Lotus Elan

Plus 2 window winding failure

PostPost by: The Veg » Mon Jan 23, 2023 3:46 am

On Saturday the passenger-side window on my my car got stuck in the fully down position. I was out with some fellow Lotus-enthusiasts and as I was about to head for home, I lowered the window to deliver a jest to the guy in the Elise next to me about his Toyota engine. Then the window would not move upward, not even a noise from a straining motor or a shudder from hitting an obstacle. Worse, the trip home would require an hour of 80 mph and it was a chilly day. While it's nice that Mr. Hickman's design doesn't create much interiour buffeting with a window open at high speed, the extra noise was annoying, especially for Mrs. Veg who was with me. At least it wasn't raining. All the way home we both repeatedly took jabs at the switch but to no avail.

Today I dug into things to see what the trouble is. I've eliminated electrical faults- no connections were found to have come loose, the switch does deliver current and the wiring from the switch to the motor does as well. After wrestling the motor out and using some jump-leads to apply current, it spins eagerly and smoothly in both directions as it should, since it's a fresh rebuilt unit that has been operated no more than 100 times.

Mechanically everything looks sound as well- it's all still well-lubricated from when I refurbished everything a few years ago (and has been sitting since until recently) and the grease is still the right consistency, the bobbin hadn't come out of the track, and looked in good shape when I removed the winder from the door. The glass moves smoothly in its tracks: I can lift it by hand from the fully-down position and it doesn't feel like anything is catching.

So with no fault identified, has anybody else experienced this, and perhaps found some fault I may have overlooked?

Part of me thinks that if I put it all back together everything will be OK and I'll never know what the problem was*, but another part of me wonders if it'll happen again and cause me more frustration.

*Something I've seen happen in my work as a service-engineer for a maker of analytical instruments. Sometimes just opening them up seems to put the fear into them and they behave after I've poked about inside and found no fault.
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PostPost by: h20hamelan » Mon Jan 23, 2023 4:12 am

Whenever I have a window or wiper etc motor out.
I soak in ATF at least overnight.

You mentioned your power and ground wires are thicker than original, and going through the door is protected?

Yup, I would agree. Striking the fear into them.
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PostPost by: alan.barker » Mon Jan 23, 2023 8:15 am

You say the window would not go up but would it go further down.
If it would still go further down then the problem is wiring.
I had a problem once like this and where the cable had flexed going through the hinge inside broken.
The interior of cable broken and outside sheathing still perfect. I run a seperate cable direct from switch to direct contact with motor.
On my Sprint the windows go down with Ignition off but up only with Ignition turned on (food for thought).
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PostPost by: seniorchristo » Mon Jan 23, 2023 1:00 pm

My guess is an intermittent ground fault.
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PostPost by: The Veg » Wed Jan 25, 2023 1:35 am

alan.barker wrote:You say the window would not go up but would it go further down.
If it would still go further down then the problem is wiring.
I had a problem once like this and where the cable had flexed going through the hinge inside broken.
The interior of cable broken and outside sheathing still perfect. I run a seperate cable direct from switch to direct contact with motor.
On my Sprint the windows go down with Ignition off but up only with Ignition turned on (food for thought).
Alan


No, I lowered it fully and then it would not go up.
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PostPost by: The Veg » Wed Jan 25, 2023 1:50 am

seniorchristo wrote:My guess is an intermittent ground fault.


When I refurbished the mechanisms (including rebuilt motors) I ran nice stout
12-awg ground wires directly from the motors to the chassis-bolts behind the dashboard, so I rather doubt it, especially since the fault -whatever it is- wasn't intermittent. Those new wires made the motors work fantastically BTW, after cleaning the switches did not.
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PostPost by: HCA » Wed Jan 25, 2023 2:43 am

Two possibilities assuming all wiring, connections and switches are good:

1. Unlikely to cause a sudden seisure though - window running crooked in tracks.

2 More likely and often happens - limit switch inside motor. This in older cars before electronics is basically an overload switch that might not show up as a fault on a bench test without a load applied.
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PostPost by: h20hamelan » Wed Jan 25, 2023 7:18 am

Carbon arching inside motor, or switch?
Like points in a distributor, or flint in a gun etc. Clean your gun! Or points!
ATF is cheating, sure you could disassemble too, but.
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PostPost by: The Veg » Sat Jan 28, 2023 1:41 am

Putting the fear into it hasn't worked. Tonight I put it all back together, with the window about 2/3 up, and it would lower but not rise. I have however determined that the problem is electrical, so I'll start a new thread in that section.
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PostPost by: alan.barker » Sat Jan 28, 2023 4:53 am

Hi Veg,
So it seems electrical and no power supply for up. I would bypass power cable for up where it goes from inside car direct to motor. Easier than looking at back of Window Switch in Dash. I have used a length of cable with a Dot Pin soldered to each end. You can pic the suspect cable to bypass the part of cable in question.
I imagine you do the test with Ignition turned on.
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PostPost by: The Veg » Sat Jan 28, 2023 5:48 am

Alan, see my post in the electrical section.
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