The right side is a good 10 mm lower (measured at the pinch welds and fenders) with no one in the driver’s seat. So it’s even worse when I am driving the car. This makes getting into / out of my garage a challenge, as one side of the bumper is significantly lower.

This seems strange, since I put the shocks at exactly the same case length when I had them installed.
The bushings are all urethane or rod ends, so preload shouldn’t be an issue.

The rear is exactly the same ride right on both sides at the fenders.

Or is a 10 mm discrepancy normal?

I can’t easily get the car corner weighted or aligned.

 

It could be any combination of things, but I remember reading the battery was placed on the left front to offset some of the weight when the driver in the RHD models was present.

So does this mean that would be more weight on the left side in a LHD car with all the steering components moved to that side? No idea.

One other possibility I've seen in other cars is if the control arm bolts are not loose when installed then tightened with the car sitting at ride height, you can have some pre load in the suspension causing it to sit funny.

Otherwise, the easiest solution if you have coil overs is raise the spring porch a small amount and recheck after going around your block.

Vince

 

Not normal. How did you measure the "case length"? What coilovers?

 

The car doesn't weight the same L/R F/R, so each corner is going to have a bit different natural load on it. That's what corner balancing is, they adjust the heights subtly till it reads equally on the scales, the changes subtly load/unload each wheel. If you set em all exactly the same, i'd say its pretty close.

10mm isn't a ton, I've seen 1/4" differences. I'd take it to get it aligned and corner balanced and see what's what.

 

The battery is in the back of the car, so it should actually be lower on the left in my case.

I would suspect bushing preload, except my bushings are polyurethane, so preload shouldn’t effect them.

 

HKS. The distance between the top mount and the bottom mount, which I set to the default length in the installation manual.

 

I wanted to get it balanced but for a number of reasons I wasn’t able to.
Getting the car aligned is significant investment, since it has to be trailered.

I wouldn’t worry about it if it wasn’t for the fact that the bumper looks visibly uneven. Not sure how much of that is from ride height, though…

I wonder how much moving one corner would upset the alignment.

 

Did you adjust the spring perch, lower perch, or both?

Since both perches can affect your ride height, they are probably not even. Make sure that not only the overall length is the same R-L, but the height from the top mount to the upper spring perch are the same R-L, and the height from the upper spring perch to the bottom mounting eyelid are the same R-L.



You likely need to raise the spring perch on the right side ~6-7mm or lower the left side 6-7mm depending on which height you prefer.

 

I just went and measured it again and it was more like a 20 mm difference. That explains why the car looks cockeyed.

I thought I had done exactly why you said.

I applied an equal amount of preload (using a ruler) with the spring perch and the used the length adjuster to make them the same length. The preload and length were both based on the “as-shipped” specs of the coilovers.

It’s possible I simply set one to a different length by accident, so I will jack the car up and check the length.

Probably can’t get away without an alignment if the difference is this big…

 

(forum database seems to be wigging out again, so I will repost...)

I just went and measured it again and it was more like a 20 mm difference. That explains why the car looks cockeyed.

I thought I had done exactly why you said.

I applied an equal amount of preload to both springs using a ruler, and then measured the distance from the top mount to the bushing.
It's possible I just set the lengths wrong, so I'll jack it up and double check.

I might just adjust it and then fix the camber change myself, without touching the caster.
Or I might buy literally a dozen bathroom scales, a laser level, etc. and do a full corner weight and alignment.

 

The top mount pivots and if it is not flat, it could have messed up your measurements. You can measure from the top of the spring (which can't move) to the bottom spring perch, and then from the top of the spring to the bottom bushing to avoid variables.

I would not bother with bathroom scales. Concrete floors are not even and often can lead to crossweight inaccuracies of 1-2% or more. Trying to shim 12 scales to be even with a laser level, and then evenly distribute the weight of each corner across 3 scales would be pretty difficult to do, and I would be surprised if it was accurate within 2%.

Doing cross weights is not quick or easy. If you don't know what you're doing and don't know how to methodically change the heights, you can have decent corner weight numbers with the car sitting wonky with greatly uneven heights and awkward handling characteristics. Close to even cross weights can be achieved with goofed up shock heights as well as with fairly even shock heights when done correctly.

Personally, I would just make sure the perch heights are even and you'll likely be within 1-2%.
​​​​​​

 

In hindsight, based on the actual specified "case length" (and the term "case length"), I probably set the length of the shock before assembling the coilover.
So I didn't actually measure from the top hat.

