BMW Alpina wheel tyre valve repair.

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BMW Alpina alloy wheel.
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BMW Alpina alloy wheel.

Thread repair of a BMW Alpina alloy wheel.

Hi, the image is of a BMW Alpina alloy wheel which has a screw in Schraeder valve, I was recently commisioned to repair one of these wheels with a stripped thread and this post describes my experiences.
I measured the thread on the OEM valve which was M9.5 x 0.9, it looked for all the world that no one made a repair kit in that size, I was visualizing scenarios of dealers informing customers that a new wheel would be required at £945* (2014 price mentioned in a forum), one method of repair would have been a solid bushing threaded insert made of bronze which is the normal repair my engineer performs for thread insert failures.
It came down to looking through my Zeus tools book with a vernier and thread gauges revealing that the 1/8" x 28tpi BSPT thread has only a very minor difference, a final try of the valve on an old British Seagull outboard fuel tank's fuel tap thread confirmed that the original valve does screw in, it was just a simple matter of buying a Recoil kit of that size.
The installation isn't straight forward on account of the narrow angle of the tyre valve making it impossible to use an electric drill to clear out any remaining threads and pre-size the hole, neither was there any room to use a normal tee handled tap wrench, I performed the task using a 13 inch long tee handled tap wrench to firstly ream out the hole with a 3/8" reamer, then I tapped out the hole with the tap from the kit, cleaned out the hole with brake cleaner, applied loctite to the insert & finally fitted the valve with copper slip on the threads, this repair does leave the possibility of a future solid bushing thread repair in the event of a future helicoil failure.
I do stress that this is a task which requires the greatest of care, I did perform a successful repair on this wheel which has given me the experience to tackle more of them.

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Helicoil

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