CLUNK! What the heck is that new noise??

[timecapsule]

My 48 Chrysler Windsor with fluid drive has recently started making a clunking noise.  The clunk is fairly loud, short, and only happens when taking off.  But not all the time. Come to a stop sign, stop look both ways, take off,,, usually no clunk.   It will pretty much do it all the time if I'm fully stopped, I depress the clutch, put it in low or high and slowly take off. One clunk just as the car starts to move.  Stop, depress the clutch and put it in reverse and the same clunk. So definitely it happens when I change direction using the clutch and transmission. Sort of the sound you'd expect from a loose drive shaft U-bolt.  Or maybe a loose set of wheel lugs.  It sounds like it is coming from all 4 corners,,,, maybe. At least front and back as opposed to the transmission area.   It's a different sound than the usual transmission shifting noise with the fluid drive, but about as loud, maybe louder.  So sometimes it sounds like it's coming from the back wheels. A couple times I get a double clunk, very close together.  I think I've discovered that if when I start out, I keep the brake on, depress the clutch, put it in gear, then release the clutch, then ease off the brake, then there is no clunk.  But I've only just tried that a couple times, so I'll have to do that a few times to see if I get a consistent result.  If the car is on an incline, and I release the emergency brake and just let it role forward without putting it in gear, no clunk.  

Has anyone ever experienced this?

[m-mman]

In addition to all the suggestions that will likely be forth coming about driveline issues, check for looseness in your front end. 

A loose upper control arm can slide back and forth. Stabilizer bars without bushings can clunk

 

Tie rod ends dont typically clunk, but A-arms can. They are pulled out of place when direction changes. 

Edited April 30, 2021 by m-mman (see edit history)

[timecapsule]

2 minutes ago, m-mman said:

In addition to all the suggestions that will likely be forth coming about driveline issues, check for looseness in your front end. 

A loose upper control arm can slide back and forth. Stabilizer bars without bushings can clunk

 

Tie rod ends dont typically clunk, but A-arms can. They are pulled out of place when direction changes. 

So true,  I left out the usual and obvious stuff that a guy would check, that I've already done like pull all the wheels off to check the brakes and of course the U-bolt and look for any obvious oil deposits on the ground for something leaking.  Plus I greased all the nipples about a week ago.  Everything looked fine and not out of place at that time and I haven't gone through a pot hole. 

[c49er]

Might check the rear axle brake drum/ axle nuts...142lbs torque.

A 5/16" key holds the drum to the axle shaft. 

[timecapsule]

2 minutes ago, c49er said:

Might check the rear axle brake drum/ axle nuts...142lbs torque.

A 5/16" key holds the drum to the axle shaft. 

Yes all good there, I pulled the drum off when I checked it.  I didn't check the torque to be at 142 though when I put it back on.  I just went tight, and then backed off to the first opening in the castle nut for the cotter pin to slip through. 

[Bloo]

On a rear wheel? There's your clunk.

 

[timecapsule]

4 minutes ago, Bloo said:

On a rear wheel? There's your clunk.

 

Please explain in a little more detail.

[Bloo]

If that was a rear wheel it needs to be TIGHT!

 

Really tight. You can't back off for adjustment. 142 foot pounds is a lot. If the cotter pin wont line up you have to go tighter. It might be really tough to do. Also there might be more than one hole for the cotter pin. I'm thinking a ridiculously long cheater bar, but I'll sit back and see what @c49er has to say.

 

Backing off sounds like something you might do on a front wheel. Rear wheels on on old Chrysler products (and some other makes) have a key and a taper, The taper needs to lock and hang on for dear life. That is why they are so hard to get apart. If you depend on the key it will probably shear off, and right away.

 

Edited April 30, 2021 by Bloo (see edit history)

[timecapsule]

I don't follow " if the key won't line up"  You put the key in the axle keyway,  then line up the keyway in the hub/drum assembly and simply slide it on.  Then tap the end of the key until it is flush with the end of the keyways, right?  As far as tight goes, I'll go back and check what the torque is now. So are you saying once you get to 142 ft. lb.  and your hole in the castle nut was not lined up with the hole in the axle for the cotter pin, then I should add more torque until the next hole lines up?

