Tire vibration / thumpping issue at track
 

All,

Went and did a casual track day at MSR in Cresson, TX and very quickly noticed something developing on my Boxster S.

Running R888'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 had 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?

My '98 Boxster made the same noise in the right rear tire, and the cause for it was due to that strut having leaked out its oil, and eventually wore out.

Once I replaced the rear struts, the car no longer made that vibration thunking sound on hard right turns. Just like your car, it was silent on left turns.

I would take a look at the strut, and see if their is oil all over the body of the strut.
If there is, its time for new ones.

BC.

Lots of possibilities. Failing bearing, uneven tire wear, alignment problems, tire pickup, failed drop link or A-arm bushings, failed strut. You can check your bearing simply grabbing the tire and giving a yank left or right. You should not hear a clunk or feel any play in the wheel. Other suspension components are best checked on a lift where you can get a good look.

Brad Roberts is our local suspension Guru. He probably forgot more about Porsche suspension then I will ever know. Perhaps he will chime in.

Bad wheel bearing can be identified by pushing in hard on the tire at the top of the tire towards the center of the car. Use all your weight to do this. If the bearing is going bad you will feel a definite little click-click as you displace the outer bearing race.

Different option: front engine mount.
I had the exact same problem at a PCA event at MSR and couldn't figure it out. everyone tried the car and identified the vibration to front right wheel. Not knowing was driving me insane! eventually got it on the lift at fifth Gear and saw immediately the front mount was toast. Replaced t and the vibration was gone. mystery solved.

Good luck, and let us know when you find the cause!

Mike

Front Engine mount....hmmmm, worth a look
 

I use Fifthgear too. Great folks. Can't wait to see their new facility.

I will take a look at the front motor mount when I have the car up on a lift.

funny story,my daily driver was having major issues and since it is not a Porsche I have neither the time nor the desire to mess with it so I dropped it off at 5th gear on Sunday night a week ago. When I got there there was only one old 911 in the front where there was 15-20 before and the building was vacant. Fearing the worst, I finally saw a note on the door mentioning the new facility accross the street. I walked over to the building I had never seen before and sure enough they were all scrambling trying to complete the move. I was their first customer in the new place!
It is such a major step up and looks awesome.

Got the car up on a lift today and....
 

Shook the cra% out of the front wheels. No slop, no clicking, no nothing. The bearings seem very tight.

Now we move back to the motor mount and....all chewed up. So I will be ordering a new Delrin Motor mount from Cheetah ($125) and probaly a new AOS as I noticed a lot of oil buildup around it. Get the car back up on the lift next weekend to take care of those two items. The bearings can wait! I will keep them frozen until then.....

Very interesting. This is the first I have heard of a failed motor mount causing clunking noise at the right front wheel. Good to know.

Going with the WEVO mount
 

I took a look at the WEVO mount and have decided to go with that. I plan to order today or tomorrow.

Called it! :cheers:
Glad to know you got it solved! let us know how the wevo mount feels!

Ordered the WEVO mount from Brad Roberts (Thanks Brad!!!!). What a beautiful piece of engineering. The photo does not do it justice. It looks like an orange delrin surround (although it is of a lighter material...I think). The two insert halfs look like very heavy duty rubber or plastic...but NO, they are metal and fit together perfectly. You may have to put a clamp on the whole assembly to get it started onto the motor mount frame, but it all went together well. Total time, including pressing out the old mount was about 90 min. I had access to a lift, so we were able to access all the bolts from under the car. If you have it on a lift, no need to take off the access panel from inside the car. One note, the old one was completely shot. I had inspected it (while still in the car) and it looked cracked, but when we got it out.....it was a mess. A couple of wacks with a small hammer and it completely dislodged from the insert.

Now for the results. The drive train feels much tighter and the transmission slop is gone. But....boy does it vibrate! Especially at 3200-3400 RPM. I think that is a factor of the WEVO mount being metal and there is really no rubber in the assembly to dampen the vibration. I am still getting use to it. I think it has changed the whole feel of the drivetrain, even the sound is a bit different. But once again, that should be a function of going from rubber (especially since the old one was fried) to metal. I will report more after I get used to it a bit. Eventually I will add the WEVO transmission mounts and the drivetrain will be solidly located for sure!!