Gernby

I just installed my JIC coilovers this weekend. Thanks to tips from cdelena, Clovis, and several threads, it only took 2 hours. However, getting everything adjusted took several more hours over a few days.

I originally installed the units without any preload on the springs at close to stock ride height. I set all the dampers to full stiff, then went for a test drive. The ride was really stiff, but the ride quality was better than I expected. However, the county roads that are around my home are really wavy, and under certain conditions, showed that something wasn't "right". For example, with the stock suspension on a particular county road, I typically drove 70 MPH without any severe bumps or bangs. The contour of the road would throw the car around a lot, but that's it. With the JICs, the ride was similar at about 65 MPH, but at 70 MPH ... BOOM! ... BAM! My first thought was that it was due to the dampers being at full stiff, so I set them to full soft. As I expected, the ride was about as it was stock, but to my surprise, I was now getting the BOOMs and BAMs at even slower speeds. I then realized that I was bottoming out the dampers.

I went back home, and looked to see how much damper travel was available when the car was at rest. I was surprised to see that there was no visible space between the damper and the bump stop on the fronts, and there was about 1/4" of travel on the rears. Basically, when the car is raised, and the JICs are fully extended, there is about 2" between the damper body and the bump stop. Since the springs were not preloaded, the weight of the car alone was compressing the springs and dampers almost all the way to the stops!

I figured it would be best to preload the springs in the front by 1", and the rear by 3/4", so that I could position the dampers at the middle of their stroke while the car is at rest. I thought this would be a difficult thing to do, but it was not. After raising the spring perches 1" (front), I was still able to adjust the height of the damper body just as before. By adding the preload, I had to lower the damper body by the same exact amount to keep the ride height the same.

The result was amazing. The ride quality is unchanged, but the suspension is able to handle my roads MUCH better. The only noises I've had since the adjustment has been the front splash guards scraping the pavement on smooth, fast dips, which is much more enjoyable than BAM!

Elistan

Good information - we'll have to swap cars for a fun-run to compare.

cdelena

Thanks for sharing. I have been wanting to find the time to try a setup different than what the distributor recommended. Seems he has updated his advice since I talked with him (I think I had the second set in the country) so maybe his 'no preload' tip was not accurate just as his shock adjustment advice was later changed.

SEVNT4

Thanks for the update Gernby!

Gernby

Have any of you experienced the same issue that I have with the dampers bottoming out? I just don't see how these would be very streetable if the springs weren't preloaded.

CMiS2K

I figured out 3 weeks ago, that the no load was not the way to go. After the BMW event a few weeks ago, I went home and made an additional .25 inch front and rear load adjustment.

I made even more of an adjustment on saturday, it seems to take a week of daily driving before the suspension settles. That is based on my experience and observation.

I have been adjusting and re-adjusting to get rid on the bam for a month now. This is the 1st set of coil overs I have ever had on any vehicle. I am not as versed with coil overs as some of you are.

This has been a learning experience for me.

appreciate to read and review this thread, unlike the flamed feed back on a thread, that I started few weeks ago on the JIC's.

mxt_77

Without seeing this first-hand, I'm not able to get too good of a mental picture. But I'm wondering: Do you actually have to pre-load the springs? Is it not possible to accomplish the same thing by adjusting the lower perch to take into consideration the fact that the spring will compress a couple of inches when the weight of the car is lowered onto it?
BTW... I want to ride w/ you, too... now that you have the JICs installed. Are you coming out to the next BMW event?

-Marcus.

Gernby

These are my 1st coilovers too, so I'm not very experienced either. That is why I had to spend so much time adjusting them. I also don't know the correct terminology for what I'm talking about, so I am making up my own.

mxt_77, the way I see it, the spring perch must be adjusted to set the desired relative position of the spring with the damper. A stiffer spring would require less preload, and a softer spring would require more preload to set the "at rest" position of the damper piston where you want it. I chose the middle of the damper stroke as my target. Once this is right, then the height is adjusted by raising and lowering the whole assembly in the base of the coilover.

mxt_77

Hmm.. I guess I'd just have to see it to understand. The spring is going to compress the same (total) amount whether you have pre-load or not. So, intuitively, it would seem like you would set the spring perch to a position where it was just holding the spring in place, then you would adjust the ride height by moving the damper body up & down, and moving the spring perch the exact same amount (in the opposite direction, I think).
I'm probably wrong, though, since I've never worked with the JICs.

CMiS2K

yes, the height is raised by turning the threaded body up and down in the base. by raising the height through this method actually puts too much pre-load on the springs, then you have to back a little out.