XJ COUPE Rear Windows

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XJ COUPE Rear Windows

Postby sean » Tue Aug 15, 2017 5:46 pm

Is there a cure for slow coupe rear windows. So far I have stripped down removed the motors cleaned commutators brushes etc, lubricated all rollers and springs..........not a nice job as a bit fiddly all back together but still slow!!

Can electric motors get "tired" or magnets get weak.

is there a better motor that could be adapted?

Any help appreciated



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Re: XJ COUPE Rear Windows

Postby mike020150 » Wed Aug 16, 2017 10:58 am

Your refurbishing of the electric motors and lubing of the mechanisms sounds comprehensive. Could it be a wiring or poor earthing issue? What about the condition of the electrical overload device? Mike.
2014 XK Dynamic R convertible; 1977 Daimler Double Six Coupe; XE S

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Re: XJ COUPE Rear Windows

Postby Tintin » Wed Aug 16, 2017 8:02 pm

I had a similar issue with my XJS and Volvo. The problem turned out to be frictional resistance of the glass in its guides. Silicone lubricant gave noticeable improvement but the real problem was expansive corrosion of the metal guide channels - requiring repair or replacement.

Hope this may be of help to you.

1996 4 litre XJS Celebration 2+2
Daimler Sovereign S1 4.2 1971

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Re: XJ COUPE Rear Windows

Postby ace » Thu Sep 21, 2017 9:19 am

I had this same problem with my own car, albeit a saloon, rather than a coupé.

I would imagine that the general wiring would be the same.

The switches take all the current for the motors through them and over time they wear and the contacts get dirty. Speaking to an old mechanic friend he said they were always slow, even when new.

What I did was to run a larger power cable to each of the doors and used the switch wires in the doors to operate a couple of relays. One for up and one for down. This ensured that the motor receives full battery voltage when operated.

The windows now work better than I expected. As fast as any modern car. In fact, they work so well that I'm considering fitting a limit switch to the ends of the window travel as they now close with with a noticeable thump.

I can dig out the schematic for this if anyone wants to give this a try.


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