Project Cappuccino: Upgrading the Suspension

While our Cappuccino has been a lot of fun to fling around on back roads, there are some serious shortcomings in the suspension department.  The lowering springs (or Down Suspension as it is known in Japan) are too soft and the cars bottoms out easily.  The soft springs also contribute to a lot of weight transfer causing understeer under braking and oversteer as the suspension rolls over and lets the differential unload.  Like most cars on lowering springs, the Cappuccino also uses aftermarket dampers.  In our case they are mismatched with GAB dampers up front and KYBs in the rear.  These dampers are at least eight years old and are no longer damping as well as they should be.  The ride has been rough and bouncy and the handling is subpar.

Cappuccino Inner Wheel Lift
Once we installed some decent tires on the Cappuccino, the downsides of lowering springs become obvious. We aren’t even going through a very fast corner and the inside rear tire is completely unloaded. Our car has a factory Torsen diff in it so there is going to be no power transfer like this.

The obvious solution is coilovers.  Coilovers will give us stiffer springs to reduce weight transfer.  They will have shorter bodies, allowing us to keep our car low, but give us some compression travel.  We will also get damping that suits those stiffer springs as well as the option to tune that damping force. There should be all sorts of benefits to a good set of coilovers.

Selecting coilovers can be a daunting task, but in the Cappuccino it is actually quite easy.  First, there are only a handful of good coilover options on the market for the Cappuccino.  In fact, they are all nearly identical whether or not you choose Aragosta, Blitz, Tein, Monster Sport, or BC Racing.  They are all inverted monotube dampers with single damping adjustment, a threaded body, and in some cases a pillowball upper mount.  The spring rates are all very stiff: between 5 and 7 kg/mm depending on which set you choose.  Now this may sound reasonable until you realize that Project Silvia used 7 and 5 kg/mm springs in its JIC coilovers.  Project Silvia weighed 2700 lbs and Project Cappuccino weighs around 1500.  Unless the EA11R suspension has twice the motion ratio of the S13 suspension, using a 6 or 7kg/mm spring is going to be terrible in a Cappuccino. 

Silver's Neomax Coilover Unboxing
This is why the Silver’s NEOMAX coilovers immediately stood out. First, the NEOMAX coilovers come with spring rates of 5.5 kg/mm in the front and 3.5 kg/mm in the rear. This seems a lot more reasonable for American roads compared to the Japanese offerings. Second, Silvers is headquartered in the US. Finally, the NEOMAX coilovers are in the $1000 price range: a mid level damper that isn’t too cheap, but isn’t crazy expensive like a KW or Tein coilover (not that either company even offer a coilover for the Cappuccino). In summary, the Silvers NEOMAX should be a good compromise of performance and comfort for our daily driven Cappuccino.
RS-R Lowering Springs
For comparison RS-R lowering springs are 2.9 and 1.7 kg/mm respectively. In Yankee units, that rear spring is 95 lbs/in. No wonder they’re so squishy.
RS-R lowering Springs on GAB Struts versus Silver's Neomax Coilovers
The Silver’s coilovers use a much shorter shock body than the OEM length struts. This lowers the car without reducing suspension travel. Silver’s coilovers also feature threaded bodies with independent length and preload adjustments. The rear coilover also includes an adjustable mount for the rear swaybar endlink, allowing us to remove any preload from the swaybar.
Silver's versus GAB front top mount comparison
The Silver’s coilover comes complete and includes top mounts. They are a compromise mount that still uses a rubber bushing, but is much smaller than the OEM bush. This will provide less compliance than the stock top mount, but should be less noisy than a pillowball mount. Some Silver’s coilovers offer pillowball mounts but this is not an option for the Cappuccino. The Silver’s coilovers are single adjustable with 32 different settings. For an affordably priced coilover, Silver’s still includes a lot of quality features in their coilovers. The damper bodies are steel with electroless nickel plating for corrosion resistance. The upper mounts are CNC cut from aircraft grade 6061 aluminum.
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1 comment

  1. Any way to use an eccentric bolt in the front of the front LCA to get some camber adjustment? Miatas, RX-8, etc do that and it works “OK”

    Reply

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