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Driveline Vibration

money pit

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My Barracuda was originally a slant six. I replaced the engine (360), 727 trans, new driveshaft, 8 3/4 rear end and heavy duty leaf springs. I have a vibration above 55 mph. I was wondering if my pinion angle is off. Where is the best place to measure the pinion angle? I watched a number of YouTube videos and they all seem to measure them differently. The vibration seems to be coming from the driveshaft or rear end. Thanks
 

Challenger RTA

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Took a drive shaft of once and put back on and had a vibration.Did a rocket science move.turned the shaft 180 in the yoke. had no problem after that.Don't know why or how but it worked.
 

moparlifer

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My Barracuda was originally a slant six. I replaced the engine (360), 727 trans, new driveshaft, 8 3/4 rear end and heavy duty leaf springs. I have a vibration above 55 mph. I was wondering if my pinion angle is off. Where is the best place to measure the pinion angle? I watched a number of YouTube videos and they all seem to measure them differently. The vibration seems to be coming from the driveshaft or rear end. Thanks
i believe the top of the axle where the pinion snubber bolts is horizontally aligned with the input shaft. unbolt the snubber and put the angle-finder on the flat.
 

money pit

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This should help

Took a drive shaft of once and put back on and had a vibration.Did a rocket science move.turned the shaft 180 in the yoke. had no problem after that.Don't know why or how but it worked.
I just watched the video Chryco Psycho sent. It explains why turning your driveshaft 180 deg solved your problem. Thanks.
 

money pit

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Great video, thanks. It really helped.
I checked all the angles. Everything looks okay. Maybe the engine has a vibration that's transmitted to the driveshaft. I talked to my mechanic. He said to rev the engine and see if there's a vibration. There is a vibration. He then said to put a floor jack under the oil pan with a piece of wood and slightly lift the engine. The vibration is reduced but is still there. The motor mounts are about 2 yrs old but may need to be replaced. Is there anything else I need to look for? I heard the 360 is externally balanced. Are there weights on the torque converter? Or is it balanced with the harmonic balancer? Thanks
 

Adam

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If you have weights on the torque converter, do you need a flex plate with weights?
No, it’s one or the other… but be aware magnum and LA 360 balancers, flexplates, and converters are not interchangeable; they will bolt on but are balanced differently.

You can use a weighted flexplate with a neutral balance converter and vice versa.. also some aftermarket balanced flex plates like the B&M don’t have a weight but remove a piece from the other side to create an offset weight.

 
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Challenger RTA

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That's what I was thinking.Also check rear end and suspension.bad tire it could be any thing wheel wheel bearing. you have to go through a process of elimination. Transmission mount motor mount,alignment.Bad u joint or needs grease,bad saddle.
 
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money pit

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No, it’s one or the other… but be aware magnum and LA 360 balancers, flexplates, and converters are not interchangeable; they will bolt on but are balanced differently.

You can use a weighted flexplate with a neutral balance converter and vice versa.. also some aftermarket balanced flex plates like the B&M don’t have a weight but remove a piece from the other side to create an offset weight.

I'm going to take a look at the torque converter to see if there are weights. I think the torque converter was original to the trans. Thanks,
 

money pit

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That's what I was thinking.Also check rear end and suspension.bad tire it could be any thing wheel wheel bearing. you have to go through a process of elimination. Transmission mount motor mount,alignment.Bad u joint or needs grease,bad saddle.
I've checked the pinion angle, the tires, and the motor mounts. I'm going to check the driveshaft. It's a new driveshaft and U joints. I'm going to check the torque converter to see if there are weights. Thanks
 

Adam

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I checked all the angles. Everything looks okay. Maybe the engine has a vibration that's transmitted to the driveshaft. I talked to my mechanic. He said to rev the engine and see if there's a vibration. There is a vibration. He then said to put a floor jack under the oil pan with a piece of wood and slightly lift the engine. The vibration is reduced but is still there. The motor mounts are about 2 yrs old but may need to be replaced. Is there anything else I need to look for? I heard the 360 is externally balanced. Are there weights on the torque converter? Or is it balanced with the harmonic balancer? Thanks
If you have a vibration when reving the engine while parked then I don’t think it has anything to do with the driveshaft.
 

cuda joe

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to tell if it;s in the drive train ;drive the car in second gear at the same rpm as when you have the problem also i had chrome wheel lugs that bottomed out just as the wheel tightened viberated at 90 mph
 

money pit

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If you have a vibration when reving the engine while parked then I don’t think it has anything to do with the driveshaft.
I'm going to change the motor mounts and go from there.
 
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