[Stibley]

Hi All, I'm in the process of getting some new wheels for my 57 Pontiac and need to know what size and thread type the lug nuts are?

Thanks

[694.1]

1/2-20
The left side used left hand threads and I use a dab of yellow paint on the lugs to remind me. My thinking is yellow has 2 Ls in it, Yellow=Left.
Helps prevent brain farts!

[Stibley]

Originally Posted by 694.1

1/2-20
The left side used left hand threads and I use a dab of yellow paint on the lugs to remind me. My thinking is yellow has 2 Ls in it, Yellow=Left.
Helps prevent brain farts!

Thanks greatly for the quick reply and good call on the left hand nuts. Is the thread type UNF? I'm looking to get some Torq thrust originals as I would like to give my car the look in the picture. As you have a 57 Starchief do you know what the max width and wheel back space I can go to with 15 inch rims. I'm currently thinking 15x7 with 215 70 15 tires would be a safe bet. Maybe 75 profile tires like the ones in the pic.

The Chrome smoothies are my current set

[Jack Gifford]

Originally Posted by 694.1

... The left side used left hand threads...

Are you sure? I no longer have any to look at, but I thought the LH threads were used on the passenger side, which would tend to tighten the lugs as the wheels rotate forward.

[johnta1]

From 1961 Service Manual: (can't get to 1957 manual)

Left side has left hand threads

Right side has right hand threads

I'm guessing they mean left side is as sitting in car?



BTW, I think if the direction is determining 'tightness' this would be correct? The thinking could be that the axle rotation against the wheel/road friction would be correct?

[Bill Hanlon]

... unless you drove more in reverse.

[Poncho60]

If the wheel studs on your 57 are original, I believe the drivers side studs should have an "L" stamped on the end of them. Just fyi.

[b-man]

Sillyness.

Maybe a spindle nut but left-hand thread lug nuts?

[694.1]

B man, that was a thing! Pontiac was not alone, not sure when they figured out it was unnecessary-

[b-man]

My dad once owned a later 1950s Chrysler New Yorker.

Needed to change a tire and broke off at least two lug studs before figuring out the problem.

Dumb design.

[Poncho60]

Chevys & Olds used this arrangement as well. Pontiac used this all the way thru 63 including on the 8 lug setups. The concept was not bad. Check out how the true knock off setups were designed. Wheel rotation tightened knock offs, LH & RH.

[b-man]

A wheel rotates directly around a spindle nut or a wheel knock off nut. That rotation can affect those fasteners.

A wheel does not rotate directly around a lug nut or lug bolt, so the wheel simply rotating will not tend to loosen the lug nuts or bolts. Vibration can loosen those fasteners but not the rotation of the wheel itself.

Two completely different things.

My older VWs have a left-hand threaded driver’s side spindle nut. My Pontiacs have right hand threaded spindles on both sides. Both use either cotter pins, lock plates or a clamp nut to secure the nuts. So both ways are fine for that. The rear drums on an old VW are secured with a large nut and cotter pin in the center to a splined axle, both sides are right-hand thread.

Left-hand threaded lug nuts were a stupid idea. Everything that came off of the drawing board was not necessarily good.

[peters23]

Original Pontiac lug nuts and studs should be 1/2-20 (UNF).
You should be able to use Dorman 611-016 studs if you want to change LH to RH.