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Ive had the problem for about a year, & have done the the same stuff most uf us have. (rotating, aligning, balancing, & changing tires) & nothing has worked.

Two days ago, I had to take the car to the electromechanic to check for codes. & since Ive had a reprogramed computer from Itense for a long time, decided to get it installed.
Now, with the old computer the vibration would hapen in the 50-60 mph now it went down about 10 mph.
So now it vibrates in the 40-50 mph.

What Im guessing is that since the computer changes the shift points & moves them down, then the problem should be inside the tranny. & if Im guessing right its on the 3rd gear that the vibration happens.

Let me hear opinions on my theory.

My 65 MPH shimmy problem dates back to "pre-Intense PCM" install. Also, try this: Drive to a speed well above the vibration zone and then move to neutral and coast. When I did this the car still shimmied when it coasted into and down through the shimmy zone.

On rare occasions I have found the shimmy occuring at right about 50 MPH.

Someone once said a shimmy in the steering wheel is usually stemming from the front end while a shimmy in your seat is usually stems from rear end. Everyone in the car will feel the shimmy - the whole car is shimmying.

I have major rear suspension issues that I haven't attended to yet (clunking, clacking, cracking, and occassional rubbing sounds with a similar frequency as the shimmy) so that's my guess for now. Once my budget allows I'm planning on replacing the rear end-link adjuster arms and lower control arm bushings, and for a third time the upper shock mounts.

Gawd I hope we figure this all out. I'm getting tired of driving with my teeth clenched all the time.

By the way Alex, I really like your hood scoop - I've never seen a nicer one on a Bonneville. Blends in nicely with the front grill of the car.

First, thanks for the compliments.
& back to the topic, I dont think we have the same problem. My vibration only occurs while Im accelerating & if I let go of the gas, most of the vibration goes away. If I trow it to neutral, it completley goes away. If Im deselerating, I dont feel nothing.

Sounds like a tranny issue to me. Not sure what could be causing it. The only way to fix it would be to put a different tranny in, as it sounds like a planetary gear issue.

Yeah like I said b4 99% of my shake went after my trans was redone the other .1 I can live with LOL

http://www.tripleedgeperformance.com/4T ... _Info.html

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