Why so much aftermarket SAE?

[JesseT]

The JL is built with metric fasteners, but there seems to be a lot of aftermarket equipment that utilizes SAE fasteners. I even have rock rails and skid plates that use both metric *and* SAE fasteners on the same piece, so now I have to carry extra sockets, wrenches, and hex bits.

Why do companies do this? Is there any technical reason for this that I'm missing? If so, is there any technical reason that outweighs the inconvenience of having to carry extra tools?

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[Opus]

'Murica...?

 

[Zandcwhite]

Aside from a select few sizes (10mm) you can use metric sockets on sae bolts. I carry metric impact sockets and a standard wrench roll with a few pieces added. A 1/2" bolt for instance would be a 3/4" sae socket. 18mm is too small, 19mm works like a charm even when torqued to spec. You don't need 2 compete sets by any means.

 

[Terrymo]

 

[NPC 20883467]

Why do companies do this?

It comes down to where the parts were engineered and/or sourced from. It's important to remember that said parts come from one of two places- those countries who have put a man on the Moon, and those who use the metric system.

 

[Vinman]

The only size I would interchange is the 3/4”/19mm. Interchanging the other sizes is just inviting rounded off bolt/nuts.

 

[JesseT]

Aside from a select few sizes (10mm) you can use metric sockets on sae bolts. I carry metric impact sockets and a standard wrench roll with a few pieces added. A 1/2" bolt for instance would be a 3/4" sae socket. 18mm is too small, 19mm works like a charm even when torqued to spec. You don't need 2 compete sets by any means.

I don't even carry one complete set. I just carry the handful of sizes I'll actually need for anything I'm comfortable doing in the field. Even with the (imperfect) substitutions I'll still end up needing to carry more stuff than I would otherwise need to (and change sockets more often while working). I get it's not a huge problem or anything, but it is an entirely unnecessary disadvantage.

It comes down to where the parts were engineered and/or sourced from. It's important to remember that said parts come from one of two places- those countries who have put a man on the Moon, and those who use the metric system.

Oh, I get it. So it depends on whether it was engineered in the country that crashed the $300,000,000 Mars Climate Orbiter by using US Customary units when everyone else on the project was using metric?

Seriously though, it's not that I really feel that strongly about one standard vs the other, but I feel very strongly about not mixing standards.

For example, the MetalCloak UnderCloak skid system I have utilizes - among other fastener types - flat head socket cap screws. They could have just used one type, but instead they use metric (M12-1.5 x 45, 8 mm Allen) for points that attach to factory mounting points and SAE (0.5-13 x 1.75, 5/16 allen) for their own mounting points. Doesn't that seem a little bonkers? They're practically the same size. Since they're having to use some metric fasteners anyway why not just make their mounting points metric too? It would make install easier, make servicing easier, and it also seems like it would make their own inventory management easier.

 

[Opus]

This seems oddly fitting...

 

[Bill_BCNtoNY]

It comes down to where the parts were engineered and/or sourced from. It's important to remember that said parts come from one of two places- those countries who have put a man on the Moon, and those who use the metric system.

I still think the metric system makes more sense… but you can’t argue with results!

 

[GtX]

The manufacturers are likely using SAE by default and substituting metric where they have to in order to use hardware on the vehicle.

 

[JesseT]

The manufacturers are likely using SAE by default and substituting metric where they have to in order to use hardware on the vehicle.

Yes, but why? Look at the vehicles most of those manufacturers make accessories for: JL, JK, even the TJ (except for the T-case and transmission for some mysterious reason), Tacoma, 4runner, Bronco, Ram, F150, etc. all use metric fasteners. If the vehicle manufacturers are using metric fasteners as the default wouldn't it make more sense for the aftermarket manufacturers to use metric as the default also?

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