Gotcha! You probably thought this was a how-to thread. Maybe it can be, but for know I'm the one asking how-to.

Does anyone know of any motorsports biased wiring how-to books or websites? If not motorsports, then a decent airplane or aerospace focused substitute? I want to improve my own wiring abilities and figured this crowd might know of some good resources, while others might also be looking for the same thing.

I'm interested in subjects like:

• strain relief loops
  
• proper power/ground distribution
  
• loom routing strategies
  
• noise isolation
  
• insulator/sleeving tips
  
• connector theory
  
• everything I don't even know is important

Basically everything that wouldn't be obvious to a mechE in a sparkE world. Heck most sparkEs I've met don't even know this stuff.

Ok, I'll post up one link I've found with some good stuff. Details on quality crimp tools, and links to videos on how to use them properly...

http://www.heli-chair.com/wiring_101.html

Also the Motec AUS and Megasquirt sites have some good info buried within. But I'm hoping to find a "motorsports wiring harnesses for dummies" type resource.

Connector theory? I didn't know there was such a thing.

This has proved useful in the past:

NASA Wiring Standards

quote:

Originally posted by exFSAE:
Connector theory? I didn't know there was such a thing.

Well answers to things like "how heavy duty for different applications", "should I use a bulkhead connector or not", "split the harness into two branches or leave it all in one connector". I realize these are pretty obvious questions and probably just a matter of preference in some cases, but I'd like to find a resource that addresses them in some way.

That NASA link has some cool stuff in it. Thanks.

Well I don't think that there's such a ressource. If you're talking about a reference-text on these topics, I think your chances of finding it are close to zero.
You will much more likely find the answers by trusting in your own engineering common-sense and in asking the field application engineer of the connector manufacturer or reseller of your choice.

Let me give you a few examples from our car.
We've split our harness in half, because our car splits in half. We've got an "easy-disconnect flange (TM)"(1) that connects the monocoque and the engine-compartment. The car will be split each time we need to get at the engine, so we need a great big connector to easily separate the two parts of the harness. That's what I call engineering common-sense.

The question which connector to use remains though. Well we know a few things:
* number of contacts
* we want a proper attachment for the conector
* (splash-) waterproof
* we want crimp contacts
* may not vibrate itself loose
Finding them is again down to engineering common-sense and finding out which connector to order can be done by talking to your reseller or the manufacturer of your connectors or simply going through some catalogs.


(1) the easy-disconnect part is a joke, obviously

I'm a fan of the four-prong crimper that the deutsch connectors use.

dual wall heatshrink for strain-relief of connectors

i'll type up a nice big list here in the near future but right now i'm prepping the car for an autocross...GO APRILIA's HAHAHA!

I know the majority of F1 teams follow aerospace standards so that's probably a good place to look. At least adverts for F1 sparkE's specify knowledge of Aerospace standards.

also, somebody has put together a loom that integrates the wiring into a fibre (carbon I think) loom, with connectors integrated into the ends, making it light stiff and circular, plus easy to move about. Not necessarily on topic but might be interesting, I'll try and dig out the link.
B

I work with cables in defence (aerospace) and use MIL-STD codes and equipment. Some crimp tools can easilly cost $1k and alot of the small splices and terminators cost like $30 a piece so to have a truely professional cable for Formula SAE I think it out of the question unless you have some really good sponsors.

We factor in that something like a 25pin D-Sub connector on each end with each pin connected to a cable will cost around $2000US to design and manufacture.

For next year's car, we will be doing the wiring harness layout in CATIA. We already use high quality components, but the wiring could be better. And depending on the feasibility of it, we actually might pass the wiring through the walls our monocoque. Right now, we have a big 30mm OD loom that passes in the interior of the cockpit. One of the judges didn't really like that.

I'd love to see more documentation on professional aeronautics wiring (or F1).

Here's what we use:

Raychem (Tyco) SPEC 55 aeronautics cable.
Souriau aerospace connectors (MIL-DTL-38999 series III)
Astrol Tools crimper
CATIA Wiring Harness:
http://www-03.ibm.com/solutions/plm/doc/content/bin/plm...rical%20flyer_LR.pdf

Even though spec55 wiring is the best stuff, it's quite expensive for teams on a budget. I think FlexLite is a good alternative. Easily available through Farnell in Europe.
Also if you don't have enough time to completely plan your wireloom ahead of time, one made using adhesive lined shrink sleeve is a nightmare to rework. Thus it might be easier to use non-split corrugated tubing and the special junctions that come with it. It's also dirt cheap.

