Vibration inside car!!! Help and Advice Please

[Donald91tbird]

Hey there,

I own a '91 T-bird... V6 3.8 mileage: 145,000

Now everytime I take it for a ride It has a vibration feel thats really intense... So Intense that I can see my rear view mirror VIBRATING! meaning I can't really see thru it. Now I like to think thats it my stereo but it happens regardless of the music blasting.

This happens at certain speed above 20mph


Is there any way to resolve this?


I don't know much but my owner's manual says to repair the driveshaft?
but i need some experienced person's opinion and advice on how to do it.


Thanks guys.
-Donald

[97Bird]

First thing is to have the tires balanced and checked for being out of round. A previous owner may have flat spotted them.

[flewthecoupe]

I would check the lugnuts first...

[RickwithaTbird]

Im guessing you need a tranny and torque converter flush and refill. But only if the rest of this is right.....you said "at certain speeds over 20 mph" .. like if youre just cruising at one speed it will randomly happen? does it ever happen during acceleration?.....(im guessing no)... does it happen most at about 35? and up to say.. 60-65?

[flewthecoupe]

An aod going bad won't typically cause that severe of a vibration. The 4r70w may cause vibrations during upshifts due to not having mercon 5 but I've never heard of it being as bad as described. Could be wrong but I'm betting on loose lugnuts, out of round tires, out of balance tires, mud stuck inside the rim, lost a weight on the driveshaft, bent half shaft, etc.

[RickwithaTbird]

you obviously know more than I do, but when my tranny shook my car before i had it flushed, it got pretty bad. even to the point where the mirror was vibrating, and it was really loud, and shook the steering wheel. the flush solved it all. Youre probably right though, I just couldnt tell what he meant from his description.

[flewthecoupe]

Not saying I know more than you or anyone else, just haven't ever seen a tranny that bad but have seen the rest of the problems I listed.

[RickwithaTbird]

lol, im not saying you said you know more than I do, but Im saying that you do.. hehe... you definitely do.

[flewthecoupe]

Gotcha lol ... and thank you.

[Donald91tbird]

actually it happens when im cruising and it does happen above 35... Is driveshaft a concern? If so, whats your opinion?

appreciate the advice too.

[solaris=amazing]

From what i've experianced, if you get vibration (feels like you've run over several metal strips) at speed between 30-35 and 60 to 70, that is definetly the tranny needing a COMPLETE flush, including the torque converter-and having the entire tranny filled with mercon 5 (mercV). Then, it will take 100-300 miles of driving to work in the fluid, and for the vibration to *slowly* fade away. It wont happen right away, ok, it took me about a good 5-7 days to notice the vibration (transmission shudder) to fade away.

Does it still happen?? Yes, instead of happening EVERYTIME, it happens maybe 1 out of 10 times in the 30-35mph range, but is completely gone in the 60-70mph range. AND it is not even apparent as a heavy vibration, it's very very light.

What i did, was go to AVIS Lube, and had what i described done to it. They replaced everything and also put in new filter/seals in the torque converter. This cost me around $90 or so. This should be done every 20-30K miles.

PS.. I have a 95 4.6, and check the obvious also.. loose lug nuts.. dirt in wheels.. basically anything funny. My vibration was just as bad as you described, AND my steering wheel would shake like Rick said.