Here is Manual 1 and 2

http://i47.tinypic.com/m2g3r.jpg
http://i45.tinypic.com/156popc.jpg

 

bump

 

If im not mistakedn, BCs have height adjustale rear dampers. so what theyre saying is if you lower the spring, you should lower the shock too, kinda like setting sag on a motorcycle.

Rear spring preload is constant, what you adjust with the perch is basically how short or long the spring/perch assembly is.

You cant lower the shock more than its designed for. I wouldnt stress that much, just dont have the spring slammed and the shock at max height, it puts a lot more strain on the shock and shortens its life, and isnt optimum working range for the damper.

I wouldn't wory much about spring perch height too much, as long as theyre close like within 5mm of each other. With our cars, unless corner balanced, and each tire inflated the same and ground perfectly level, then usually there will be small differences due to different wear on the bushing, etc. I just measure the height from fender to rim lip a few times a week, until im getting pretty much the same no matter where i park, and everything has settled and all that.

i do not know if the perch goes at the top or the bottom. My eibach instructions said put it below, ive seen other instructions that say above. :dunno:

 

so, i probably found the way how to adjust rear shocks and springs together and correctly.

i have read on Infinity forum :

Proper adjustment for the shocks come after setting your height. Once you have measured and verified height is set properly via step 5 you will need to set the proper preload on the coils while adjusting the shocks.

Jack the rear up and place the car on jack stands. You can also perform this task one side at a time but will need two jacks if you do it this way. After the car is raised and wheel(s) removed, use the jack to support the lower spring arm and remove the shocks lower 17mm bolt to free it from the spring arm. Use the spanner wrenches to loosen the two lower locking rings.

Lower the jack to allow the spring arm to hang. Springs will be loose at this point in their basket. To set preload and shocks, jack the spring arm back up until the springs themselves are no longer loose in their mounting basket.
BC requires 10mm of preload so once the springs are no longer loose you should jack the spring arm up and additonal 10mm (or .4") to set preload.

Once complete, adjust the shocks to the proper new height until they mate back up with their mounting location. Reinstall the 17mm bolt/nut on the shocks lower mount. Use the spanner wrenches to properly tighten the lower locking rings.

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From this i understood that i have to set my wehicle height with spring only and when im satisfied, i have to properly adjust shock. In my first post, i was worried about correct rear adjustment and i probably found solution.

So...i need to use jack to support arm so the spring dont have loose and dont have compress ? Just spring is sitting without compression. Then i need to screw shock up and match the bottom shock mount with arm mount ? then insert bolt , tighten and thats all ?

Logically yes, because BC dont have spring on rear shock so i think using method above is correct. But im not sure about spring preload for BMW.

 

you cant change the preload on the rear coilovers on our cars.

 

so just adjust spring to match your height needs
screw shock so the mounting hole on shock will match arm mounting hole
put bolt
tighten

done ?

i see one problem...when i jack car and unmount shock, arm will fall lil bit down but i feel that there is lil bit of compression on spring. but its normal probably.

im still confused about shock height setting...if matching the arm mounting hole by screwing cartridge is enough

 

im not sure, you could do it a # of ways, but i think the best way is car on ground, jack on shock. set shock to the height you think is closest or max short length. :dunno:

 

next find, it looks correct :


You use the spring perch to adjust the height, then follow-up with the strut by either:
a) With minimal load on the spring bucket (i.e. jack it up just enough to keep the spring taut), match the holes up between the bucket and the bottom strut mount holes - this is zero pre-load
b) If you want to pre-load the springs, jack the bucket further (mine is by 5mm, or roughly half the hole is now covered up by nature of the bucket being higher than the strut). Then, shorten the strut assembly by the same amount until you match the holes up again.

 

 

In for later

 

Rear helper springs:
Center the spring perches on the control arm, adjust rear ride height by moving lock nuts up/down on threads, get a good reference point - measure height from where lower spring meets collar to bottom perch, adjust same for both sides.
Then push down on your brake hub and install the rear spring on the lower collar and center it in upper mount, springs will ride a bit freely laterally.

Damper: The spring both compresses and expands while traveling on uneven road surfaces. To adjust damper to control spring movement, a 1/3 of its piston should within its body housing while car is lowered with tires on on a flat surface. If your damper's piston max travel length is 6 inches - 2 inches should be in body allowing for dampening spring expansion, with 4 inches allowing for dampening spring compression. You don't want damper piston to bottom out travel all of its 6 inches under compression.
Once upper tower mounts are installed, screw downward the dampers body until it reaches lower mounting bolt on hub. The spring and control arm should be just snug on its perch. Then bolt the lower damper on the hub, do this for both sides, don't snug its lock nut down yet.
Then mount your back and front wheels/tires on a flat surface, this is a center point reference for the damper adjustment.
Then climb under your cars backside and unbolt the lower damper to adjust screw down its body, till the Damper Piston travels 1/3 of its piston travel or 2 inches. Then use a low jack to rise and bolt the damper back up again, and then tighten the body lock nut.
The damper controls both compression and expansion of the spring and control arm as your tires move across varying road surfaces.

