Question: Fuchs valve stem support?
Thread Starter
Racer
Joined: May 2008
Posts: 367
Likes: 23
From: Sacramento, CA
Question: Fuchs valve stem support?
All four of my 16x7 fuchs have these on them. Two are early production 16x7's and two are 951 16x7's. I don't recall seeing these on the earlier fuchs wheels. What is its purpose? Is it necessary? Should I keep or remove? How's it bonded to the wheel? I'm cleaning these up before mounting the new tires and just curious.
Last edited by TT Oversteer; Nov 5, 2014 at 02:09 AM.
Drifting
Joined: Jul 2007
Posts: 2,115
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From: Newfoundland
The theory is that at high speed it keeps the stem from being forced outwards and bending. You can imagine at 150mph there is a lot of centrifugal force. Rough math, if that thing weighs half an ounce and you are doing 150mph it will generate on or about 55lbf. I hope my numbers are correct. It could, in theory, shear the stem right off.
Pelican does sell these at $6/each.
Pelican does sell these at $6/each.
Thread Starter
Racer
Joined: May 2008
Posts: 367
Likes: 23
From: Sacramento, CA
Sure enough, Pelican lists it as a factory Porsche part. Interesting I've never heard of centrifugal force tearing out valve stems before! Just one more example of how seriously the factory takes SPEED! Thanks for solving that mystery for me..........
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Burning Brakes
Joined: Oct 2006
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From: NE Ohio
I put a set on some fuchs this summer and here's my understanding of the supports from a local race shop - they are recommended for 7"+ wheels, front or rear doesn't matter, and the rubber stems are believed to be better than metal for holding air when they are stressed at speed (flexed)
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I haddah Google dat
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the 356 Carreras had them too, but they were made of wire and were sort of looped around the valve stems.
Leave a little gap so that at rest the stems do not rub against the support.
Leave a little gap so that at rest the stems do not rub against the support.
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From: Bend, OR
If you drive at any sort of "High Speed", I'd most definitely leave them in place. One of mine was gone on my old 8" rears, so I took the other off to match thinking it was overkill.
Well, I'm here to tell you unequivocally that it was no fun coming into turn 1 @ Texas Motor Speedway with a "rapidly deflating" RH rear tire. Thank goodness for 24 degree banking. I was nowhere close to 150mph. I may've clicked 130 on the front "straight" of the tri-oval since we were running the ALMS course thru the infield, and we had a chicane on the front straight after the kink. They are there for a reason.
Well, I'm here to tell you unequivocally that it was no fun coming into turn 1 @ Texas Motor Speedway with a "rapidly deflating" RH rear tire. Thank goodness for 24 degree banking. I was nowhere close to 150mph. I may've clicked 130 on the front "straight" of the tri-oval since we were running the ALMS course thru the infield, and we had a chicane on the front straight after the kink. They are there for a reason.
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A number of years ago, I pulled in from a fun run at speed, and as I was leaning against the car, the valve stem failed. The tire was flat in less time than it takes to read this.
I had all new valve stems later that day.
I had all new valve stems later that day.
Poseur
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From: Santa Barbara, CA
It's nice to know that you can still get these. I ran them on any of my Fuchs wheels that were over 7 inches wide. The way the valve hole is positioned in the 6 inch rims is not a factor requiring such support. Having touched 162 mph in my turbo with 7 and 8 inch Fuchs I never experienced any problem.
