Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
22
The regulators for the rear windows have 14-tooth pinions, while most window motors – including these same motors in other applications – typically have about 10 teeth. I can’t prove it, but I suspect the reason for the 14-tooth pinions is to reduce the amount of torque available to cram those windows into their end stops.
Pretty much all electric windows cram the windows into the end stops and stall the motor, but the XJ-S convertible may be unique in that it’s a timer running the window rather than the occupant’s finger. And, since some windows naturally move faster than others, the timer had to be designed to run long enough for a slow window to open or close. Perhaps that long run time is helping cause the jamming problems.
OTOH, it’s perhaps far more likely it’s just the fact that it’s a Delco square case motor. Those things are known to be crap, even by Jaguar, who switched to Bosch motors after only a couple of years with those things, and reportedly directed their repair services to just go ahead and replace the Delco garbage with the Bosch motors and regulators when they needed service.
I suppose it wouldn’t be too difficult to rig limit switches to the windows.
I understand that the motors may be inferior. I’ve had these rebuilt and they obviously are strong enough to do the job. I don’t see how adding better/stronger motors will improve my situation if the problem is a run time issue.
Perhaps I might need to reposition the drive gear, regulator gear relationship 1 tooth different to allow for longer downward run travel before binding. Probably create more binding issues in the up run. ???
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
24
To be clear, the problem is not a run time issue. These things are designed to be stalled at the ends of travel.
I’m afraid I don’t see how that would make any difference at all.
Ok. Please explain how the regulator gear flexes at the end of travel and allows the motor drive gear to jump out of the regulator teeth, continue to run until the gears bind and over current protection shuts the power off. That or time run program shuts power off. Stronger motor will not fix this situation.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
26
It’s not supposed to do any of that. If it is, there’s something wrong with it. Shortening the run time won’t fix anything.