Track Day circles have quite a few questions that always spark a lively debate. “What brake pads are the best?” is one that always pits multiple parties against each other, each claiming their favorite brand is a gift from the Holy Patron Saint of Deceleration. This post is about another contentious topic, even if it may not be quite as common as people asking “What is the best brake fluid?”
Should I run Rubber or Aluminum valve stems in my wheels?
“Rubbin is Racin!” : None of us go on track intending to hit someone or get hit, but things happen when racing. Maybe you stick your nose in a bit too far, maybe another car didn’t know you were under them, maybe you lockup the brakes and use another car to slow down… Sometimes this contact causes huge issues, sometimes it’s minor and gets wiped off with a damp rag between sessions… but what if minor contact includes rubbing wheels with the other car?
This scenario happened in the first lap of a race at Palmer Motorsports in July. Christian Sandman and another Spec E-30 driver got a bit too close through the very tight turn 5. They had a light, but otherwise unremarkable touch. What Christian didn’t immediately realize is that slight touch snapped his rigid aluminum valve stem. A couple corners later, When he tried to turn left, the now flat tire rolled right over resulting in an unexpected spin (While still being followed closely by other cars in the class). Thankfully, due to some heads up driving and good luck; Christian was not collected by the cars coming up from behind. He limped back to the pits. His race was over.
Why did such a minor contact turn into a huge problem? How can it be avoided?
One simple way to avoid this, USE RUBBER VALVE STEMS. In that scenario, rubber would have been pushed and bent out of the way instead of snapped off with the aluminum. There are also manufacturers that make “shorty” aluminum valve stems, but I’m still not totally sold on them. While they may be mostly protected from damage as they are below the lip of the rim, I’d still fear some sort of intrusion.
If aluminum valve stems are vulnerable, why do people use them? Similar to Drilled Rotors, I don’t really know. Because someone swore they are better? Scene points? I get that there may be some minor benefits, but in my opinion they don’t outweigh the risks.
Yes, rubber does rot over time, but they can easily be swapped during our very common tire changes. Most track wheel service life is probably shorter than the reasonable life of a single rubber valve stem. (Especially if you have 6UL’s)
Rubber valve stems get pulled through the wheel and they snap in place. That’s it, no worries about proper torque or the retaining nuts coming loose (make SURE you Loctite metal ones).
You can find rubber valve stems cheap almost anywhere, on a moment’s notice. If you have a very specific metal style that you like, you’re stuck until the delivery truck shows up. The metal ones aren’t much more money the rubber ones, but don’t forget: a few dollars here and a few dollars there quickly adds up.
To be clear: Some sort of physical contact or crash that actually breaks the valve stem is RARE. But with little (or no) actual advantage to running them, do you really want to risk your race ending in the first minute like Christian’s?
Maybe I’m biased, I also had bad experiences with aluminum TPMS sensors on my 08 Dodge Charger. They would corrode and get so weak that checking pressures and filling could easily break the valves if you weren’t extra careful to keep the air chuck perfectly straight. My first aluminum TPMS stem broke when the car was less than two years old and over the next few years 2 of the remaining 3 also broke.
Speaking of Wheels and tires, have you read the earlier post about: Swapping tires on a budget? A tire machine can Quickly pay for itself : Important tips and info when shopping for your own
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