I guess my mistake was assuming it would be OK as long as the shock lengths were exactly even, without bothering check.
It was dead-on in the rear, but the rear probably has better L/R weight distribution.

I was going to put the bathroom scales on the floor, put a concrete block on top (for access to the camber bolts and tie rods), and then shim that.
I would think 1-2 percent accuracy would be sufficient for my purposes?

How exactly do you get even distributions without having slightly wonky ride height?

Unless you're talking about moving weight around. I almost wonder if I should forgo a lightweight battery, since the weight helps balance the car out when the passenger seat is out.

 

The "case length" is the overall length (OAL). You can have two shocks with the same OAL, but the spring perch height can vary drastically, which is a main factor in determining ride height. So it's important to have both of these numbers even.

Your problem is likely spring perch related. L-R weight variances will not cause anywhere near a 20mm difference. Heck, it probably wouldn't change heights more than a few mm.

You're proposing a sketchy setup. I honestly wouldn't bother. Just make sure your perch heights are even and you'll likely be within 2% cross weight and be perfectly fine. To get even weight distribution without goofing up the setup, you need to make small changes methodically across diagonal corners. Raising or lowering the LF and RR together, and RF and LR together, making small changes at a time in these pairs to dial in the cross weights. This is after you determine your ride heights and the desired rake (front to rear height). This is why shops charge a lot of money to corner balance a car. It takes time and expertise to do it right, and ive seen a lot done wrong. Set the perch heights even R-L and you'll be fine.

 

I spent a few hours staring at my coilovers and no matter what I measure, they're basically identical.

Then I remembered I am running two different front wheels (of the same size, mind you), and I found that one tire is 10 mm taller than the other.

This should only account for 5 mm of the discrepancy, though.

 

Different wheels or different tires? What model? How did you determine it's 10mm taller?

 

Unequal shock or tire heights should translate to ~the same R to L difference in height at both the front and rear fenders, unless the chassis is twisted or the floor is uneven. Otherwise I can't understand what seems to be going on.

 

Yeah, I would make sure you're on an actually level surface, but also disconnect the swaybar linkages to be sure there's no load on it.

 

Even a swaybar preload would result in a similar R to L height difference front and rear. Of course, the weight balance would be off, but that's not what the OP is trying to understand in his 1st post. To truly diagnose, you need to know both the ride heights and weights at all 4 corners. And, of course the tire loaded heights to the axle need to be the same R to L, and as ptrhahn says, the floor/platform needs to be level or at least flat with no twist F to R.

 

I don't follow you. If a car is level with zero rake, and you raise a corner 1/8", there will be a negligible effect in the ride heights of the other 3 corners as the car sits with one corner higher than the rest.

 

Unless the car chassis twists to totally absorb the 1/8" difference on one corner, it has to at least slightly affect the height of at least one other corner. You might not notice the effect of 1/8", but it's just a matter of magnitude. If 1/2 or 1" would affect this, so would 1/8". Its effect would just be smaller.

FWIW, I've aligned racecars for over 50 years, and that is always the case.

I see you're an "engineering consultant," so I'm not trying to be obstinate, I'm just trying to explain what I've come to understand in a logical way.

 

It will slightly affect the heights of the other corners, but it will often be negligible and almost never will result in the "same" (right to left) or diagonal ride height change even on a car with a torsionally rigid chassis and an "even floor". Spring rates, instant center geometry, Cgs, ARBs, etc... all vary from car to car, and all have an effect on load transfer (and corner weights) but there will rarely ever be a 1:1 ride height change R-L or diagonally.

OP has a 20mm difference in his front heights. It is possible that his rear shock heights are also not even, which is resulting in his rear heights being even with the front having a 20mm height difference; however, it is possible that his rear heights are fine. I have not corner weighted my FD to see the chassis & setup sensitivity. It sounds like something is heavily overlooked for such a big variance. Valkrie needs to put the same diameter and brand tires on the car first and foremost.

 

I agree with what you just said. Put matching tires on and see what happens. Even having tires identical but different construction/stiffness/pressures will throw off the weight balance and chassis attitude.

 

The wheels are different. The tires are the same.
i put a straight edge on top and measured the height.

 

I pumped up the tires back to 32 psi, flipped them around, bounced the car, and there's still a 10+ mm discrepancy.

I checked the rears again, and this time I found a discrepancy (maybe 10 mm), but the direction is reversed.

 

What are your 4 pinch weld heights now?

Take all the dampers off and check them, documenting with photos. Something isn't set up right.