'69 charger loud bang,pop,pop,pop,pop from back of the car...

[UH60L]

So, My car has been back on the road since April of 2016.  Still working on the glass and interior as money and time allow.  In 2016 when I first got it back on the road, I had an occasional loud bang from the left rear.  It turned out that when the shop reinstalled the rear end from a minor accident I had back in 2005, they had wrapped the parking break cable around the spring or something and it was causing the left rear break to heat up and stick, thus the bang.

That fixed, I haven't had any other issues until last week.  My wife and I were out enjoying the beautiful Oregon weather and as I rounded the last corner before our street, there was a loud bang followed by pop pop pop pop pop that seemed to change frequency as I slowed down.  Then it went away as I tapped the brakes.  It sounded like it was at the right rear so I thought it might be the same thing as before but on the other side.

Well, today as I was driving the car, going about 45 to 50 mph, bang, pop pop pop pop pop pop and then clunk and it went away.  I could feel it shaking through the whole car.  I pulled off the road and looked under for any obvious signs of trouble, nothing out of place.  Got another half mile closer to home, same thing, so I limped it home at 25 to 30 mph and eased it into the garage.

I'm leaning towards rear differential, as that is the one thing mechanically that I haven't messed with since I bought the car back in 2004. 

Anyone have similar issues and can you confirm is was the rear end?

P.S.:  My car is a mutt, it's got the original 2/76 rear end but with and adapter U-joint and a 440/727B drivetrain.

[c00nhunterjoe]

The rears are pretty robust. Sounds like something in the drum. Jack it up and make sure there is no bearing slop, then pull the wheel and drum and see if something came apart.

[krops cars]

That is what I would do. I have seen brake linings let go and do the same thing.

[UH60L]

Good call guys.  I took both rear wheels off and both drums.  Everything looked fine inside the brakes, but then I saw it.

The right parking brake cable, just to the outside of the little retainer clip on the axle housing... the cable insulation was damaged/broken and the cable was exposed and stuck, and the right brake was being applied slightly and getting hot.

I ordered a new parking brake cable, should have it tomorrow.

I'm glad it wasn't the rear end.

[UH60L]

Well, so much for that.  I replaced the damaged right parking brake cable.  Drove the car all over town yesterday, not a single problem, beautiful sunny day, me driving around in the General Lee, life was good.

Woke up early today, wife and I were trying to decide what to do.  Turns out there was a car show close, so we decided to go.

Cruising up I-5 doing 60mph, I see a dump truck full of dirt coming down the on-ramp, so I speed up to about 75mph to make sure he gets on behind us.  As soon as I let off the gas to slow back down, BANG, followed by a rapid clunking and shaking from the back of the car.

I pulled off the freeway and looked under the car.  No leaks and nothing falling off.  I put it in revers and back up a few feet, no sound.  Pulled forward a few feet, no sound.  I waited for a big gap and slowly pulled back onto I-5 and rapid clunking resumed.  Fortunately we were less than 18th mile from an the off-ramp, so drove slow down the off-ramp and slow the other 1/2 mile to the car show, clunking all the way.

When the show was over, we drove it around the parking lot and I couldn't here it, but as soon as we pulled out, it was back.  It would only clunk off it was coasting with no torque from the engine/trans, so I gently power-braked it to stop each time and managed to avoid clunking as I limped it home through town.

The U-joints look fine and other than a little slop that its always had since I've owned it, there nothing obviously wrong from the outside.

Guess I'll start shopping for third members and gear sets...

Any insight into this would be appreciated.

[John_Kunkel]

A "little slop" in u-joints isn't normal. You can't tell their condition by eyeball.

[Mopar Nut]

A "little slop" in u-joints isn't normal. You can't tell their condition by eyeball.

[Fitz73Chrgr]

A "little slop" in u-joints isn't normal. You can't tell their condition by eyeball.

Yeah that sounds a lot like a bad U-joint.

[krops cars]

Start with u joint. If it does it again pull the gears out and at least look at them. Put both u joints in.

[UH60L]

A "little slop" in u-joints isn't normal. You can't tell their condition by eyeball.

Sorry, been busy and have not replied for a while. 

I think it was the way I worded it that confused all of you.

"The U-joints look fine and other than a little slop that its always had since I've owned it, there nothing obviously wrong from the outside."

IE, there is no slop in the U-joints, there is slop in the rear end.

The U-joints are brand new and tight...


I finally got around to working on it today.  Pulled the drive shaft off.  I can't feel the exact clunking that it had while driving, but I can move (clunk) the yoke back and forth by hand about an inch without moving the axles/wheels.

I am looking at getting a complete center section from Moser.  Only downside is that they don't have the same gear ratio that my car has (2.76), so I'll probably go with the 3.23.  Its about $1800 with shipping, which isn't that bad and everyone I've talked to has good things to say about Moser.

That said, I have never opened up and worked on a rear differential before.  I'm guessing there will be some axle bearings that I will want to replace while I'm in there.  Anything else I should do or be looking at?

Wife and I are in the process of buying a house and moving, so it will be a little while before I can throw money at this , plus I'll probably have to have a flat bed tow truck take it to the new house.

Any thoughts would be appreciated.

[c00nhunterjoe]

I do not like moser. If you are buying a unit, go with strange.

[Mopar Nut]

Contact Doctor Diff (Cass) to buy Strange, stay away from Moser.

https://www.doctordiff.com/

Strange runs sales on there diff centers every once in awhile, like free shipping.

