big difference in rear ride height adjuster

[usdmej]

i spent some time fine tuning my ride height recently (running TCK SA with their standard rear ride height adjusters, 13.5" front 13.0" rear) and have noticed that to get an even ride height all around my rear ride height adjusters are really off from each other.

LF 13.5" RF 13.5" (within 1/8" of each other)
LR 13.25" RR 13.0"


the left rear ride height adjuster is almost all the way at the bottom of the range to get this height
right rear side height adjuster is almost an inch taller

i've been making the adjustments incrementally, car on quickjacks every time, and ten minute ride around the neighborhood after every adjustment.

anybody else run into this? it makes me concerned something in my suspension could be binding.

[cobra]

I have seen small differences before, but a whole inch on the adjuster is a lot, especially considering it's inboard so that is like 1.5 inches difference at the wheel.

Are your springs the same rate and length?
Are the adjusters seated fully?
Are you measuring in a consistent way or going by eye?

[usdmej]

rear springs are the 600# TCK beehive springs
top of springs are secure and snug to an oem spring pad. adjusters are at the bottom and of course a little loose since the inner diameter of the adjuster is alot bigger than the nipple on the lower control arm
i've been doing my best to measure correctly, for ride height i line up a level horizontally to the center of the hub and measure up to the top of the fenderline. to measure the difference in the heights i just measure from the ground to the fender and subtract

i guess the only thing i didnt measure is the difference in the ride height adjusters, maybe it's not an entire inch, it just seems like way more threads of difference than it should be

[Tbonem3]

Stock rear sway bar and links?

Ebrake off when measuring/eyeballing height?

Would would be the outcome (worth trying imo) if you measured and set all perches/spring seats equal to their opposite side? Find a fixed point to measure from like the swaybar tabs on the strut or the rear lower control arm surface.

[maupineda]

Sometimes you can find variance in the spring rate. only way to tell is measure them in a bench tester. could be a quality issue. i have a similar issue where on one side my perch is a good 10mm different side to side. This is with swift springs which are supposed to be top notch

[usdmej]

Stock rear sway bar and links?

Ebrake off when measuring/eyeballing height?

Would would be the outcome (worth trying imo) if you measured and set all perches/spring seats equal to their opposite side? Find a fixed point to measure from like the swaybar tabs on the strut or the rear lower control arm surface.

- CSL sway bar and links (not sure if the links are different than stock, bought them as a package from ECS). no binding that i know of based on lack of popping noises from the rear

- ebrake is actually on when im doing the measuring (in my garage) but this is after a drive to settle the suspension. i can try it again in gear instead

- oh man that sounds like a ton of work for an experiment and then a lot of work to get it back to where im currently at. i'll save that as a later resort lol

[usdmej]

Sometimes you can find variance in the spring rate. only way to tell is measure them in a bench tester. could be a quality issue. i have a similar issue where on one side my perch is a good 10mm different side to side. This is with swift springs which are supposed to be top notch

i have actually deleted all audio/nav components which would theoretically raise the rear left. but those specific components were only ~16 pounds . . .

[discoelk]

Have you swapped springs L/R to validate the rates? Pretty easy to do on the rear.

[mrgizmo04]

1) is one of your rear jacking pads collapsed and 2) do you have racp reinforcement bar kit welded in 3) quality of springs and/or was one of the springs hammered on curbs (they can deform plastically with enough stress from a large hit).

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[bigjae46]

Stock corner weights aren't the same so the adjuster height will be slightly different. Normal.

If you get the car level and then put it on some scales, you should be relatively close to a 50% corner weight.

[old///MFanatic]

If you lift the front end (evenly) and the rear is level it’s something in the front end that’s off.
If it shows the rear is lobsided then it’s something in the rear.

[old///MFanatic]

i've been doing my best to measure correctly, for ride height i line up a level horizontally to the center of the hub and measure up to the top of the fenderline. to measure the difference in the heights i just measure from the ground to the fender and subtract

Well sorry to go on a tangent but is the 13.5 front and 13.0 rear a generally accepted “standard” height for our M3s?

Also I’ve known of two ways to measure suspension height. Check tire pressures are same all around.
One is from the centerline of the center wheel cap to the bottom center of fender arch.
The other is as the Bentley Manual states and that’s to use the bottom lip of wheel and measure up to bottom center of the fender’s arch.

[Slideways]

The other is as the Bentley Manual states and that’s to use the bottom lip of wheel and measure up to bottom center of the fender’s arch.

This is a good way to do it. Measure the outer diameter of the wheel (it is not always the same diameter as the wheel spec, ex. 18" wheel can have a 19.5" face), divide by 2 and then subtract by the bottom lip to fender arch distance. Much more accurate than trying to eyeball the center of the wheel at the center cap.