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Discussion Starter #1
Hey Guys, I've noticed a high rpm vibration right around 5500 rpm in first gear and wonder if it's possible with a C4? I tried to duplicate that vibration in Drive and went all the way up to 90 mph and didn't feel a thing....so I ruled out tires not balanced right and my drive shaft has new U-joints in so figure that might not be a problem either.

I feel the vibration more in my seat then anywhere else.
 

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Not sure I follow when you get it. Sit in Park or Neutral and slowly rev through your range. Vibration? Then it's between your pullies and your torque converter. No vibration in Park? Then it's behind your torque converter, and most likely between your ouput shaft and your rear axle pinion - assuming you're sure the balance and straightness of your wheels/tires/axle flanges is positively good.

David
 

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Discussion Starter #3
Hiya PSIG,

The vibration shows up around 5500rpm when I floor it in 1st gear driving down the road. If I floor it in drive I never get the vibration even if I'm going 90 mph.

I'll try your method and see what happens....seems like a great way to determine which area.

Thanks!
 

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But are you doing 5500 rpm's @90mph?
 

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Discussion Starter #5 (Edited)
I don't think so Stuart but I'll find out, I've got to do some house chores first this morning then I can see how things work out on the 66 after that.

Hell with the house chores for now....just got back after running her up to 5500rpm and didn't feel a thing but I did notice it didn't want to go any higher then that while sitting in park. With this 289 being bone stock inside is that normal even if it's got 101K on her?

I did also notice a belt tensioner making quite a bit of noise at that rpm but it slowly stopped and quieted down so that tensioner will be replaced soon.

I wonder if I turn the drive shaft 180 and hook her back up if that'll fix high rpm vibration?
 

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I wonder if I turn the drive shaft 180 and hook her back up if that'll fix high rpm vibration?

The drive shaft is not your problem.

5500 rpm on an older engine is asking for bigger problems.

I am surprised the pistons aren't shaking hands.
 

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Hiya PSIG,

The vibration shows up around 5500rpm when I floor it in 1st gear driving down the road. If I floor it in drive I never get the vibration even if I'm going 90 mph.

I'll try your method and see what happens....seems like a great way to determine which area.

Thanks!

I know whats going on.

You're so damn scared that your whole body quakes in fear of going 90 in first gear.... LOL :)

I have same Vib in my falcon 5 speed in 4th and 5th gear. not in 1 2 or 3 though even though I can hit about 85 in 3rd.
 

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Discussion Starter #8
your a lot of help FE.....:)

Guess I won't push her that far then and fix it later when I get a new engine and tranny in. I plan on rebuilding the rear end too so maybe it'll get fixed when I change every part anyway...LOL!
 
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