Driveline vibration at 80mph

[67+05CaddyV]

My V has an annoying vibration at about 80. Put it in neutral and it's gone. Touch the gas and it's back? It vibrates up through the steering wheel and seems to vibrate through the cabin and cycles about 1/2 sec. The tires were balanced a few months ago but this is the first time I've had a chance to drive it. Has anyone had to replace the rubber dampers between the driveshaft and trans? - thnx

[CTSV_510]

There was an issue with 6th gear causing vibrations in some cars. I assume this was in 6th gear, did you try 80 mph in 5th?

[NormV]

I heard that one of the previous owners thought that compeased air at each corner would support amphibious adventures.

The pause in resonance are surely tires. Just have to replace them to get rid of it. Happens to some of us after a track weekend where the tread blocks create some weird harmonics.

Norm

[Maximusthefarmer]

I have the same thing but mine goes away actually at higher speeds, only seems to be present at the interval of about 80-85. No idea what mine is from, I have brand new tires less than 500 miles and still the same.

[StealthViggen]

I have it right now too. Freshly balance wheels, same thing, winter wheels, same thing. What was this 6 th gear issue that caused vibration? Anybody have any info on that?

[CTSV_510]

I think it was a TSB. Yup, here: http://www.cadillacfaq.com/faq/tsb/data/pip3425.pdf

[rlj5]

Originally Posted by CTSV_510

I think it was a TSB. Yup, here: http://www.cadillacfaq.com/faq/tsb/data/pip3425.pdf

Ya, I had that. Had to carry in the tsb & show them before I could get anywhere with them. They reindexed the drive shaft about 20 times and finally ordered a new tranny under warranty.

Don't have a warranty anymore though

[AlmostAV]

my headers touch my steering shaft or w/e its called, this may cause the vibration.....just a thought

[PISNUOFF]

Mine had it bad and went away after having the tires spin balanced. No vibration at all now all the way to 150.

[dqw1]

Originally Posted by PISNUOFF

Mine had it bad and went away after having the tires spin balanced. No vibration at all now all the way to 150.

Same here. I went to a different shop, told them what my symptoms were and they cleaned up the vibration with a "re-balance". If you went to a different shop and the issue remains then the TSB may be valid.

[67+05CaddyV]

It sounds like getting a rolling balance done is the first step.
I had one done before on a previous car for about $100 bucks.
I'll see if 5th at 80 has the same vibration that might point to re-indexing the shaft(s). The TSB helps explain it a bit.

BTW, even inflated tires couldn't keep it afloat.... an entire wiring replacement has all but two issues resolved

[ewill3rd]

GM forces us to have a tool on hand called "EVA", and a newer version most shops have, "EVA 2".
You punch in some data on gear ratios and tire sizes then take it for a road test with a g-force sensor.
It will identify the culprit if they can't pin it down by guessing.
I use it on real problem cars, have found some really weird stuff with it.

[rb1]

By the way you origionaly described it, it stopped vibrating in when off the gas or out of gear. It can't have anything to do with the tires. Mine vibrates at a slower speed (50-65) in both 5th and 6th. I think its the driveshaft needing a balance. No warranty!

[ewill3rd]

There are a lot of ways to isolate the source of a vibration.
If it does it in gear but not out of gear it cannot be the propshaft (drive shaft). The propshaft would still be rotating at the same speed.
It would have to be in the transmission or possibly something in the engine that is felt more with something else setting up a bit of assistance for it.
If you are sure the vibration is not there at any other time than in 6th gear at 80 mph then the choices are cut back, remove the propshaft, diff and tires and you have even less to look at.
EVA would really be helpful in your case.

If the car is under warranty this should be a covered repair unless it is something you did to directly affect it, propshaft or not.