Lotus Elan

harness wrap

PostPost by: USA64 » Wed Feb 26, 2020 10:45 pm

What exactly is the purpose of wrapping the wires? I can understand how it would make assembly of the new car easier but is it necessary after that? Wouldn't it be easier and facilitate repair if the wires were just put in one of those split plastic conduits? I have a new, wrapped, harness which I am modifying somewhat. I'm thinking I will unwrap the harness for ease of access. Any advice would be welcome.
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PostPost by: steve lyle » Thu Feb 27, 2020 2:47 am

USA64 wrote:What exactly is the purpose of wrapping the wires? I can understand how it would make assembly of the new car easier but is it necessary after that? Wouldn't it be easier and facilitate repair if the wires were just put in one of those split plastic conduits? I have a new, wrapped, harness which I am modifying somewhat. I'm thinking I will unwrap the harness for ease of access. Any advice would be welcome.


Tape wrap is certainly less expensive than split plastic conduits. And more flexible, in several meanings of the word. It also takes up less space.

This past summer I rebuilt my dash harness. While building the harness, I kept the wires together using short velcro strips wrapped around the runs. Then when I had the harness the way I wanted, I wrapped it.

FWIW, tape seems to be more commonly used behind the dash by the OEMs I'm familiar with (likely for space and sound/rattle reasons), and plastic conduits in engine bays and around the chassis (greater heat protection?).

Maybe I should have been, but I wasn't worried about access for maintenance. I was more worried about getting the harness right in the first place, and correctly fusing the circuits - so that maintenance wouldn't be necessary.
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PostPost by: Frogelan » Thu Feb 27, 2020 3:19 am

In addition to Steve's very valid comments...

Wrapping the harness has the advantage of adding protection to the cables (fraying against edges, oxydation, connections becoming undone) and keeping them tied up away from moving parts where they might get tangled / damaged.

The process is usually completed to meet road traffic certification standards and to avoid problems with loss adjusters.

Reliability is also considered advantageous by passengers who may be discontenanced long walks in suboptimal conditions or by sparks from loose wires...

Fibreglass is also highly inflammable, just in case you had any remaining doubts!

For historic racers, electrical problems are often the most frequent single source of car related DNFs.
1965 Lotus Elan S2 26/4022 (originally Dutchess Lotus East, PA and NJ Area, USA)
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PostPost by: 2cams70 » Thu Feb 27, 2020 3:55 am

OEM practice is to lightly wrap all wires. This keeps them together whilst still maintaining flexibility to bend around tight areas underneath the dashboard etc. An additional layer of split conduit is used on parts of the harness externally exposed - eg. under bonnet and along chassis rails. The split conduit is sealed at each end by PVC wrap.

Even when using split conduit the wires enclosed are still lightly wrapped underneath. This keeps them all together and prevents individual wires escaping through the split.
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PostPost by: Craven » Thu Feb 27, 2020 11:07 am

Current rating of wires is based on temperature rise, so there is an advantage in not having closely bundled wires also avoid tight bends.
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PostPost by: JonB » Thu Feb 27, 2020 12:54 pm

Maintain the wrapping, and use the correct non adhesive tape. That's what I did when I rewired my nosecone with relays. Looks original. I found that when Lotus made the looms, they used a sort of double sided sticky tape at regular intervals along a wire run and at branches; this sticks both to the wires and the (non adhesive) loom wrapping tape. So when I rewrapped my loom, I did the same. So far, no issues.
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PostPost by: USA64 » Thu Feb 27, 2020 2:06 pm

Thanks everyone! :D
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PostPost by: derek uk » Fri Feb 28, 2020 5:26 pm

Tesa tapes are good, various types available. 51608 good for wiring looms.
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