Pre He lazy window

Hi Guys, I am just fitting up my 76 Pre He after a full bare metal respray and have discovered that the drivers side window is lazy and will not quite close to the top. Its also not parallel , it slightly tilts towards the top. I guess if the motor gave it a bit of welly it may straighten up as it get to the top of the frame but we are not getting that. The rest of the car is pretty low mileage and I have no reason to think its a worn out motor. Anyway, if anyone can shed any light on my problem I would be very grateful. I have lubed the various runners. Is it possible to test the motor performance in any way?

First check if the driver’s side is much slower than the passenger side.
A common problem is the wiring and console mounted switches have a fair bit of voltage drop so the motor does not get full battery voltage.
Fitting relays in the footwell just forward of the door hinge will give more voltage and help.
You can get at the wiring in that area and break the circuit, then apply full battery voltage to check for that problem.
Note that with the engine running you get more voltage available and that can make a difference anyway.

A number of years ago I had the window seals replaced on my '76. The seals were new Jaguar labeled parts, but once installed the windows would barely move. It was not a motor or wiring issue at all. The glass guy said it was because the seals were to thick, so to speak. IOW, when the seals were pressed into place in the door the distance between the bottoms of the grooves was less than the width of the glass. He whittled some rubber off the back sides of the seal to solve the problem. Even today, though they are a bit slow, especially on the passenger side. Another problem with this fix is excessive wind noise. It probably would have come out better if had ground off the edges of the glass.

This is just one more example of the terrible quality of Jaguar parts. Supposedly, they are made to Jaguar specifications, but my guess is no one from Jaguar checks the product. They just slap a Jaguar label on the bag and ship them to our suppliers.

I also had a lazy driver’s side window. I found that the motor was not securely mounted and could “tilt.” Some Loctite was the cure. OTOH, if you have lubed the runners, perhaps you have already checked the motor fasteners…

Thanks Richard, I will fit up the other window frame and check to see how it performs. There are already relays for the windows down by the lower door hinge. Standard Jaguar fit. If it persists I will apply 12v down there and see how the motor performs then. As you say the window switches are pretty dreadful things. I did start the engine, and it does as you say improve the performance but not enough to make it fully close. More work needed I think! Do you know if the motors themselves give trouble, do the brushes tend to wear? thanks

thanks for the idea Ed. I am actually using the original door seals for just this reason. I have restored a number of early Range Rovers and the windows will hardly wind up with new seals. the best supply of material for the window felts in the UK is COH Baines of Tunbridge Wells , Kent.

thanks Dave. I have not checked this but will do so this morning . Much appreciated.

Really? Because they were not standard Jaguar fit on the early 80’s. There were standard Jaguar fit on the facelift, but that’s a lot later.

My fault. You are of course correct, the relay is for the door locks. I didn’t look that they were for the windows! Anyway, I am going to spray silicone lubricant on the felt seals and see whether this helps. Meanwhile the near side window has now stopped working, so just looking into that!!

my passenger right side is slower than the drivers side…had difficulty with the motor on the drivers side and replaced it with an older unit (mine is a 1988) and now it goes up and down real quick…back to the passenger side which I hardly use…I put a little silicone spray lube in the track and that helps immensely…I believe certain years motors work better than others…I heard that the 1988-9 ± motors are not as good…If all is well with wiring and switching try lubricant…also my window on drivers side has always been a little bit tilty in the track but I don’t want to overtighten the track either…so I live with it quite well.

Thanks scrimbo . I have siliconed the runner and it does seem better but not perfect. I cannot quite work out why the glass is not quite parallel at the top but I am sure I will with more investigation. When you refer to tightening the track. Are you talking about the lower separate channel?

Yes you will Andrew, and you should because it’s adjustable.
One of the window lift mechanism’s screws on the door panel is there for that. (At least on my XJ)
Also you should look at the channels inside the door, they should too be adjustable, they could be tight causing high friction.
Another thing is that the rubber in those channels has a tendency to move from its place, up or down, either jamming the glass, either giving lots of slack.


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thanks. I have got it working better and will live with it for the time being. If it doesn’t get better with use, I can have it all apart again.

There is an adjustment down at bottom of track. …might help…