Drag racing is all about violence. From gear banging shifts to multi-g launches to engines powered by what basically equates to a liquid explosive, he or she who harnesses that violence best usually wins. Outside of the factors just mentioned, there is another element of violence in the sport that attacks high horsepower machines and that is the devil known as tire shake.
A drag slick’s functional brilliance is the sidewall that can wrap up, absorb some of the initial shock of the engine’s load on the launch, plant into the track and then maintain that grip as the car accelerates. Those sidewalls are a double edge sword though. When the car does not jump “up on the tire” and head down the track, as you’ll see in this video, they can wrap up, basketball, and in racing terms, “go square”. This whole phenomenon takes place in increments of hundredths or thousandths of a second and produced violent shaking and vibration in the car. We’ve seen it happen so bad that welds in chassis have broken, doors have flown off, and guys have been literally knocked out cold.
This video shows tire shake in ultra slow motion and it is enthralling to watch. Realizing that it all happens so quickly in “real time” seeing it in this realm is really something else. Watching the tires work and then go crazy in slow motion gives us a whole new appreciation for how badly they get abused on every run!
Press play to watch a cool video featuring tire shake in super slow motion!
It’s unreal how much flex and movement the chassis can absorb.
What are the factors that cause drag slick tyre shake, and can they be ‘designed out’ of the tyre in manufacture?
By no means am I an expert. I have been told that there is not enough wheel speed and the tire is trying to run over itself. When the tire first flex from the hit it fold and its the tire refolding over itself that starts it. Once started the unbalance is amplified until either power is removed or wheel speed is increased.
That is my understanding but please if I am incorrect, someone correct me.
Drag slicks are designed to stick to the track. When you have a high horsepower vehicle that stages and launches, the rims, which are attached to the drive train spin faster than the tires that are sticking to the track. This is why the tire tries to fold over itself.
It
It looks like a standing pressure wave is set up in the tire.
Found this, Mike Kloebers nitro university:
If the tire wraps up too much there is an unwanted effect of tire spin when the stored energy is released. You can think of the tire as a spring, the more downward travel there is the result will be more upward travel. It’s one of these Newton’s Law kind of things. This results in tire spin when it releases during the end of the upward travel. Then after the tire gets unloaded it tries to grab and squat again. This up and down kind of action lends itself to initiating tire shake.