21 replies to this topic

[Deejayry]

Hi all, I am about to embark on building a brand new custom fit wiring loom for my trackday mini it will be made to conform with the motorsport / mil spec using Deutsch / Souriau connectors, Raychem Spec55 wire, DR25 heatshrink sleeving etc.i will use service loops at all connectors and the wire will be counter axially twisted to ensure flexibility & durability

 

have built wiring looms before using automotive grade wiring where the wire is often sold by current rating which makes it easy to chose the correct size wire.

However the Raychem Spec55 does not specify the current it can take, so i'm wondering if anyone here can tell me how to chose the correct wire sizing?

[KaneH]

Here's a reference for wire current rating.

http://www.gwrmotors...be_EC55A20.html

I would say though do you have the correct crimps etc. for the raychem wire/deutsch connectors? They're non standard crimps and cost a small fortune so kind of makes a one off loom mega expensive.

As it's Just a track car I'd say you could make a new loom up with standard (cheaper) connectors/wire and use what extra money you Would have spent on the deutsch stuff on other performance mods.

They do look the part but I'd be looking to shave seconds off my lap times before worrying about a fancy looking part that's seen very rarely if at all

Edited by KaneH, 15 September 2016 - 06:11 PM.

[nicklouse]

I, likewise, don't see the point.

[Deejayry]

Here's a reference for wire current rating.

http://www.gwrmotors...be_EC55A20.html

I would say though do you have the correct crimps etc. for the raychem wire/deutsch connectors? They're non standard crimps and cost a small fortune so kind of makes a one off loom mega expensive.

As it's Just a track car I'd say you could make a new loom up with standard (cheaper) connectors/wire and use what extra money you Would have spent on the deutsch stuff on other performance mods.

They do look the part but I'd be looking to shave seconds off my lap times before worrying about a fancy looking part that's seen very rarely if at all

Thanks, i don't know why i didn't manage to find that page, i must have skipped past it when googling

 

I am fully aware that the connectors require special tooling, but it is a cost that i am willing to take up, after this project is finished i will be taking on the wiring for a FIA historic MK1 mini and also rewiring our Mini grand 24hr race car, i'll be able to reclaim some of the cost of the tooling through that. 

 

I understand that many people would rather spend the money on other things but my car is pretty much as it needs to be, the electrics are the main thing that needs attention as the previous loom built to be close to motorsport / mil spec but using cheaper components has had problems with contacts failing after less than 10 connector cycles & corrosion on the externally mounted connectors, this time i'm going to do it properly using components that are going to last.

[Spider]

 

However the Raychem Spec55 does not specify the current it can take,

 

As it's an Aerospec Cable, you need to find the Aerospec Standards for this, BUT, don't expect to find a straight forward table as you would for other wires as this will take in to account the number of other wires in the same space and how much current they will each be carrying (as they will all make contributing heat) along with various environmental conditions. You'll almost need a computer program to work it out.

 

While I admire your enthusiasm, respectfully, given your application, you are making this way more complex and VERY much more expensive than it need be. Don't under-estimate the cost going this way with some of the parts you've spec'ed up, it will easily cost more than your gearbox.

[nicklouse]

I have to also ask what form of Motorsport are you considering?

[holmesy]

I used to work doing wiring looms and telemetry for such F1 cars, areospace and such projects although I have most of the gear.

Tools cannot be bought cheaply and if you do then they are total ******* and will mess crimps up.

Expect to pay 400-600 for crimp tool( you'll need two as pin and sockets use different tool, correct pin/socket adapters costing around 30 quid each depending on different sizes.

Boots will need filling with s11, you can mix it by hand but never works perfectly so ideally need to buy rs mixing gun.

For boots you'll also need an adjustable very high temp heat gun.

Strippers you can get some cheaper awg strippers for 150-200quid but after 400 strips we found we had to send away for resetting.

