1996 Cavalier manual transmission slipping with all new clutch components

My friend has a 1996 Chevy Cavalier with the 2.2 4 cylinder with 5 speed manual trans. It has 83,000 one owner miles.

The clutch was slipping after it warmed up. He just replaced; flywheel, pressure plate, disk, slave cylinder, hydraulic throw out bearing.

All components are new brand name, no reman stuff at all. The rear main seal is bone dry.

Now after warm-up, clutch slips in 3rd and 4th gear. He is pulling his hair out. Any help will be greatly appreciated!!

Thank you.

I wonder if the brakes are dragging. There wouldn’t be as much power in the higher gears to overcome a sticking caliper or an emergency brake that is partially engaged.

The only things you have not replaced are the master cylinder and any flexible hose(s) to the slave cylinder. It sure sounds like the pressure plate is not being released completely. Unless someone else can come up with an appropriate diagnostic procedure, you may be stuck with replacing these parts and rebleeding the system.

No chance that the motor is leaking oil (out of, say, the rear main seal), is there? I’m thinking he could be getting oil on the clutch.

He didn’t by chance put the clutch disc in backwards did he?