[beeotch]

Mason Engineering. Heres mine.

[bolestuff]

Holly NOS Batman!

[jblack]

A couple things...

1. You don't have struts in the back of the car - you have shocks, so they are shock towers in the back, strut towers in front - so it's a shock tower brace.

2. The difference in design of the front and rear of the car's suspension is huge. The struts and springs meet at the top of the front suspension - this is the main attachment point of the front suspension (other attachment points in the front are the lollipop and the ball joint at the bend of the front control arms, as well as the steering rack, but that is not load bearing). The rear is attached at the trailing arm front point and two other spots where the control arms meet the rear subframe. The shock mount at the top is really not load bearing part of the rear suspension, like it is in the front with regard to the strut.

I decided to test this out - I have a Spec E30 (close to identical front suspension, different rear suspension, but the mount of the shock to the shock tower is the same). I mounted my video camera low and rearward facing in the race car, and tied a piece of string between the shock towers, and did a 30 minute session at Sebring Raceway. The concept is, if the string bowed, there is flex in the unibody at the towers (and I would get a bar made, as they are allowed in the rules). If the string didn't bow, there is no need. The video shook a lot (I have a pretty stiff suspension in the car, but it is not much different than some use on the street - H&R Race springs, Bilstein Sport shocks and struts, and slightly bigger sway bars, as well as delrin everywhere there used to be rubber). Net is the string vibrated from the video, but there was no noticeable flex or bow.

So... no visible flex in that car - and it's an '89 325i - I'm sure E30s have much less rigid unibodys than E46s.

Finally - for subjective results - I installed a friend's bar in the back. Similar lap times, no difference I could feel.

Net is - if you think you can feel a difference on the street - I'd suggest you have an incredibly well calibrated butt dyno, as I could not measure or feel a difference on a race car with a more flexible unibody.

Your Mileage May Vary...