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      10-26-2019, 01:07 PM   #1
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Getting rear ride height right on coilovers

I just installed coilovers on my Z4MC and lowered the rears too low. Almost 1.5 inch drop. I know it's too low because now the rear wheels have visible negative camber.

How much drop is too much on the rears? How do you guys decide your ride height in general? Stick with stock for best performance, or is slightly lowered better? How much lower?

How do alignment shops do the alignment for rear wheels? I read different things about it online. Some say it's only adjusted by the spring height. I've seen mention of an eccentric bushing.

Also, how do you guys make sure your front/rear ride heights are balanced, i.e not too much drop on one vs the other.

Also, will the alignment shop adjust my ride height and shift the front struts around to fix camber? Idk what these shops actually do beside put the car on a machine and attach the sensors to the wheels.

Thanks for the help.
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      10-28-2019, 11:00 AM   #2
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Answered some of my own questions -

rear alignment:
https://www.newtis.info/tisv2/a/en/e...rement/FxWnmWJ

confirmation that adjusting ride height sucks and therefore alignment shop will prob not do this:
https://www.zpost.com/forums/showthread.php?t=729211
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      10-28-2019, 11:51 AM   #3
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The rear height would be determined by the front height, this is called 'Rake'. My last track alignment had me at F: 25.5 R: 25.

Depending on where you're located in NY, we have a lot of really good performance shops that can assist you.

Also, you might want to consider Ground Control articulating weight jacks in the rear to make adjustment easier. Hope this helps!
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      10-28-2019, 01:05 PM   #4
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Thanks Azeka, do you have recommendations near Brooklyn?
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      10-28-2019, 04:13 PM   #5
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Originally Posted by filtercoffee View Post
Thanks Azeka, do you have recommendations near Brooklyn?
You're welcome! It might be a little bit of a hike with traffic, but Rogue Engineering in NJ would be a great resource that is around 30 miles or so away.

Also New Palumbo's in Millburn, NJ is owned by a BMW club racer that really knows his stuff.
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      10-28-2019, 07:52 PM   #6
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Rake matters to certain extent but ideally your indiv heights are based on corner balancing. Also factor in what camber settings are and how much tire you can practically stuff without rubbing.
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      10-28-2019, 08:29 PM   #7
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Quote:
Originally Posted by 3002 tii View Post
Rake matters to certain extent but ideally your indiv heights are based on corner balancing. Also factor in what camber settings are and how much tire you can practically stuff without running.

👆🏻This
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      10-28-2019, 11:42 PM   #8
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If I'm getting the car corner balanced, I guess I don't need to bother with the ride height adjustment at all?

Also is it just me or is ride height adjustment is > 50% of the work of installing coilovers properly? Since you have to tweak drive the car around, rinse and repeat. Corner adjustment places might as well install the coilovers too, no?
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      10-29-2019, 07:39 PM   #9
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Quote:
Originally Posted by filtercoffee View Post
If I'm getting the car corner balanced, I guess I don't need to bother with the ride height adjustment at all?

Also is it just me or is ride height adjustment is > 50% of the work of installing coilovers properly? Since you have to tweak drive the car around, rinse and repeat. Corner adjustment places might as well install the coilovers too, no?
On a roadster the install is more involved because of additional trim removal but for a coupe it’s pretty straightforward. Setting initial ride height from a visual standpoint is only time consuming if you’re going so low (slammed) that you’re looking for ever mm to close that gap without rubbing or bottoming out. But I’ve learned over the years that ‘waiting for springs to settle’ is over blown and whatever static height you get is pretty much it. The Rogue rear adjusters are nice but it’s just essentially cutting out the time spent on jacking up the car and removing the wheel.

If you’re looking to corner balance, then yes it’s time consuming but only because you can’t adjust the car while it’s on a lift. Every adjustment needs to be made while it’s sitting on the scales so it basically takes a shop the same time as it would take you. But more important is whoever is doing the corner also takes care of your alignment at same time. Assuming you got adjustable camber plates installed with the coilovers?

