3/8 unf wheel nut minimum internal diameter

[GrahamFountain]

Does anybody have any idea what the 3/8 unf wheel nut minimum internal diameter might be?

I've a couple of new ones that measure close either side of 8.3mm id, and the one that the garage overdid measures 9.3mm. So that
gives me the limits.

But where less than 9.3 is good enough for road use, and where wants replacing?

I've also got 4 well used spares that look good in the thread and measure up to about 8.5mm.

I plan on looking at what the ones that still take 48 lb.ft (65 N.m) of torque on the car are.

But is that they take torque the only measure that matters or, if I find some are a bit big, like 9mm or more, should I worry, and how much?

Graham

[GrahamFountain]

Went and checked all the nuts on the car. Other than the one that wouldn't take 48 lb.ft, the worst was 8.6 mm id, and a couple pf 8.5s. I've rotated them into the spares box for now, though the ones I replaced them with don't look as good. The rest were still close to the 8.3 mm of the unused ones. So I reckon they're still good for a while.

I will have a go at helicoiling the 9.5 mm one, and depending how that goes, maybe try the one that's 8.6.

Anybody got any 3/8ths nuts with the threads stripped?

Graham