I also think there would be very few books going deep into autosports wiring, people are making tons on money on the racing looms and don't want others to know how to :-)

Some other tips:
Use crimped connector terminals and buy the proper tools ($$$). This is worth fighting over.
If using Faston connectors, use a ratchet crimper. NEVER EVER the sheet steel cheap tool.
Turned connector terminals survive more abuse than stamped.
Don't use terminals that are too small, they'll bend and break under mating abuse. (and are hard to work on)
Use waterproof connectors
Use enough connectors, you'll be happy you did later.
Don't use solder on a wire before crimping, it makes the connection worse.
Use strain reliefs and use them in the right places. (on the wire not closer than 5cm to the connector)
Don't use gold plated terminal for anything carrying high current. (you can for signal wires)
Do calculate the temperature rise above abient due to the electrical current for big loads.
Don't use wires that are too thin, even if they carry little current. They need some mechanical robustness as well.
Use firesleeve (don't remember the exact name) for wiring close to the exhaust.
Get tie-wraps that you can also undo
Ask a practical EE for his judgement on noise, shielding and ground layout.
Etc...

Sorry to rant in your post Dan, you probably already know most of this, but there are still too many cars breaking down due to electrical issues.....

Igor

The Question is, are 'autosport'/aerospace quality harnesses necessary in FSAE or will a production car quality harness do just fine?

Sure a full out harness with autosport connectors, mil spec Teflon coated wiring, and DR-25 covering looks cool, but can you justify a wiring harness that costs $1000 on the cost report? Does it make you go any faster? It might be a little but lighter but not by much. You can build a cheap harness that is reliable and durable enough from production car grade connectors, wiring and sheathing if you put some thought into it.

Just because its done in F1 or airplanes does not mean it should be done in FSAE. Our competition has different problems goals and objectives. We are not dipped in money.

I hate engineers, you guys make everything so complicated. Why not take a trip to a local race shop and see what they do? They aren't going to give you information over the phone or email but they will if you hang out at the shop enough.

Believe it or not it is possible to build a car without a CAD model, CNC machines, or the internet.

A lot of things are possible. Doesn't mean they should be done, asshole.

this isn't club racing. we are trying to be professionals. We do things the correct way and we like to know how to do things the correct way and leave out the redneck engineering if at all possible.

Some good info here
http://corner-carvers.com/forums/showthread.php?t=34419

one way to clean up the messy fusebox/relays that are typically used is the power distribution box that motec came out with also the Ole Buhl Racing box is amazing and is used by a number of ALMS and LMS teams.

one huge thing is the current sensing technology that allows limits to be set and the power will switch off if the current exceeds the limit.

I think Rickertsen and Flat Black have a point. Formula 1 level equipment doesn't fit in an inexpensive prototype. You have to consider the big picture.

Does your team have enough money to build such a wiring harness? If your team is 100% dedicated to performing well in the competitions there are definitely better places to spend money. A light, inexpensive, functional wiring harness is possible with some thought and ingenuity.

On the other hand, if your priority is to learn about 'professional/aircraft/F1' wiring go for it. "Because I'd like to learn how to do it" is a decent justification to do something. Just don't sacrifice the rest of the car if you want it to succeed.

We're really talking about a spectrum, with F1 cars on one side, and Flat Black's piece of shit Camaro on the other.

FSAE is a harsh environment with a lot of heat and g's and things that make bad connections break, wires melt, and overheated electronics not carry enough current to restart after 11 laps. If you're aiming for 40th place, you can probably build your harness at the auto parts store.

If you're aiming for 1st, your wires need to be lightweight and heat resistant, connectors need to be lightweight and reliable with good conduction and well sealed, and the harness has to be laid out with foresight and care. If you've accomplished that, you are going to be much closer to F1. You don't need to be at F1 quality, just closer to that than the alternative. Mil/aerospace spec allows you to trust the part quality is at least what you need.

Also, It's my opinion that the only connectors you should have fall into two categories 1) sensors, injectors, coils and others that use existing engine connectors and 2) One connector for all engine wires, one for all dash wires, and one good one for the brake over-travel switch. Two big connectors, and one small important one that you can spend a little extra on. Think Deutsch. I don't think you need expensive crimpers and individual wire connectors.

This message has been edited. Last edited by: Superfast Matt McCoy,

Well said Matt. A large amount of the entry-level motorsports jobs out there are DAG positions, whoes responsibilities include maintaining the integrity of the electrical systems. I think that the knowledge we're talking about here is quite valuable to any ME looking to break into a racing career. In general, I think it's also something your average ME graduate is lacking.

A full-blown Atlantic/ChampCar/IndyCar harness will range in the tens-of-thousands of dollars, which obviously exceeds any FSAE budget. But the principles used in its construction can (and should be!) easily carried over to FSAE application. Even if your team absolutely cannot afford anything from Raychem/Deutsch/Autosport/etc, just knowing their products and how they should be used would be a bonus!