This note is about 993 RS top mono-ball mounts/camber plates. This topic is well covered by 993 owners (see links below), but they also fit 964 with PSS9/10.
Factory part differ from most aftermarket units:
1. Dust control. Porsche parts are sealed from both top and bottom and also between plates. Dust/sand really hurts open ball joints, using open balljoints on the street or on autocross parking lots wears them off very quick. Most DE tracks are not clean either.
2. Street/track setting - it's not unusual to drive 100miles to and from driving events. Trip will wear inner tire very quick with 2+ degree camber. Factory units can be switched from street to track configuration in 5mins per side - 3 bolts.
3. Factory units cost only $200 more compared to most of aftermarket parts.
4. Here's not good one - you need special top mount nuts described by ToSi (Tom) on rennlist in
this thread. Otherwise failure described by Richard on his website in this
post will happen. Richard eliminated spacer #18 - turned to be bad idea.
Here are some pics with details.
Parts needed (also described in 993 links above)
part #'s
ToSi nuts (I bought them from him, there was discussion on rennlist to do batch), dimensions see
his thread.
Factory street/track settings description:
And illustration:
Top sealing nut (all aftermarket have hole in it to get dirt/sand inside
Inter-plate hard rubber seal:
Lower strut seal (rennline started to use similar seal, but most of other aftermarket plates have open ball joint)
Also, strut brace is highly recommended with hard ball joint. Stock rubber mounts have enough rubber to flex and not transfer load to chassis, so I do not see need for strut brace and rubber mounts. There was nice post on miata forums where somebody calculated all loads. Also, I think with autocross tires strut brace is probably enough. Full blown race slicks may stress chassis more and extra welds on chassis is probably good idea - factory did that on RS
Oleg.