Is my 8 3/4 rear dying?

[DAmatt]

After 5 months of bureaucracy, I finaly got my plates and took my Charger for its maiden voyage.

I get the most horrible sound from the rear, which I can only recall from our communist busses 30 years ago, both when accelerating, and when letting off the gas.

Needless to say my trip was cut short, I originally thought I ran out of oil (car sat for 4 months, leaks were on the floor), but when I arrived home to check the diff fluid level, it was at the brim! Got me wondering how could it have leaked, you can't overfill the diff now, can you?

Anyway, on the last hundred ft I had the idea to record a bit, you can't hear the wine because the engine was louder pulling uphil, but believe me it's there. When I let off the gas you can clearly hear it.

What might it be?

Please don't say I have to setup the diff...

If all comes to worst, please suggest me the easiest, simplest option, even if it's more expensive - there is NOBODY in a thousand miles who knows how to work on American cars, let alone specialized in mopars. All I have is myself, and support from general mechanics.

I'll post a link to the short clip:

https://youtube.com/shorts/n2vbm7DxvPs?feature=share

P.S.: when the car was restored, there were troubles with the diff's setup, but finally the jag dealership who undertook my project found someone who made it work, I took it for a drive a couple of miles, and the noise was deffinitely not there.

[b5blue]

U Joints? Outer wheel bearings? 

[green69rt]

U Joints? Outer wheel bearings?  

Yes, check these first.  Get the car on a lift and have it checked out while running.

Just saw "Jag Dealer"??

[DAmatt]

I took a couple of pics of the U joint, can you guys tell me if it looks alright, and what I should order? I see there are several variants online.

To my untrained eye, I don't know if the fact that one end sticks out, and the other sinks in is fine, but then again, what do I know?

Thanks!

[DAmatt]

U Joints? Outer wheel bearings?  

Yes, check these first.  Get the car on a lift and have it checked out while running.

Just saw "Jag Dealer"??

Yes, you saw right, they were cool enough to take on my '04 Super V8, and swap the (h)Eaton with a Kenne Bell twin screw supercharger, so when I asked them about a rotisserie resto on the Charger, they said yes

[cdr]

looks like possible pinion nut may have come loose

[RallyeMike]

The U-joint is so clean it looks new to me. Sorry to say that the whining sound, if it is indeed coming from the axle, sounds more like bearings or gears. If gears, it definitely could be caused by a loose pinion nut (as mentioned above).

A differential is a common thing and how you set them up is pretty similar across all makes. Any decent mechanic should be able to go through it. A heavy truck repair business might be able to help you - they often deal with live axle differentials.

[John_Kunkel]

looks like possible pinion nut may have come loose

Yep, the yoke dust cover is pretty close to the housing, could be scraping. Grab the rear end of the driveshaft and wiggle it in/out and side-to-side.

[DAmatt]

This does not bode well...

*WARNING - RANT*

We have no decent mechanics, only parts replacers (par example they put a scanner on the car, scanner tells them there's a code in the transmission. No matter which code, they put the VIN in a computer, computer tells them the part no. for the complete transmission, they will only replace the whole transmission even for a broken nut, if that entails opening up the trans). When communism fell 30 years ago, it suddenly became a shame to learn an honest, blue collar profession, so almost everybody from my generation & younger has 2 university degrees, a masters, and a doctorate - although they do not find work in their studied field, because they went through university by memorizing & reproducing information. Yes, our education system sucks big time. Nobody knows how to actually do something.

So basically our mechanics have NO formal education in auto repair, because schools that taught this closed through lack of students (remember it was a shame to do blue collar work), and I am stuck in this situation.

*END OF RANT*

I lucked out the first time, the guys at the jag dealership found an old man who knew how to set up these things, but now I am high and dry. As a last resort I can send the car to them, but they're 300 miles away.

What I CAN do is educate myself, and either purchase all the tools myself (took the first step, and ordered a quickjack yesterday ), or assist the mechanic to tell him exactly what to do.

Could you please tell me, were it to be the pinion nut, what must I do?

Do I have to pull the yoke off, or is it accessible by removing the drive shaft? Do I just put a socket, and torque it? 160lbft?

[WhiteOnGreen]

"What I CAN do is educate myself, and either purchase all the tools myself (took the first step, and ordered a quickjack yesterday Smiley ), or assist the mechanic to tell him exactly what to do."

First step is FSM
https://mymopar.com/service-manuals/
Looks like R&P setup, Recently I rebuild mine and same whine sound before.
Case# 489 741 742?

[b5blue]

  B body cars from this era are simple and solid as a rock unless you just constantly beat the crap out of them. Get it's ass up and undo the 4 small bolts on the straps that hold the U joint on. Have tape ready and slide the joint forward while being sure to keep the joint caps in place, run tape around that joint to hold the caps on. Lay the end of the driveshaft gently on the ground and do NOT let the yoke out of the trans. or you will have fluid running out the back of the trans.
  Now you can inspect the yoke situation.    Get online and find others with 60's cars they are all the same more or less.

[DAmatt]

I have the 1968 Charger manual, and I began searching guides, but I wouldn't want to practice my novice skills on this car, only as a last, last resort. Isn't there another way, like buy a whole assembly that somebody in the States used to this adjusts, so any incompetent mechanic over here can swap it?

Coming back to an earlier question, if it's just the nut that's loose, can I get away with tightening it? How can I do that?

