Z4C Composite Star Spoke Alloy Problem

[Vroomer]

I have composite star spoke alloys on my Z4C and they are starting to show strange patterns on the outer rims. It looks like a sort of metallic fungus rather than corrosion.

Anyone know what this is and whether it will be covered under warranty?

[S3_Graham]

Vroomer said:

I have composite star spoke alloys on my Z4C and they are starting to show strange patterns on the outer rims. It looks like a sort of metallic fungus rather than corrosion.

Anyone know what this is and whether it will be covered under warranty?

pictures?

There are different forms of corrosion. could be intergranular.

[playalistic]

If you mean the BMW style 108 two-piece rims this is well documented and is just corrosion. Some dealers have replaced the wheels on newer and/or warrantied cars as goodwill.

[Mattt]

I had my 108 rims repaired about 4 times by the dealer, until they finally did a good job - proper strip back and repaint/lacquer.

[koolchris99]

the 108's do that. just refurb or change for a diff alloy style.

[Vroomer]

Thanks for the responses.

My dealer has now taken pics of the wheels and sent them to BMW. They are reasonably confident BMW will pay for refurbishment.

It seems this is a 'known' fault on composites – I wonder why?

[playalistic]

It's the construction of the wheel being two piece that causes issue. Water and crud gets between the two pieces and does its thing.

[DennisCooper]

Hi,

The lacquer that's used will have stone chips hit it from general road use. When the layer of lacquer is breached right through, then water gets in underneath and causes the 'milky' sometimes spidery looking corrosion to occur. There's nothing you can really do to prevent it as such and it's not a 'fault' of BMW etc. A good quality refurbishment will see them back to new - however, the same will happen again over time.

I have a set of very rare Hartge wheels and I decided to refurbish them but the final finish was to polish the lip and leave as bare metal. This way, I do have to keep getting the autosol out every few days , but I won't need to having to keep refurbishing and re-lacquering every 12-18 months or so.

Cheers, Dennis!

[E30M3SE]

The answer is to not have the outer polished rim lacquered, just hit it with some metal polish and wheel wax once a week/fortnight.

[Mr Whippy]

Indeed.

ALL lacquer over polished finish go, even non-split wheels do it...

If they put on about 5 coats of lacquer it'd last ok, but since it's just a light coat it gets chipped and that is it.

VS paint where you have lacquer, metallic coat, base coat, maybe a base under that, and then the alloy, you have loads more protection before metal is exposed to the elements.


Better to leave it exposed and then just clean it up now and again, just like chrome exhaust tips etc...

Dave

[Vroomer]

Update!

Back in September BMW agreed to replace two of the wheels but reserved judgement on the other two, so I did nothing until this month.

All four wheels had continued to deteriorate.

BMW have now agreed to replace all four wheels under warranty.

First class service!

[Shurv]

Far too common an issue on 108's.The reason why I took mine off, sold them and fitted MV2's instead.No corrosion issues in over 2 years with them.I got really fed up of trying to keep the 108's in good order.

[Vroomer]

Shurv said:

Far too common an issue on 108's.The reason why I took mine off, sold them and fitted MV2's instead.No corrosion issues in over 2 years with them.I got really fed up of trying to keep the 108's in good order.

Apparently the problem was sorted a while back. It was a faulty lacquer. I'm told there will be no problem with the new wheels.

[Sortie 10]

I had (have) this problem on mine. When under warranty, they replaced one wheel and then a few months later refused to do another...because wheels are not covered by warranty! Go figure...

Suffice it to say that looking at the car now, several years on I cannot recall which wheel was replaced as they are now equally bad. All need a serious refurb which I understand is more complex (and hence pricier) than non-two piece wheels. I dont think it is much more expensive to buy a new set from the internet and move your tyres across.

Until I come to sell my car, I am not prepared to refurb and have the same happen again. And again. From close up the corrosion looks horrendous, but from a distance I think the wheels look good and are probably the best looking OEM/optional wheel (IMHO) for the Z4 (although a CSL wheel does run it close).

[Mr Whippy]

Vroomer said:

Shurv said:

Far too common an issue on 108's.The reason why I took mine off, sold them and fitted MV2's instead.No corrosion issues in over 2 years with them.I got really fed up of trying to keep the 108's in good order.

Apparently the problem was sorted a while back. It was a faulty lacquer. I'm told there will be no problem with the new wheels.

It must be faulty lacquer the world over.

The problem is purely a lack of depth of protection vs normal painted wheels.

Any wheel that is lacquer over polished finish fails horribly.

Porsche through to Ford, it's common.

Dave

[Vroomer]

Vroomer said:

Shurv said:

Far too common an issue on 108's.The reason why I took mine off, sold them and fitted MV2's instead.No corrosion issues in over 2 years with them.I got really fed up of trying to keep the 108's in good order.

Apparently the problem was sorted a while back. It was a faulty lacquer. I'm told there will be no problem with the new wheels.

Six years on (yes, I've still got the car), the replacements are now worse than the originals.

Does anyone know if a refurb will cure the problem, or have I got to buy new wheels?

[Mr Tidy]

Vroomer said:

Six years on (yes, I've still got the car), the replacements are now worse than the originals.

Does anyone know if a refurb will cure the problem, or have I got to buy new wheels?

Well it's a bit yes and no!

Yes, a refurb will cure the problem.

But over time it will happen again. It's because the rims are alloy and the bolts are titanium. The 2 different metals react over time causing corrosion and this lifts the lacquer.

Luckily a previous owner of my Z4 had my 108s refurbished a few years ago, so I've bought a different set of wheels and plan to swap wheels and sell the 108s while they are still in good condition!

I guess it depends largely on how much you like them, and how long you plan to keep the car.

[helix402]

As above, they can be refurbished. If the refurb is done as factory after a few years they will deteriorate again. You can have them all painted, this will last longer.

Or go for a set of 107s. Look worse, last longer.

[Mr Whippy]

107s on a Coupe will look pants.

But on a pre-facelift roadster 107s are the best

I’d get on CM wheels and fit 19” CSL reps.

[Mr Tidy]

Mr Whippy said:

107s on a Coupe will look pants.

But on a pre-facelift roadster 107s are the best

I’d get on CM wheels and fit 19” CSL reps.

107s on a Coupe look OK, but 135s, MV3s or 224s look better - unless you have to spunk money on CSL reps!