So I've not posted anything for ages about the car due to a whole series of things but recently I've been able to pick up on the project and start to do some actual work. The last time I wrote about it I'd reached a "crisis point" and was debating whether to kick the whole project, sell the bits and get into Scalextric.
Anyway this little post is to do with wiring and more specifically the undoubted temptation of those shiny motorsport connectors with the, OMG, milspec rating. At some point if you do any wiring you're going to be tempted to enter this murky world so I thought I'd save you a little time and effort by providing some information.
Firstly why milspec? well come on it sounds good and if it's good enough to be used by people with guns it's got to be good enough to use in my car. Well sort of, kind of - milspec simply means that at some point the Military (the mil bit) came up with a specification (the spec bit) that describes the characteristics of the connector. This specification is very detailed and whilst you can't assume that it inherently means the connector(s) will be of very high quality, quality is a side effect of meeting the specification.
My reasons for going down the milspec route were not so much about the vanity side but more about the sheer number of "profiles" available, the fact that, although expensive, standard tooling is used (yes even the tools have a milspec) and that solving problems like getting 40 conductors of different sizes through a buklhead becomes trivial (although expensive).
So here's a little guide focused on the Souriau 8STA connector series. Why Souriau? well they took the time to implement a range focused on Motorsport but is based on MilSpec, a range that looks at things like lightweight, high density layouts, small size and special considerations like in fuel tank connectors. The other reason is reputation, those immaculately prepared WRC cars, F1, MotoGp harnesses more often than not have 8STA series connectors on them. And finally - you can buy them, in 1 off quantities - no need to order 20 a time.
The entire series is documented in this 8STA but to try and give you a laymans guide here goes...
Firstly, before I start, be under no illusion this is not a cheap way to go. Other multi-way connector series are available although you'll end up in the murky world of bespoke tooling and once you drift outside of milspec the supplier you select "owns" you.
The cost of the connectors is only part of the cost you must figure in the intial tooling cost to give you and idea, assuming you can remain within the Size 20, 16 and 12 contact ranges (which for the vast majority you should be able to since that covers from 0 amps through to 23 then the good news is you only need 1 crimp tool, oh and the correct turret. Here's how it works;
The tooling is also designed to a given MilSpec; you do not need to buy Souriau tools to make Souriau connectors you just need to buy a tool which meets the MilSpec so in the case of the contact ranges I mentioned that means you need a crimp tool that meets/complies with M22520/1-01 and your best bet is to look at RS and specifically the DMC AF8. However that's only the tool you now need a turret - this is simply a devise that fits in the tool and ensures that the contacts are correctly positioned during the crimping operation in this case you need one which complies with M22520/1-04 and fits in your chosen tool, again save your time and jump straight to RS and get the M22520/1-04 turret for the AF8. At this point you've spent around £450.00 but you now have MilSpec tooling for your MilSpec connectors.
I said about staying within the 20, 16 and 12 contact ranges this is because doing so means this does become practical to do at home. If you stray into the smaller sizes you will need an additional crimp tool and locator, if you go above you will need a pneumatically operated crimper and that will make £450 look like an absolute bargain (I'll mention a solution to those of you who want to stay inside MilSpec but need to go higher than 23amps per contact a little later).
So what does staying in that range mean?
Size 20 contacts will take wire from 24AWG -> 20AWG or in English 0.21mm2 -> 0.60mm2
Size 16 contacts will take wire from 20AWG -> 16AWG or in English 0.60mm2 -> 1.34mm2
Size 12 contacts will take wire from 14AWG -> 12AWG or in English 1.91mm2 -> 1.34mm2
What this does is give you coverage up to 23amps per contact which means the majority of things in your car with the exception of starter motor, large radiator fans and electric power steering pumps.
Within the 8STA series there's a whole range of shell sizes available, the shell is the cylindrical container into which your pins and socket contacts fit but the most expansive range is the 08 -> 24 range. To give you a rough idea staying inside that range will give you options ranging from 3 ways (the number of contacts) to 61 ways in a single connector.
In the land of MilSpec connector technology it appears they like their own way of describing things so here's quick breakdown of how "it" works.
A connector comprises a shell, a shell size, a contact layout, a contact type and possibly some optional extras. They are not supplied in pairs it's down to you to make sure you order both halves!
The document I linked to contains a section, Contact Layouts, that shows you all the possible contact layouts grouped by shell size. The shell size ultimately determining the number of possible ways that can be accomodated. Fortunately in the 8STA range backshells are not something you need to worry about, just opt for a straight or right angled heat shrink boot and you'll be good to go.
Shells are either receptacles or plugs, now you need to know that a shell being a receptacle or a plug has nothing to do with whether the contacts are pins or sockets - it's up to you to choose (and my tip here is to be sensible and not have power presented on pins for obvious reasons).
