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stup stup is offline
Registered User
Join Date: Sep 2006
Location: scotland
Posts: 248
My boost started to vary up over 1.05-1.1 bar on my gauge at around 4k revs and then the clutch would slip!

Car has over 400rwhp at just less than 1 bar so maybe 1.1 bar may be nearer 415+rwhp and then i have slippage on a sachs 964 turbo clutch after only maybe 3-4k miles

99% sure no issues with any fluid etc going on to my clutch plate causing slippage!

Another subject but this boost pressure varying i tracked it down to being a worn valve guide on my aftermarket wastegate...pressure which should have been lifting open the valve with pressure on the diaphram was leaking down past the valve stem..
I noticed this by applying very little air pressure to the wastegate and before the valve was lifting i could hear leakage through my 965 wastegate tailpipe(or dump pipe in the 930 application).

Made new st/st valve guide on my lathe(old one was mild steel and had over 0.012" thou clearance)....

New st/st one i made was reamed out to only have 0.004" thou clearance..Fitted and boost as steady as a rock now so no slippage however i reckon the clutch may be needing replaced sometime in future or i require more clamping force!

Turning new st/st valve guide

Reaming I/D of guide so closer tolerance to valve

New stainless steel guide next to old mild steel worn one which was causing boost varying issues
SP Autobahn
Porsche inspector for Peter Morgan UK
"92" 964 turbo,Modified and recently rebuilt using all ARP hardware..
Purpose built fuel controller set up to acheive perfect fuel curve on CIS inj.
Old 10-13-2009, 09:56 AM
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