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stup stup is offline
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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
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SP Autobahn www.spautobahn.co.uk
Porsche inspector for Peter Morgan UK
http://www.porscheinspections.com/
"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, 08:56 AM
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