In a classic scenario where you need to get a loom through a buklhead the receptacle would be the part attached to the buklhead and the plug would be the part attached to the loom. Receptacles in the 8STA range can be 1 of 3 types, Oval Flange, Jam Nut or In Line and here's what that actually means:
Oval Flange = bulkhead/panel mounting, Needs 2 bolts to secure in position. Jam Nut = bulkhead/panel mounting, Needs a D shaped cutout and the connector has a great big nut on the back of it. In Line = cable/loom mounting; used to connect, for example, a spur from a main loom to a headlight sub-loom
Pins and Sockets - ok this should be obvious but just in case; Pins and Sockets are both types of contacts, they are ultimately the things that your individual wires connect to. A mating pair is a pin and a socket. A complete connector pair is a 2 shells, one comprising pins and one comprising sockets - simple stuff.
Within the range and allowed for in the MilSpec is what's know as a mixed configuration/layout - this is simply where one shell contains different sizes of contacts (it doesn't mean from what I can find that a shell can also contain a mix of pins and sockets). This does offer the potential to carry both signal (lets say a Size 20 contact so low current conductor) along with power (say a Size 12 contact) which may be helpful - personally I've tried to avoid it prefering to keep 23 amps away from .25 amps where possible and avoidig the problems of heat generation that you can get in very large looms with high current travelling along them.
Ok that's a lot of information and may or may not ever be used! but if it save you the time I spent trying to work decipher the various cryptic sites then that's a good thing.
Crimping vs Soldering - so the introduction to this started with a rough guide on how easy it is to dump £450 on tools and you may be wondering why you can't just find a series that uses soldered connectors well firstly if there are any that offer densities up to 61 I've not found them yet but the real issue is that crimping is an order of magnitude easier to get consistently right. Those crimpers are expensive because they are rated to deliver exactly the same crimp 1000s of times on critical things like the loom connecting the doo dah that controls a rudder on a 747 (an application which has somewhat more stringent safety margins than your car for example).
One last thing, how to move high current around on connectors: your best bet is to look at an older standard like 5015 which in the ITT Canon range allows for a solder cup type contact. I used PEI Genesis to obtain 2 way 5015 connectors that are rated at 60amps per way (so max 120amps across a single connector divided across the 2 contacts). Going this way obviates the need for a pneumatic crimper but you do need a dirty great big soldering iron!
These people are who I've used for supply filcon based in Germany but very responsive and reasonable delivery charges.
Anyway this little post is to do with wiring and more specifically the undoubted temptation of those shiny motorsport connectors with the, OMG, milspec rating. At some point if you do any wiring you're going to be tempted to enter this murky world so I thought I'd save you a little time and effort by providing some information.
Firstly why milspec? well come on it sounds good and if it's good enough to be used by people with guns it's got to be good enough to use in my car. Well sort of, kind of - milspec simply means that at some point the Military (the mil bit) came up with a specification (the spec bit) that describes the characteristics of the connector. This specification is very detailed and whilst you can't assume that it inherently means the connector(s) will be of very high quality, quality is a side effect of meeting the specification.
My reasons for going down the milspec route were not so much about the vanity side but more about the sheer number of "profiles" available, the fact that, although expensive, standard tooling is used (yes even the tools have a milspec) and that solving problems like getting 40 conductors of different sizes through a buklhead becomes trivial (although expensive).
So here's a little guide focused on the Souriau 8STA connector series. Why Souriau? well they took the time to implement a range focused on Motorsport but is based on MilSpec, a range that looks at things like lightweight, high density layouts, small size and special considerations like in fuel tank connectors. The other reason is reputation, those immaculately prepared WRC cars, F1, MotoGp harnesses more often than not have 8STA series connectors on them. And finally - you can buy them, in 1 off quantities - no need to order 20 a time.
The entire series is documented in this 8STA but to try and give you a laymans guide here goes...
Firstly, before I start, be under no illusion this is not a cheap way to go. Other multi-way connector series are available although you'll end up in the murky world of bespoke tooling and once you drift outside of milspec the supplier you select "owns" you.
The cost of the connectors is only part of the cost you must figure in the intial tooling cost to give you and idea, assuming you can remain within the Size 20, 16 and 12 contact ranges (which for the vast majority you should be able to since that covers from 0 amps through to 23 then the good news is you only need 1 crimp tool, oh and the correct turret. Here's how it works;
The tooling is also designed to a given MilSpec; you do not need to buy Souriau tools to make Souriau connectors you just need to buy a tool which meets the MilSpec so in the case of the contact ranges I mentioned that means you need a crimp tool that meets/complies with M22520/1-01 and your best bet is to look at RS and specifically the DMC AF8. However that's only the tool you now need a turret - this is simply a devise that fits in the tool and ensures that the contacts are correctly positioned during the crimping operation in this case you need one which complies with M22520/1-04 and fits in your chosen tool, again save your time and jump straight to RS and get the M22520/1-04 turret for the AF8. At this point you've spent around £450.00 but you now have MilSpec tooling for your MilSpec connectors.
