Prolene

[QUOTE]Originally posted by Jason Saini
[B]I'm going to help Comptech with the testing of their new bar also.

Jason Saini

Yes, it's stiffer than the Mugen... they are testing this bar to make for the release of a slider-adjustable bar. The 'test' bar is an un-painted 1.25" bar, with .25" wall thickness... the Mugen is 1.25" with a .197" wall thickness. A very subtle difference, but hopefully on target as a starting point. My guess is that this size should be sufficient for all but the stickiest of surfaces, where even more stiffness may be required. Our first test will be the Ft. Myers ProSolo, which is in 3 weeks. Ron and Annie are trying it out the weekend before that, I believe, at a local event. The Mugen bar is more than sufficient for street tires, but putting sticky tires on increases the roll considerably, requiring a stiffer front bar. I'll keep everyone posted on the progress of this project... Also, King Motorsports is still planning to develop a blade-adjustable bar around a March timeframe... I'll keep everyone posted on those developments as well.

solo2racer

[QUOTE]Originally posted by Jason Saini
[B]Yes, it's stiffer than the Mugen... they are testing this bar to make for the release of a slider-adjustable bar.

RandyP

One thing to consider before someone builds a 2" solid steel bar is that since the springs on the car cannot be stiffened and the car frame cannot be stiffened in A Stock, at some point, a stiffer bar only adds weight to the car. Does anyone know how much the stock bar twists under autoX conditions?

Gregg Lee

At this point, we are down to testing, but since I have done all this already:

Stock bar wall is 5mm = .197 inch, so mugen is only 52% stiffer, etc.

5% shorter arm does not yield 5% stiffer rate. It's not linear. My reference book says its a mix of 2nd and 3rd power relationships to arm length, which comprehends both bend of arm and rate ratio vs. motion ratio. Rate ratio is motion ration squared, and apparently bending is a cube ratio.

For the fanatics, the whole equation for single side spring rate of a round steel bar in a mix of algebra and excel is

k = 500,000*d^4 / (.4244*a^2*b + .2264*c^3)

where d is diameter, b is length of straight, c is the arm length along the arm, following any bends, and a offset from the straight section to the end of the bar arm at right angle to the bar.


[QUOTE]Originally posted by soloiiracer

Well, the formula for torsional stiffness of a sway bar is proportional to the diameter to the 4th power!

Banannie

the Comptech bar actually ended up being shorter than stock, thus a severe PITA for Ron to get on the car... but without changing shock settings, and on the stock tires, the car actually PUSHED a little after - even in situations guaranteed to get the back to step out with the Mugen bar... handles more like the Type R we raced did! WOO HOO!

Banannie

just talked to Mike from Comptech - they hadn't intended to have the bar shorter.... very interesting!

Jason Saini

We should be getting the bar tomorrow, and istalling it this weekend. I'll measure both and report the differences. Maybe I'll get some end links together if this is going to be rough to install... it will be a much stiffer link anyway. I'll post pics of the install as it happens... shocks should be going on at the same time! (thankfully)

We will then have every stock-legal mod!




[Edited by Jason Saini on 01-29-2001 at 02:25 PM]

RandyP

What about roll cage? A stiffer car is a more tuneable car. Also, there are other legal mods that don't improve performance.

Jason Saini

I guess I meant every important one... a cage does add stiffness, but at the cost of too much weight in my opinion. Although at 6'3" I might think about it just to protect my dome in the unlikely event the shiny side ends up down. For now I will remain the optimist and hope that doesn't happen!