Electric window wiring

[Donels]

I’m adding a few more relays and fuses, other than the 4 original, during the rebuild of my +2 S130. These are for cooling fan, lights, fuel pump etc, but going through the wiring diagram I was surprised that the electric windows are unfused. I think they need a 15A fuse minimum but probably relays as well. What's the advice, what have others done.

Dave

[Lotus fan]

I rewired throughout using Autosparks looms and wired it up as per the S130 wiring diagram in the workshop manual.
The original 4 fuses and no extra relays were used.
Alls well so far 18 months after rebuild

I'm touching a lot of wood and still looking for a 4 leaved clover

[stugilmour]

A 15 amp fuse per side is the ticket. I found 10 amp would blow quickly when the motor hit the upper stop.

I tried resettable breakers but they did not work well as they would blow too easily at motor stall.

I used relays to protect the fifty year old dash switches. I used micro relays to save mounting space, but a standard Bosch style make & break would work fine.

My motors were both rebuilt. They are pretty standard Delco motors using a GM call up from Cardone in the US. Not sure of availability in the UK, or shipping from the US; they require return of your core though, so that could make them cost prohibitive.

Can’t recall the thin wall wire gauge I used to the motors, but it was the larger size within my somewhat customized loom. Three wires fit OK in the door tube, but fitting the door lock wires became a challenge. If your loom doesn’t use thin wall wire, I suppose a short length from the motors to the inboard side of the door tubes would work well to assist in pulling wire thru the tubes.

I chose to wire power supply to Hot at All Times Brown; can’t recall how my Federal car was wired originally. I like being able to run the windows without the key.

Depending on how you are mounting and managing the extra relays, I suppose one could put a single 15 amp fuse per side on the power supply side of the relay. I don’t think running off of a Purple Hot at All Times Fused would be wise due to the possibility of blowing the fuse at motor stall. I think I actually used two 15 amp fuses per side (up and down).

Windows sprint up and down at a frightening speed by modern standards. Seem to have slowed down a bit after a few years of use, but greatly helped with a quick spray of silicone lubricant in the window tracks.

HTH

[Lotusian]

Like ‘Lotus fan’ above, I rewired my 1968 Plus 2 exactly as the factory diagram, using Autosparks looms, with only the 2 fuses as originally installed in the early cars. Nearly 3 years have passed, and no problems.
Before I rebuilt the car, it had covered 127,000 miles on the original (2 fuses) wiring.
Ian

[Lotus fan]

That's spooky.....I"m an Ian aswell

[HCA]

I was surprised that the electric windows are unfused. I think they need a 15A fuse minimum but probably relays as well. What's the advice, what have others done.

Dave

My tuppence - fuse yes, relay no.

Back in the day, the UK cars used a minimum of fuses - I guess cost was the reason. But surprisingly, most cars survived! Clean out your window motors, connect with decent size cable, dry lube the tracks well and you will be surprised how low the amps are. The standard window switches are from Westinghouse's washing machines and are pretty well bomb proof , so imo, relays not necessary.

[Bigbaldybloke]

I’m with HCA, fuses yes, relays no. Probably because I’d had no problem with them so didn’t think of adding relays when I custom made my own wiring harness. Fairly easy retro fit if I do want to fit relays though, probably fit them under each end of the dash as it’s tight in the tube into the door already and adding an extra power supply wire might be a challenge.

[The Veg]

I'm not an Ian but I've known several Ians and they've all been decent chaps.

What helped my windows the most dramatically was to run a big stout earth-lead directly from the motors to the chassis-bolts behind the dashboard.

What didn't make any real difference:
Rebuilt motors
Clean & lubricate mechanisms
New up/down power leads
Clean contacts inside switches

[RichardHawkins]

Veg,

I have read this before many years ago, but do not understand why an additional earth is helpful. Do you have an explanation, or was this just trial and error?


Richard Hawkins

[HCA]

The motors should not need an ‘additional’ earth. What they need is a well connected earth.

Many mistakes are made in auto electrics by not paying attention to the return path of the current, typically by undersizing the return wire and not maintaing their connections.

Car wiring is notoriouly bad quality because it is designed and installed to economics first and foremost that means circuits are shared with each other that often have large current draw devices using a return that is far too small. Modern cars are better and they do icorporate more fuses,

I have rewired many cars and like one does on a house, each device has a dedicated fused feed and its own return directly back to the battery. Using thinwall, the loom size is still smaller than the old pvc stuff ,

Back onto topic - for window motors on the Elan, use 2mm thinwall minimum and importantly check the terminations regularly and you should be fine

[RichardHawkins]

Hal,

Thanks for the advice and explanation.

Richard Hawkins

[alan.barker]

I've found the big problem with Window wiring is the Wires breaking internaly where they are threaded through near the Door Hinge. They look perfect from outside no damage to Insulation but inner wire threads broken.
If problems the first thing i do is bypass the Wire where it goes through Hinge area.
Alan

[Andy8421]

The motors should not need an ‘additional’ earth. What they need is a well connected earth.

With Lotus, you can never be sure, but later cars used a re-purposed permanent magnet wiper motor (it has a round body) that didn't need an earth to operate. I can only assume the earth was included for radio suppression.

The connections out of the motor went to the motor's brushes, the window switch effectively connected one brush to positive and one to negative to make the motor run one way, then swapped the connections to make the motor go the other way. No earth involved.

Andy.

[HCA]

I've found the big problem with Window wiring is the Wires breaking internaly where they are threaded through near the Door Hinge. They look perfect from outside no damage to Insulation but inner wire threads broken.
If problems the first thing i do is bypass the Wire where it goes through Hinge area.
Alan

Replace all 28/.030 pvc cables into the door with thinwall 44/.030. Same overall diameter and much greater flex properties..

The motors should not need an ‘additional’ earth. What they need is a well connected earth.

With Lotus, you can never be sure, but later cars used a re-purposed permanent magnet wiper motor (it has a round body) that didn't need an earth to operate. I can only assume the earth was included for radio suppression.

The connections out of the motor went to the motor's brushes, the window switch effectively connected one brush to positive and one to negative to make the motor run one way, then swapped the connections to make the motor go the other way. No earth involved.

Andy.

Indeed, what I meant was that the motor does not need any extra earths than it already has - just make sure what is there is well connected AND where it is permanent magnet, the same - good connections and decent cabling.

[Craven]

Most important, +2 & Elan window motors are different.’The Veg’ has a +2. Elan motor has rotor windings but permanent magnet fields, a two wire connection. +2 motor has 2 field windings and an armature a 3 wire connection. With the Elan motor you just reverse the polarity of the two wires and the motor runs in the opposite direction. You may need to look up principles of DC motors, but basically with a +2 motor the magnetic field generated by an armature and the magnetic field generated by the field windings is fixed by the direction of the windings, reversing the polarity of the supply changes both the armature and field winding(1), fields, the motor does not change direction. So a second field winding(2) wound in the opposite direction, a third wire, produces a field polarity opposite to field(1) causing the motor to run in reverse. Motor case or earth negative supply connection is a common current path for both forward and reverse.
FWIW