Fine tune ride heights both front and rear; then be sure to get wheels aligned and corner weight balanced by a certified know how shop; and they're few and far between in some areas.

It would be nice if BMW would design engineer for all wheel coil overs; struts and helper rear springs blah !

 

this is not for BC and similiar types

 

Ok per instructions ! :smokin: if you haven't called tech support yet

Top mounted perch rear spring system - just adjust cars ride height by lowering or raising lock nuts on perch.

Dampers ! assuming the factory diagram here - adjust them from the lower screw mount bolt area for long travel .... once you have ride height figured out with spring perches, lower your car on a level surface with all four tires on, unbolt lower damper then screw down the body till 1/4-1/3 of its known maximum piston travel is past the hubs bolt point. Then raise or compress the shock back up to the bolt point with a jack.

With this poor factory diagram given - the dampers piston will always be at max travel when bolted up, the dampers body won't allow for the cars control arm and spring to lower/expand; a compression only damper setup.

Referring to upper piston rod that's the travel length; if its 10cm long at max travel then part of its rod while the car is static on a level even surface should be 2.5-3.33cm in dampers body under a preloaded damper compression - the damper has to control springs expansion as well.

It also states stretch distance with spring is 40-50mm - expansion of the spring when tires goes through a pothole for instance; tire drops and cars unloads its weight at the spring area.

Dampers body don't control ride height, their pistons have to control springs expansion and compression on uneven road surfaces.

I don't like the OEM BMW spring setup on any of these highly marketed consumer kit variants available - its only for rear body drop purposes.
A free spring ride on rubber top and bottom mounts - naaa! a better top body perch and bottom control arm perch system needed here or a true rear coil over control arm to body system like the front coil over system.

also check out Vorshlag Varishock and Hyperco sites - good luck ! call the tech folks for a fine tune - my K-Sports came with @#$% instruction and diagrams also ...may ditch the rear springs for a better Hyperco setup later and keep the dampers

 

thank you for your time. Very amazing reading..but its totally different what i read on other sites. I`ll try to apply your instructions soon

 

using this better explanation :smokin: found under shock ride height

http://www.hypercoils.com/spring-rate-calculator/

Shock Ride Height From Extended Height

Determine the total travel of the shock absorber using the shock manufacturer's catalog; or by pulling the shock shaft to the full extension position and measuring the length of the chrome shaft. Generally, the shock should be compressed 40% - 50% of its travel at ride height.

For example, if a shock has 4.8" of travel and you want the sprung weight of the vehicle to compress the shock 45% at ride height, you would enter 2.16" (45% x 4.8") of shock compression to ride height.

my K-Sports wanted 1/3 piston compressed 2/3 uncompressed around 15cm max travel with 10cm out and 5cm in body or when I adjusted them past bolt point on level surface 5cm then compressed them back for bolt up

call tech BC support for piston shaft preload measurements at static even level on all four corners/tires .... a somewhat level driveway
or take it to a shop for a corner weight balancing / adjustment - they should have scales and the know how to tune both spring and damper ... no more than 2 hours labor at under $200 for alignment included ... Slovakia is this where the car is ?

 

Bump the old post

I also have problem with rear bc br coilover,
There was some knocking sound coming from the rear.
I have own it two years , and never happen before.
Any bc user know hats the problem is?
My guess is rear top mount, if so are they changeable or replace the whole struct

 

Bump the old post

I also have problem with rear bc br coilover,
There was some knocking sound coming from the rear.
I have own it two years , and never happen before.
Any bc user know hats the problem is?
My guess is rear top mount, if so are they changeable or replace the whole struct

It's easy for you to check if one or both of your RSM's have failed. If you have a failure, it will easily make the noise you're talking about, if so they'll need to be replaced. Since there is a lot more force involved with your upgraded BC C/O's, I wouldn't recommend OE BMW parts for this job. Before you order anything, measure the threaded stem diameter of your BC C/O's, they should be either 10mm or 12mm.

Here are several good choices:

1) Rogue RSM
2) Powerflex RSM
3) Bimmertune RSM
4) Ground Control RSM

http://forum.e46fanatics.com/showthread.php?t=1049401&highlight=rsm



Good luck,
Rob43