Powder coated wheels - safety issue

Powder coated wheels - safety issue

Author
Discussion

ash reynolds

Original Poster:

468 posts

190 months

Thursday 4th July 2013
quotequote all
I wanted to share my experience with powder coated wheels with respect to using my car on track on one occasion. This is not intended to be a discussion thread but purely advisory. Any are welcome to comment but I shall not be posting further once I have shared this.

My wheels were prepared by a specialist company in accordance with their warranty conditions and seemingly global policy, so expect the same procedure to have been followed by any branch.

The overall finish and appearance of the wheels was completely satisfactory, however, the area of concern in my instance was both the hub face and tapered wheel bolt seats. These had been powder coated fully.
During my time on track the coating became sufficiently hot to melt this coating on both the hub face and tapered seat. I have received advice from well respected businesses who have experience in preparing vehicles for track use and they have advised that this could have potentially had serious consequences such as wheels parting company with the vehicle had I persisted in using the vehicle.

The trader has resolved my issue by stripping, masking off appropriately and re coating.
As I have said, this thread isn't intended to discuss the process of powder coating wheels or indeed the trader but to highlight a potential safety issue. It is for the individual to decide what to do with this info, if anything.








Edited by ash reynolds on Tuesday 15th July 14:04

rigga

8,727 posts

200 months

Thursday 4th July 2013
quotequote all
Struggling to realise how the wheel bolts/nuts could come loose and the wheel fall off even with melted coating.

caravelle190

11 posts

130 months

Thursday 4th July 2013
quotequote all
rigga said:
Struggling to realise how the wheel bolts/nuts could come loose and the wheel fall off even with melted coating.
Because powder coating can be quite thick and the effect of it melting could potentially negate the torque that was put on the wheel nuts/bolts during the tightening process. Highly unlikely, but theoretically possible.

ash reynolds

Original Poster:

468 posts

190 months

Thursday 4th July 2013
quotequote all
Could somebody please explain why the trader name has been edited out? I thought I had worded this carefully enough to avoid issues. Thanks.

adeel_gt

226 posts

199 months

Thursday 4th July 2013
quotequote all
Most wheels are powder coated from factory so i'd struggle to see it being unsafe to use them.

dudleybloke

19,718 posts

185 months

Thursday 4th July 2013
quotequote all
another consideration is if they burn the old coating off before powdercoating as the temperatures involved in some methods can cause cracks in the wheel.

thread here.

http://www.pistonheads.com/xforums/topic.asp?h=0&a...

Krikkit

26,500 posts

180 months

Thursday 4th July 2013
quotequote all
caravelle190 said:
rigga said:
Struggling to realise how the wheel bolts/nuts could come loose and the wheel fall off even with melted coating.
Because powder coating can be quite thick and the effect of it melting could potentially negate the torque that was put on the wheel nuts/bolts during the tightening process. Highly unlikely, but theoretically possible.
This makes sense - even sub-mm thicknesses of powder coat melting away from the hub face it will have an impact on the tightness of the joint.

If in doubt, sand the hub face of the wheels down before fitting to expose metal.

tannhauser

1,773 posts

214 months

Thursday 4th July 2013
quotequote all
ash reynolds said:
Could somebody please explain why the trader name has been edited out? I thought I had worded this carefully enough to avoid issues. Thanks.
Stupid "name and shame" rules.

Can you PM me to let me know which company? As I'm getting some wheels done soon.

AFC1886

3,343 posts

149 months

Thursday 4th July 2013
quotequote all
Your wheels got so hot it melted the powdercoating!? WTF?

mwstewart

7,554 posts

187 months

Thursday 4th July 2013
quotequote all
Whilst the practise above isn't correct, I disagree that it is a safety issue. The action of tightening the bolts will score the coat off of the bolt chamfers, and the coat on the mating face will at worst cause (very minor) wheel balancing issues.

Mave

8,208 posts

214 months

Thursday 4th July 2013
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How does a smooth conical surface score off the material? Where does this material end up going?

jeremyc

23,336 posts

283 months

Thursday 4th July 2013
quotequote all
ash reynolds said:
Could somebody please explain why the trader name has been edited out? I thought I had worded this carefully enough to avoid issues. Thanks.
We don't allow naming and shaming - it's against the rules you signed up to when you joined.

Besides, the specific trader wasn't the point of your post, was it.

s3fella

10,524 posts

186 months

Thursday 4th July 2013
quotequote all
I think the issue is that most coasters will use grease on all the mating faces before coating, the powder sticks to this even during baking in, but when its cooled, the mating face can be cleaned easily using a Stanley knife blade. So this should mean the face is just metal once complete.
If you had a mating face with powder on it, that then melted, it sounds to me that this may have been the greased up powder surface that should've been removed by the canter first time round.

Well maybe!

m4tti

5,426 posts

154 months

Thursday 4th July 2013
quotequote all
Isn't powder coating supposed to result in a layer which is 1 to 3 thou in thickness. Have you ever checked out a 3 thou feeler gauge. I doubt it would result in a catastrophic wheel fastener failure.

Human hair is approximately 4 thou.

Edited by m4tti on Thursday 4th July 23:48

B17NNS

18,506 posts

246 months

Thursday 4th July 2013
quotequote all
AFC1886 said:
Your wheels got so hot it melted the powdercoating!? WTF?
My thoughts too. At what temperature does powdercoat 'melt'?

405dogvan

5,326 posts

264 months

Friday 5th July 2013
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I'd love to see a picture of the hub that came off - because that's a VERY neat pattern for 'melting'. It's defined perfectly between the inter-stud spaces and the edge of the bolts!?

What car did it come off - anyone know?

Hubs do get pretty hot - I still have a burnscar I got from one when changing a wheel once...

AGK

1,601 posts

154 months

Friday 5th July 2013
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The alloy looks like it is off the mk5 golf platform.

richwig83

14,193 posts

137 months

Friday 5th July 2013
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AGK said:
The alloy looks like it is off the mk5 golf platform.
Pirelli Edition?

pits

6,423 posts

189 months

Friday 5th July 2013
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ash reynolds said:
What OP meant to say

ging84

8,832 posts

145 months

Friday 5th July 2013
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when i painted my wheels i got a reasonable amount of paint on the back

after a good hard run this did indeed soften on one of the wheels and cause the wheel bolts to be slightly loose
after a couple of days of thinking i had a drive shaft on it's way out i was spared any expense by adding half a turn to each wheel bolt.
hardly anyone died because of this incident