Tyre Dust Covers

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Fairynuff
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Post by Fairynuff »

One went missing - why / how - I do not know!

I went on-line and bought some (cheap as chips). They are described as . . . . . . .Made of quality aluminium they will fit any standard valve stem and feature a rubber seal on the inside for further protection from dirt which ensures the valve is clean when air is needed. and a domed gel top to protect the logo.

I have since read posts on another forum talking about metal dust caps 'welding' themselves to the fitting!!! Is that just the steel caps or does that happen with aluminium also?

Madelvic
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Post by Madelvic »

I had a Nissan GTR with very nice hex valve covers. One was stiff so I put a small spanner on it and the valve stem snapped. I'm fairly certain it was an aluminium cap.

A dab of grease would prevent the problem
2017 Macan GTS Carmine Red
2005 Boxster S Artic Silver
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SAC1
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Post by SAC1 »

^^^^ Never had this problem and have been using them for years on all our cars.

I do check the pressures every fortnight though with a dial guage. So they would not have the time anyway to get stuck. ;)
Steve

2020 GTS in Sapphire Blue
(sold) 2017 SD in Rhodium Silver
Fairynuff
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Post by Fairynuff »

I wonder what is welding to what? What type of metal is the 'male' screw head on the tyre inlet valve - it looks like brass. I wonder what the chemistry/physics is behind two different metal types welding together without any heat?
Madelvic
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Post by Madelvic »

Aluminium oxides and swells. I recently spent may hours cutting a carbon fibre seat post out of an aluminium bicycle frame as no amount of pulling and twisting would free it
2017 Macan GTS Carmine Red
2005 Boxster S Artic Silver
B737NGWS
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Joined: Sun May 03, 2015 7:36 pm

Post by B737NGWS »

Somebody pinched all 4 of our dust caps a while ago on our other car! I seem to remember after a bit of research that there are ‘special’ caps to suit TPMS? Not sure why they should need to be ‘special’ given that TPMS has been mandated for years but possibly a consideration?
Fairynuff
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Post by Fairynuff »

B737NGWS wrote: Tue Aug 17, 2021 10:03 am there are ‘special’ caps to suit TPMS? Not sure why they should need to be ‘special’ given that TPMS has been mandated for years?
I don't know either but the TPMS is currently active/working on the tyre with no dust cap.
Fairynuff
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Post by Fairynuff »

I started by trying to buy an exact match, they are grey plastic with letters on the top (letters which I presumed read 'Porsche'). I took one off, got my glasses on . . . . . Alligator, it reads Alligator!!!! What's that all about?
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Neil1911
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Post by Neil1911 »

I don't believe the dust caps are "special" for TPMS, they are just to keep the crap out of the valve, tgat said the original Porsche plastic ones are better quality than the 'orrible black one I got with my new tyre after the recent puncture (note to self: don't let that happen again). However, I bought these from Amazon: PNA70500199 Silver Valve CAPS
No complaints!
http://www.porsche-code.com/PP37WLA6, a Dolomite Silver S, collected from Stockport OPC on Valentine's Day 2023, after a 399 day wait.
Ex.: Gen2 S, Volcano grey 1/9/19 - 3/2/23 & 39,235 Smiles, RIP
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Nuclear Nick
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Post by Nuclear Nick »

Fairynuff wrote: Tue Aug 17, 2021 9:49 am I wonder what is welding to what? What type of metal is the 'male' screw head on the tyre inlet valve - it looks like brass. I wonder what the chemistry/physics is behind two different metal types welding together without any heat?
The manual states that only plastic caps should be used. The reason is that two dissimilar metals with water present will set up a corrosion cell. The process will chemically bond the two metals together, so it’s not ‘welding’ in the true sense.
Nick

Defender 90 V8

991.2 C2 GTS

Macan Turbo - sold

BMW K1300S, BMW R1250 GSA
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