Zenski

Hi guys, I started to get a shake from my front end.

The first thing I did was rotate the wheels from side to side. That didn't help.

I took them off and had them rebalanced (they said they were out of balance), put them back on and the shake is not as bad as it was. They shook at about 40mph and up, now they just shake at higher speeds (70 and up).

I have Sumi's III with about 7,000 miles on them. This is my first set of tires I have put on for the fronts.

I checked to see if if I had any play in the front and didn't (it doesn't pull at all).

I've had no issues at all for the last 25,000 miles.

My question is, can a tire just go bad or should I start looking at the front suspension?

Also, I did add a front brace strut at the beginning of this summer.

Any thoughts

Zenski

Medevack1

Nice pic i also have a R1 50th . I believe if the tire was ever patched it can make a wobble.

Zenski

Nice bike, I love mine.
No patching, just stated out of the clear blue

AndyK

Did you hit any large bumps or pot holes recently? Could be one or both rims are slightly out of round?

Medevack1

thats what I was gonna say!!!

Byprodriver

This process is always simplified by insuring visually the tire/wheel is free of excessive movement, up &down &/or side to side while spinning on the balancer. With the training & dedication I experience at most tire shops here in SoCA, I trust only my eyes for the visual confirmation, coupled with Michelin Hi-Performance tires.

targa996

Where did you get them balanced ? Make sure they are using Hunter Roadforce balancer - the tech should be able to check for suspension play at the same time. I used to have shake in front as well - took it to more specialist shop - and problem was cured ...

Byprodriver

This is neither required nor guaranteed to solve the problem.

alpine003

Check ball joints and control arm bushings. Tires just don't magically go bad unless there is some failure with the suspension or if you ran over something and bent something.

996pp

Do you have wheel spacers in the front? Sometimes if you get the universal spacers they have a very slight play and its impossible to center the spacer with the wheel when mounting it back on. That will give you a nice shake or bounce when you hit speeds over 60. The P.O. on my previous 996 had put universal spacers on the back and that thing would start bouncing like a rocket ball on the freeway. That was the first thing I got rid of when I took delivery of the car.

frisbee91

With the title of this thread, I would have expected the subject matter to go downhill quickly. Nice to see Rennlisters can stay on topic.

porsche-t

I had this problem on my S320 Benz. It would get a slight bounce on speeds above 40 MPH. I installed hub centric rings to correct the issue. I don't know if you have spacers like 996pp said.

San Rensho

Check the tires for out of round. Jack the front end up. Take a screw driver hold the handle against the body work and get the tip as close as you possibly can to the tread surface. Spin the tire and you will immediAtely be able to tell if its out of round

If the tires are good then you have to take the wheels off and shake, bang on every suspension component until you find out whats loose. Pay special attention to the wheel bearings and tie rods. Finally, check all the fasteners for looseness.

Macster

A tire can go bad at any time. Usually, of course, a tire doesn't go bad. But in some cases a belt can fail and the tire will not behave.

Now I'm not sure a rebalance, even a load force balance, can detect a tire in this condition. I would think so, but one never knows. There is the possibility the tire balances to within spec on the machine but when the wheel/tire assembly is mounted to the car it will go out again as the car is driven and the tire subjected to varying axial and radial loads.

But given this you might be able to eliminate this possibility by having the tire balanced again, or at least checked. If the tire doesn't have the same balance characteristics as before, well, at least you know.

But before you go to the trouble of having the tires checked for balance be sure the tire inflation pressures -- at all 4 corners -- are correct.

I can introduce a vibration that is very much like a tire balance problem by over inflating the front tires of my Boxster. And not over inflating them a lot either, just a few PSI over the nominal 29psi (cold) that is called for.

Do you feel any signs of feathering or cupping or scrubbing on the front tire tread? If you do there can be an alignment problem.

And as others have covered there is the possibility of a suspension or steering problem. So you need to think about having the car checked by a knowledgeable Porsche tech for any trouble in these areas if you do not turn up some other explanation for the behavior.

fpb111

Here is one for the collective:

I had a slick low on air at Watkins Glen.
I went to the air station down at the end of the garage and filled my tank.

Vibration was so bad out on track I thought the front end was going to tear off. Then it would mostly go away and then come back with a vengeance.

I put on my rains and finished the day.
We couldn't see anything wrong with the tire. When we put it on the balancer it would cycle from smooth to trying to tear the machine off of the floor???
When the tire was removed from the rim there was ~1 cup of water in it.
Evidently the water would disperse evenly until something upset things. Then it would all get together and throw the tire way out of balance.
So if you get a crazy in/out/in balance situation check for water.

I took all of the tires off. There was a little water in one but nothing like the problem tire.

Moral of story, Drain your air tank occasionally.