Just keep in mind that a proper corner balance can get really expensive. So unless you’re chasing tenths, it may not be worth the cost, especially if you plan on messing with ride height down the road. Else just pick something that’s visually appealing yet practical and make sure your alignment is dialed in.
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      10-29-2019, 08:34 PM   #10
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My rear ride height lowered significantly after a day of hard driving. Not sure why. i hope it's not because the shocks are bad. Hopefully just the springs were not seated or my car hasn't settled after driving it up a level of my condo parking garage. Will take another look this weekend. I agree that if you just assume static ride height is correct, the job of setting ride height isn't too bad.
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      10-29-2019, 09:43 PM   #11
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Quote:
Originally Posted by filtercoffee View Post
My rear ride height lowered significantly after a day of hard driving. Not sure why. i hope it's not because the shocks are bad. Hopefully just the springs were not seated or my car hasn't settled after driving it up a level of my condo parking garage. Will take another look this weekend. I agree that if you just assume static ride height is correct, the job of setting ride height isn't too bad.
What setup did you buy and how many miles on it? What length spring and how much adjustment do you have left on the perch?
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      10-29-2019, 09:49 PM   #12
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Fortune auto msc-1. I don't know the exact mileage but probably 20-30k miles. the ring is 2 inches up on the perch, I think the swift springs are 5". I have roughly another 2 inches or more to go.
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      10-29-2019, 10:26 PM   #13
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Quote:
Originally Posted by filtercoffee View Post
Fortune auto msc-1. I don't know the exact mileage but probably 20-30k miles. the ring is 2 inches up on the perch, I think the swift springs are 5". I have roughly another 2 inches or more to go.
Will you be tracking at all? Always wonder if those Coilover are good enough for the track.
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      10-30-2019, 09:34 AM   #14
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I will probably not be tracking this year, maybe next year. If you're ever in NY, let me know, you can test it out.
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      11-02-2019, 03:26 PM   #15
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I'm 23" or 584mm on the rears, measured from the bottom of the rim up to the fender, which is a 10mm drop from the stock ride height of 594. The rear wheels still seem too cambered, by my visual estimate.

Front is 23.8" or 604mm, which is close to the stock height of 607mm. So i'll probably drop it a bit more, till it's a 10mm drop all around, then take it for an alignment.
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      11-03-2019, 10:47 PM   #16
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Quote:
Originally Posted by filtercoffee View Post
I'm 23" or 584mm on the rears, measured from the bottom of the rim up to the fender, which is a 10mm drop from the stock ride height of 594. The rear wheels still seem too cambered, by my visual estimate.

Front is 23.8" or 604mm, which is close to the stock height of 607mm. So i'll probably drop it a bit more, till it's a 10mm drop all around, then take it for an alignment.
So you raised it back up and that put you at 23”? Or that’s what you had before when you said rears were too low? 10mm is less than half inch... that’s not much of a drop at all TBH.

Also try measuring from center of hub to fender instead.
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      11-04-2019, 09:32 AM   #17
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Quote:
Originally Posted by 3002 tii View Post
So you raised it back up and that put you at 23”? Or that’s what you had before when you said rears were too low?
I raised it back up (about half an inch) and that's what put me at 23".

Quote:
Originally Posted by 3002 tii View Post
10mm is less than half inch... that’s not much of a drop at all TBH.
Yep. I think I'm going to stick with it, i don't feel an urge to go lower. I got the coilovers for performance.

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Also try measuring from center of hub to fender instead.
Will do.
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      01-30-2020, 03:35 PM   #18
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Got it aligned properly. My rear camber was previously -2.9 degrees on each side. They adjusted it to the minimum they could, which was -2.3 degrees on each side. Visually, it looks more normal

Fronts are at -1.4. Not too dramatic.

Also, front total toe .2, rear total toe .4.
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      02-01-2020, 07:53 PM   #19
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lol id go that ,but backwards.. -2.3 in the front and -1.4 in the rear. weird that you cant get less than 2.3 in the rear?? isnt spec something like -1.5 in the rear?? how are your bushes?
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      02-01-2020, 08:00 PM   #20
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No issues with ride quality so I think bushes are fine but I haven't really checked to be honest. I think lowering in the rear changes the camber pretty quickly.
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