[DAmatt]

  B body cars from this era are simple and solid as a rock unless you just constantly beat the crap out of them. Get it's ass up and undo the 4 small bolts on the straps that hold the U joint on. Have tape ready and slide the joint forward while being sure to keep the joint caps in place, run tape around that joint to hold the caps on. Lay the end of the driveshaft gently on the ground and do NOT let the yoke out of the trans. or you will have fluid running out the back of the trans.
  Now you can inspect the yoke situation.    Get online and find others with 60's cars they are all the same more or less.

I'll save up the guts till the quickjack arrives 

[cdr]

I have the 1968 Charger manual, and I began searching guides, but I wouldn't want to practice my novice skills on this car, only as a last, last resort. Isn't there another way, like buy a whole assembly that somebody in the States used to this adjusts, so any incompetent mechanic over here can swap it?
However I understand that

Coming back to an earlier question, if it's just the nut that's loose, can I get away with tightening it? How can I do that?

You can order a complete assembled center section & have it shipped, Dr Diff is who I recommend  

[WhiteOnGreen]

Coming back to an earlier question, if it's just the nut that's loose, can I get away with tightening it? How can I do that?

If 489 case, I don´t think. This case have a crush sleve and may be overthigtening ruins it

[DAmatt]

AFAIK, the 489 came in 1969, along with the dreaded crush sleeve. Mine should be a 742, but I'll try to check it.

If it's the 742, I'm good to go? just disconect the driveshaft, and torque it to what value?

[cdr]

AFAIK, the 489 came in 1969, along with the dreaded crush sleeve. Mine should be a 742, but I'll try to check it.

If it's the 742, I'm good to go? just disconect the driveshaft, and torque it to what value?

put some loctite on the threads & get it tight

[John_Kunkel]

If 489 case, I don´t think. This case have a crush sleve and may be overthigtening ruins it

OP's casting number is 207xxxx, a 489 would be 288xxxx.

[ACUDANUT]

489's have always been great to me.  
50 plus years of different jokers messing with it, is always a concern.

[b5blue]

Lets not forget an outer axle bearing can brindle and emit a slight growl also. (Ask me how I know.) You could order a new pig complete (Center chunk.)and half shafts with green bearings installed on them. That would overhaul the entire axle and be eazy-peezy lemon sqweezy to do. (Just costly with shipping.) 

[DAmatt]

While I am weighing in my two options, may I ask if I have the correct U joint? From the pictures, two caps stick out, and the other two are recessed. What do you guys think?

[John_Kunkel]

As long as the C-clips (3) are in place, you're good to go.

[DAmatt]

So I took it on a lift, and before disconnecting the driveshaft, I had it running. With a stethoscope I can confirm noise is coming from front of diff.

Took driveshaft off, zip-tied the trans end (thanks for the heads-up b5blue!), and taped the needle bearing caps on the u joint. Lo and behold, the pinion nut could be turned by hand (almost). Took it off for a grizzly sight - at first I thought both the nut, and the pinion have eaten their threads. Luckily it was only the nut.

I put another nut in, but at 200ftlb torque it felt like it was letting go, so I chickened out. The manual says 240ftlb minimum, but I wasn't to risk ruining the only nut I found at the shop.

On the way home, the noise was still there, but I feel it was a bit subdued compared to before, and the driving felt a bit "tighter" for lack of a better word. I hope it's not placebo.

My questions now are:

1. could this still-too-low torque be the reason for the continued noise?

2. can you guys tell me at this stage if there's any other causes beside the pinion nut? I am praying I don't have to get the pig out. Below there's a short clip of it when I got it running on the lift.
https://youtu.be/_oNUQhHrdHc

3. is the pinion nut made out of mithril? I mean, the one I got off was dead, the one I replaced it with wanted to die at 200ftlb. Is there a difference in ordering the nut specifically made for the pinion as opposed to any one compatible?

Thanks!

[OzCharger69]

So I took it on a lift, and before disconnecting the driveshaft, I had it running. With a stethoscope I can confirm noise is coming from front of diff.

Took driveshaft off, zip-tied the trans end (thanks for the heads-up b5blue!), and taped the needle bearing caps on the u joint. Lo and behold, the pinion nut could be turned by hand (almost). Took it off for a grizzly sight - at first I thought both the nut, and the pinion have eaten their threads. Luckily it was only the nut.

I put another nut in, but at 200ftlb torque it felt like it was letting go, so I chickened out. The manual says 240ftlb minimum, but I wasn't to risk ruining the only nut I found at the shop.

On the way home, the noise was still there, but I feel it was a bit subdued compared to before, and the driving felt a bit "tighter" for lack of a better word. I hope it's not placebo.

My questions now are:

1. could this still-too-low torque be the reason for the continued noise?

2. can you guys tell me at this stage if there's any other causes beside the pinion nut? I am praying I don't have to get the pig out. Below there's a short clip of it when I got it running on the lift.
https://youtu.be/_oNUQhHrdHc

3. is the pinion nut made out of mithril? I mean, the one I got off was dead, the one I replaced it with wanted to die at 200ftlb. Is there a difference in ordering the nut specifically made for the pinion as opposed to any one compatible?

Thanks!

It really depends if you have a crush sleeve or a solid spacer. If it's a crush sleeve and you undo and do the nut, I believe you loose the pre-load setting and the pinion/ring need to be re-aligned. Someone correct me if I'm wrong.

[DAmatt]

I can confirm I do not have the crush sleeve, my case is 742