Proper Lug Nut Thread Engagement (1 Viewer)

[Backwoods Rambler]

Hi all, I've searched for over an hour now and cannot find an answer. I know, me and everyone else, right?

Anyway...

I have a '93 cruiser that came with some ridiculous 20" rims. It also came with some factory tapered acorn style (not shank lug) 80 series rims.

The lug nuts being used on the 20" rims, when used on the factory rims, only allowed the stud to engagedabout 2/3 or 3/4 of the threads in the lug nuts. I, nor the tire store manager were comfortable with this since the aftermarket rims had the studs protruding just above the head of the lug nut.

So I went and got a factory acorn style lug nut from a dealer (holy $$hit!) and the taper of the lug nut seat appears to be identical. This leads me to believe that the factory lug nuts thread engagement will also be insufficient.

How much thread engagement should there be?

Did Toyota ever use different different wheel stud lengths?

How long are the studs as measured from the wheel mount surface?

I wish I had images to share, but I didn't think to take any at the tire store.

Thanks in advance

- JD

 

[Golgo13]

Ugh, 20's on an 80?! What a travesty!

I can't answer everything now, but I can try to get some measurements from my truck.
I have a '92 with aluminum rims and the original hub studs/nuts.
Also, I guarantee, if you have the original parts, the thread engagement is sufficient.
I believe all hub studs are the same across the board (except the M14 size is different, of course).
Should be M12-1.5x40mm. As long as you have the correct hub nut for your wheel, there shouldn't be a problem.

I'll check what I can measure in the garage tonight.

 

[Backwoods Rambler]

I appreciate that.

I wonder if the early, pre '93, 80's had the same stud length since they came with different tire/wheel offerings?

 

[Backwoods Rambler]

I mis-spoke. The studs don't protrude out of the lugs with the 20's, they are just shy of being flush. I can't figure out how to upload an image from my phone so I still have nothing to show...

 

[Backwoods Rambler]

Here we go...

 

[Golgo13]

Rambler, those are definitely not stock hub nuts.
Toyota OE does not mark their parts with "METRIC."
Get some OE nuts from ebay, a junkyard or your favorite MUD dealer.
I know they are expensive, but its worth it to have the best quality parts.
Any Toyota with steel wheels will have the same nut.
Of course, don't forget to torque to spec.

That being said, you definitely need new wheels if you plan on wheeling or carrying any load at all.
Those multi-pattern wheels with extra hub nut holes for other patterns are not strong enough to support a real load.
See what you can find with Toyota OE parts.

Chances are, those are the original studs and that is the stock length.
The actual stud protrusion with stock wheels and studs is about 1/2" (around 10-11mm) not including the conical portion.
I don't know the exact numbers off memory anymore, but once you get some OE wheels, you'll be fine.

Good luck!

 

[Backwoods Rambler]

Just to be clear, I have OEM wheels and one OEM lug nut. I'm just waiting to get specs on the OEM stud protrusion length from the wheel mount surface before ordering the remaining 23.

And yes, I'm well aware that these wheels HAVE got to go. They're no good for anything really. I would NEVER wheel or haul a load with these. LOL.

This whole situation came about because I purchased 5 new 285 Coopers and tried to mount them today.

 

[Qball]

Also never seen silver cone washer and nut for the hub flange, is there even a washer?


...Misspelled via IH8MUD app

 

[Backwoods Rambler]

Qball: I can't account for the color... I just used the nuts, cones and washers that I took off when I did my knuckle rebuild a couple of weeks ago. I'm sure I didn't miss a washer since I had zero extra parts unaccounted for and zip locked all parts immediately upon removal, but I'll double-check today since I can't spot it in the pic either.

 

[Backwoods Rambler]

I took a rough measurement and my studs appear to protrude 24-26mm from the wheel mount surface

 

[Backwoods Rambler]

Also never seen silver cone washer and nut for the hub flange, is there even a washer?


...Misspelled via IH8MUD app

It definitely has a washer

 

[Golgo13]

Rambler, your dimensions show that your studs are the correct length.

I have updates with actual dimensions now...

