Odd clutch problem-Subie Legacy GT
 

Son has a Legacy Gt with some sti engine bits. Last winter his clutch began to slip under boost-new clutch a pp not long before, so he put the car aside for a while. Just had it repaired, new clutch, pp, master and slave cyls. Car was fine for a week, and as soon as temps dipped into 30's clutch slips again under boost. Common denominator is the cold, as its fine once temps climb into 50's.

What could cause this? Could wrong vis/bad trans oil? Something with the awd mechanism?

Incorrect slave cylinder (rod too long?) for the current application? Is it a full STi conversion? Bell housing adapter wonky?

That's a head scratcher.... first things first, are you sure you have the correct pp and clutch installed? Same with other items like the fork, PP bolts, etc?

Temps seem like an odd factor as I assume that once the engine is warmed up the temps at the pp/clutch surface are going to be the same whether it is 30 degrees outside or 50 degrees outside.

STI long block, lower end.I don't think that's the problem as the car was fine for many thou miles before this episode.

When I replaced the clutch on my 04 WRX a new flywheel was recommended. I was told that resurfacing the flywheel wasn’t a good idea.

Is there any free play in the pedal before dis engagement ? and was the flywheel machined ?
Im good at this sort of stuff, Id sort it out in no time if it was on my lift . Tough to take guesses on the google machine though

I have a story I posted before about a knock-off Sachs 911 clutch kit that of course didn't work. I'd pull the motor, do some digging.

How much boost?

slave fully bled?

Flywheel surfaced? Thrust bearing issue?

Just heard from the wrench. Pin to rf axle was gone, and it had slipped out somewhat. He thinks that when trans oil got viscous it caused the issue. Clutch not actually slipping.

Well, that would do it ! He forgot the pin though, they just do not fall out . Ive done lots of clutches on these. First they turn up the boost, then they smoke the clutch, then a heavy duty clutch, then they start breaking expensive stuff .

My Subaru Forester slave cylinder died about six months ago. Replaced everything, including the oil soaked clutch.

The clutch has never been right since. The pedal engagement is about the last 1" of travel, it shudders when it's hot...I'm so sick of problems with this car...back to the shop with it.