Thumping tire at track event

[rob76turbo]

All,

Went and did a casual track day at MSR in Cresson, TX and very quickly noticed

something developing on my Boxster S.

Running Toyo R-888's and I felt a vibration and heard a thumping coming from the

right front tire. This only happened during right corners, when the right tire

in normally unloaded. During left hand corners, there was no noise. I looked at

the tire itself and saw that the outside edge was down to slick and the inside

edge still has some of the grooves left. This got progressively worse as I ran

sessions, and to note, there was some tread at that outside edge at the

beginning of the day. I am wondering if the uneven tire wear was contributing

to the vibration / noise. Another PCA / Boxster guy happened to be there

and as I described the issue to him, he thought wheel bearing, but I am not

sure... Any thoughts?

[jmatta]

Nowhere near enough negative camber for a track event, first off (extreme wear on outer edge). You probably flat spotted the tire, as well, which would translate to thumping.

[ericinboca]

All,

Went and did a casual track day at MSR in Cresson, TX and very quickly noticed

something developing on my Boxster S.

Running Toyo R-888's and I felt a vibration and heard a thumping coming from the

right front tire. This only happened during right corners, when the right tire

in normally unloaded. During left hand corners, there was no noise. I looked at

the tire itself and saw that the outside edge was down to slick and the inside

edge still has some of the grooves left. This got progressively worse as I ran

sessions, and to note, there was some tread at that outside edge at the

beginning of the day. I am wondering if the uneven tire wear was contributing

to the vibration / noise. Another PCA / Boxster guy happened to be there

and as I described the issue to him, he thought wheel bearing, but I am not

sure... Any thoughts?

Agree with jmatta you don't have enough negative camber. If you are going to do this more, you probably want to go to -1.5 in the front.

It is possible you flat spotted the tire or put spot on the outside edge that is like a flat spot - I would also recommend you balance the tires and put metallic duct tape (not the fabric stuff, but the metal stuff) over the wheel weights - the heat can cause the adhesive to melt and the weights come off - you will get weird vibration with out of balance tires.

[Loren]

Look at your rotors and pads too.

If you over cooked the brakes you could have left pad deposits on the rotors and distorted the pads.

[rob76turbo]

Everyone, thanks for the suggestions. I am going to take a look at the tire tomorrow and the rest of the suspension / brake components as well. I am giong to take it for a spirited drive (albeit with my street tires) and see if I can duplicate the issue. I will post once I get past the next stages.

Thanks again!!