Need ideas; Vibration trouble [Archive] - SaabCentral Forums

: Need ideas; Vibration trouble


99Saabnut
14th December 2007, 05:16 PM
The patient:

2002 9.3 SE Convertible
16X7 Sport Edition wheels
Dunlop SP Winter Sport 3D Winter Performance Tires; 205/55/16

OK, so I have a problem with vibrations; not the good kind. I took it to a shop today and had the wheels and tires balanced on a Hunter 9700; so they are as balanced as they can get. This issue seems to have started abruptly about 4-7 days ago. It wasn't gradual or anything. I parked the car after my commute home one night; the next morning I left the garage and noticed it once I reached about 38-40 mph...

The vibrations start during acceleration at about 40 mph. If the car is under throttle; then the vibrations strengthen up to 60 mph; and are still very noticeable to about 70 mph. If I am just cruising; maintaining speed; then the vibrations are much more minor, but still constantly noticeable during the entire range. If I am coasting then you can just barely feel it; I cannot guarantee it isn't more than just variations in the road at that point as the shake is so minor.

The biggest thing I noticed while testing today was this: The vibration is most noticeable through the body of the car and through the gas pedal itself; it is almost non-existent through the steering wheel.:o

I have a brake issue currently; one caliper is not working and so the pad is gone on that one. It is the left rear. I considered that maybe uneven wear on rotors is causing this; but if so wouldn't it be minor from the back? This shake is strong enough to make hard acceleration feel truly dangerous, as if the car is almost out of control. If a rotor in front were worn unevenly; wouldn't it show up through the steering wheel more? Just thoughts I had, not sure if they are accurate.

I hope I explained this well; if not feel free to ask me anything I forgot. I could use some ideas; and ways to test them out so I can figure out where this is coming from. Thanks in advance! :cheesy:

kpa2004
14th December 2007, 05:23 PM
Engine Mount mabye? Take a crow bar to each one and pry on them in the direction they would absorb the engine vibration.OR you have a warped rim?

tucksayre
14th December 2007, 05:26 PM
I'm a little confused about how you are feeling it? Is the car litterally shacking you as you drive?

So the vibrations are shaking the car? or are interior pieces rattling (common complaint about SAABs)? Any modifications to the car?


Could be messed up rims? (hit anything lately?) Did they check tire pressure (a tire running low can mess up everything)?

99Saabnut
14th December 2007, 05:42 PM
Engine Mount mabye? Take a crow bar to each one and pry on them in the direction they would absorb the engine vibration.OR you have a warped rim?

I had thought that may be it but I didn't know how to check them. I'll do this this weekend and see, thanks.

earthworm
14th December 2007, 05:46 PM
Check the rear wheel balance; from what you say, the fronts are OK.

hkayssi
14th December 2007, 05:50 PM
I had thought that may be it but I didn't know how to check them. I'll do this this weekend and see, thanks.

Well, if you put someone in the car while the hood is open and you tell them to put the car in reverse then forward, you can see if the engine moves alot front to back or side. Bad engine and transmission mounts get soft and crack with time.

99Saabnut
14th December 2007, 05:50 PM
I'm a little confused about how you are feeling it? Is the car litterally shacking you as you drive?

So the vibrations are shaking the car? or are interior pieces rattling (common complaint about SAABs)? Any modifications to the car?

I cannot swear that the body of the car is actually shaking, but that is what it feels like. I have pushed the car at near WOT and watched/felt the steering wheel carefully to be sure I wasn't crazy; but it doesn't shake; or it only transmits what is already through the seat; floorboards etc.

I know it sounds strange, but that is the best I can describe it. Not interior rattles no; in fact I only have 1 noise in the car, from the driver's door comes a clunk now and then; but this doesn't make it happen (it is more from quick acceleration/deceleration I think)

Oh, and no mods yet no.


Could be messed up rims? (hit anything lately?) Did they check tire pressure (a tire running low can mess up everything)?

Haven't hit a thing recently; I checked tire pressure this morning; and all are within a hair of 35 psi. If it was a bent rim (still possible I suppose) wouldn't the issue have changed once the wheels were rotated?