I said about staying within the 20, 16 and 12 contact ranges this is because doing so means this does become practical to do at home. If you stray into the smaller sizes you will need an additional crimp tool and locator, if you go above you will need a pneumatically operated crimper and that will make £450 look like an absolute bargain (I'll mention a solution to those of you who want to stay inside MilSpec but need to go higher than 23amps per contact a little later).
So what does staying in that range mean?
Size 20 contacts will take wire from 24AWG -> 20AWG or in English 0.21mm2 -> 0.60mm2
Size 16 contacts will take wire from 20AWG -> 16AWG or in English 0.60mm2 -> 1.34mm2
Size 12 contacts will take wire from 14AWG -> 12AWG or in English 1.91mm2 -> 1.34mm2
What this does is give you coverage up to 23amps per contact which means the majority of things in your car with the exception of starter motor, large radiator fans and electric power steering pumps.
Within the 8STA series there's a whole range of shell sizes available, the shell is the cylindrical container into which your pins and socket contacts fit but the most expansive range is the 08 -> 24 range. To give you a rough idea staying inside that range will give you options ranging from 3 ways (the number of contacts) to 61 ways in a single connector.
In the land of MilSpec connector technology it appears they like their own way of describing things so here's quick breakdown of how "it" works.
A connector comprises a shell, a shell size, a contact layout, a contact type and possibly some optional extras. They are not supplied in pairs it's down to you to make sure you order both halves!
The document I linked to contains a section, Contact Layouts, that shows you all the possible contact layouts grouped by shell size. The shell size ultimately determining the number of possible ways that can be accomodated. Fortunately in the 8STA range backshells are not something you need to worry about, just opt for a straight or right angled heat shrink boot and you'll be good to go.
Shells are either receptacles or plugs, now you need to know that a shell being a receptacle or a plug has nothing to do with whether the contacts are pins or sockets - it's up to you to choose (and my tip here is to be sensible and not have power presented on pins for obvious reasons).
In a classic scenario where you need to get a loom through a buklhead the receptacle would be the part attached to the buklhead and the plug would be the part attached to the loom. Receptacles in the 8STA range can be 1 of 3 types, Oval Flange, Jam Nut or In Line and here's what that actually means:
Oval Flange = bulkhead/panel mounting, Needs 2 bolts to secure in position. Jam Nut = bulkhead/panel mounting, Needs a D shaped cutout and the connector has a great big nut on the back of it. In Line = cable/loom mounting; used to connect, for example, a spur from a main loom to a headlight sub-loom
Pins and Sockets - ok this should be obvious but just in case; Pins and Sockets are both types of contacts, they are ultimately the things that your individual wires connect to. A mating pair is a pin and a socket. A complete connector pair is a 2 shells, one comprising pins and one comprising sockets - simple stuff.
Within the range and allowed for in the MilSpec is what's know as a mixed configuration/layout - this is simply where one shell contains different sizes of contacts (it doesn't mean from what I can find that a shell can also contain a mix of pins and sockets). This does offer the potential to carry both signal (lets say a Size 20 contact so low current conductor) along with power (say a Size 12 contact) which may be helpful - personally I've tried to avoid it prefering to keep 23 amps away from .25 amps where possible and avoidig the problems of heat generation that you can get in very large looms with high current travelling along them.
Ok that's a lot of information and may or may not ever be used! but if it save you the time I spent trying to work decipher the various cryptic sites then that's a good thing.
Crimping vs Soldering - so the introduction to this started with a rough guide on how easy it is to dump £450 on tools and you may be wondering why you can't just find a series that uses soldered connectors well firstly if there are any that offer densities up to 61 I've not found them yet but the real issue is that crimping is an order of magnitude easier to get consistently right. Those crimpers are expensive because they are rated to deliver exactly the same crimp 1000s of times on critical things like the loom connecting the doo dah that controls a rudder on a 747 (an application which has somewhat more stringent safety margins than your car for example).
One last thing, how to move high current around on connectors: your best bet is to look at an older standard like 5015 which in the ITT Canon range allows for a solder cup type contact. I used PEI Genesis to obtain 2 way 5015 connectors that are rated at 60amps per way (so max 120amps across a single connector divided across the 2 contacts). Going this way obviates the need for a pneumatic crimper but you do need a dirty great big soldering iron!
These people are who I've used for supply filcon based in Germany but very responsive and reasonable delivery charges.
