body mount bolt pic

[jiho]

Ah, but this car had 12.8 in all positions (2,3,4,6,7) on both sides. And remember, these are M10x1.50, whereas the control arms are M12x1.75. So this was a totally different run of bolts that had to be explicitly supplied for body mount use, in particular lengths.

 

[jiho]

You're probably right about "not as critical" though.

Anyway, the reason they wanted to use 12.8 instead of 10.9 was the desire to use flange head bolts -- because they didn't trust installers to remember washers -- and a problem one supplier had cold-forming flange head 10.9 circa 1977. When they recalled the control arm bolts in early 1981, they replaced those with un-flanged 10.9 and washers. All of this according to the SAE paper.