How to adjust my Apexi N1 coilover ?

[cobrAA]

Here's a picture of the coil..



I will be installing these coil on my car this week-end and would like to adjust them right away.

The thing is the coil can be adjusted by the lower part and also ( as usual) at the spring. How should I adjust it ? Start by the lower part and if it's not low enought, I adjust the spring?

[DarkCaporaL]

The top 2 rings are for shock preload and shouldn't be used to adjust height.

[cobrAA]

but they are ''slack'' they need to be tighted. So, I have no clue at which height they should be tighted and adjusted. but thanks for the info, this already helps me!

[DarkCaporaL]

I have no clue how to adjust shock preload, since I have never done it. Maybe some other members with experience can shed some light (like C-unit, he seems to know everything about suspension lol).

In general you do not want to lose suspension travel by putting on too much preload. And of course you wouldn't want your suspension to bottom out when you hit a bump.

[GTRDemon]

I would like to know as well please
However I did find this thread on rx7 club:
http://www.rx7club.com/showthread.php?t=600868

[DarkCaporaL]

I remember reading something similar to the above thread. It appears people aim for least preload as possible? As in they just tighten down the rings where there's minimal compression on the shock prior to installing them on the car.

[MarusGTR]

Hmm the only reason I can think why you'd want to keep preload to a minimum is if you want more negative travel (extension). If preload is pre-compressing the spring to exert a force to put the car at a certain height, it's the same as making the coil longer and using the car's weight to compress to the same height. the difference between the two is the longer overall stroke of the latter. Maybe a shorter extension stroke would cause the car to induce skid in high roll, like having too stiff sway bars? I could also see preload making the spring retract a wheel in high enough roll.

Or am I figuring this out wrong?

[nelsonmxmarc]

There's a few ways to do this..

First, if these are second hand, get a hold of the user manual and restore all values to stock to start with a clean slate, so to speak.

From there you'll note you have 3 varieties of adjustment.

1. the lower portion that mounts to the spindle is the HEIGHT adjustment boot.
You turn this either up or down and lock it in position to acquire the appropriate ride height
NOTE- preload is not the proper method to set the height of these particular suspension.
The right way, and most simplistic way, is to put these all on a bench - bring the preload back to stock then measure the distance between lock-rings to roughly acquire a value you can use to make BOTH the same.

One important thing is to mention is that, unless otherwise specified by a professional (corner balancing will / can effect this), the values for both front , and both rear should be the same. You dont want one side 5 mm higher and etc. Though it wont cause too much of an issue, it's best to take the time to do it properly..

Once you've found a baseline value for both fronts and they're both the same, mount them then see how the wheel fits. If it's good, make sure your lock rings are tight on the height-adjustment portion.

2.Work on the preload. Assuming you replaced the preload values to stock, with the car up and the suspension weighted by the lower control arms and etc, you should be able to grab the spring and it should move ever so slightly. In other words, it should be TAUGHT when the suspension is at full extension - lets call this S1.

Now if you're interested in setting preload you have to take into account 2 factors - weight of the vehicle, and typical driving conditions.

A stiffer (more preload) suspension setup will yield less deflection in corners, making the car skidish or 'too light' in bends if the preload is too drastic. The opposite will create a dive affect which will have the front end diving in corners. Though the latter isn't BAD, it will make cornering predictability a huge issue for the driver.

To set this, grab your S1 Value by measuring from the top of the shock to the bottom (everything). This will give your baseline workable value.

Next, with the wheels on (MUCH less time consuming with a lift.) Lower the car but do not get in. Have someone measure the suspension in the same manner (top to bottom). This will give your S2, or your Static-sag. Static sag is the sag value of the cars weight under normal circumstances without the driver.

NOTE* This is best done with NO FLUIDS aka DRY WEIGHT - if you're as particular as i am..

Now, CURB WEIGHT (Full fluids, full tank of gas and normal load); get in the car as well to mimic a daily driving scenario. Have someone measure these values we'll call S3

To determine the race-sag for this application;

S2 - S3 = Race sag with that particular spring preload and your typical weight additional to dry-weight. This value will give you a good baseline to work from in determining what options are best. To test this, take it to the track! Try going up and down around this baseline and see how it feels.

In general, if your race sag value is 20mm, decreasing preload by extending the spring (bringing collars down) may bring the value to 30 mm. Typically decreasing means better turn in like discussed above. The front will dive more than baseline, but due to the small increment in change, it won't have a drastic uncontrollable effect. This would be better suited for more twisty roads/track, whereas increasing preload will increase straight line stability by stiffening the spring and creating less roll in jerky, high speed settings.

You must also take into account the suspension dampening, which is generally Compression (rebound / hi-speed / lo-speeed adjustment found on more high end equipment) Compression should be dialled in according to preload and track conditions. If the track has a lot of turns, reduce compression to increase the stroke thus initiating a dive earlier into the corner to keep consistent contact with the road throughout. High compression may seem better, but running full-soft first, with either stock or adjusted preload, will give you a good bassline to work from. High compression will cause a lot of bump-steer and unpredictable braking/cornerning.

Suspension is MEANT to move. So setting the preload too stiff or using the old-style height adjustment suspension whereby height is based on preload, is not a proper method. Too stiff will increase oversteer (generally), lead to unpredictable and snappy conditions, minimal roll and decreased braking distance, as well, you'll find yourself fighting the corners on a constant basis.

Decrease your ride height to lower the cars C of G, but maintain a well balanced preload/compression ratio that allows optimal suspension motion..

[cobrAA]

So I tried ajusting the lower part.. and i'm still not happy. it's only like .5 cm lower than my Tein.. I want lower.. so I need to play a bit with preload but I have no clue how to do it..

[cobrAA]

If I understand.. to adjust the preload, you need the suspension bolted on the car right? Good.. so I will swap all 4 coilovers and play with the preload this summer when I will have my car on a lift.

[MarusGTR]

Thanks for the walkthrough Marc, guess I was thinking right. Glad to know my engineering skills can manage outside my speciality, even if my hands-on car knowledgability is non-existant.

The more and more I'm on here, the more I wish I would of specialized in automotive. I'm jack of all trades mechanical engineer, master of none, I guess. I'll have to live and learn when it comes to cars.

[nelsonmxmarc]

The more and more I'm on here, the more I wish I would of specialized in automotive. I'm jack of all trades mechanical engineer, master of none, I guess. I'll have to live and learn when it comes to cars.

Welcome to my life! I'm doing an honours degree in PSYCHOLOGY! lol

It's nice to have hobbies

[MarusGTR]

welcome to my life! I'm doing an honours degree in psychology! Lol

it's nice to have hobbies

NO WAY!

[cobrAA]

well.. I couldn't remove my wheels.. there frozen and I guess some rust happened too and it glued to the hub.. F*ck it. I will do it in may.