Vibration

[trailblz]

I think this is caused by a thrown wheel weight/out of balance situation but I thought I would run it by the board as well.

My car has a slight to medium vibration between the speeds of 55 and 65. Any speed above or below is very smooth.

It just seems too simple....

Thanks.

 

[BennyBlown2v]

Go to the place you bought your tires...they should rebalance your junk at no cost. If that doesn't fix it, post back again

Most likely it's improper tire wear and/or a front end alignment issue.

 

[Mattstang04]

When I bought my car it did the same thing. Same speeds and all. The front tires were badly worn on the outer edge and I had to replace them. If your tires are still in good shape you should be able to rebalance and allign them.

 

[merc123]

Check your air pressure

 

[MBDiagMan]

Tire imbalance is the vibration source in the vast majority of vibration complaints. A thrown weight will certainly cause the problem. If this is what happen make sure that they are using the correct weight type. These days there are about a dozen different clip type weights. Using the wrong type will OFTEN result in thrown weights.

 

[Bolt on 5.0]

You are talking about a steering wheel vibration correct? If it is in the wheel, itll be a wheel balance issue.

 

[BlackenedSVT]

my guess is a wheel vibration like you suggested. But to confirm...its not a drive shaft noise and vibration is it?

What work did you recently have done to the vehicle?

 

[clockstopper]

if it was a driveshaft imbalance, wouldnt it only happen at a certain RPM?

 

[BlackenedSVT]

if it was a driveshaft imbalance, wouldnt it only happen at a certain RPM?

Not necessarily. It would happen at a certain RPM sometimes at a certain SPEED. Like my 98GTs drive shaft would make noise at about 80-85mph, and if you went faster than that or slower it wasn't there.

BUT a driveshaft imbalance is a pretty intense vibration, i think you'd know if it was your driveshaft..

But like i said, what work did he recently have done?

 

[MBDiagMan]

Driveshaft imbalance will not produce a vibration at only one RPM range, it will be at most any speed. If, however, it is a driveshaft vibration it will be at a higher frequency than if the imbalance is wheel related. The driveshaft spins 3 or 4 times as fast as the wheels. The exact factor is the rear axle gear ratio.

AGAIN, when experiencing vibration, ESPECIALLY if felt through the steering wheel, start by checking wheel balance first. A quick way to start is to rotate tires front to rear and see if you still feel the vibration in the steering wheel. If not, then concentrate on the rear wheel balance.

If after balancing the wheels, the vibration remains, go to www.gsp9700.com to find the nearest shop with one of these machines. This machine has a pressure roller that applies 700 pounds pressure to the tire and analyzes road force variation (RFV.) This is basically stiff spots on the tire.

I can tell you from years of experience in chasing vibrations, that the problem is almost always wheel/tire related.

For those rare cases where it is NOT tire/wheel related, probably the next most common cause is driveshaft related. When this is the case it is not necessarily imbalance of the driveshaft. It will often be a worn slipyoke bushing or sometimes simply disconnecting it at the pinion yoke and turning it 180 degrees before reconnecting will cure such a vibration. If it does not cure it, however, put it back like it was.

It's always a good practice to mark the driveshaft, pinion yoke relationship when removing the driveshaft for any reason and then replacing it in the same relationship which you found it. THis is quickly done with a little spray paint.

When it gets past tire/wheel or driveshaft it can get more difficult. One way to see if it is clutch related is to feel the driveshaft at speed and then press and release the clutch and see if the vibration changes. Sometimes changing the relationship of the clutch plate and the pressure plate will change the vibration. If so then the problem is clutch related.

Good luck.

 

[trailblz]

I have not had any work done. Just a couple of hand washes.

The steering wheel is not whats vibrating, it is the enitre car...like a shimmy.

I haven't had a chance to get the tires balanced, but I checked the pressure last week or so and I have it set a 33 psi. Is that about right for 275's front and 295 rear on 18's?

 

[DerekStangGT]

I have not had any work done. Just a couple of hand washes.

The steering wheel is not whats vibrating, it is the enitre car...like a shimmy.

I haven't had a chance to get the tires balanced, but I checked the pressure last week or so and I have it set a 33 psi. Is that about right for 275's front and 295 rear on 18's?

might be the rear tires then. rotate the rears to the front and see if the wheel shakes