[krops cars]

Why don't you just pull the center section out. If it is clunking and banging there should be some type of shavings or something. I have heard of dirty posi units making noises like that. That was in GM's. I never experienced this on a mopar. If you tear it apart  buy the bearing kit for the axles so you do not have to adjust end play. You are sure that all of the u joints have been replaced. Even if you think there good replace them if they have not been replaced before. Old u joints can cause head ache. Had it happen more than once. They had no slop. Fine rusty as heck though when I replaced them.

[UH60L]

Why don't you just pull the center section out. If it is clunking and banging there should be some type of shavings or something. I have heard of dirty posi units making noises like that. That was in GM's. I never experienced this on a mopar. If you tear it apart  buy the bearing kit for the axles so you do not have to adjust end play. You are sure that all of the u joints have been replaced. Even if you think there good replace them if they have not been replaced before. Old u joints can cause head ache. Had it happen more than once. They had no slop. Fine rusty as heck though when I replaced them.

Well that was my plan, but we got word last night that our offer was accepted on a house, so we're gonna be moving in the very near future.  I have to figure out how I'm gonna get the charger to the new house without driving it.

I only have a two car garage and our modern challenger gets parked in the other half so there is usually not room to work on anything unless my wife has the car and I'm off work.

The house we're buying has a bigger garage, so hopefully I can disassemble it once we get moved.

Now back to the symptoms, it wasn't just a noise.  After the initial sounds (which we could feel inside the car) it has a constant clunk clunk clunk feeling in the back of the car that goes away if I hold slight tension on the brake while holding slight acceleration with the gas (had to so this all the way home to keep if from clunking).  Basically had to do a very slight power-brake all the time to keep tension on whatever is loose.

Talked to a couple local Mopar guys last night and they recommended "Randy's" for rear end parts but I don't know if they sell a complete center section.

[c00nhunterjoe]

If it makes the noise on accell, but not on accel while braking, its not the diff, its the brakes.

[UH60L]

If it makes the noise on accell, but not on accel while braking, its not the diff, its the brakes.

It makes the noise and physically felt "clunk clunk clunk" mostly (and more loudly) while coasting without braking.  If I very gently power brake it, it goes away completely.  I had to do that to drive it home after it happened, about 8 miles at 35 mph and gently power-braking to slow down.

As for the brakes, the drums and shoes are new as well as the right parking brake cable.  Considering the amount of slop I have in the yoke, I tend to doubt its the brakes, but what in the brakes would cause that? 

[c00nhunterjoe]

I missed the part about slop in the yoke. If the yoke is physically moving, then it sounds like a failled pinion bearing or crush sleeve. The clunk clunk clunk, would be the ring gear contacting the pinion gear in that case.

[c00nhunterjoe]

So now begins my treading into dark territory.  If the 3rd member is shot and you were pricing a moser replacement 8.75, you will see that a stock 30 spline replacement will run you 1600 dollars. For 2200, you can get an end to end strange s60 with 35 spline axles, brand new housing, all new internals and your new brakes and backing plates will bolt right to it. The dana is twice the strength and in this case, not much more money and considering that the moser kit is reusing your 50 year old axles and the dana comes with brand new ones and a housing, its a wash and no brainer.

[krops cars]

Is the slop in the yoke? Left to right or up and down? Left and right doesn't bother me. If it moves up and down side to side. Then I will agree that the bearing and or crush sleeve is bad. If the slop is left to right put the car on jack stands and run it. Have someone check it out with you.

[timmycharger]

So now begins my treading into dark territory.  If the 3rd member is shot and you were pricing a moser replacement 8.75, you will see that a stock 30 spline replacement will run you 1600 dollars. For 2200, you can get an end to end strange s60 with 35 spline axles, brand new housing, all new internals and your new brakes and backing plates will bolt right to it. The dana is twice the strength and in this case, not much more money and considering that the moser kit is reusing your 50 year old axles and the dana comes with brand new ones and a housing, its a wash and no brainer.

Wow that isn't bad. I seem to remember paying a similar amount almost 15 years ago for my S60.  One of the best decisions I ever made!

[krops cars]

Sometimes it would be nice if people lived closer so you could swing by and check it out with them.

[UH60L]

Is the slop in the yoke? Left to right or up and down? Left and right doesn't bother me. If it moves up and down side to side. Then I will agree that the bearing and or crush sleeve is bad. If the slop is left to right put the car on jack stands and run it. Have someone check it out with you.

The slop is circular, as in I can turn the yoke 1 to 1.5 inches clockwise or counterclockwise without turning the axles/wheels.  There is no axial or radial play in the yoke itself, the slop is internal to the rear end.  If I wasn't busy packing everything I own to move, I'd tear into it, but right now just isn't a good time.

Hopefully towards the end of February I'll be able to open it up.

As for previous questions about the U-joints, the U-joints and driveshaft are brand new, installed in 2016, with very few total miles driven since then, mostly to local car shows.  Transmission was rebuilt back in 2008, reinstalled in 2008, and the car wasn't running/drivable until 2016.

[b5blue]

  This is nuts just find a decent 8 3/4 center section ("Chunk" or "Pig") have it checked and slap it in? Open the fill plug and stick a tiny magnet on the end of a hunk of wire, fish around a bit and pull it out. If it's failing you'll have chunks of steel on the magnet. 

[krops cars]

Agreed.

[Highbanked Hauler]

 A 2:76 chuck should be a couple hundred I'd think but it depends on what you want to spend.