In motorsport, people often call connectors “MIL Spec,” but what does that actually mean?
A customer recently asked me to specify a MIL-SPEC connector. I suggested both Deutsch Autosport or Souriau 8STA connector ranges, to which they responded, “No, I mean the green Military connectors.”
Ah!…let me tell you a story.
Military-SPEC connectors are a bit of a byword in motorsport, meaning a certain style of circular connector, but the specifics of the term has become blurred over time. When we talk about MIL-SPEC connectors in motorsport, we are often mean connectors that are based around the Military specification MIL-DTL-38999.
This is a Military specification that has been in existence for several decades; it is still current and receives contemporary updates. The specification is a set of design guidelines for individual manufacturers to design their own range of connector series but ensuring some level of interconnection and interoperability from different manufacturers. However, it is not an absolute design guide so manufacturers can implement the specification to varying degrees depending on their aims and destination market.
The 38999 specification itself has four series of connectors within it, two of which are based on Imperial units, two are on metric units. For each of those, one covers scoop-proof designs and the other is for a non-scoop-proof design.
As a side note, “Scoop proof” simply means that the connector housing recesses the male pins and keys the body; this ensures correct pin and socket alignment before contact when mating connector halves. This reduces the risk of bent or miss-aligned pins, which is essential with today’s densely packed and relatively thin pins.
Choosing a connector design based on the 38999 specification does imply a level of cross compatibility with similarly designed connectors from other manufacturers but in reality, it is always advisable to mate connector halves from the same supplier. For examples, some of the Deutsch AS range will safely mate with the corresponding Souriau 8STA range, but it is not something advised by either manufacturer.
For 80s and 90s motorsport common options were chunkier in style and typically olive drab in colour; many of these were based on the MIL-C5015 series. ITT Cannon MIL-C5015 connectors of this era offered the standard / CT range with a threaded coupling and the CA / CB variants with a bayonet. The part number system was complex, many specialist variations existed, and back-shell options was huge. But it did prove an excellent development period for the contacts and we are still benefiting from that very demanding real-world testing today.
However, as the motorsport market grew in the 90’s, the unique demands of motorsport created a marketplace for an industry-specific connector family. These non-military certified connector series were based on the MIL-C38999 Series 1.5 connector, also known as the EuroFighter connector.
These motorsport-focused connectors didn’t need the same certification but required robustness and reliability at minimum weight. The great advantage for the motorsport industry was that manufacturers could leverage the lessons learnt from their military connectors and contacts to develop a lower-cost but still extremely capable connector system.
Offering reduced weight and size over the older Military designs, these connectors became the dominant solution in high-end Motorsport for the following decades. The two most common today are Deutsch’s Autosport range and Souriau’s 8STA range.
Classic Style Never Dies.
If you require a MIL-DTL-38999 based connector but in a classic military style; either for specification, certification or just an aesthetic, then the 8D series from Eaton is an excellent option. The 8D series is available in aluminium, stainless steel and composite body materials. It uses the same insert arrangements and contacts as the 8STA range so they share tooling. They are slightly heavier with a marginally larger shell, fix with a square style flange and have the option of a screw coupling as opposed to the standard bayonet.
FC Lane is the UK go-to supplier for the Eaton 8D series connectors.