Coil over question

[16MagST]

Hi all…
Finally installing my coil overs (going from Mountune Koni sport setup) . My question is does the rear axle droop differently left to right? I have a 1” variance with the collars exactly the same. I unbolted everything, put it back in and it’s the same. The drivers side of the axle also is harder to get the coil over in. I have a stock rear sway bar, and I did install a rear axle stiffner.Also since I forgot to mention it earlier, the car was on jack stands, axle was drooped. Thanks for the advice.

 

[SteveS]

You don't want to tighten up the suspension with the wheels drooping. It needs to be sitting on the wheels or you put tension ("preload") into the bushings.

 

[jivenene]

@16MagST did you take measurements before the install of the new springs? I had the same experience, but I went from stock rear springs to the 10 inch x 2.5 inch + helpers that @Dialcaliper experimented with in his thread Feisty the "Family Car". My unevenness L to R is bout 5/8 inch in the rear. It was the same with the stock springs though. I verified that by using a digital level on the roof (0.40 deg with pass side higher), just in case my rear fenders were mounted crooked after an accident where someone hit me in the right rear.

there is no way to adjust the torsion beam height, unless you put shims between the L side mounting point and the frame? As an added data point, I am sitting 1/4 inch higher on R side in the front. fronts are Bilstein B6 with shims like spec'ed in that @Dialcaliper 's thread above. The only thing I can think of is the rear axle is bent somewhere? But the car drives perfectly straight and I don't think it's crabwalking. Actually I can verify the rear is centered as I have done string box alignment and the wheels are square.

Next I may try cutting the R side helper spring so it has fewer coils to sit on , hence bringing down the R rear?

 

[Dialcaliper]

@16MagST @jivenene Interesting - sounds like also some corner weight issues going on. Be aware that you can start chasing your tail trying to adjust for ride heights as adjusting one corner will load/offload the opposite diagonal. For example adjusting one corner (right rear/front left for example) by 1/4” with a spacer or coilover ring will not result in 1/4” corner height change due to some weight being redistributed to the opposite pair (left rear/front right)

What type and/or manufacturer of springs are you using. One thing I’ve noticed, especially outside of the higher quality brands of coilover springs (Swift/Eibach/Hyperco) is that both the actual free length and actual spring rate can vary significantly from the “advertised” values.

If you have the springs off the car and set them next to eachother you can see if the free lengths are significantly different from eachother, which would introduce a fixed offset. You can also try swapping springs left to right to see if it makes a difference.

Lastly, the car corner weights are not quite the same which can affect things as well

 

[jivenene]

In my case, since the rear had the same mismatch L-R with the stock springs, I don't think the new springs introduced the height discrepancy. Also I recall comparing all the new springs before installation, they were the same height. They were bought from FOA Springs in Vegas.

I hear you about the diagonal pivoting when adjusting height on one corner. The heights , from lowest to highest , are LF, RF, LR, RR. So if I added shims under the spring on the LF strut, theoretically it would pivot on the RF/LR diagonal, raise the LF and lower the RR? That might be the ticket. Is there anything wrong with that approach?

 

[Dialcaliper]

In my case, since the rear had the same mismatch L-R with the stock springs, I don't think the new springs introduced the height discrepancy. Also I recall comparing all the new springs before installation, they were the same height. They were bought from FOA Springs in Vegas.

I hear you about the diagonal pivoting when adjusting height on one corner. The heights , from lowest to highest , are LF, RF, LR, RR. So if I added shims under the spring on the LF strut, theoretically it would pivot on the RF/LR diagonal, raise the LF and lower the RR? That might be the ticket. Is there anything wrong with that approach?

That’s probably the right approach - diagonals are difficult because while it does kind of act like a tippy 4-legged stool, it’s more vague because it’s partial weight transfer to the springs instead

Check your front heights as well - if it’s just the corner you could do as you say with opposite corners, but if the front is also out the same way, it could mean adjusting just one side F/R instead