Edited April 30, 2021 by timecapsule (see edit history)

[Bloo]

Sorry, I edited that. I meant cotter pin. Yes. torque it and if the hole doesn't line up you will have to go tighter. There may be a second hole to help you get lined up quicker. If not, you will have to keep tightening.

[timecapsule]

1 minute ago, Bloo said:

Sorry, I edited that. I meant cotter pin. Yes. torque it and if the hole doesn't line up you will have to go tighter. There may be a second hole to help you get lined up quicker. If not, you will have to keep tightening.

I'll check that out Bloo.  Rain tomorrow though   So assuming you're right in this being my problem, what would actually be making the clunk noise?

[Bloo]

The drum being loose on the shaft. It will damage the keyway in your shaft. Don't drive it until you have either fixed it or verified it is ok and the clunk is coming from somewhere else.

 

Edited April 30, 2021 by Bloo (see edit history)

[timecapsule]

When I said I backed it off,  I didn't mean the way you'd set your front bearings.  I mean it was still super tight when I slipped the cotter pin through.  Plus my first instinct was loose lug nuts, so when I checked them all I lifted each wheel off the ground and tried to tilt them back and forth and there was no movement front or back wheels.

[Bloo]

I would still check (and retorque) since it's been apart recently. If it's fine, then it's time to look elsewhere. In the long distant past, I recall jumping up and down on a 6 foot cheater bar for a while to get those nuts loose. I weighed about 165 then. I wasn't exaggerating when I said they were really tight.

 

Edited April 30, 2021 by Bloo (see edit history)

[timecapsule]

4 minutes ago, Bloo said:

I would still check (and retorque) since it's been apart recently. If it's fine, then we start looking elsewhere.

I agree Bloo.  I'm pretty sure I have the socket in my tool box in the trunk.  1 1/8" I think if I'm not mistaken. I can take my other car over to my shop to get my torque wrench and the longest Johnson bar I have is about 2 feet but I have a 4 foot pipe I can slide over it.  

Edited April 30, 2021 by timecapsule (see edit history)

[c49er]

That nut on the rear drum is 1-1/4".

142 lbs...if the nut slots don't line up for the cotter pin turn a slot tighter till they do.

Never back the nut off a slot...go a slot tighter till the cotter pin fits.

I have had a couple of these drum nuts loose on customers mopars..makes a snapping noise upon take off forward or reverse.

Not saying this is your issue but could be.

You will not strip the nut or axle threads from over tightening the nut by hand using a 3/4" breaker bar.

Just make sure that nut is real tight if not using a torque wrench!

Now find the problem clunk!😁

Edited April 30, 2021 by c49er (see edit history)

[normanpitkin]

I had this on my 48 new yorker ,it proved to be very low fluid in the fluid drive unit ,have you checked that?

[ojh]

You said you pulled the rear hub to check the keyway, you make it sound as if the hub just came off.  You had to use a puller and it took a LOT of omph to get the hub off, right?  

[timecapsule]

7 hours ago, normanpitkin said:

I had this on my 48 new yorker ,it proved to be very low fluid in the fluid drive unit ,have you checked that?

I haven't checked it in about a year or so, but it's a good thought.

28 minutes ago, ojh said:

You said you pulled the rear hub to check the keyway, you make it sound as if the hub just came off.  You had to use a puller and it took a LOT of omph to get the hub off, right?  

I wouldn't say it took a LOT to get it off.  Definitely a LOT more than a really tight lug bolt.  I got it off using a 2 ft. Johnson bar.  I have a standard puller, not one of those HD ones that you hit with a sledge hammer though.  At one point I thought it might brake under the pressure, but then I heard a semi-loud snap when the hub let go.  Both rear wheels were about the same.

[JACK M]

When I read the first post I started to think about engine mounts.

[timecapsule]

4 minutes ago, JACK M said:

When I read the first post I started to think about engine mounts.

That was on my mental list at first too.  But I revved the car up while looking under the hood and the engine doesn't move.

[Grimy]

1 hour ago, timecapsule said:

That was on my mental list at first too.  But I revved the car up while looking under the hood and the engine doesn't move.

