It's a Blue World! Cusco "Pillowball" Suspension Top Mounts

If you're using uprated shocks and want more improvement in steering and suspension feel and damping, the next step to go would be to replace the stock rubber mounts on top of your front and rear shocks with spherical bearinged versions. The spherical bearing eliminates unwanted rubber flex which can hinder the shocks damping. The 101 in Suspension Theory states that the shock absorber should be the only component doing the damping. This is however not the case for road cars. Rubber bushes reduce NVH and maximum ride comfort but they also flex and introduce unwarranted uncontrollable damping movement of their own. The Japs like to call spherical bearings "pillowball mounts" hence the term.

I emailed DMS on which was the most suitable top mount for my 50mm shock and was surprised to hear Cusco. In fact Cusco even used to oem for DMS Japan. Since then DMS has manufactured their own specific and improved version of the top mount but last I heard these are only available for the newer Evos and Imprezas. Picture below of the new DMS Top Mount. Picture below of the new DMS top mount for Evo7-9

Anyway, back to my Cuscos. I decided to replace both my front and rear top mounts at one go. Also had to order the DMS fitting kit (top nut and metal adapter) to enable to Cusco to clear the larger diameter DMS 50mm shaft. Price per mount is about RM750 so to replace both the front and rear sets would set you back RM1.5K. For those on a budget I would recommend only replacing the fronts as these are designed to allow you to adjust the camber easily. The rears are fixed. Picture below of the front Cusco pillowball mount (Part Number 508 410A). The nut with the shorter shaft (left most) is the DMS fitting kit.

Picture below showing the bottom of the mount. The camber is adjusted via the bottom sliding steel black plate and pillow ball section. The top blue anodized plate is made from 60mm thick 2017S heat treated aluminium alloy.

Both top and bottom plates are held together via 4 M6 X 20mm bolts which Cusco supplied the el cheapo mild steel variety. Arrgh! Needless to say I dutifully replaced these with stainless steel versions.

The Cusco rear mounts are available in 3 types to incorporate different spring diameters used by different shocks. The rear mounts are availble to suit 60mm, 65mm and 70mm coil spring diameters. Yes, these can also be used for conventional non-coilover shocks. If in doubt check with your shock manufacturer. Picture below of rear mount, part number 508 421S for 70mm spring which was advised by DMS to be used for my shock. The part number for 60mm spring is 508 421 A60 and 65mm spring is 508 421 A65.

Installation took the most of the day and the shocks would have to be removed from the car. Closeup picture below of the Cusco top mount installed on my DMS 50mm front shock.

Closeup picture below of rear shock/damper with Cusco top mount.

Rear shocks ready to be installed back on the SP.

So how does the car perform with these mounts installed? One word.. "Excellent"!. Steering feel is much improve and so is the suspension damping. For those using rubber top mounts you can literally feel the mounts flexing under hard cornering load and this is totally eliminated with the Cuscos installed. The cons? Well if you want first class NVH then the Cusco mounts are not for you. You can really feel the road! Also, until the spherical bearing is fully broken in, you will get an alarming clunk from your springs when turning on an uneven surface. Takes a couple weeks to clear up but then honestly I couldn't be bothered. The SP's loud as it is already. Also the flex on the rubber bushes helps to reduce the load to your chasis suspension turrets. Going to stiffer mounts simply means all this load is now acting on your chassis shock mount turrets. Inspect them regularly for signs of fatigue or crack at the seams.