trying to identify driveline vibration at higher speeds...

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MustangNJ

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so I was really paying attention to the vibration in the car, and I'm a bit stuck....

when I approach 59-60mph on the throttle, my rear louvers start vibrating like crazy.  if I ease off the throttle it stops.  to get the louvres to vibrate seems to require a combination of speed 59mph+ and being on the gas pedal....

recently I've replaced the suspension( springs, and shocks) control arms etc.  I have also had a computerized alignment and wheel balance completed.  The car tracks dead straight at highway speed.  the vibration is only minimally being transferred through the steering wheel, so it seems its in the back end somewhere.

at first I thought it was the wind causing just the louvers to vibrate, but now I'm pretty sure its something in the driveline, like the driveshaft being out of balance, but not sure how to explain the vibration going away at speed, but off the throttle.

any ideas?  thanks

 

kcmash

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First choice would be u-joints on the driveshaft. Do you hear a clunk or ping when going from forward to reverse?

Other option is tire balance. If you go above 60, does the vibration go away.

1) If the steering wheel is shaking it is the front tires,.

2) If the body/seat is shaking without the steering wheel, it is the rear tires or u-joints.

My bet is the u-Joints

kcmash

 

Don C

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+1 on the u-joints being the most likely. If it's not the u-joints let us know, we'll run through other options.

 

Don C

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If the ring or pinion gear were severally pitted they could be the cause. The pinion bearing is also a possibility, due to the pinion seal leak. A pinion seal leak is often caused by a bad pinion bearing.

I would start with u-joints, though, start with the simple and work your way up.

 
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NOT A T5

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so I was really paying attention to the vibration in the car, and I'm a bit stuck....

when I approach 59-60mph on the throttle, my rear louvers start vibrating like crazy.  if I ease off the throttle it stops.  to get the louvres to vibrate seems to require a combination of speed 59mph+ and being on the gas pedal....

recently I've replaced the suspension( springs, and shocks) control arms etc.  I have also had a computerized alignment and wheel balance completed.  The car tracks dead straight at highway speed.  the vibration is only minimally being transferred through the steering wheel, so it seems its in the back end somewhere.

at first I thought it was the wind causing just the louvers to vibrate, but now I'm pretty sure its something in the driveline, like the driveshaft being out of balance, but not sure how to explain the vibration going away at speed, but off the throttle.

any ideas?  thanks
Sorry, no idea but if I were to guess...U-Joints!

About your alignment...can you please post the print-out or at least the specs where they set it to? Thanks!

 

73pony

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so I was really paying attention to the vibration in the car, and I'm a bit stuck....

when I approach 59-60mph on the throttle, my rear louvers start vibrating like crazy.  if I ease off the throttle it stops.  to get the louvres to vibrate seems to require a combination of speed 59mph+ and being on the gas pedal....

recently I've replaced the suspension( springs, and shocks) control arms etc.  I have also had a computerized alignment and wheel balance completed.  The car tracks dead straight at highway speed.  the vibration is only minimally being transferred through the steering wheel, so it seems its in the back end somewhere.

at first I thought it was the wind causing just the louvers to vibrate, but now I'm pretty sure its something in the driveline, like the driveshaft being out of balance, but not sure how to explain the vibration going away at speed, but off the throttle.

any ideas?  thanks
Sorry, no idea but if I were to guess...U-Joints!

About your alignment...can you please post the print-out or at least the specs where they set it to? Thanks!
Here is a good thread on alignments. Post 16 has what mine ended up being set at and I am very happy.

https://www.7173mustangs.com/thread-alignment-specs?highlight=alignment

 

73pony

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And yes. U-Joints most likely the cause. I was having the exact same issue, right around 60 would start vibrating in my seat and the rear view mirror was difficult to see out of. Replaced both u-joints and double checked driveline angle. Solved the problem.

 
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I had a vibration at around 60 and it ended up being the transmission mount. It was really old and coming apart. I’m sure the others are probably right about the ujoints though, especially if you are hearing a clunk. But something else to check, plus they are really inexpensive, about 10 bucks. Good luck!

 

NOT A T5

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so I was really paying attention to the vibration in the car, and I'm a bit stuck....

when I approach 59-60mph on the throttle, my rear louvers start vibrating like crazy.  if I ease off the throttle it stops.  to get the louvres to vibrate seems to require a combination of speed 59mph+ and being on the gas pedal....

recently I've replaced the suspension( springs, and shocks) control arms etc.  I have also had a computerized alignment and wheel balance completed.  The car tracks dead straight at highway speed.  the vibration is only minimally being transferred through the steering wheel, so it seems its in the back end somewhere.

at first I thought it was the wind causing just the louvers to vibrate, but now I'm pretty sure its something in the driveline, like the driveshaft being out of balance, but not sure how to explain the vibration going away at speed, but off the throttle.

any ideas?  thanks
Sorry, no idea but if I were to guess...U-Joints!

About your alignment...can you please post the print-out or at least the specs where they set it to? Thanks!
Here is a good thread on alignments. Post 16 has what mine ended up being set at and I am very happy.

https://www.7173mustangs.com/thread-alignment-specs?highlight=alignment
Thanks Jason, I've read all I could find on here.

 

MustangNJ

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1973 Mexican Mach 1 ( final confirmation TBD), 351C
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I did a resto-mod on my '90 Bronco last year. it also had a vibration above 60mph, in that case it was caused by a driveshaft out of balance and a completely worn out rear diff, but the real clue there was the whine that would develop at highway speed.

 

MustangNJ

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1990 Bronco, Eddie Bauer, 306ci
1978 F150 Ranger, 545 Stroker
1973 Mexican Mach 1 ( final confirmation TBD), 351C
[url=https://ibb.co/kqFMPqf][img]https://i.ibb.co/GCjFrCL/pic1.jpg[/img][/url]
drove the car today with replacement u-joints and a rebuilt diff. man this car is dead smooth. its amazing really. I have no driveline vibration at all now. zero. took it up to 70mph today. I was impressed. my louvres are still rattling like little bastards over 60mph, but at least I now know its not because of a rear end vibration. its the louvres themselves. not sure what I will do about it. no I am not going to remove them.

 
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