Hope your used to doing service loops in DR boots as this is a ******* to learn correctly, I used to grind down different size punches to help start

Also don't forget your lacing cord and kevlar thread, you'll need good teeth as they becom your third hand for tying up service loops and when twisting wires together ( you don't twist wire when sleaving, you use your open hand to braid the wires together passing wires between each finger)

Edited by holmesy, 16 September 2016 - 06:48 AM.

[holmesy]

If you want a loom for track and race mini's then give John at Snetterton speed shop, he can give you a nicely made loom and control panel that he uses in his FIA cars that runs just the basics needed.
Great weight saving and professional and at a fraction of the cost of tools alone

I can't see where your gonna need more than 2 multi pin connectors, any more than this is just unnecessarily weight and even the best ali and plastic deutsch connectors fail

Edited by holmesy, 16 September 2016 - 06:38 AM.

[Steve220]

Take your standard loom, strip it, remove all non-essential and superfluous wiring then rebuild using better heat shrink and wrap.

[Deejayry]

Take your standard loom, strip it, remove all non-essential and superfluous wiring then rebuild using better heat shrink and wrap.

 

Nope... for a start a standard wiring harness will not actually fit in my car, it is not your run of the mill mini, it has seen an extensive range of modifications to the body and the components fitted, the only original mini electrical components are the wiper motor, steering column stalks & the light fittings.

 

It runs a polestar HS management system, ignition only at the moment, but the harness will have the wiring to literally plug & play for a closed loop injection system for up to 4 injectors.

 

The standard wire used in minis is barely fit for road car use let alone in on track conditions & the connectors are even worse. How many of you have had to wiggle a connector to get the headlights to work properly?

 

If you want a loom for track and race mini's then give John at Snetterton speed shop, he can give you a nicely made loom and control panel that he uses in his FIA cars that runs just the basics needed.
Great weight saving and professional and at a fraction of the cost of tools alone

I can't see where your gonna need more than 2 multi pin connectors, any more than this is just unnecessarily weight and even the best ali and plastic deutsch connectors fail

I used to work doing wiring looms and telemetry for such F1 cars, areospace and such projects although I have most of the gear.

Tools cannot be bought cheaply and if you do then they are total ******* and will mess crimps up.

Expect to pay 400-600 for crimp tool( you'll need two as pin and sockets use different tool, correct pin/socket adapters costing around 30 quid each depending on different sizes.

Boots will need filling with s11, you can mix it by hand but never works perfectly so ideally need to buy rs mixing gun.

For boots you'll also need an adjustable very high temp heat gun.

Strippers you can get some cheaper awg strippers for 150-200quid but after 400 strips we found we had to send away for resetting.

Hope your used to doing service loops in DR boots as this is a ******* to learn correctly, I used to grind down different size punches to help start

Also don't forget your lacing cord and kevlar thread, you'll need good teeth as they becom your third hand for tying up service loops and when twisting wires together ( you don't twist wire when sleaving, you use your open hand to braid the wires together passing wires between each finger)

 

Thanks Holmesy technical advice is what i am looking for. The decision has been made to build a harness to this spec, i didn't come here to be told not to do it.

 

I hear you on using the correct crimping tools, i think that is why i have so many problems with my existing wiring, with pins not retaining in the connectors, wires pulling out of terminals etc. I can get the correct crimp pliers for £270 and the turret for the Souriau pin & socket terminals for £100(both terminals use the same turret), i believe the plier frame can also take the turrets for deutsch DT & DTM connectors.

 

So i own a pair of "ideal" strippers for Teflon coated  AWG wire (not the specific ones for Spec55) but can get the correct blades, i will try stripping the wire with the blades i have before i spend out on the 55-1987 blades. I don't yet have any experience in wiring service loops in this type of connector but i have had limited experience in larger industrial connectors, space is less of a premium here but the principal is the same, i've just ordered a cheap set of punches from ebay to help out.

 

Ive not heard of the s11 epoxy before, i had planned on using Resintech RT125, i already have the mixing nozzles and the 3M applicator gun. how does the s11 compare with RT125?

