ATS*Mark

I have not been able to find a real explanation that makes sense on adjusting rear preload. Most talk about how much of the piston shaft needs to be exposed or recessed into the shock body, but this video that BC has explains it a different way, and I feel that it is way easier to understand. BC was nice enough to send me the video as I emailed them about adjusting the rear on my 2014 Civic Si. It is very simple and very easy to understand now for me, so hopefully this helps, and maybe it can be made a sticky. Here is what you do:

1. Install the rear coilover setup, put the wheel back on and set desired ride height.
2. Jack up the rear and remove wheel, then remove lower shock mount bolt.
3. Compress spring 7-10mm (1/4 to 1/2 inch basically) by jacking up the rear LCA.
4. Loosen shock body ring, and screw the shock body into or out of the base until the lower shock mount hole aligns with the LCA shock mount.
5. Reinstall lower shock bolt, put wheel back on and lower the car. Congratulations, you have just set rear preload on your multi-link rear equipped Honda (or any other multi-link car for that matter)!

Video for a graphical representation:

[MEDIA=youtube]tWgQ-BPd6ck[/MEDIA]

View: https://www.youtube.com/watch?v=tWgQ-BPd6ck

Email response from BC regarding preload adjustment:

Basically what you are doing is adjusting the shock length so that the spring is still compressed about 1/4-1/2" when the shock is fully extended. Set the ride height first and then adjust the length of the shock. You may need to readjust the shock length each time you change the ride height.

B serious

iTrader: (1)

Yes. If 1/4 to 1/2" is all the preload you want or need, in order to get the desired shock travel...then you're all set.

ATS*Mark

Technically that is for zero preload. 1/2 is just to get the bottom of the spring to sit flush on the control arm.

B serious

iTrader: (1)

right on.

well...I suppose you could follow that procedure for more preload as well.

Preload is mostly added to add compression side shaft travel (bump travel) on the shock.

zero preload is *probably* fine on the rear of most FWD hondas though.

ATS*Mark

Yea to be more specific, my description is for a zero preload setup, to add more, add more. Every off the shelf coilover for multi link Hondas that I have seen are a zero preload setup but obviously to start tweaking and adding more preload, the process is the same.