Valve stem failure Options

[John2kx]

I'm running 5 lug Fuchs on my 914 and have had two valve stem failures since wheels were installed 6 months ago. Both failures have been on the front and on opposite sides. Failures both seem to be from shank section of stem and have shown up as slow leaks luckily and not total failures while at speed.

I use the best tire shop in town for mounting and balance and see many high end cars worked on there.

Is my tire guy missing something? The stems used are a rubber material. I seem to remember seeing some type of stem support back in the 70's. Are these required?

My car does see 100 mph on a regular basis and 130 or so on occasion if this makes a difference.

John

[ArtechnikA]

Now to find a source for bolt in valve stems. I'll speak to my tire guy in a few hours.

the set i used was from Revolution Wheels, aluminum, very lightweight. long time ago, haven't seen anything like them in years...

also - different but related topic - where possible - use valve stem caps. "centrifugal" force works in the direction of pulling the valve core open. if the spring is a little weak, and the air pressure a little low, it can be pretty easy for that valve to collapse and let a lot more air out ...

i don't use them much on the street - but i like to have them on the wheels for track events. i think the last time i looked at the numbers typical wheel speed at the end of the straight was about 2400 rpm...