Pulsating vibration above 60 ?

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mbaird

mbaird

mbaird
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My Barracuda has a harmonic vibration over 60 mph (3000 rpms) that I can feel in my seat .
It is rythemic... but slight .

I have checked my angles and had driveline shop check them .
Same shop built driveline.
Axles are Mosers with Green bearings.
Springs and shocks are new.
No vibration revving engine in neutral.
Happens with both my drag radial and michelins ( different rpmsdue to size differance) .

Possible that Shop messsd up but he has been doing my stuff for 30 years.
 
I would think those would make a constant vibration. And it does not vibrate revving in neutral.
Trany mount is a stock rubber one. New as well.
 
Try taking the driveshaft loose & rotating it 180* at the rear axle.
 
Look at pinion angle again, maybe install some shims to see if it gets worse or better. Is the transmission yoke side of driveshaft new also?
 
Dragging brake or drum/rotor out of round. An infra-red thermometer would find it.
 
Are you sure the engine isn't just running lean (or even rich?) at that highway speed? You're certainly running on the main jets at that RPM. What happens if you vary the speed?
 
I had the same problem. Ended up being an endplay issue. I got everything up to temp with a drive then adjusted all the endplay completely out of the axle setup. I think .008” is spec. Fixed the problem. I see you are using the green bearing setup. What is your end play? If I recall no ability to add preload correct? I have a feeling mine was related to wear in the splines and when I loaded the center button in the center section everything sort of snugged up. Just my guess
 
DARTGAME said:
Look at pinion angle again, maybe install some shims to see if it gets worse or better. Is the transmission yoke side of driveshaft new also?
Click to expand...

Had my driveline guy check the angles and add a shim... still has vibration . Unless he did it wrong ???
 
I am running rear disc brakes ... dont think its there but I could check...
 
Have used 3 different center sections . Same problem around 3200+ rpms.
 
What is the trans angle and the diff angle. R u just using factory leaf springs? Don’t even look at the drive shaft angle, just pretend it’s not in the picture. Kim
 
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