No, they are carrying twice the load or more as the reaction point is now further out than the length of the studs, and as the spacer is not welded to the wheel or drum, the assembly is considered flexible.

If the nuts had a taper lock into the wheel then they wouldn't be able to flex as much and the design would be stronger, similarly if the spacer and wheel were spigoted together.

I'm not saying they're unsafe, I'm not saying they will break under most likely any load condition, I'm not saying its a bad design.
However if I wanted to use them on a car, I'd defininitely be fitting new wheel studs, grinding the spacer to make sure its dead square and parallel, and never use them on a track.

Hmmm... what do you mean by "the reaction point"? I was thinking that given the holes in the wheel and spacer are the same size and are only just big enough to push the wheel nut through, the spacer and wheel are locked together in shear.

The shear force is what might cause the studs to fail with spacers, is it not? Because if you think they're going to fail in tension, then it makes no difference if there's a spacer or not. The offset of the wheel is the critical thing in that situation. The fact that the offset is increased with a spacer is not really the issue there.

Note: I'm trying to get my head round the situation. I'm no expert and am happy to be wrong. I'm just struggling to understand (and therefore be convinced) that this is a bad setup.

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- Simon -

In simplest form: the wheel stud is weakest at the point where the thread runs out and becomes shank. The closer the wheel is to this point the stronger the setup.

(so if you have standard drums and real fat wheels, the studs won't fail, the bearings are more likely to cop the load and flog out)

The further the wheel is from this point (like with spacers or an incorrect wheel stud) the more leverage it has to work and possibly break the stud. General road use probably won't do this, it'll be if the stud is old, rusted, damaged, etc.

The reaction point in this case is the face of the wheel that fits to the spacer or hub, and its where the loading comes from. If the spacer was welded to the wheel then this point is moved inwards.

Does any of that make sense?

The bending moment will be increased because the point where the load is applied is moved outwards. The loading is cyclic, so fatigue is an issue. By increasing the bending moment, you will lower the number of cycles (i.e. wheel revolutions) before the stud fails.

The inherent flexibility of the design with no tapers or other means to lock the mating faces together is probably the worst part. If it was all locked in place and only tension was placed on the studs it would not be as much of an issue.

This is why race wheels get dowelled.
cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

Hi,

i believe your wheels are not the same as the GKN's used in the UK 1275GT Trophy, yours were made/used in the Metros, hence the wrong offset when used in the minis.

Jan ( Asphalt ) should be able to confirm that.

Cheers
Luis

The long wheel nuts work like dowels to lock two of the mating faces of the wheel and spacer together. As i've said before, the nuts and the holes in both the wheels and spacers are a tight fit (eg: if you drop a nut in the hole it will slowly slide into it... it is not lose or free to move sideways). So given that the wheel nuts are put fully into the holes, the wheel and the spacer are unable to move independently of each other.

The nuts are long enough that they thread almost entirely onto each stud. When the nuts are done up, there is probably less than 5mm of gap between the face of the hub and the end of the nut. So as i see it, almost all the forces exerted onto the studs will be shear forces. The bending forces will be minimal. and no different to any other wheel of the same offset. Especially given that with my superlights the studs span about 15mm from the face of the hub to the end of the nuts.

Note: The offset of these wheels with the spacers fitted is identical to my superlights without spacers. This is what i'm comparing things to. I'm not comparing these spaced wheels to a set of skinny original wheels.

_________________
- Simon -

The point you are missing is that bolts/studs/nuts are not designed to take any bending or shear load, they are only designed for tension. The tolerances for a dowel fit are such that the wheel will not move relative to the hub flange (or any spacer in between if this too is dowelled).

You cannot possibly get the tight fit of a dowel with those nuts because you need to rotate the nut inside the hole. If it was dowel tight, then they won't spin!

If you try to tighten them down so much that there is enough friction to stop the faces moving relative to each other, then you are overloading the bolts/studs in tension.

Most old style wheels and their nut/stud combination get away with it because of the minimal (relative) loads applied. The reason there are four or five studs is for redundancy when one fails. I have personal experience of Mini studs failing in a very lightly loaded application - road 850 with 3.5" wheels, 145 tyres, standard narrow drums. You are talking about adding an extra 25mm of width to an already wider drum/disc setup.

Biggest mistake made in design of things like this is using studs/bolts/nuts as a location device. They are meant to clamp things together and only that. Dowels are made for locating things - no one ever makes the mistake of trying to clamp something with a dowel.

Look, you said yourself that you don't know how to recognise a standard or spacered drum, and I applaud you for wanting to learn. For reference on this kind of thing, read Engineering to Win by Carrol Smith.

Like M1100 said if the spacer is permanently fixed to the wheel, there is no issue. Likewise, dowels will give the location without putting extra load on the studs that they are not designed for. If you are going to restore the wheels it might be a good idea for your own peace of mind to have the spacers dowelled to the wheel (put the hole in the wheel and the dowel in the spacer so the wheels can be used without the spacer).


cheers
michael

_________________
the world is a book, and those who do not travel read only a page
66 Mini Minor sponsored by http://www.lifeonthehedge.com.au/ The Dog Harness Specialists
It was a pleasure ausmini. I'll miss all you misfits and reprobates

So all the aftermarket wheels that are wider than standard wheels are unsafe and the studs are at risk of failure? My Superlights are located only by the studs, unlike the wheels on my Toyota that are located by and bear on a 65mm dia. bit protruding from the centre of the hub.

