Racers - thoughts on a harness bar...
 

There is no ready-made solution to get 4 point harness belts into the X3. The Schroth system for the E46 does not fit.

I was looking around the inside of the X3 and there is no way to mount a harness bar to either the b-pillar shoulder belt mounting points or the d-pillar back seat upper seat belt mount points.

What would you think about creating a bar from roll bar tubing that ran the width of the trunk and attached to the child seat teather points in the floor of the trunk. It would have 3 vertical legs that weld onto one horizontal bar. The harness belts would wrap around that bar, pass through the rear and front head rests. From there it would just be a matter of bolting the front belts to the lower stock seat belt bolts.

My reading of the Federal Motor Vehicle Safety Standards is that the teather attachment points must be designed to withstand the same force as seat belt attachment points (5,000 nm I think). In theory they should be safe enough. By using all three you distribute loads across three points thereby maximizing strength.

Any thoughts?

My thoughts are "why would you put a harness in a X3"? What are you planning on doing with it?

I have been using my X3 for auto-x and occasional driver's schools. I think harnesses would help me focus on driving.

OOooookkkkkaaaaaa
I could think of a few other car to autocross but I'm thinking any BMW would work. Enjoy

White05X3 has posted some videos of his X3 experiences on the autocross track. It looks like the X3 acquits itself quite well on the track for a large vehicle and it looks like a fun time.

Actually the X3 is not a bad auto-x car at all. During my last event with the San Diego BMW CCA, I was faster than many of the M stock and some of the M Modified class cars. Although I only finished 8th out of 20 cars, I was not disappointed. In my class I beat a Z4, 550i 6-speed and a flock of E46's.

At the last LA Chapter auto-x I was .37 seconds off of 1st place (which was won by a 330i on much better tires).

I too could think of a few other cars to auto-x, but this is what I've got. A good 4 point harness (like what Schroth makes for the E46 and E39) that is not permanent would make a big difference in helping my times.

And for what it's worth... both R6Girl and I have used our X3's on the track, and they are very competent.

ASAWADUDE - thanks for that! It is tons of fun to drive on the track!

just a heads-up -- literally lol -- remmeber that with a harness, YOU become the roll bar if you don't have one installed: you cannot duck!! so just keep that in mind and consider installing a roll bar or street-legal (read: no helmet needed) cage first. any of you open-track guys correct me if i'm wrong here please?

You are absolutely correct. That is a huge danger of harnesses on non roll bar equipped cars. I am less concerned about it for auto-x since I consider the rollover risk to be relatively low. I believe I would continue using my CG Lock for track events if I actually had a harness bar. Keeping totally still is more important during auto-x because you are constantly turning, braking, etc... versus track events where there is usually some period of straight ahead where you can rest a bit.

Now if somebody would make a bolt-in roll bar for the X3, I could just use a cross brace on that to mount the harness. Oddly enough, there is just not much call for roll bars in X3's :dunno: :dunno: Go figure (just kidding)...

But getting back to the original question...I wonder if my design would work well??

go ahead and try the cg lock and all the other gizmo's that claim to hold you in better...

then try what works and what pro drivers teach:
slide the seat back a few inches, buckle up, pull the belts all the way out to lock it and slowly let it in till its where you want it, then slide the seat up. that will hold you in place the correct way.

btw: the slide back and forth technique is the proper way to buckle in with race restraints also...

imo, 4 pt harnesses are dangerous and should be outlawed. you still have a street car so use the safety gear that was designed for a street car.