Wheel lug nut issue

[Fotog]

My car ('73 TC) has 70's era Appliance wheels.  I broke one of the nuts, as the clearance between the extended shaft of the nut and the wheel is near zero, and I wasn't aware of the potential problem.  It was binding, and I just broke off the shaft.  Jeez!

After some research and contacts with a number of people selling 'wheel accessories' (nuts and the like), including some that specialize in vintage wheels, it seems that a similar nut is not obtainable.

I've learned that wheel nuts and studs are surprisingly non-standard, with many sizes being used. 

I'm thinking that I'll make the holes in the wheel a 60 degree taper to accept more common nuts.  Not many nuts are made in the 3/8-24 size any longer that are the standard for the Europa hubs.  I did get some nuts made for use on ATVs that are that thread specification though.

There are nuts of this "mag wheel" type (not tapered, with an extended shaft) in that 3/8-24 size intended for Minilites and similar for Minis, Spitfires and MGs.  But they all have larger diameter shafts rather than the .520 that my wheels have.  I'm more inclined to make my existing holes tapered rather than make them larger.

I might want to go to a more common 12mm x 1.5 thread stud in the future, and tapering the holes shouldn't cause any problem with that I believe.

As I assess things, I think that my studs are actually too short for these wheels.  Just not enough thread engagement, so that's another thing that leads me to think that a new, more modern, thread size would make sense if I should get new studs anyway.  The wheel/hub mating surface is .600 thick, much thicker than that of the original steel wheels, and whoever put these on the car apparently didn't give any thought about that.  But going to a tapered nut and getting rid of the washer that is part of the old nut will give more thread engagement on the existing studs.

So is there any good reason why I shouldn't modify the wheels to take a tapered nut?  Your thoughts would be appreciated!  I'm ready to do it, but can't 'pull the trigger' until I'm without any serious doubt.

I may get new wheels down the road, but it's not a priority.  There's lots to check out and improve upon, without taking on that expense.

Some pictures follow.  One shows the broken lug nut next to an unbroken one, and another shows the proposed replacement alongside the 60 degree countersink bit i would use to make the taper.

Thanks,
Vince

[BDA]

Converting to a tapered nut design is a good idea. An even better idea is to press steel interfaces into the wheels for the cone of the nuts to press against. But failing that, keeping a bit of anti-seize on the counter sink should fine. I would be a little concerned with a small stud in a large hole with a tapered nut because all the support for the wheel goes through the area of the taper, but I'm probably way over cautious about that.

[Clifton]

I went with a 12x1.5 studs and I had the hub offset machined for 4x100.  As far as your studs being too short, the general rule is you should engage 1.5 times the width of the bolt. If you have other priories, I would do what ever fix is the easiest and less time consuming right now.

[cwtech]

There are numerous reports of that type of lugnut failing if the stud is not long enough to engage the threads inside the hex portion (larger diameter) of the lugnut.

The shank of that style lugnut is designed to center the wheel on the studs, but does not retain the wheel on the hub.  .....The larger diameter of the lugnut  is the portion that "holds" the wheel against the hub.

In your case, since the studs are not long enough, you are relying on the tensile strength of the material, at its thinnest point.  ...Not good, as you have learned.

[Fotog]

Thanks, fellows.  Clifton:  4 x 100mm is your bolt circle?  That's one thing I didn't measure.  I'm unclear how you made a change to that.  I agree, right now I want to make the simplest safe fix.  I'm willing to make a modification to the wheel, but I don't want it to be something I regret in the future.

BDA:  it seems that the tapered steel inserts have an OD that's large enough that they would break into the hub opening in the center of the wheel.  There's only ~ 1/16 in. of metal now between the recess for the washers and the center hole with the present setup (see the picture of the wheel).  Discussing it with the owner of Prestige Wheel Accessories (seems knowledgeable), he didn't have any issue with making the tapered holes without the inserts.

CWtech:  I hear you! That's what I concluded.  P.O. setup.

Any other cautions?

[cwtech]

https://www.minimania.com/part/21A2064L/Classic-Mini-Wheel-Stud-3-8-24-Unf-X-2-In50mm

I don't know what length your current wheel studs are, but there are several lengths 3/8"-24 studs available at the link.

You would not have to modify your wheels, but you will have to verify the dimensions of the serrated portion of the stud.

The lug nut which you need could be made by turning down the shank of a lugnut  to your needed .520" diameter.

[Rosco5000]

As CW has posted there are mini studs that will work but I have also see that style of lug nut a lot in the mini scene so you may save yourself some work if you can find the right wheel lug nut from a mini supplier.

https://www.minimania.com/ss/WHEELS_TIRES,WHEELS,WH_LUG_NUTS

Ross

[BobW]

Given the Europa's low production numbers, any aftermarket wheel fitted was likely made for the Spitfire/GT6. I have 5-1/2 x 13 JPC wheels. I bought them new in 1974 and remember that as being their application. The bolt holes are slightly countersunk and the nuts are threaded almost to the end. The shank size is 0.622". If you could find some of these they could be turned down, as cwtech suggests.

I torque my wheel nuts to 25 lb-ft. with never-sieze and still have all of them.

[Fotog]

As I had already purchased a 60 degree countersink bit and thought I could do it successfully, I ultimately decided to make the holes in the wheels tapered. 

That led to an absolute requirement to install new, longer studs in the hubs.  The originals seemed shorter than ideal for the old nuts; they would be really too short for the tapered nuts without an extended shank.

So I decided to move up to larger, longer, 12mm x 1.5 studs.  After some research I found that studs used on a Land Rover Freelander, P/N CLP9037L are the same diameter knurl as the original 3/8-24 studs, and the head is similar.

They worked well.  I'm pleased by the more robust setup.  The old studs were a bit on the wimpy side and I have no concerns now.  I'll have to do the rest of the wheels.  I thought I could press them in with a large c-clamp and a socket over the shaft of the stud, but not quite.  I used a hammer in the end with no issues.

[EuropaTC]

When I fitted mine I used the wheel nut and a spacer (a large nut from the "junk" box) to draw the studs into place. Very easy with the leverage from your wrench and little chance of driving one at an angle.

From the last image it looks like your wheel nuts are open ended so you shouldn't hit the same snag I did, namely that the studs as supplied were fractionally too long for the setup I had then with Cosmic alloys.  The wheel studs were a closed dome end and bottomed out before the wheel was secure, very close but still a hassle. Worth checking should you buy some shiny new wheel nuts !

Brian

[Fotog]

That all sounds good, Brian.  I went for those nuts both because they were inexpensive and it would assure that I wouldn't have the problem you had.  I think it was $16 for 20 of them.  When I get to the point where cosmetics start to get some priority, I may go for some closed-end nuts.

Funny how satisfied some danged studs can make me feel.

For reference, the diameter of the knurled part of the studs is .520 in. , both replacements and original.
Vince

[surfguitar58]

Funny how satisfied some danged studs can make me feel.

That's what the filly said.
(There's a horse joke in there somewhere...) 

t

[Bainford]

Funny how satisfied some danged studs can make me feel.

That's what the filly said.
(There's a horse joke in there somewhere...) 

t