warning ...wheel spacers

[QD MBE]

For these to have failed, there must have been some movement. 

I am not suggesting that you didn't have the wheels tight, the movement i refer to, is the alloy flexing with the fluctating loads on the wheel and eventually fatigue cracks set in (much the same if you constanly bend a piece of metal) and it reaches its fatigue life, and fractures.

Plain and simple.  I think you make a good point as to the thickness of the spigot being only 2 mm, not a great deal considering the loading.  Another concern of mine, is dis-similar metal corrosion setting in, hence not being able to remove them from the wheels.

They may look good, but their fitment does carry risks.

[RedRobin]

^^^^
Confirms more or less what I've been advised - Using them definitely carries risks.

The only way around such risks might be to fit new spacers after every trackday or after just a few hundred miles.

[jamiekip]

^^^^
Confirms more or less what I've been advised - Using them definitely carries risks.

The only way around such risks might be to fit new spacers after every trackday or after just a few hundred miles.

There is a small risk - though this is the first failure i've seen/heard about.  I think replacing them every couple of hundred miles is a bit of a knee jerk reaction.... not to say bl00dy expensive 
The H&R one's seem very well engineered - in fact I have a spare set, will take a pic and post what the 'hub' element is like on them for reference against the OP's spacers.

[RedRobin]

^^^^
Of course it's expensive to regularly replace them and that's why motorsport is expensive because parts get regularly replaced before they fail.

The risk may indeed be small, but it's definitely a risk, otherwise this thread wouldn't exist.

It's up to the individual what risks they are happy to take.

[jamiekip]

Here you go....





These were on my car for about 12k miles - no signs of damage or cracking

 

[jamiekip]

^^^^
Of course it's expensive to regularly replace them and that's why motorsport is expensive because parts get regularly replaced before they fail.

The risk may indeed be small, but it's definitely a risk, otherwise this thread wouldn't exist.

It's up to the individual what risks they are happy to take.

Personally, I think the risk is what you buy. As always, you get what you pay for!
I've seen all sorts of spacers advertised and some look pretty cheap.
As mentioned, the H&Rs seem a sound engineered piece of kit adn have not caused me any problems.

There is a risk with any modified part - remaps, exhausts, intakes etc, etc, etc

[Greeners]

What risk? 

The damage to the OP's spacer wouldn't have made any difference other than maybe a small vibration at high speed! Let's not get too over excited here. The wheel bolts are more than capable of keeping them in place, they have no where to go! I think the point that needs to be made he is more to do with a failure of one manufacturers part and not to now label all spacers risky/dangerous! 

[gazbutS3]

^^^^^I agree^^^^^

[QD MBE]

Nathan, I agree.

The OP spacers may not have been made of fairly durable material.  An Audi S3 (correct me if I am wrong) has Alloy wishbones.  Many aircraft have alloy frames. Longerons and stringers, which are designed to flex with load, it is part of the way Loads are transferred.

I think that the material spec used in the Op post, may have been an inferior.  An alloy wheel is designed to deform slightly, to absorb loadings that are not absorbed by the tyre.  But when something you fit is allowed to flex at a lower stress level, ie the spacer, then this will happen.

The load will always find the easiet and path of least resistance.  when you fit spacers you increase the leverage loads invoalved at the whell bearing, something you can not get away from, but be careful and inspect your spacers when you remove the wheels.

All it takes is a stress raiser be machined into the spacer profile, and this will happen.  by this i mean the inner face is machined with a very sharp tool, all the way to the horizintal face of the spigot, this will creat a very sharp corner, and an immediate path for the loads to create havoc.

But i still think that the thin wall has allowed flex, and a lower durability material has fractured.

[matt a]

FK are very hit and miss with the quality of their products, I'd trust H&R or Eibach, but never FK.

[QD MBE]

Buy the best you can afford.  Plain and simple.  and inspect at a regular interval.

[gazbutS3]

Nathan, I agree.

The OP spacers may not have been made of fairly durable material.  An Audi S3 (correct me if I am wrong) has Alloy wishbones.  Many aircraft have alloy frames. Longerons and stringers, which are designed to flex with load, it is part of the way Loads are transferred.

I think that the material spec used in the Op post, may have been an inferior.  An alloy wheel is designed to deform slightly, to absorb loadings that are not absorbed by the tyre.  But when something you fit is allowed to flex at a lower stress level, ie the spacer, then this will happen.

The load will always find the easiet and path of least resistance.  when you fit spacers you increase the leverage loads invoalved at the whell bearing, something you can not get away from, but be careful and inspect your spacers when you remove the wheels.

All it takes is a stress raiser be machined into the spacer profile, and this will happen.  by this i mean the inner face is machined with a very sharp tool, all the way to the horizintal face of the spigot, this will creat a very sharp corner, and an immediate path for the loads to create havoc.

I noticed the difference in the radius at the foot of the spigot, like stoke points out that sharp radius, or complete lack of radius will create a potential weak spot, stoke will back me up here I'm sure, you never see a sharp edge like that on any aircraft structure, everything has a smooth radius to prevent this sort of thing

[QD MBE]

A load path in an aircraft is designed to be a gradual transfer and sharing of load, ie no sudden load direction changes.  Hence nice radius frames and fittings.  The slightest damage caused by a slip with a spanner, a slight dent, a slight gouge with a screwdriver will afffect this path, and you have created a stress raiser and subsequent variation in load paths.  Hence overloading of the material.

http://en.wikipedia.org/wiki/Stress_concentration

ps Gaz I agree!

[RedRobin]

....

The spacer is obviously a stress critical component and so it's essential to know you have chosen the best product and probably to include consideration of what brake kit you have fitted too.

[jamiekip]

^^^^^I agree^^^^^

I agree too...
... I'm a fan of spacers... good for the stance of the car and I also notice a negative difference in cornering performance when ever I have removed them 

Robin - what have the brakes got to do with the purchasing decision?