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Race spec wire preference

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Hi All,

What is the preference for wiring for a "race spec" harness? You see a lot of reference to M22759 which seems to be an old outdated MIL spec for wire and superseded by "Spec 55" / 55A0111 spec wire which seems very very close in spec to the M22759 - both of these are TE specs.

If you get out of the TE mindset (seems almost everything in this space is owned by TE) and look at alternate providers, you get wire from the likes of Alpha Wire with their 2922 series ThermoThin wire which is very similar in spec to Spec 55 / M22759 in that say for 22 AWG is is 19 strand / 32 GA, Fluoropolymer (same as ETFE / TEFZEL) insulation but seems better suited to motorsport in that it has a higher 300 deg c temp rating (compared to 150 for Tefzel / M22759 / Spec 55) and also has a thinner insulation meaning it is both smaller and lighter.

Is the space pretty much brainwashed with TE / "Mil Spec" or are we seeing other specifications get some traction at the "race spec" end of the market?


Gday Ben

To be honest, I'm most certainly guilty of being brainwashed by the TE dominance over the space. I'll used M22759 wire as my go-to for a race-spec harness, as its what I've always used, and its worked great, and I'm tooled up to use it.

I'll be having a google of the alpha wire 2922 though. 19 strand 32ga sounds great, would be very flexible I'm betting.

I had posted a link to (a) supplier(s) in the Wiring and Suppliers thread a few weeks back.

To save you looking - http://www.alphawire.com/

Cheers Gord. I've requested some samples of Alphawires thermothin wire, will see what comes of it :-).

I have ordered some ThermoThin wire, I need to see what turns up though, I thought I ordered a 305m spool but there is a chance a 30.5m spool may be delivered, I will find out in the next few days.

If it is a 305m spool then price wise it is similar pricing to TE M22759 but if it is a 30.5m spool then it is about 9 times the price and at that price I can see why it may not be a popular choice in motorsport - the cost : benefit ratio just isn't high enough in my mind - its not like it is hexagonal strand or anything trick like McLaren use. . . .

First I had heard of Thermothin too, I suspect some of the reason it hasnt caught on in my world is it is about 3X the cost of M22759/32, at least here in NZ if I compare retail prices. And since its far more common you can often get M22759/32 way below retail to make that an even bigger gap.

M22759/32 has a 0.006" insulation compared to Thermothin's 0.0055", so there is only "half a thou" difference. I cant find the mass data anywhere but 3X the cost to save maybe 50grams per 500ft typical loom may not make sense to many end users.

@Adam yes cost may well be the factor here. Looking at the specs, for 22ga there is only a 2though (+- 2though) difference between the M22759 and ThermoThin wire but there is double the heat handling on the ThermoThin which is still a compelling factor but not at 3+ x price.

I guess the point of the thread is that there does seem to be valid alternatives (from a spec point of view) to the TE items so would be interested in seeing if anyone else is using other alternatives.

My main reason for ordering the ThermoThin was that a) it looked like the same price as M22759 but I may be proved wrong once the delivery turns up and b) the supplier I used only had M22759 in white whilst they stocked ThermoThin in 20 colours - if ThermoThin is the same price then I will take the ease of colour coding but if it is 3+x then I will stick with white and label every wire . . .

My delivery has just turned up and it looks like I got 30.5 (100ft) spools instead of the expected 305m spools which makes it around 9x the price of M22759 :(

1 quick update - looking at the AlphaWire ThermoThin that has just been delivered, it is not very flexible, or at least not as flexible as M22759 - the wire itself may be as flexible but it would seem the insulation is quite stiff which is interesting as it basically the same insulation - ETFE / Fluoropolymer, but also interesting that it is "basically" the same material but double the heat rating.

Furhther to different wire options, it looks like I have found an alternative to the Deutsch Autosport connectors. Souriau have a motorsport range based on MIL-DTL-38999 which seems like a pretty comprehensive range offering a heap of barrel sizes and configs up to 128 way 22d pins with support for both sensors and power options with differnt pins. see ww.motorsport-connectors.com for thier 8STA / 8TA ranges (as well as the other MIL connectors they do) - They are stocked by RS Components.

Yeah, many of the Soriau and Autosport connectors are interchangable, and intermateable. They're just as expensive typically though :-/.

Yeah price looks very similar, is mainly that they seem to be available through some of the more mainstream suppliers like RS and Mouser etc. My business has an account with RS so anything Ican get through them is easier than other products :)

Ben, did you end up using the ThermoThin wire? What was it like to handle and use, and was the flexibility still an issue? I am very unlikely to move away from M22759 but keen to hear how you got on.

No Josh, I ended up sending it back - When I purchased it the specs indicated I was ordering a 100m spool however a 10m spool turned up and the price was actually for a 10m spool which made it pretty expensive. Ended up going the TE route.

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