Virbration, its gonna end me.

PorscheGuy79 · PorscheGuy79's Garage

I am going to try and be as descriptive as possible. Since I purchased the car I have had an issue with a vibration/pulsation of the front end and a pulse through the brake pedal. So I when to work with the logical. First I rebuilt the front brakes, tough job but I got through it. Slight improvement but no cure. And I still had a pulsating pedal and the noise was still there. So I went with new rotors and wheel bearings figuring it was a warped rotor or something of the sort. The job was fairly simple and worked out great. But the noise is still there. Also to note the car has signs of a somewhat rough off-track and when I removed the drivers side hub the dust seal had a dent in it. This wobble or pulse noticeable moreso when I brake but after the new rotors its not coming through the pedal, so far it seems to be frim and the pulsing gone from it but I can still hear it through the car. Also I notice more when I ture the steering wheel slightling in a turn. Im running outta ideas besides replacing the whole front. Please help me identify whats wrong here.

Miguel Antonett · 04-14-2005, 06:38 AM

What model car, year, miles. When does it occur? At a certain speed? When you brake? Going downhill gets worse? If you back it up and apply breaks hard, does it make a noise? It could bushings, tire balancing, rod ends... More information would help to trace it down.

David · David's Garage

I haven't had this problem with my Porsche but with my Datsun and BMW the front vibration problem was mostly in the front suspension bushings. Obviously the rotors need to be true end the tires need to be balanced, but without good bushings any inbalance or runout problem seems to get magnified.

PorscheGuy79 · PorscheGuy79's Garage

Quote:

Originally posted by Miguel Antonett
What model car, year, miles. When does it occur? At a certain speed? When you brake? Going downhill gets worse? If you back it up and apply breaks hard, does it make a noise? It could bushings, tire balancing, rod ends... More information would help to trace it down.

1979 911 SC; 126,000miles; it occurs at most speeds noticeable mostly at low speeds were you can really hear it. You can hear it most of the time driving striaght but gets louder under breaking and when the wheel is turned slightly; I will try the backing up and braking; tires were balanced and it does this with my winter wheels and tires;

RickM · RickM's Garage

Have the tires been on throughout your troubleshooting exercise?
I've had tires with separated or broken steel belts and I experienced the same symptoms.

PorscheGuy79 · PorscheGuy79's Garage

As I said pervious I have a spair set of wheels and tires and there is no difference between the two.

mb911 · mb911's Garage

check

Front strut mounts, bushings in the a arms and tie rod ends(myguess)

MotoSook · 04-14-2005, 06:58 AM

Matt, it's going to be a guessing game without looking at the car. Get under there and start looking. Understand how things should work, then see if you can see anything out of shape.

jevvy · 04-14-2005, 07:33 AM

Have you replaced your flexible brake hoses?

It could be a tired one with a squshy bit in it that is flexing under load and causing other symptoms

Just a guess

Rondinone · 04-14-2005, 08:48 AM

I had something similar, it turned out to be worn strut cartridges. In my case, I could grab the top of the front wheel(s) when the car was jacked up and push it in and up and hear a click.

Slider79SC · Slider79SC's Garage

OUr BMW had the same issue and it turned out to be bad ball joints. After replacement the issue wes gone.

randywebb · 04-14-2005, 09:43 AM

yes, grab the top & bottom of the wheel...

after that do the same at L & R sides ... report back

lateapex911 · 04-14-2005, 10:01 AM

911s are THE most sensitive to issues with the front end.

Tires and wheels have been eliminated, as have rotors. Dbl checl lateral runout on tehm for giggles though.

Then it's off to suspension land. Lot's of miles, when was the last rebuild of the major components? If more than 50K miles, look seriously at all the connections...Arm bushings, BALL JOINTS, strut top bushes and the struts as well, tie rods, and the steering rack.

Get a friend to help and with the car off the ground, shake each tire in both axis, feeling for slop. Then turn each tire, while observing that the motion is translated to the other side exactly. IF not, find the slop in the steering joints.

It's gotta be in there!