Nuts and bolts. SAE, Metric, or both
I been wrenching on vehicles all my life. It use to be only SAE, then it became a mix of SAE and Metric. I thought they we're going to phase out SAE and go all metric at some point, but it seems like ...
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I was running a durability lab in the early 80's, What was real good was GM (a client at the time was changing from SAE to Metric. So, things that screwed into production major castings would still be SAE until the casting was revised. Everything else was Metric. Sounds easy - Right?
But there were two problems:
FEAD (Front Engine Accessory Drive) stuff often connected to other FEAD stuff and a block or head. Where it connected to a major casting it was "probably" SAE. Where it tied to another bracket, it was Metric. Unless the head casting was a new design (which was happening a lot because they were trying to reduce weight), then it might be metric.
Then there was the supplier issue. When they called for an 8mm fastener and did not specify, it was a toss-up if the supplied fastener was DIN or JIS and the pitches were different.
That has fortunately been solved by an SAE edict that describes all the fasteners as laid out ISO.
As it is for me right now, our coach is only SAE (being OLD), but I carry a set of tools for ISO too. That is just so I can help someone that may need it.
Matt
But there were two problems:
FEAD (Front Engine Accessory Drive) stuff often connected to other FEAD stuff and a block or head. Where it connected to a major casting it was "probably" SAE. Where it tied to another bracket, it was Metric. Unless the head casting was a new design (which was happening a lot because they were trying to reduce weight), then it might be metric.
Then there was the supplier issue. When they called for an 8mm fastener and did not specify, it was a toss-up if the supplied fastener was DIN or JIS and the pitches were different.
That has fortunately been solved by an SAE edict that describes all the fasteners as laid out ISO.
As it is for me right now, our coach is only SAE (being OLD), but I carry a set of tools for ISO too. That is just so I can help someone that may need it.
Matt