I'd suspect the front (center) mount *under torque* (not just at idle) if the rear hub/wheel has been cleared.  It's been a long time since I had one of these cars, but as I recall there's a rectangular piece of rubber running left to right vulcanized to the metal. Try rocking the engine laterally with engine not running, but I can't guarantee that will be sufficient force.

[timecapsule]

6 hours ago, Grimy said:

I'd suspect the front (center) mount *under torque* (not just at idle) if the rear hub/wheel has been cleared.  It's been a long time since I had one of these cars, but as I recall there's a rectangular piece of rubber running left to right vulcanized to the metal. Try rocking the engine laterally with engine not running, but I can't guarantee that will be sufficient force.

Your memory serves you well. The front mount is exactly as you described and I can see how if it was broken or the rubber had deteriorated and separated that the two metals could easily clash, since that rubber section is very thin.  However the problem is now solved as I am about to post.

BINGO!  No more noise thanks to c49er and Bloo's suggestion.  I torgued the crown nuts to 142+ ( tightening them tighter to get to the next crown nut slot/axle hole lining up).  So thank you both very much and once again I'm reminded to check my manual for specs.  I got both wheels off the ground and there was no visual signs of anything wrong and the wheel wouldn't rock back and forth.  I suspect I travelled 4 trips of about 15 minutes each, so I don't suspect that I did any damage to the keys or keyways.  I have axle seals on order so when they arrive, I'll be sure to inspect everything when I take the wheel hubs off.

Thanks again guys!

[chistech]

I had a clunk in my 31’ chevy and it turned out to be the rear axle nuts and worn keys. I bought the car in pieces but the chassis had been “expertly” restored by what all the friends of the deceased previous owner told me. Turns out the PO did do a thorough job but for some crazy reason installed very worn key stock into the key way slots. The slots weren’t worn at all but the keys were atrocious. It just didn’t make sense to me but the hubs were twisting slightly on the tapered axles causing a clunk!

[timecapsule]

6 minutes ago, chistech said:

I had a clunk in my 31’ chevy and it turned out to be the rear axle nuts and worn keys. I bought the car in pieces but the chassis had been “expertly” restored by what all the friends of the deceased previous owner told me. Turns out the PO did do a thorough job but for some crazy reason installed very worn key stock into the key way slots. The slots weren’t worn at all but the keys were atrocious. It just didn’t make sense to me but the hubs were twisting slightly on the tapered axles causing a clunk!

That's crazy, one has to wonder why someone would even think about installing worn key stock

[ojh]

Glad you solved it, I will suggest that when you pull it back apart to replace the seals that you measure the axle freeplay, I think that rear is shimmed between the backing plate and axle bearing, if the axle has too much freeplay it'll clunk and when tightened further as you have done it could briefly preload the axle to mimick proper shims but will loosen itself back up with the Klunk returning unabated.  Just a solid push-pull on the axle snout will tell you whats what, I'd expect it to have about .003 freeplay.

[timecapsule]

35 minutes ago, ojh said:

Glad you solved it, I will suggest that when you pull it back apart to replace the seals that you measure the axle freeplay, I think that rear is shimmed between the backing plate and axle bearing, if the axle has too much freeplay it'll clunk and when tightened further as you have done it could briefly preload the axle to mimick proper shims but will loosen itself back up with the Klunk returning unabated.  Just a solid push-pull on the axle snout will tell you whats what, I'd expect it to have about .003 freeplay.

That's good advise.  I think I'll take it to a "old car mechanic" to replace the seals so I'll pass on that .003 freeplay stat. I've watched videos on measuring and setting that freeplay before.  That process might be over my head since I don't even have a garage for my car to work in.  Are those shims available at AB, or Roberts, or moparmall, etc?  Or are the fairly generic in shape?

[ojh]

Likely won't need shims, you pull one out to tighten the package.

[Bloo]

Are we still talking about the Chrysler? If so, I can't imagine how the nut we have been talking about could affect the axle freeplay. The axle freeplay is adjusted with shims as ojh mentioned. Use the shop manual spec if you change it. The little bit of slop specified allows the axle shaft to expand with heat without putting excessive preload on the bearing.