The OE Stud is P/N 90942-02052 it is M12x1.5 - 44mm long
Pressed into a rear axle shaft or hub it should protrude 33mm.
The brake drum is ~6mm thick, so it will protrude about 27mm from the brake drum
The OE wheel, P/N 42611-60090(16x8 with 0mm inset from Topy Industries) has a nut-seat thickness of 15mm from the mounting face of the wheel to the top of the steel insert. Note the steel insert is there to protect the aluminum from galling.
The stud protrudes ~12mm from the face of the steel insert.

Nut, Hub for alloy wheel is 90942-01081. The threaded length is 19mm and there is ~5mm overlap due to the cone.
Finally, the stud actually sits inside the threads about 2mm.
Of course you can't see this because the hub nut has a dome welded to the outside to prevent the stud from corroding.

In reality, it is only the first few threads which do the majority of the work, so don't be too worried about the threads protruding to the other side.
I know it is in every guide-book as a rule-of-thumb that a good design has threads protruding, but if the nut is longer than it needs to be, there is no harm done by not following that rule-of-thumb.

In any bolted joint in any Toyota, someone took the time to calculate the proper torque AND test it to make sure it was correct.

If your OE wheels are '95 or newer, you need flat-seat nut with attached washer. P/N 90084-94002

 

[Backwoods Rambler]

Amazing information! Thank you for that leg work! I've been on the phone all morning and no one could provide that data for me. Hopefully this thread helps others down the road as well!

 

[Golgo13]

Well, this sort of thing is actually my job, so it isn't a big deal.

Glad I could help!

 

[Howard705]

Not that I wouldn't want it through, but have read. (maybe on here) that 2/3 thread engagement is enough.

 

[livinoffroad]

Rambler, your dimensions show that your studs are the correct length.

I have updates with actual dimensions now...

The OE Stud is P/N 90942-02052 it is M12x1.5 - 44mm long
Pressed into a rear axle shaft or hub it should protrude 33mm.
The brake drum is ~6mm thick, so it will protrude about 27mm from the brake drum
The OE wheel, P/N 42611-60090(16x8 with 0mm inset from Topy Industries) has a nut-seat thickness of 15mm from the mounting face of the wheel to the top of the steel insert. Note the steel insert is there to protect the aluminum from galling.
The stud protrudes ~12mm from the face of the steel insert.

Nut, Hub for alloy wheel is 90942-01081. The threaded length is 19mm and there is ~5mm overlap due to the cone.
Finally, the stud actually sits inside the threads about 2mm.
Of course you can't see this because the hub nut has a dome welded to the outside to prevent the stud from corroding.

In reality, it is only the first few threads which do the majority of the work, so don't be too worried about the threads protruding to the other side.
I know it is in every guide-book as a rule-of-thumb that a good design has threads protruding, but if the nut is longer than it needs to be, there is no harm done by not following that rule-of-thumb.

In any bolted joint in any Toyota, someone took the time to calculate the proper torque AND test it to make sure it was correct.

If your OE wheels are '95 or newer, you need flat-seat nut with attached washer. P/N 90084-94002

^^^^This.
In general, as a rule of thumb, if you can catch as much (length of threads), as any given stud or bolt is, in diameter, That should, IN THEORY, be enough, in most all given situations, to achieve proper torque. We are however, talking about wheel studs here, and lug nuts are usually a little deeper than that. Specifically, there is a relief past the end of the threads of the lug nuts, under the dome, to accommodate extra length. HTH

 

[Golgo13]

Livin',

You're right, in all reality, it is only the first few threads that do most of the work. I always thought it was amazing how those tiny little threads can actually hold so much tension in a bolt. When you add up the surface area in contact it is basically the same area as the cross-section of the bolt. That is the kind of stuff I loved to learn in school and then I actually get to apply it in real life.

 

[Backwoods Rambler]

Well, I wasn't going to fork over the $ for 24 factory lug nuts, even at the wholesale price, but I found some that had the right specs from www.titanwheelaccessories.com for MUCH cheaper, that worked great.

Thanks for all of the specs and advice.