Pesky vibration...

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Blackhatguy

Blackhatguy

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1964 dart two door, originally slant 6 with 904 and 7.25 rear end.

When I got it, it had a rhythmic vibration that became appearant at 45 and intensified as speed increases. More prevalent under load but still there on decel.

Replaced all front suspension parts: no effect.
Replaced tires: no effect.

Replaced axle bearings, engine, transmission, motor mounts, transmission mount, driveshaft.. Still there.

The only thing left original is the saggy leaf springs and rear end...

I have plans to put new springs and an 8.8 rear end in the car, but I'm not there just yet. The reason I mention this is because when I get those parts in I will be setting the pinion angle, and there will be no more original parts left in the drivetrain.

Could those last two things be where all those damned vibes are coming from??
 
Mopar-Mitch said:
What engine and transmission combination are you running in it now?
Click to expand...
Magnum 5.9, balanced, with the matching damper and weighted flexplate, 904 transmission with neutral torque converter. Because I have the same vibration before and after the engine swap, and a brand-new driveshaft, I'm thinking the vibration has to be because of the rear end but I'm not sure why. No telling how many miles that rear end has on it though, and the Springs are really sagging..
 
That's why I asked about the engine and Tran's combo, I've seen a lot of mixed internal and external balanced mismatched engine's and torque converters, but it looks like you have that in order. Look's like it may be the small rear, pinion bearing may be failing. Other than that could be a bent or unbalanced rim. Hopefully your rearend swap will cure the problem.
 
Mopar-Mitch said:
That's why I asked about the engine and Tran's combo, I've seen a lot of mixed internal and external balanced mismatched engine's and torque converters, but it looks like you have that in order. Look's like it may be the small rear, pinion bearing may be failing. Other than that could be a bent or unbalanced rim. Hopefully your rearend swap will cure the problem.
Click to expand...

Or a bent axle.
 
Have a schmart phone? Get this app.
AC57AFFE-1004-4956-AEBB-B5CBECE9D450.png
Will help you with finding driveline angles.
45 mph and up seems like a pinion angle/diff issue. Check for a bent axle too.
 
check pinion angle.this is very important.if you dont know how ask.2-3 deg down will be good
 
There are wedges you can buy, they are cheap,will aid with diagnosis. Will need u-bolts to go with, unless you have had them apart recently.
 
Tooljunkie said:
There are wedges you can buy, they are cheap,will aid with diagnosis. Will need u-bolts to go with, unless you have had them apart recently.
Click to expand...
Next time I have time to do so I'm going to jack up the car and check the pinion angle against the transmission. That very well might be the case. Otherwise, it might be the pinion bearing after all because there is a little bit of play. It didn't feel like a whole lot by hand, but at 3000 RPM that might be plenty of room the wiggle
 
Should be no play in the pinion.
Preload takes all the play out.
If it has play, its not long fir this world. Would be cheaper to fix it Before it kabooms.
 
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