i've got two front windows that rise reasonably ok but about 5/6ths of the way up they slow right down and then speed up a little bit for the last bit to close.

what can this be?

this must be a known problem!

 

Look like friction to me, but if you don't hear any abrasive noise and it occurs to both front windows it could be the battery?

 

I have experienced similar symptoms in assorted older cars, although not thus far on my XJR. Having spent many happy hours stripping down motors and mechanisms to lubricate them, along with the channels which the glass runs in, I have found that the best improvement comes from making a point of "exercising" the windows by regularly and frequently raising and lowering them. Not lots of times in immediate succession, but say 3 or 4 times whenever I drive the car. Lubricating the runners helps too.

 

hi, thanks for your reply, there are no noises that sound inappropriate, just the sound of the electric motor and the battery is new.

 

hi, thanks for your reply. it almost sounds as if the motor just isn't powerful enough for the job but it could very well be friction that's slowing it down.

 

Yes, as with the sun roof, I suppose regular lubrication of the motor, roller and cable may reduce friction and prolong the life of the window mechanism.

 

My front windows don't go up and down particularly quick, but I prefer them like that, fast windows can appear a little undignified. Oh dear, that sounds a bit pompous, lol.