Happened twice since I started driving the car, once to me about 2 weeks ago, once to my wife today.

Driving down the highway, a severe vibration/shake will suddenly appear. It can be felt throughout the car, steering, pedals, ect. Car doesn't run rough or anything during incident. First time it happened I slowed from 75 and proceeded off the highway, vibration stayed with the car til' it was going rather slow, correspondent to vehicle speed. I visually checked wheels/lugnuts tight, brakes looked ok, ect. Finished my drive to work without incident.

Today same thing happened to my wife on the highway, but as she was preparing to pull over, it just went away she said.

I retorqued the lug nuts tonight, and they were all tight enough with just a hair of TQ needed by the wrench.

Thoughts? Ideas??? I've never experienced anything like this before. Car's been running and driving fine otherwise.

 

Torque Tube issues!

Is it RPM or LOAD initiated? Something to think about. That rubber dampener in the center of the shaft can do some weird things.

BC

 

That's kind of what I'm afraid of. The only odd thing is that it's only happened twice, both times the car was cruising down the highway in 6th, nothing to instigate it, and it went away on it's own. The car has been driven MUCH harder than that already with no ill signs being shown. I need to save for a u-jointed driveshaft anyway though.

 

How old are the tires?

 

especially if the issue is on decel....

 

The ring attached to the center of the propshaft is not a damper. It is a shaft deflection limiter. Under hard acceleration or deceleration the center of the shaft can deform. The limiter is designed to contact the torque tube to limit the deflection. If the limiter was not there the shaft could be permanently bent.

When you get this vibration you need to push the clutch in and see if the vibration is still there. If not, then it is something engine related.

Has anything on the differential been changed? How about the output shafts? CV joint can cause this on and off type of vibration.

 

Things that can produce vibration are:

Torque tube issue
Harmonic damper issue
CV output shaft
wheel/tire
Wheel hub
Pilot bearing

Just throwing ideas out so you can consider them.

 

Bill,

The items on your list are good things to consider. Some of them can be eliminated from the list knowing the type of vibration they typically will cause.

Torque tube issue (Propshaft issue)Harmonic damper issueCV output shaftwheel/tireWheel hubPilot bearing

 

My car will vibrate some but only when I'm decelling from 3k rpm to lets say 2.5k rpm. No other RPM but it seems to do it in every gear. Any ideas?

 

Check your tie rods........

 

Nothing has been changed. As far as I can remember, it was happing in neutral clutch out. I can't remember exactly what I did to diagnose though. I was more concerned with getting off the highway asap.

Hasn't happened since and the car was driven last night and today. The thing that really perplexes me is that it happened both times at absolute minimal effort cruise going down the highway.

 

Wife came home one day complain about vibration comes at random while on highway took car to shop 1/2hr ride 15 min highway no vibration e=thing checked ok off and on next couple weeks took again to shop just before got off highway felt it reasonablly severe, gave thorough check e=thing checked ok again decided then a second opinion was needed friend had front end shop put on rack entire front end was checked rear suspension also wheels tires balance... out of round... lateral run out... all checked ok kept car f/week wife got tired of driving my junker and no vib. that week after visit to front end shop he had tweeked a couple things checkjed and adj. wheel brgs. thought maybe he had inadvertently fixed it ...three weeks later while wife was driving on highway front rim broke in a manneer I have never seen before or since nor have I ever heard of a wheel breaking in this manner the center of the wheel with lug nuts was still attached to the rotor the outer part of the rim with tire attached had come off along with a like new michelin it was a stock style steel rim car was only couple years old w/about 25,000 mile. As a new father your presence is required for the next 20 years or so while I doubt this is youre prob. it would be easy to switch wheels/tires w/ a friend (temp. to rule out this problem) also you mentioned some parts are clearance issues you might want to mark those that are close to see if they make contact.Just throwing this out there 'cause it happened to me and a few guys looked over the car including the rims and nobody caught it apparently at rest the crack and was not visible but it fed on itself until it came apart.I never found the rim/tire to examine that

 

I'll take a look at the wheels. They're repro C5's. Nothing strange has happened since the other day and it's been driven both days.

 

This is crazy Fastbird.... i'm running into some serious vibration issues myself right now.

My vibration is repeatable though.
This vibration started really small and intermittantly.
Vibrates on decel any gear at 1700rpm
Vibrates severely in gear accelerating starting around 3500-4000 up. Worse in 1st gear, and progresses as not as bad in each gear up change.
If i push the clutch in while this is happening goes away instantly.
I tried revving the car in neutral and didnt feel with clutch out... so I thought.
I put the shifter into gear and rev with clutch pedal in and revved to 4k rpm and sware I feel a slight vibration.

This all came after a new motor, harmonic balancer, spec twin disc, new pilot bearing ofcourse.

So took the car apart cause it was not speed related. Only RPM related.
Torque tube bushings look ok, clutch was tight and measures 2grams out of balance which is nothing i'm told by the machine shop. Replacing the torque tube with a 12mm Z06 version, replacing the pilot bearing and going back together hopefully today(sunday). I'm really scared I can't figure this one out. If it still does it my guess is I'll replace the harmonic balancer next. Thing is I dont recall the vibration being there when the car first came together. VIBRATIONS SUCK!
Good luck with yours and i'll post my results in hopes it helps someone.

 

What harmonic balancer are you currently running?

Is it pinned to the crank?

Sorry to hear you have a vibration. Any chance of getting the car up on a lift or jack stands and examining the drive train at the point of vibration from under the car?

Bill

 

Bill,

balancer is a powerbond, not pinned. Vibration hasn't happened since the week before last according to my wife. Problem is that it's so intermintent that we can't pin it to drivetrain or suspension.

 

I know it sounds a little far fetched but, Im one that wont rule stuff out until I actually eliminate that as a source of the issue.

Try this:

Put a line (I use white out) on the balancer and the bolt. When the vibration happens again, check that line and make sure that the balancer hasn't moved on the crank.

If it hasn't, you can put that theory to rest and move on to something else.

Bill

 

You know, this sounds familiar. It's is a long shot but I had a similar issue. Mostly happened on the highway in 6th gear at low RPM with some load on the engine. It was a random misfire due to badly worn plugs. Replaced the plugs and the problem was gone. How old are your plugs? Have you checked the gap lately? Mine were around 0.070" when I had the issue.

 

The couple of times it happened it had Autolite 103's and they came out of the car after 500 miles before the dyno tune and looked brand new. Definitely NOT the plugs. Although I did notice that when I pulled out of the garage on Sunday last week after changing a couple of things, the car was vibrating pretty badly, and I had left the passenger side coil harness unplugged. No codes, no nothing, but running on four cylinders. I thought this might have been a pointer in the right direction but my A/F guage doesn't go wacky, nothing. I'd say I'll diagnose next time I have the car out but I simply can't drive it often at all right now.

 

Mine does the same thing except at 3k rpm, I have no idea what it could be though.