CDK: Spec-RS CDK Height Adjustment
The first step to correctly setting the ride height with Megan Racing coil-overs is to set the spring pre-load. You must aim for zero-preload, meaning the spring does not have any vertical play/movement within the coil-over assembly when the suspension is not loaded and the vehicle is in the air. For the amateur tuner, it is better to leave pre-load at zero unless you are fully aware of effects of spring pre-load. For further information about setting spring pre-load, check the "Installation" section under the "TECH" section.
After spring pre-load is set to zero, you may proceed to adjust the ride height. The photo below provides directions on how to adjust the shock length by threading the shock body into or out of the lower bracket to lower or raise the vehicle ride height, respectively.
NOTE: For McPherson strut suspension designs, pay attention when threading the shock lower into the lower bracket when setting ride height. The shock body may potentially contact the CV boot of the drive axle and may cause the damage to the CV boot resulting in costly repairs. Be aware that such damages result from install error alone, so please pay attention when adjusting the ride height.
NOTE: For Spec-RS suspension adjustments:
1. Always remove the reservoir brackets before doing any height adjustment.
2. Always stick with the default spring rate or use stiffer spring rate. A softer spring rate may cause the reservoir to hit other parts and damage may result. Any damage caused from incorrect use, installation, and/or softer spring rate will not be covered by warranty.
Please remember to set the spring pre-load. It is considered the first step to setting the ride height. Once spring pre-load is set to "zero-preload," you can proceed to set the ride height by adjusting the shock length. It is recommended to get a baseline measurement of the shock length. A good way is to measure the threaded portion of the shock body between the two locking spring perches that lock the spring into place and the third perch that locks the lower bracket into place. The following photo gives an example of doing so:
Once you get the baseline measurement of the shock body between the perches, you must now loosen the lower perch that locks the lower bracket in place. Take the smaller spanner wrench and position it on the perch according to the photo below:
With the spanner wrench positioned like so, spin the wrench in the direction indicated by the red arrow in the above photo. If viewing the coil-over assembly from below, you are rotating the spanner wrench and perch clockwise. If viewing the coil-over assembly from above, you are rotating the spanner wrench and perch counter-clockwise.
It may be beneficial to loosen the allen head bolts that hold the external reservoir brackets in place. Use the appropriate sized allen head tool for all allen head bolts and loosen.
Now that the lower perch is loosened from the lower bracket, it is time to adjust the shock length by threading the threaded shock body further into the lower bracket to shorten the shock length or threading the shock body out of the lower bracket to lengthen the shock body. Lengthening the shock body will increase the ride height and shortening the shock body will decrease the ride height.
NOTE: It is important that you are very cautious when rotating the lower bracket and / or strut / shock due to the external reservoir connection to the main cylinder body being very sensitive.
To lower the ride height, you need to shorten the shock body. To shorten the shock body, you need to thread the shock body further into the lower bracket. If you are performing this while the coil-over assembly on the vehicle, it may be more difficult to rotate the shock body into or out of the shock body due to the unsprung weight pulling against the coil-over assembly. Since the spring pre-load was already set, the two locking perches that lock the spring in place should be tightened against each other. You can use the spanner wrenches to twist the shock body using the locking perches.
For example, if you are trying to thread the shock body further into the lower bracket, you can use the larger spanner wrench and position it on the top of the two perches and rotate the shock body as indicated in the following photo:
To do the opposite and lengthen the shock length, take the smaller spanner wrench against the lower of the top two perches and rotate in the opposite direction. Position the smaller spanner wrench against the lower perch and rotate the shock body as indicated in the following photo:
Once the shock length is set, proceed to tighten the third/lower perch against the lower bracket. Take a new measurement of the distance of the threaded shock body section between the perches and compare to the base-line measurement.
Now would be a good time to re-mount the wheels, remove the vehicle from jackstands, roll the chassis forward and backwards to let the suspension settle before judging the ride height. You may have to make adjustments to get the ride height you are aiming for.
NOTE: When the shock is physically limited from being shorted due to design restraights, or bottoming the shock into the lower bracket, the physical limitation has been reached. People sometimes proceed to go lower by lowering the two locking perches on the shock body. When this is done, shock travel is decreased by the amount of vertical movement of the spring within the coil-over assembly when there is no load present. Decreasing the amount of available shock piston travel increases the chances of bottoming out the shock against the bumpstop which decreases the life of the shock. Doing this will void the warranty of the dampers. Please be aware of this before making the decision to do so.
After you have set the ride height, which is done after setting spring pre-load, the coil-overs are ready to be installed on the vehicle. For a general instruction on how to install the coil-overs, please refer to the articles in our "TECH" section under "INSTALLATION" or follow this link: "HOW TO INSTALL COIL-OVERS."