Hello all, I’ve been dealing with this issue for some time but can’t for the life of me sleuth out what’s causing it besides something in the window regulator.

When I go to roll down the drivers window it seems to jolt slightly forward into the front part of the door frame and then slowly roll down the rest of the way. It goes up just fine and only seems slow on the way down. Any guesses as to what the issue might be more specifically?

1986 XJS
V12

 

You may want to add your model year and engine, so that people don't have to ask you everytime you have a question.

You may need to lube up the tracks. I am guessing that something is making the window stick. Could just be some dried up 40 year old lithium grease. Take the door panel off and get some silicone paste to lube up the tracks.

You will have two vertical tracks on both sides of the glass, but don't forget to lube up the bottom horizontal track either.

It could also be the beginning of the end of your regulator....