 

At the moment it looks like i'll need around 3-4 multi pin connectors to pass through the bulkhead, one connector with size 16 terminals for high current noisy ECU circuits (injectors, ignition coils, power feeds etc), another with size 20 terminals for ECU sensor wiring etc, then the chassis wiring which might all be in one connector or may have to be split between the high current circuits and low current circuits.

There will be one connector with size 20 terminals that will connect the rear harness to the power distribution/circuit breaker panel and a handful of 4-12 pin connectors for sensors, injectors, ignition coils, stack dash display etc. these will mostly be DT/DTM series with the exception of the injectors which will be Souriau (due to the fact that the connector will be fitted with a blanking cap until the addition of the injection system).

 

I know John and I am aware of the harnesses made at SSS, but i will not spend my money there, i have my reasons for this but i am not prepared to discuss on an open forum.

The other thing is that the harnesses made by john are mostly an off the shelf setup for FIA historics, my harness is somewhat more complicated than the minimalist setup of a FIA Historic.

 

As people have said this is a massive undertaking and is very time consuming to plan out, i am almost finished with the planning stages now, i have ordered everything apart from the souriau, DT/DTM connectors & the heatshrink boots, the mock-up sections have all been made and are due to be transfered to boards in order to start laying the wiring out in the next few weeks.

 

I am happy to share my progress on here if anyone is interested in how its all done?

[mattmiglia]

Would be very interested in seeing it done as you go along!

[Magneto]

Absolutely!

[cal844]

I'd be interested to see progress!

[Deejayry]

So the car is now back from being resprayed and has now been locked up in a well lit, heated, clean and tidy workshop unit, where i can work on it without having to depend on the weather and as a bonus it will should last a lot longer before the dreaded tin worm sets in again!

 

The schematic wiring harness design is now finished, at least in theory! i expect there will be one or two minor changes when i start building it which i will have to document as i go, mainly the lengths of various conductors & position of multi wire splices etc.

The only area that is not finalized from a layout point of view is the Power Distribution Board. This relies on me having finished making the new centre console for the dashboard, which is where all the breakers, relays and most of the switches will be mounted. The centre console will be one part of a 3 piece carbon fibre dashboard, i am currently making the pattern for the centre console, the pattern for the main dash panel is done, although i am thinking of changing the design from a curved profile in to a flat profile. The final part of the 3 will be the instrument pod, this can wait for a while so that I can crack on with the wiring ASAP

 

I now have a box full of ETA 483 circuit breakers (about 20 of them) purchased for a bargain price of £15 each from eBay, i did have to buy one at retail price from Demon Tweeks (£65... Ouch) but DT was the cheapest place in the UK, I also have a new relay board that takes six mini relays, a relay board for two standard size relays (this one will be used for the indicator & hazard flasher units), all the dashboard warning lamps, LED replacement bulbs for sidelights, brake & tail lights, reverse lights and indicators, a compact heater unit & ducting system for the windscreen vents & a brand new Polestar HS management system for fuel injection, this i will be running in ignition only mode for a while until i finally replace the 48DHLA with a set of throttle bodies.

 

I figure that i had better hang fire with the wiring harness for a while until i have finished making the centre console for my dashboard, 

[tiger99]

For selecting the wire size, the limitation is going to be voltage drop. Type 55 can in theory safely pass more current than PVC etc, but the actual conductor in both cases is just copper and ohms law still applies. Voltage drop matters very much in alternator, headlight etc circuits, not so much on low current circuits like instruments such as fuel gauge where the thinnest is ok. So use the same gauge as the original in the high current circuits.

Oh, and holmesy has very well said what I would have felt the need to say about tooling. It matters very much with "ordinary" wiring materials, as I have pointed out a few times, but much more so when you are using proper materials instead of the cheapest grade of material as is normally the case. It is actually not easy to make a reliable loom. Most people will use inadequate tooling to save money, and will fail. (So do some so-called professionals, who are using sub-standard tooling and even crimping by feel.) Skill is needed too, but for most people of normal ability that will come with practice, which needs spare wire and crimp pins, which means cost....

Please, never try making a loom on the cheap.

Mods, how about making holmsey's wise words a sticky?