What causes my driveshaft to "jump" in this video?

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jcolman

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I'm trying to track down a "whining" noise I can hear when driving. I put the car on jack stands, lifted the differential, and ran the car up to about 40mph, trying to see if I can recreate the noise. I didn't hear the whining sound, but my driveshaft jumps at the :37 mark. Thoughts?

 
Gear changes and changes in the position of the gas pedal.
 
I think it was 1/2 shift ? Normal just like when you put it in gear .
 
I thought it might be the 1/2 shift too but since the rpm didn't change, I wasn't sure. I guess the car has to be under load. Question. Is the driveshaft jumping normal or is the transmission mount the issue like the first reply said?
 
I thought it might be the 1/2 shift too but since the rpm didn't change, I wasn't sure. I guess the car has to be under load. Question. Is the driveshaft jumping normal or is the transmission mount the issue like the first reply said?
Normal. You have nothing wrong, so don't look for something.
 
If it’s a wine your looking for use a stethoscope and an assistant in the car run it up to where you hear the wine and narrow it down but please be careful that spinning shaft is not forgiving!
 
Do you have aftermarket ring gears in the Diff ?
 
How many miles on the new gears??? If it's jumping at each shifting point then it's normal.
 
Here's a video of the "whine" that I'm trying to track down. You can hear it much clearer towards the end, as I'm slowing down.
 
Noise on decel is either too much pinion depth or too little, I can never remember which. You might try dropping the drive shaft and see if there's any slop at all in the pinion yoke, as if the pinion nut is trying to back off. That's actually a pretty common issue. What casting is the case? I "THINK" I see "742" as the last three, but I'm not sure.
 
Noise on decel is either too much pinion depth or too little, I can never remember which. You might try dropping the drive shaft and see if there's any slop at all in the pinion yoke, as if the pinion nut is trying to back off. That's actually a pretty common issue. What casting is the case? I "THINK" I see "742" as the last three, but I'm not sure.
Looks like 2881488?

RQZnokO.jpg
 
I just uploaded a pic
Ok, that last digit is a 9. Although, there was a 488 case, too, it was the same physically as the 489, so both cases are referred to as the 489, since the 489 was MUCH more prolific. Well, I WAS gonna say to maybe just give the pinion nut a few pops with a 1/2" drive impact.....and you still can, but do it CAREFULLY, because that has a crush sleeve. But I'd drop the drive shaft and check for any movement first and report back......and you know what? If there's no excessive play, I'll be damned if I wouldn't leave it alone. That noise is very faint.
 
Ok, that last digit is a 9. Although, there was a 488 case, too, it was the same physically as the 489, so both cases are referred to as the 489, since the 489 was MUCH more prolific. Well, I WAS gonna say to maybe just give the pinion nut a few pops with a 1/2" drive impact.....and you still can, but do it CAREFULLY, because that has a crush sleeve. But I'd drop the drive shaft and check for any movement first and report back......and you know what? If there's no excessive play, I'll be damned if I wouldn't leave it alone. That noise is very faint.
Thanks Rod for the info! Much appreciated! I'm a little concerned about the noise because it's new. It just started about two weeks ago. The car is going into the shop at the end of January for a transmission swap so I'll have them look at it then since they have to replace the driveshaft anyway.
 
Thanks Rod for the info! Much appreciated! I'm a little concerned about the noise because it's new. It just started about two weeks ago. The car is going into the shop at the end of January for a transmission swap so I'll have them look at it then since they have to replace the driveshaft anyway.
I understand the concern now. I would check it out too in that case. It might be a pinion bearing going out and now's the time to catch it, before any other damage is caused.
 
Thanks Rod for the info! Much appreciated! I'm a little concerned about the noise because it's new. It just started about two weeks ago. The car is going into the shop at the end of January for a transmission swap so I'll have them look at it then since they have to replace the driveshaft anyway.
What transmission are you going with?
 
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