Adjusting Coilovers: why uneven ride height?
 

Hi all,

To those who have coilovers, I've run into an odd issue: all coilover adjustment rings are symmetric from side to side within a millimeter, but getting widely different ride heights/fender gaps. Anyone else run into this? To reiterate, front left and right adjustment rings are at the exact same height, but my fender gaps and off by a centimeter or more. Same thing in the rear. Car is on perfectly level ground.

Car is balanced basically 50/50 F/R and side to side, right?

In particular I am running a brand new set of Bilstein PSS9s.


Thanks all in advance for your help!

how are you measuring fender gaps ... on a lift? I only ask because what might look like level ground to you may not actually be level ground

second, are both the front and back on one side different heights? Did you tighten endlinks while the car was off the ground? Did you get an alignment yet? Poor camber settings on both sides can give the impression that the heights are off.

If you're measuring fender gap then a bad alignment (likely) will make toe and camber differences appear as ride height differences. First, try measuring from the frame rail to the ground for a bit more accuracy.

The car isn't 50/50 left to right but the difference should be negligible with stiffer springs like the PSS9's have.

If you didn't pre-load the bushings before finally tightening everything down, and you just finished the install very recently, that could be contributing as well.

Each corner has a different weight, left front is the heaviest, right rear is the lightest.

Corner balance the car and forget about the fender gaps but in most cases they will be pretty close from side to side, and the rear gap will be less (thats how the car is designed).

If you didnt loosen the front upper control arm bolts, with the suspension compressed, the front will be high.

car is not balanced 50/50 as you would expect, which is why people who track corner balance their cars to get the cross weights equal.
Corner balancing wont solve your issue tho and will end up probably making it worse, my car looks lopsided sometimes when im not in it if you look at it closely

If you measure ride height from the center of the wheel to the edge of the fender, you will get more accurate results as to measuring from a point of the body to the ground. Difference in tires pressure can be more misleading than you think.

Pretty much everything said above is correct. One thing you do NOT want to do is to try & "levelize" the ride height left-to-right by adjusting the collars - this will really screw up your corner weights. Just leave it as-is until you get it on a set of scales for corner-weighting.

The ideal solution is to certainly take it to a performance shop, I'm sure there are plenty in Chicago, and just pay for an all-in-one alignment and corner balance. They'll probably put a ballast in the driver seat similar to your weight, and they'll worry about the correct ride height and collar settings. I'm not sure if you have a need to go very low on the ride height or not, but you can still be pretty dang low to the ground with a 100% perfect corner balance (ie: my car).

It's an investment, but well worth it to get the most out of your coilovers. Having the infinitely adjustable ride height is the whole point for coilover perches instead of regular lowering springs, so you might as well take advantage of it :)

A corner balanced car will feel very "light" in mid-turn, even like a curvy highway on-ramp, and it will feel like you can easily change steering direction in mid-corner, despite there being a cornering load on one side of the car. I had never had any of my track day cars professionally corner balanced prior to the RX-8, and it was well worth the money.

Tip for corner balancing. If you dont track the car its not a big deal. This is kind of off topic from the OP's original concern.

Set the car up just like you would if your about to go on track. Driver in the seat or a ballest, Tire pressures, fluids (3/4 tank gas), drivers seat position (yes it matters), passenger seat position matter too, I watched the cross weight move with the seat back.

Disconnect the sway bars. 1 end link front and rear will do the trick.

Next, the car should be rolled on and off the scales, not jacked up. If you do jack up a corner to make an adjust ment, give the car a minute to settle after you bounce each corner. The front control arm bushings stock and effect the weights.

Start with an even ride height or slightly higher in the rear. Measured from the framt, not the wheel well gaps. Then balance the car, make small adjustments and it best to adjust opposing corners. Basicly, you could raise the right front 1/8" or you can adjust the right front 1/16 and the left rear 1/16. Better to do the latter.

Once balanced, align the car. After its aligned you will need to balance the car again. After balance check you alignment. Keep repeating until alignment and balance are correct.

Also, 50 crossweight may or may not be the best for your driving needs. Adjust and play with it at the track to fine tune your handeling. It is not uncommong to use different crossweight at different tracks, or with different track conditions and tire seletions. Just like may teams use different alignment setups in different places. The key is to make small adjustments, gather data and dont be affraid to try different stuff.