Suggested Adjustment Procedure for Road Course Use

Bump damping controls the unsprung weight of the vehicle (wheels, axles, etc.). It controls the upward movement of the suspension such as hitting a bump in the track. It should not be used to control the downward movement of the vehicle when it encounters dips. Also, it should not be used to control roll or bottoming.

Depending on the vehicle, the ideal bump setting can occur at any point within the adjustment range. This setting will be reached when “side-hop” or “walking” in a bumpy turn is minimal and the ride is not uncomfortably harsh. At any point other than this ideal setting, the “side-hopping’ condition will be more pronounced and the ride may be too harsh.

Step 1: Set all four dampers on minimum bump and minimum rebound settings.

Step 2:Drive one or two laps to get the feel of the car.
NOTE: When driving the car during the bump adjustment phase, disregard body lean or roll and concentrate solely on how the car feels over bumps. Also, try to notice if the car “walks” or “side-hops” on a rough turn.

Step 3: Increase bump adjustment clockwise 3 clicks on all four dampers. Drive the car one or two laps. Repeat this step until a point is reached where the car starts to feel hard over bumpy surfaces.

Step 4: Back off the bump adjustment two clicks. The bump control is now set.
NOTE: The back off point will likely be reached sooner on one end of the vehicle than the other. If this occurs, keep increasing the bump on the soft end until it too feels too hard. Then back that side off two clicks. The bump control is now set.

Once you have found what you feel to be the best bump setting on all four wheels, you are now ready to proceed with adjusting the rebound damping. The rebound damping controls the transitional roll (lean) as when entering a turn. It does not limit the total amount of roll; it does limit how fast this total roll angle is achieved. How much the vehicle actually leans is determined by other things such as spring rate, sway bars, roll center heights, etc.
It should be noted that too much rebound damping on either end of the vehicle will cause an initial loss of lateral acceleration (cornering power) at that end which will cause the vehicle to oversteer or understeer excessively when entering a turn.

Too much rebound control in relation to spring rate will cause a condition known as “jacking down.” This is a condition where, after hitting a bump and compressing the spring, the damper does not allow the spring to return to a neutral position before the next bump is encountered. This repeats with each subsequent bump until the car is actually lowered onto the bump stops. Contact with the bump stops causes a drastic increase in roll stiffness. If this condition occurs on the front, the car will understeer; if it occurs on the rear, the car will oversteer.

Step 1: With the rebound set on full soft and the bump control set from your testing, drive the car one or two laps, paying attention to how the car rolls when entering a turn.

Step 2: Increase rebound damping three sweeps or 3/4 of a turn on all four dampers and drive the car one or two laps. Repeat this step until the car enters the turns smoothly (no drastic attitude changes) and without leaning excessively. Any increase in the rebound stiffness beyond this point is unnecessary and may in fact be detrimental.
EXCEPTION: It may be desirable to have a car that assumes an oversteering or understeering attitude when entering a turn. This preference, of course, will vary from one driver to another depending on the individual driving style.
The following is a guide to try to solve handling problems AFTER the car’s initial setup has already been found.

FRONT Rebound
> Setting is too Firm– Can cause the car to “jack down” which can cause the driver to think the car is too firm in compression. Can also cause a lack in grip from the tire not separating from the chassis fast enough and cause the car to push.
> Setting is too Soft – Though a soft rebound setting will allow better compliance with the road, the car may feel floaty or excessively oscillate after hitting bumps.

 Front Compression
> Setting is too Firm- Can cause the car to feel skittish and lose grip over rough sections of pavement. Can cause outside tire to be loaded too quickly. The car won’t stabilize in a turn.
> Setting is too Soft – Can cause a corner entry understeer. Can possibly cause excessive suspension movement.

REAR Rebound
> Setting is too Firm– Can cause oversteer on corner entry from rear tires loosing traction. Can also cause the car to “jack down” in the rear.
> Setting is too Soft – Can make the car feel like it is diving too much on corner entry. Vehicle may feel floaty or excessively oscillate after hitting bumps.

Rear Compression
> Setting is too Firm - Can cause the car feel unstable or loose on rough pavement. Can also cause the car to want to step out when getting back on throttle..
> Setting is too Soft – Can cause corner exit understeer and possible excessive suspension movement.

1.When changing to firmer springs, the shocks usually need to be set firmer for rebound and softer for compression damping.
2. On rainy or slick tracks, softening the compression damping will help to delay initial loading on the tire which increases grip.
This is a guide for Shock Setup only. Other factors such as the spring rates, sway bars, alignment and tire pressures will also have an affect on the handling of the vehicle.

For applications that use an upper spherical bearing mount, please check the following points for adequate clearance through the entire range of suspension travel.
> Make certain that the mounting hardware does not contact the outer bearing race or the housing that retains the bearing. The mounting hardware includes any nut, washer, or spacers that are use to locate the mounting pin in the bearing.
>Make certain that the retaining clip for the bearing does not contact the piston rod shoulder or mounting hardware.
Any contact at these points can cause excessive side load that could cause damage to the damper or bearing mounting assembly

Tips for Coilover Shocks
Ride Height – The ride height measurement given in the tables above is the point at the center of stroke for the shock. Ideally, you should be within a half inch above or below this depending on your chassis setup.

Bump Rubber – The bump rubber, or bumpstop as it is also called, can be cut down some depending on if the travel is needed in compression. The bump rubber should not be removed though as this protects the shock from damage. Any trimming done to the bumpstop should be done from the top down. The conical part at the bottom should be left alone as it allows a more progressive stop of the suspension movement.

Spring Seats – The spring seats and threading on the shocks should be kept clean at all times. Dirt and other debris could otherwise lodge into the threads and possibly damage them.

Car Transport – If you trailer your car to the track, it is possible that you are wearing your shocks out faster. If the tires of the car are tied down instead of the chassis, the shock is trying to work to stop the movement the chassis by the trailer. This can cause premature wear of the suspension components.
28 Series Adjustments

NOTE: Do not place shock absorber in a vice (except at the lower eye).   
The rebound and compression adjuster requires a pin with an outside diameter of 1.5mm or a 1.5mm hex key. The adjusters are marked with the letters that are stamped on the mounting eye.

The Rebound adjuster is marked with an R (rebound), is red in color and the closest to the body of the damper. To increase the rebound force, put the adjuster pin next to the minus sign and turn the pin towards the plus sign (left to right).

The Compression adjuster is marked with a B (bump), is black in color and is furthest from the body of the damper. To increase the compression force, put the adjuster pin next to the minus sign and turn the pin towards the plus sign (left to right).

The adjusters each have 7 distinct stop (clicks), each of which marks an adjustment position. There are a total of 8 adjustment positions for both the compression and rebound adjusters. There are stops at the minimum and maximum position.