What does it mean when a transmission slips?

Summary:

Jaden gives a mechanical explanation of slipping rather than a symptom list. Inside an automatic transmission are clutch packs that apply to hold and create each gear. Slipping happens when the friction material on those clutches has worn down far enough that clearance inside the pack becomes excessive. He emphasizes that every clutch pack must be set within a specific tolerance during a build. As the friction material wears, that clearance climbs toward the high end of the tolerance, and the pack begins to slip. Once the clearance exceeds tolerance entirely, the slipping becomes severe and the clutch is eventually destroyed. His framing presents slipping as a progressive wear condition with a defined mechanical cause, not a vague drivability complaint, which is useful for customers trying to understand why a slipping transmission gets worse rather than staying the same.

Answer:

So when a transmission slips, what's happening is, inside the transmission there's different clutch packs. The clutch packs apply, and that's what holds and makes your gear. So when a transmission is slipping, the clutches inside the transmission, the friction material on them is worn down far enough that there's too much clearance in the clutch pack, and so they'll start to slip. Because every clutch pack in a transmission, you have to get it to within a certain tolerance. Once it starts getting to the high side of the tolerance, it's going to start slipping. And then once you exceed the tolerance, it's going to slip very bad, and then eventually it'll lose the whole clutch. So it's a wear condition, and it doesn't stay where it is. The clearance keeps growing as that friction material keeps wearing, and the further out of tolerance the pack gets, the worse the slip gets, until there's no clutch left to hold at all.