vibration from rear above 60

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Shock won't cause a vibration. Driveshaft out of balance? Are the u-joints good? No binding or tight spots in the caps & needle bearings? It may sound simple but are the wheels out of balance?
 
brand new u joints. (driveshaft shop installed them) move freely. I work at a tire shop. Balanced them myself. No hopping even put the slicks on same thing.
 
Im leaning toward the shop you used can't high speed balance, if you're at 3400 rpm when it starts.... there are only 2 machines that can exceed that rpm.
 
Supershafts said:
Im leaning toward the shop you used can't high speed balance, if you're at 3400 rpm when it starts.... there are only 2 machines that can exceed that rpm.
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Well I'm running out of things to check. Last night I put the trans back together with the new bushing (didnt help). Ran it on jackstands with the wheels off, then with the brake drums off, finally with the axles out (same issue). I have a different third member and a different slip yoke to try (labor is free).
 
Are you setting pinion angle in relationship to the driveshaft or the ground?
 

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Unless his pinion angle is beyond 5 degrees at 3400 it shouldn't be a problem, and since he isn't having a issue under load getting to 3400 rpm on the shaft, it's most likely the shop that played with the shafts issue.....

He said earlier that it does it on decel also, it is impossible to go from positive pin to negative pin getting on and off the gas... UNLESS the rear springs are broken (or you have a ford expedition and have rotted links).
So now you rule out playing games with the pin angle, and trans bushing and everything else to make him replace something and its not that...


The driveline shop either didn't do something right or really don't have the ability to balance the shaft properly, or immediately after they re-welded the weld yoke that balanced it and then it cooled and pulled to one side and that will also make this problem. .

I had this same issue with a gentlemen upstate, the shop he used had a machine that can not do any real rpm shafts correctly , so the shafts must be less then .010 and his shaft was just under that, but there machine can't get it at the rpm he was in, so he had to use the long drawn out method but we were able to start at a area since the shop there allowed him to watch so i could tell him where to start with weight.
 
Going through the exact same issue as you. I have made the same changes to my springs and have tried all the same solutions that you have as well. Have you tried throwing it into neutral at the speed it vibrates and just coasting? Does it still vibrate while coasting until you get back below 60? Mine will. I can roll in neutral at 60-70 and it will not stop vibrating until I get back below 55. Im very interested to see what solution you come up with. Thanks.
 
emnestor said:
Going through the exact same issue as you. I have made the same changes to my springs and have tried all the same solutions that you have as well. Have you tried throwing it into neutral at the speed it vibrates and just coasting? Does it still vibrate while coasting until you get back below 60? Mine will. I can roll in neutral at 60-70 and it will not stop vibrating until I get back below 55. Im very interested to see what solution you come up with. Thanks.
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still vibrates in neutral. I put the leafs back to the factory location so the only thing that is different is the torsion bar crossmember. It did not vibrate before the crossmember was swapped.
 
Forgot that I also switched leaf springs (used ss) and added a snuber.
 
skep419 said:
still vibrates in neutral. I put the leafs back to the factory location so the only thing that is different is the torsion bar crossmember. It did not vibrate before the crossmember was swapped.
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this sound like more of a motor problem to me if it doing it in neutral.I cant see were changing the x member would make the motor vibrate:-k are you sure you didn't over rev this one time or another? or maybe cracked the flex plate?from what I have raid you have dun allot of things....Id be cheaking the motor........Artie
 
I can have it in second gear hold 6000 rpm zero shake. 3rd gear 3400 on up vibration.
 
We need a trans expert to chime in here. What part of the trans is not spinning in 2nd gear but is spinning in third?
 
Vibrates while coasting at 60 and above? Mine is directly speed related since it vibrates while idling at 800 and rolling in neutral at 60 mph.
 
skep419 said:
I can have it in second gear hold 6000 rpm zero shake. 3rd gear 3400 on up vibration.
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Wait a minute, if you get to the speed you have a issue and only drop to 2nd gear its gone... ? ? ?

The speed is the same as per mph the only change is RPM at the motor and the front half of the trans and the vibe is gone? then your trans is the problem.
 
Supershafts said:
Wait a minute, if you get to the speed you have a issue and only drop to 2nd gear its gone... ? ? ?

The speed is the same as per mph the only change is RPM at the motor and the front half of the trans and the vibe is gone? then your trans is the problem.
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I was trying to say it was not the engine by saying the 2nd gear comment. It does shake in 2nd at 60. I didn't think how fast mph that rpm was. Sorry for the confusion. I checked the output shaft with spare yoke. Same play. Checked just the shaft for play. Got a lot.
 
I can't get your video to open showing you shaking the output shaft but without a yoke in place they have a good bit of play normally. Hard to say it's as much as yours since I can't get the video to open, just sayin a lot of play is normal with no yoke installed.
 
[ame="http://www.youtube.com/watch?v=4SFuAhBdAm0&feature=player_detailpage"]http://www.youtube.com/watch?v=4SFuAhBdAm0&feature=player_detailpage[/ame]
 
Have you checked thrust angle in the rear axle that could cause that problem to? Also had 2 other thoughts. 1. U joint needle bearing fail out while putting them together and is sitting at the bottom of the joint and causing the you joint to be misaligned on the yoke. 2. Drive shaft is butted up against the transmission while on the ground. It would put alote of pressure on the rear yoke.
 
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