to the tube as recommended, this was just mounted up to show you how it connects):



How the straps basically route. The harness straps are the ones with the striped line, the solid black/gray strap is the OEM belt. Again, the hardware should be snug up against the tubing and the ends should be neatly wrapped up but this was for a quick pic. It looks crooked here but it is more of a camera angle trick:



Harness straps loose through the holes in the seat:





Geometry is not ideal as it's recommended to have the straps at a better angle but it is fine for autocross. Also getting a different mounting location set up would be considerably more work and might not be as strong.

[Beedub]

i like the idea.....

under the roll hoop covers is a metal u shape, wouldnt it be alot cleaner and safer to weld a straight piece in to create an A shape, this will be massively stronger, and you could even cut the roll hoop covers so they could be re-used for ultimate levels of detail on the install... options for the z4 are really limited so it was great to see this attempted.

[intoflatlines]

Originally Posted by Beedub

i like the idea.....

under the roll hoop covers is a metal u shape, wouldnt it be alot cleaner and safer to weld a straight piece in to create an A shape, this will be massively stronger, and you could even cut the roll hoop covers so they could be re-used for ultimate levels of detail on the install... options for the z4 are really limited so it was great to see this attempted.

Yeah that'd be a good idea but I didn't want to mess with cutting the roll hoop cover especially since it still wouldn't be legal/safe for street and track. So I figured I might as well stick with a temporary removable solution until I commit to doing a proper roll bar, etc.

Also, today we had an autocross. The seat was amazingly supportive, didn't hit the door at all during cornering, and the harness was solid and held me very tightly. Normally during an autocross I have to tighten the stock seatbelt so much that it almost hurts my chest in order to keep me glued to the seat, with the harness I am immovable in the seat with lots of breathing room still. Also I always had a bruise on my knee after autocross from bracing myself against the door during corners, it was unnecessary with the new seat/harness so my knee is bruise-free!

[Beedub]

yeah the stock seats LOOK great, but are totally rubbish at giving support during proper driving....