There doesn't seem to be any provision for locating wheels on the face of the hub by any means other than by the studs.

_________________
- Simon -

Originally the wheels were located by the taper in the wheel nuts. Because the distance from the seated nut to the drive flange (in original form) is relatively short its okay not to have a locating spigot. It's a feature that should have been adopted into later minis (mg metros had them) that had bigger wheels, but obviously wasn't since the hub nuts are in the way.

Right... and the distance from my aftermarket nuts to the face of the hub is less than 5mm.

And the only way the wheel and the hub surfaces are going to slide (to induce shear or bending in the studs) is if the nuts are loose. If they don't slide then i can't see how cyclic loading and thus fatigue can occur.

Evidence that the wheel and hub don't regularly move is that the surfaces are dirty instead of smooth and shiny looking like you would find on any other object that reguarly slides against another. A big hit, or forces experienced in an accident is a different story. But that's not the cyclic loading from wheel revolutions that was mentioned previously

_________________
- Simon -

The wheel nut is doweled only really for location on the hub.
Much like a HCR (Hub centric rings) locate your wheel on a modern car; these wheels do it with the wheel nut.

Over this small amount of distance, I doubt you'd get enough leverage to run yourself into any troubles.
Just make sure your studs are nice and fresh and you should be ok.

There's much much MUCH more engineering behind it than what your ideas allow, Molina.

I was talking about it with an engineer at work and we both decided that far to much theory is being applied to this and that in practice it simply is not a problem.

A friend's father is a VASS signatory... I will take my wheels and spacers over to him and show him the setup. I will report back with his informed opinion.

http://www.vicroads.vic.gov.au/NR/rdonl ... st2011.pdf

_________________
- Simon -

Well said!

Wide [25mm] spacers should [in your example] be 8 hole...4 X 101.6 bolted to the Hub/original studs... nuts flush with the face of the spacer & a separate "offset" 4 X 101.6 PCD with a 2nd set of studs to suit the rims with appropriate nuts.

Confused yet??

Your pictured setup works on a Track Car because [apart from the Road Legal aspect]wheel nuts are "usually" checked more often & majority of Racers torque the nuts down properly.

My 2.5 cents

_________________
1974 1150cc Leyland Mini S racer,
1975 No motor Leyland Mini "ute"
1991 IPRA Honda Integra (in the build)
1995 Land Rover Discovery 300Tdi

CAMS Scrutineer

Lets have a quick look at that statement.

Givens: 4 studs 3/8x24 thread torqued to 43 ft.lb.
Vehicle mass: 700kg total, 60% front bias = 210 kg = 2060 N vertical load at front wheel.
Assumptions: Threads and mounting faces lubricated but not fully as would be done for a head stud. Assume coef of friction to be 0.25 for thread and head.
Wheel to hub mounting face friction 0.35. Not very clean and some contaminating oil/grease.
Simplifications: Ignore all bending moment transferred through flange face as bending will increase pressure on some portions of face and decrease it in other so average face pressure will be the same.

Calcs: Work out tension in wheel studs. Can work it from first principles but I went to www.norbar.com calculators and got a load of around 20kN.
4 studs gives a clamping load between wheel and flange of 80kN.
What load is required to slide the faces under this clamping load?
F=mu.N therefore F=0.35x80kN=28000N or a wheel carrying 2850kg.
2850/210 = 13.5g.

So the load applied to the wheel to make it slide on the hub under the tension of the wheel studs is 2850kg or 13.5g. This is a very high load that would have substantial influence on the suspension movements and tyre behaviour. It would be unusual to encounter this level of load on a decent road. It is conceivable that hitting a kerb or big pot-hole could generate this type of load when at speed but the duration of the load would be very short and the corresponding movement of the wheel relative to the hub would be small. The likelihood that sufficient cycles of this type of load and displacement would cause bending fatigue in the wheel studs is very remote. the faces would fret and the wheels would become loose first.

The above leads to a conclusion that correctly lubricated and torqued wheel studs/nuts and clean bearing faces between wheels and hubs (or spaces and wheels and spacers and hubs) would be entirely satisfactory for cars that are driven on good roads.

Any failure to tension the studs correctly or excessive, damaging wheel impacts could well lead to the wheel moving on the hub and placing the studs in bending. Dowels, hub-centric locators, or short studs with cone/cylindrical mating faces are really a belt and braces back-up for correct installation of the wheels.

So, I reckon that if you want to run spacers then you have to be diligent with how you install your wheels and what you drive into. If you don't want to be diligent, don't use spacers. The current rules are set for the lowest common denominator and that is why spacers are not allowed here. Perhaps road inteh UK are better or people are about their maintenance more. I do not believe that flat wheel spacers are inherently dangerous.

M