[c49er]

Rear axle bearings are very reliable on the old MoPar's.

I have not had to replace that many over the years.

So..

If you need to remove the shims to correct excessive end play to proper end play of .003" -.008".....

Your axle bearings and or differential center block are worn....

Bearings are most likely worn out.

The shims installed on different cars varies greatly.

Many thicknesses were used. .005", .010", .012", .020" etc.

A dial indicator is needed to set the end play of axles...also shim stack thickness  needs to be pretty equal side to side.

Skill is needed to do the job right.

As mentioned the drum/axle nut has nothing to do with rear axle shaft end play....

The shim stack between the backing plate and axle housing sets the end play.

The OP probably has to do nothing with the seals or axle shaft end play unless he saw oil leakage on the brake backing plate....

Oil leakage means replacing inner and outer axle shaft seals plus checking bearing condition and end play.

 

Edited May 1, 2021 by c49er (see edit history)

[timecapsule]

5 hours ago, c49er said:

Rear axle bearings are very reliable on the old MoPar's.

I have not had to replace that many over the years.

So..

If you need to remove the shims to correct excessive end play to proper end play of .003" -.008".....

Your axle bearings and or differential center block are worn....

Bearings are most likely worn out.

The shims installed on different cars varies greatly.

Many thicknesses were used. .005", .010", .012", .020" etc.

A dial indicator is needed to set the end play of axles...also shim stack thickness  needs to be pretty equal side to side.

Skill is needed to do the job right.

As mentioned the drum/axle nut has nothing to do with rear axle shaft end play....

The shim stack between the backing plate and axle housing sets the end play.

The OP probably has to do nothing with the seals or axle shaft end play unless he saw oil leakage on the brake backing plate....

Oil leakage means replacing inner and outer axle shaft seals plus checking bearing condition and end play.

 

 

5 hours ago, Bloo said:

Are we still talking about the Chrysler? If so, I can't imagine how the nut we have been talking about could affect the axle freeplay. The axle freeplay is adjusted with shims as ojh mentioned. Use the shop manual spec if you change it. The little bit of slop specified allows the axle shaft to expand with heat without putting excessive preload on the bearing.

No No,,,,, No connection intended. I just mentioned about replacing my axle seals, that are leaking slightly, as being an opportune time to have a look at the condition of the axle key while I had things apart back there.

[Frank DuVal]

On 4/30/2021 at 12:39 AM, Bloo said:

Sorry, I edited that. I meant cotter pin.

Don't know what you wrote first, but I learned the term cotter KEY as a young lad. I do call them Cotter Pins these days. I have not yet adpoted the term Split Pin.😉

 

 

[Frank DuVal]

On 4/30/2021 at 10:16 AM, timecapsule said:

2 ft. Johnson bar.

Not sure what you mean. I am guessing a 2 foot long breaker bar.

 

A Johnson Bar is a brand name of a pole with two wheels for moving stuff around on the floor:

 

https://www.mcmaster.com/johnson-bars/

https://kk.org/cooltools/johnson-bar-or/

[Bloo]

13 minutes ago, Frank DuVal said:

 Don't know what you wrote first, but I learned the term cotter KEY as a young lad. I do call them Cotter Pins these days. I have not yet adpoted the term Split Pin.😉

 

It was "if the key won't line up" and it was pure brain fart. Cotter key is also my default, but as you know these axles also have a key and keyway in addition to the cotter pin or key so that didn't make a lot of sense.

 

Edited May 5, 2021 by Bloo (see edit history)

[JimKB1MCV]

9 hours ago, Frank DuVal said:

Not sure what you mean. I am guessing a 2 foot long breaker bar.

 

A Johnson Bar is a brand name of a pole with two wheels for moving stuff around on the floor:

 

https://www.mcmaster.com/johnson-bars/

https://kk.org/cooltools/johnson-bar-or/

  I think Mr. Johnson has been around a while.

  Steam locomotives ( I think) have a Johnson rod which controls the steam admission valves and being an old sailor I can't help mentioning its a nickname for part of the male anatomy that isn't  usually mentioned in polite company.  😀