It’s not. A worn clutch is losing its ability to connect the engine to the transmission. With the pedal depressed, the clutch should not be touching the engine [flywheel] at all. So a worn clutch would provide slightly more of an air gap between the engine and the transmission. So to answer OP’s question, assuming there’s no computer programming involved with the drop and it’s a purely mechanical effect, then the clutch is dragging. There’s many possibilities, including misadjusted clutch mechanisms (cable/plunger nut, pedal free play screw), worn clutch mechanisms (bent clutch fork, leaking fluid/worn cable sheath/stretched cable, broken pedal mount, bent levers), or a jam (extra carpet under the pedal, debris in transmission lever) to new several possibilities.
I had both a worn clutch and a dragging clutch in my Geo at different points. The only result of a worn clutch is having the engine rev up faster than the trucklet was accelerating, as if it was a loosey goose automatic. No shifting issues. When the cable was out of adjustment, it wasn’t disengaging properly. It happened while driving and made it very difficult to drive since I came to a stop. I had to ride the poor synchro to get it up in speed to, essentially, clutchless shift into 1st. 3 blocks later, I forced it in just in time to climb my driveway.
But, to a much less dramatic experience, often enough, the aftermarket floormat would slip under the pedal and just slightly limit the clutch pedal travel to an effect more like the parent comment’s experience. It go into gear with a little crunch and a little shudder and a little engine drop.
Side note, it’s normal for letting the clutch out in neutral and having the engine drop a little. If the clutch pedal is up, the engine will be driving multiple input components - they just won’t be further connected to the output components. It takes a little energy to spin those back up to 700rpm. They should spin down after a few seconds. If 5-10 seconds pass with the pedal depressed and the gears still resist then comply being engaged with the shifter, they aren’t slowing down. That’d be another symptom/diag point for OP to test for a dragging clutch. A caveat is that if there’s zero input and output speed on the transmission, the dogs may not be lined up and will still prevent engagement. It takes a few tries to confirm “sometimes won’t engage” vs “really will not engage”
Perspectivist@feddit.uk 2 weeks ago
It’s normal. Worn out clutch has different and more noticeable symptoms.