Problem at the track today-VERY expensive valve stem!

efhughes3 · efhughes3's Garage

While in the PCA DE today, I was going into the 3rd lap of my 2nd session, and had a bug surprize. The typical DE track setup at TMS had a chicane at the end of the front "straightaway" prior to NASCAR turn 1. While exiting the chicane, you're moving the car a bit to the right.

My rear end kicked out (quite a surprize), and at first I thought I'd really screwed up the line thru the chicane. I continued on thru turns 1 & 2 and made a 180 degree left to enter the infield. At that point, she was really goofy.

To make a long story short, I had a flat. It turns out my VALVE STEM had split. This caused the air loss, but the tire sidewalls basically were trashed. I was able to buy a non-matching tire at the track, and finished the day. From now on, I'm checking my valve stems more closely when checking air pressure. BTW, I THINK it was the chrome sleeve over the rubber stem that was a little loose, and sawed thru the stem over the 4000 miles it's been on.

Hladun · 07-08-2004, 03:49 PM

Don't you have the valve stem supports on your wheels?

john walker's workshop · 07-08-2004, 03:58 PM

chrome sleeves and heavy metal caps really stress the stem centrifugally. supports are a must.

no substitute · 07-08-2004, 04:01 PM

Speaking of which, does Pelican or someone sell the metal stems?

Vipergrün · 07-08-2004, 04:08 PM

Ditto

-B

singpilot · 07-08-2004, 04:15 PM

I got mine from Performance Parts. Probably more expensive that discount, but they are the OEM ones.

Their site is their name. The only reason I say this is because I do not think PP has them.

Dantilla · 07-08-2004, 04:37 PM

The REALLY expensive valve stem is inside your engine. Your misfortune is a relief from what I was expecting.

I'm going to go check my stem supports now......

jpachard · 07-08-2004, 04:44 PM

Stem supports are a marginal solution, especially in the hot weather and at high speed tracks. The best thing to do is install metal valve stems and caps with the seal on the insides of the cap. This gives you an extra margin of safety since the schrader valves can develop their own problems. I'm glad you're Ok!!

Cheers, James

Zeke · 07-08-2004, 04:47 PM

Quote:

Originally posted by Dantilla
The REALLY expensive valve stem is inside your engine. Your misfortune is a relief from what I was expecting.

I'm going to go check my stem supports now......

Hehe. I thought the same thing.

Gordo2 · Gordo2's Garage

Not sure if Pelican carries them. I bought solid metal valve stems from Napa for about $5 per pair. They have a nut that screws them onto the rim (very solid) Can't recall the size (hole diameter) but the smaller diameter/shorter length ones fit well.

I had a little bit of a difficult time installing the fronts on my six's, but they fit with a little coersion (the rim has a sharp angle where the valve stem seats, the washer on the stem winds up slightly cocked between the flat surface and the edge of the rim that protrudes. They fit perfect on stock rear rims.

Good luck, Gordo

SteveStromberg · 07-08-2004, 09:19 PM

I just had to rotate the photo.

efhughes3 · efhughes3's Garage

Thanks guys-metal stems it is! Sorry for the misleading title.

osidak · 07-09-2004, 05:09 AM

Has anyone used the stems that sit flush to the wheel. To check pressures or add air you had to screw in a stem and when done you unscrewed the stem and capped it off.

Nothing to flex or fatigue

kqw · 07-09-2004, 07:27 AM

If you install the valve stem savers, wouldn't you have to re-balance your tires?

}{arlequin · }{arlequin's Garage

If I'm using the regular lightweight plastic stem/cap, am I still going to have the centrifugal problem? I've never had this problem on any other car I've tracked/driven...

KNS · 07-09-2004, 12:33 PM

Is there any thing wrong with plain 'ol plastic caps?

JeremyD · JeremyD's Garage

Sorry I missed you - I did the PCA DE on Wednesday - driving the banking was pretty wild - as was the 130mph before the chicane!

masraum · 07-09-2004, 12:49 PM

I think you need the supports whether you have plastic caps or not. They come from the factory for a reason. It seems to me that on a car with 16x6 and 16x7 they only come on one end, but I can't remember which end. I had metal caps on my car for quite some time, but then I noticed a spot on the wheels that didn't have the supports where the cap would touch the wheel so I changed to plastic. The metal is probably better.

I would think you could have taken a file or grinder to the washer on your metal valve stem, filed a small flat spot, and gotten them to sit flush.

efhughes3 · efhughes3's Garage

Jeremy: Ditto on not catching up with you. That stretch after coming out of # 4 is pretty fun-head toward the wall, and then do the chicane. They had a couple of cars wreck there last year at the Club Race.

Bill Verburg · Bill Verburg's Garage

As Jim said

Quote:

Stem supports are a marginal solution, especially in the hot weather and at high speed tracks. The best thing to do is install metal valve stems and caps with the seal on the insides of the cap. This gives you an extra margin of safety since the schrader valves can develop their own problems. I'm glad you're Ok!!

You need to use the short metal stems w/ metal caps w/ an inner seal, like this

At speed the unsealed caps have been known to leak