speed sensitive vibration after swapping center section
#712831
05/31/10 09:57 PM
05/31/10 09:57 PM
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Joined: Jan 2003
Posts: 1,771
Jamestown, Indiana
James74
OP
top fuel
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OP
top fuel
Joined: Jan 2003
Posts: 1,771
Jamestown, Indiana
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So I bought and swapped out a used center section last fall. Since then, I have noticed a speed sensitive vibration, that occurs between 60-70 mph. Its nice and smooth cruising along at 55. As soon as I creep above 60, the back window/package tray starts vibrating. Can't really feel it in the steering wheel or the rest of the car. Past 70, the vibe sound stops. Stats are : 74 roadrunner, 8 3/4 489 center section. Switched from 3.23 suregrip to 3.91 suregrip. I did have to swap yokes between the two center sections, and just bolted them on as tight as I could. The vibe is not there when revving the engine, and occurs at the same speed if I hold the car in second (different rpm). I've swapped tires with the ones on my Duster, and it was still speed related, not rpm related. I've tried adjusting and readjusting the axle adjuster, but doesn't seem to make much difference. The driveshaft is the old original, U joints were replaced a couple years (probably 8k miles) ago. Not sure if I should start with the driveshaft, the axles, the pinion, or something else? brake drum? Any ideas would be appreciated 
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Re: speed sensitive vibration after swapping center section
[Re: James74]
#712834
05/31/10 11:02 PM
05/31/10 11:02 PM
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Joined: Feb 2003
Posts: 10,220
Someplace you aren't
SomeCarGuy
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 10,220
Someplace you aren't
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If I read that right, you are saying that you took the yoke off and didn't change the crush sleeve?
I want my fair share
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Re: speed sensitive vibration after swapping center section
[Re: James74]
#712837
06/01/10 12:03 AM
06/01/10 12:03 AM
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Joined: Nov 2009
Posts: 2,275
Desert Tracker
HYPER8oSoNic
top fuel
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top fuel
Joined: Nov 2009
Posts: 2,275
Desert Tracker
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Quote:
So I bought and swapped out a used center section last fall. Since then, I have noticed a speed sensitive vibration, that occurs between 60-70 mph. Its nice and smooth cruising along at 55. As soon as I creep above 60, the back window/package tray starts vibrating. Can't really feel it in the steering wheel or the rest of the car. Past 70, the vibe sound stops. Stats are : 74 roadrunner, 8 3/4 489 center section. Switched from 3.23 suregrip to 3.91 suregrip. I did have to swap yokes between the two center sections, and just bolted them on as tight as I could. The vibe is not there when revving the engine, and occurs at the same speed if I hold the car in second (different rpm). I've swapped tires with the ones on my Duster, and it was still speed related, not rpm related. I've tried adjusting and readjusting the axle adjuster, but doesn't seem to make much difference. The driveshaft is the old original, U joints were replaced a couple years (probably 8k miles) ago. Not sure if I should start with the driveshaft, the axles, the pinion, or something else? brake drum? Any ideas would be appreciated
As Stumpy replied, check the driveshaft position
then check for a dented shaft or missing weight pad. If all are satifactory, check bearing play at the pinion (yoke end) and check the crush sleeve against specs.
"Stupidity is Ignorance on Steroids"
"Yeah, it's hopped to over 160" (quote by Kowalski in the movie Vanishing Point 1970 - Cupid Productions)
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Re: speed sensitive vibration after swapping center section
[Re: James74]
#712839
06/05/10 11:09 PM
06/05/10 11:09 PM
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Joined: Jan 2003
Posts: 5,791
Hamilton, Ontario Canada
Magnum
master
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master
Joined: Jan 2003
Posts: 5,791
Hamilton, Ontario Canada
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If flipping the shaft 180 deg works. You are a lucky man.
You replaced it and now the vibration is gone. That tells me the old one is not balanced.
Find a driveshaft shop that can balance it. With steep gearing better than perfect balancing at a minimum.
69 Super Bee, 93 Mustang LX, 04 Allure Super
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Re: speed sensitive vibration after swapping center section
[Re: Magnum]
#712840
06/06/10 06:53 AM
06/06/10 06:53 AM
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Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
1MYTGTX
master
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master
Joined: Jan 2003
Posts: 3,967
S.I. N.Y.
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Im kind of going through the same issue right now.
I had swapped out a spare 3.23 center section & spare small yoke driveshaft temporarily till I fix my broken 3.55 unit.
With the 3.55's I too had a cyclic vibration at pretty much the same speed as you. Swapping in this spare stuff the vib is 98% gone!
Now by process of elimination I will start by having my original shaft balanced (even though it was a brand new built unit about 5 years ago) im hoping its that & not my gearset....
1MYTGTX
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