Help! Bad Vibrations

[Copdogcorvettes]

Hi, I'm pulling my hair out trying to figure this thing out. ;help I have a vibration at cruise speed that will make the steering wheel shake. The strange thing is it doesn't happen under power or when I let off the pedal a little; only at a cruise above 50MPH. :bash

Maybe some of you can think of some things for me to look at. Thanks ahead of time for your thoughts. Oh, This is a 78' 4 speed L-48 with the stock rally wheel.

Gary

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[bill81vette]

check your wheel balance...

 

[Copdogcorvettes]

check your wheel balance...

I thought of that; but it doesn't happen under power and balance should happen any time you our at the speed. If I'm running thru the gears up to 80+ no vibration. I am going to change the wheels soon, I have a set of Enkie mesh wheels. I've been waiting to find centers for them before putting them on. So, maybe I'll just go ahead and put them on just the rule that out.

Gary

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[petes74ttop]

Wild Guess!

You might want to check out the fan clutch. PG.

 

[Rodney Gold]

Universal gone bad ? Propshaft or 1/2 shafts.

 

[minifridge1138]

Does it get worse as speed increases?
Does it get worse as RPMs increase?

 

[Copdogcorvettes]

It's at it worse between 60 & 70 MPH; but as I said, ease off or on the gas just a little and it lessens. I feel it most in the steering wheel.

Gary

 

[Vette79]

You might want to check out the fan clutch. PG.

The Fan Clutch??? Why?

 

[Vette79]

Universal gone bad ? Propshaft or 1/2 shafts.

This is a good suggestion. Half shafts or drive shaft balance. Maybe one of the weights came off. Bad universal joint. Wheel Balance.

 

[Evolution1980]

Universal gone bad ? Propshaft or 1/2 shafts.

Would that cause noticeable vibration in the steering wheel? I could understand feeling a shimmy or vibration overall due a problem in the rear, but not so much it the steering wheel. :confused
Possibly he's got something loose/worn in his front suspension or in the steering linkage that's only noticeable when there's no load on it.

 

[minifridge1138]

I have a similar problem on my daily driver. Mine is caused by my exhaust. When cruising, things start to vibrate.
If I speed up or let off the gas it goes away.

The PO put 3 inch magnaflows on and they make the interior shake at a certain mix of RPM and speed.

Has your car always done this or is it something new?

 

[Copdogcorvettes]

This is something new. The exhuast is 69' style side-pipes that has been on the car for about 5 years.

Gary

 

[Evolution1980]

Gary, have you jacked up the front end of the car and gotten under and checked for any play/slop in the suspension or steering components?

 

[gmjunkie]

The Fan Clutch??? Why?

Because they can vibrate and transfer it through the car!!

Would that cause noticeable vibration in the steering wheel? I could understand feeling a shimmy or vibration overall due a problem in the rear, but not so much it the steering wheel. :confused

It can,just depending on the circumstances!!Heck a bent wheel in the rear can feel like it's up front on the opposite side!!

Possibly he's got something loose/worn in his front suspension or in the steering linkage that's only noticeable when there's no load on it.

You could be very well on to something Evo!! First thing I'd check All Control Arm,Trailing Arm Bushings,and Steering Components!! Also I'd check the Motor,Transmission and Differential mounts too, any of them can cause this problem!!

 

[damoroso]

Does it vibrate based on RPM or MPH? If you haven't already, try it in different gears. This should tell you if it's in the wheels and suspension, or, if it's in the power train. Seems like it could be a bad U joint, fan clutch, harmonic dampner or wheel balance, or bearings. Gotta narrow it down some!

Let us know what you find would you?

 

[Rodney Gold]

If you ease on or off the gas and it dissapears , it could be symptomatic of a bad universal on the prop as easing off and applying gas will load the universal and thus take up some play.
Easy way to check is if the car clunks at all when putting it into gear if its an auto. If its a bad universal on a 1/2 shaft , you would generally hear a ticking sound.

 

[howard]

I have a vibration at cruise speed that will make the steering wheel shake.

sounds like wheel balance to me...try swapping wheels front to rear
Could be bad tire, unbalanced wheel/tire

Drivetrain vibration would be felt in the seat of your pants

 

[Copdogcorvettes]

Hi Everyone,

I thank you all for your help. I found the problem: U-joints bad on the drive-line and a minor balance one tire. The pulling to the left was due to the left rear brake flex line was bad, holding pressure on the brake.

I've got it all fixed now but for the u-joints. At least I know what the problem is and just have to find a little more free time to get them replaced.

Again Thank you all for your help.

Gary

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[Rebelrob]

Hi, which U joint. Im not an expert, but arent their several U joints?
My shakes a little as well between 70--75 mph... the tires are over 10 yrs old and its sat for a while.

 

[Copdogcorvettes]

Hi, which U joint. Im not an expert, but arent their several U joints?
My shakes a little as well between 70--75 mph... the tires are over 10 yrs old and its sat for a while.

It's the drive shaft u-joints; which there are two. One front and one rear. There are 2 each on the half shafts for a total of 4 on the half shafts.

Sound like yours is most likely a tire balance problem. Luckily that is easy to fix and doesn't cost much.

Gary