Hmm, just re-read my original post; and I forgot to mention that sorry ;oops: . I had the shop balance and rotate the wheels today; assuming if it was a bent rim I would be able to tell if the problem moved or changed. It still seems exactly the same; though perhaps a very small amount gentler.

99Saabnut
14th December 2007, 05:53 PM
Check the rear wheel balance; from what you say, the fronts are OK.

All 4 were balanced, and rotated front to back/back to front (directional tires). Sorry again that I forgot that earlier ;oops:

Another thing I hadn't mentioned; but these wheels and tires are near brand new. They have exactly 1 month of use on them as of today; and maybe 2000 miles. They did not have any issue when put on originally; as I said this just started.:cheesy:

Thanks again for the ideas and help so far!

G96nt
14th December 2007, 05:57 PM
Axles, carrier bearing, Ball joints, or Tie rod ends. Start lookin' around there.

My car shakes pretty bad when the tread gets low, too, because of the wider tires n' all.

Leon
16th December 2007, 12:24 AM
Alignment my friend! I had all 4 tires rotated, re-balanced, etc. Still the tires shook and I felt it in the wheel. For some reason, my tires were wearing in the front and back on the inside, sort of like I had negative camber like those sports cars you see with insanely tilted inward wheels. Remember, get a 4 wheel alignment, even though the rear is NOT adjustable, and only the TOE is adjustable in the front, they need to and SHOULD make reference to the rear wheels so they can compensate for it, if any, in the front. Good luck! Oh yea, my alignment fixed it for me! I think it'll fix it for you too! :p

mikey9864
16th December 2007, 01:50 AM
This is not a directional tire is it? It will shake the devil out of you if they are turning backwards. Look for an arrow on the side of tire. I don't specifically know this tire. Just checking. Also, I have seen tires be out of round. You should be able to tell when balancing, look for up and down motion instead of side wobble., especially if you came to a sudden stop recently. The belts can seperate internally and cause this. Definitely have your alignment checked. Its somewhere in the rear if you don't have vibes in the steering wheel.

Saabohème
16th December 2007, 01:59 AM
Coasting at speed rules out balance fairly effectively and isolates the problem to the drive line usually, although motor mounts and tie rod ends are still suspect too. Since the problem only manifests itself when the engine is under load, I would check the companion flange on the passenger side first. Also, check the control arm bushings. I hate this issue. The cars are exceptionally sensitive to wider wheels. I replaced a number of components after going to 17x8's, including the rear and right side motor mounts, the companion flange, the half shaft on the passenger side and both tie rod ends. All of these had failed or were marginal at best, so the problem was sort of a blessing by calling my attention to these issues before catastrophic failure occurred. The improvement was monumental, BUT there is still slight vibration near 65 mph. The hammering accelerator pedal is gone, but steering wheel shake is noticeable at the magic (cursed) speed. I will say that changing back to 16x6.5 for the winter improved things even more, notwithstanding that my Vikings have been beaten into submission over the years. One of them took a pothole blow so hard that the tire deflated and I had to hammer it out at a gas station to get it to hold air. It has an enormous amount of balancing weight on it.

mikey9864
16th December 2007, 07:49 AM
ROF (run flat tires) , I have seen do this also. Tried to edit my last post but, I could not. Hope all this info helps. At least you have a project for the weekend huh?(lol) Not really that funny though. I hate the problems that go away when you stop.

99Saabnut
16th December 2007, 01:10 PM
Thanks again all; I have a lot to look at :cheesy:

These are directional tires yes; though I installed them myself so I know the arrow is right :D Alignment was done recently; but I'll keep that in mind if nothing else works or shows results.

Thanks all!

AZR Racing
16th December 2007, 03:55 PM
try running the car about 3500rpm out of gear, not moving. if its kinda like a pulsing vibraton, you could be needing a harmonic balencer. this is located behind the crank pulley

earthworm
16th December 2007, 04:12 PM
Welcome to SaabCentral, AZR Racing.

Good suggestion - along the lines from Saaboheme....

Isolate the problem by coasting at 65 mph, that will clear the wheels/tires if the vibration diminishes quite a bit..

Checking the joints, bushings, mounts can be done "statically"... I'd prefer using the crowbar or a lever...but the mounts are soft, so one must know the wear limits.