How many threads should be showing on a lugnut?

^ I was gonna say the same thing, ago. Most newer cars only take 72-75 ft lbs.

 

You need the same depth of minimum thread engagement as the thread diameter. 7/16 studs need 7/16 engagement, 1/2 studs 1/2 etc to be NHRA legal.

 

Really not much differant than a mag wheel with no hub centric that people have run for years as long as the adapter is a good quality piece. A good torque wrench is your best friend to get them tightened evenly and routinely checked .

 

You should really get a billet adapter instead of those old cast ones

 

You mean the kind with shanked lugs ?

 

Yes, but similar in the way the studs center and support the wheel without a center register. I just pickep up a set of the plastic center adapters from jegs for a set ot steel slots I have for this very reason.

 

The rule of thumb has always been what Hoop98 posted. I have used it as a standard for 45 + years ,and it has never failed.

 

There are thousands of mag wheels and custom wheels that don't fit snug on a center hub, even without an adapter. What's the difference with a wheel that doesn't fit the center hub without an adapter, and one that does?
There are also thousands of unilug wheels that use washers inset in recess, and people said those were scary for years, but they've proven over time to work fine.
As long as the lugnuts are properly torq'd and checked occasionally, I doubt it will ever become an issue. I'm not a fan of cast adapters, and I'd rather see billet or none, but they do work if properly installed and torq'd.

 

I'm with Mike Miller, Machineryys Handbook and major bolt manufacturers say 3 threads visible for maximum strength. The last 2 threads are of an incomplete profile.

 

As far as the center hole not touching the hub, my 56 MGA came from the factory with an 1/8" clearance all around. This style adapter has been on the market for ever, how many failures have they caused? (no other contributing circumstances) Run them if you need to!

 

I hear you, perfectly.
but you or anybody else can have my share of them

 

Aircraft Industry says 3 threads that flies for me

 

Last few threads are tapered and don't bite. I was in a car once that was radically loud and had traction bars that were close to the ground. The driver yelled "Hey there goes some guy's wheel!" not realizing that it was his own bouncing past us. We were sliding along on the left traction bar as we crossed the Cabin John bridge.

 

Ok loking at my machinists handbook here, and recalling my structural design courses and believe it or not they both say the same thing 1.5 threads past the end of the bol when properly torqued.

Now here is something to consider, you have created several shear points by using a spacer. I would not be too concerned about it if it were my car but good design practice says this is not your optimum situation.

 

I have run billet spacers (just like adapters, but same pattern) of up to 3", over 200, with no issues.

I would not run a cast adapter, on a wheelbarrow.

 

In the aviation world one full thread is good. But that is with self locking fasteners. I think 3 full threads and the lug nuts torqued to spec would be fine.
Mark

 

I'm obsessive about hub centering, not for strength but to minimize runout/vibration.

I agree regarding cast adapters.

 

Lose the adapters before you lose a wheel.

 

Not just more shear points but also further out on the studs.

 

Whatever combination of spacer or lug centric nuts you use, be sure to check the torque often on that new paint, it WILL compress

 

Its a good idea to check the torque after mounting new wheels for the same reason, seating in.


Ago

 

^^^These three comments are gospel.

 

past the end of the nut...

Silly and excessive.. but it's their sandbox, want to play? Follow their rules.