New Clutch, slipping sometimes in high gears

How do you know the clutch was done when the transmission was done? Were you given any proof (invoices, workorders, etc)? By your own admission you say the clutch looks old and worn out. Yes I realize most people change a clutch when the transmission comes out but that isn't always the case.

 

I am assuming you have a hydraulic clutch, self adjusting as it sounds like the problem I’ve had with a few of my Volvos. The clutch mechanism adjusts at the bottom the clutch pedal stroke. So with the truck parked, push the pedal to the floor REALLY HARD like trying to push it thru the floor hard. That insures you are getting maximum stroke and should advance the self adjust mechanism.

 

Sounds like mechanic put wrong clutch in there. Or didn’t adjust linkage properly after install. So it’s not getting clamp force. Easy to check these things if you remove your inspection cover. First check in there to make sure you have solo clutch

 

Cascadia is hydraulic clutch. Only worked on them for a month, but replaced two slave cylinders and one master cylinder in that time. As far as transmission being replaced, in fleet environment sometimes it's cheaper to go ahead and replace transmission at clutch replacement to make most out of the downtime. Nothing worse than doing clutch, then 2 months later pulling transmission for a synchro or bearing problem.

 

Help me understand what possible could be the bigger problem? With a new transmission and new clutch I would think the big issues would have been fixed, if done correctly.