Andy69

I almost forgot, removing weight from the car necessitates remeasuring the center of gravity height.

I'm back on the CRX now.  I've reduced some more weight and swapped in the HF axle, and updated the model to match.

I've got to go back to my notes and continue posting the results of the suspension model.  Briefly, what I discovered with the front model in Racing Aspirations was that the least body roll was achieved with the front roll center slightly below the ground level. Beyond that, the virtual lever arm got longer and body roll increased.  In other words, going too low on the front increases body roll.   Adjustment to the optimum RC location resulted in an LCA angle that sloped UP toward the ball joint rather than down as the conventional wisdom dictated. I think -3 degrees was the angle I ended with.  This minimized body roll and maximized static negative camber at around -2 degrees.  I decided that was a good starting point for adjustment and will go with that in the initial setup. 

I used two different model sources to model the entire car.  DGATW and a spreadsheet I downloaded (from where I can't remember, a rally team iirc).  DG recommended 400# rear springs and the other model nearly 800# because it recommended a much higher rear frequency based on the calculations it made.  Right now it has 550# springs.  I'm undecided but 800# seems way to high and 400 I've already determined was too low (but had rear aero at the time).

Initially I'm going to go with the 400s and no aero and see how it handles and go from there.  

Sun roof is on my list as well.  I thought there was an old post that found it was 35 lbs that you save.  35 or 45 it is still in the highest point on the car.  I cut the roof off of a non sunroof car to reskin mine.

 

i want to do mine for a few reasons.

1) it doesn’t work any more.

2) due to headliner shape, for tracks, my helmet rubs and bumps on right hand turns.

3) weight is in a bad place.  Getting it lower and in right rear will improve balance.

It was about 33# including the headliner.  I have one from an HF that I'll put back in that's lighter.  I thought I'd have to get a roof from one without the sunroof but the movable panel is sheet metal.  It will require some modifications but will work.

Also removed the stock rear spoiler for another 10#.  I'm adding a custom spoiler so don't need it.  I've been keeping track of weight and it's now 1681

Yes, and next up for weight reduction will be removing the sun roof and replacing it with a plain panel.  Between the mechanism, motor, movable panel and headliner, it should take another 45# off.  I've been keeping track of weigh reduction and I should have the car at around 1650# after that.

Swapped out the rear axle to the HF one.  Saved 12# and got rid of the internal torsion ARB which I couldnt quantify in my suspension model.   I can easily make up for any loss of roll stiffness by changing the spring rate.