Rear End Creak on Stop and Pulling Off

[copb8 97]

Took my car in to have the tires balanced and now for some reason it creaks from the rear end as it comes to a stop and then again as I pull off. It stops almost immediately and doesn't happen again until I stop again. For the life of me I can't figure out how this could happen from pulling the wheels and putting them back on.

A friend thought it may be a parking brake or drum brake adjuster issues so I pulled the wheels and drum brakes and cleaned everything up and ensured proper operation but it made no difference.

Prior to the balancing I recently removed some 1" lowering blocks from the rear suspension but the car ran without creaking for some time before dropping it off for the work. I checked to make sure the U-bolts were still torqued ok and all seemed good.

Only other thing that I thought of was they somehow jacked the car up on the leaf spring perches and that somehow twisted something. But if that's the case I can't tell just looking at that area.

Any thought?

 

[stangnet33 88]

Spring shackle bushings maybe ? Changed position while it was hoisted and didn't resettle to ride height when put back down ? Can you duplicate it just jousting the back end ? Just a thought.

[copb8 97]

3 minutes ago, stangnet33 said:

Spring shackle bushings maybe ? Changed position while it was hoisted and didn't resettle to ride height when put back down ? Can you duplicate it just jousting the back end ? Just a thought.

No, if I either bounce the back end up and down or rock it for and aft it doesn't make the noise.

My uneducated thought was that the axle housing was somehow 'twisting' in the u-bolts that hold it to the leaf springs. I was thinking that applying brakes would want to twist the front of the differential down and accelerating would want to raise the front of the diff. Not sure how I'd check this out though. 

[LoneWolf2U 136]

Use white chalk to make a set of witness marks on the housing near the spring.

a set of lines on both front and rear of tube, drive it. When you hear the noise coast to a stop and look at the marks to see if or which way it moved.

[1969_Mach1 333]

U-joint creaking and or squeaking.

[stangnet33 88]

If you could get a hold of a set like these it would help take the guess work out for you. 

[copb8 97]

Does anyone know what the torque setting should be for the U-bolts that hold the axle housing to the leaf springs? 

And am I correct that the only thing from keeping the axle housing and diff from rotating in the u-bolts is the tension of the bolts themselves and the little pins that go into the leaf springs? 

[Ridge Runner 1,113]

I doubt that the squeak is coming from the housing to the leafs ,more likely from the brakes or rear shackles .The ubolts keep the rear end housing from spinning ,along with the mounting pad on the housing and the locator pin in the leafs  ,no way it will spin unless the bolts are loose to the point of allowing the housing pads to skip over the pins , or the U bolts are  broken or you have to much horse power ...and that would take a whole lot .

[copb8 97]

My friend who was an ex-professional mechanic just dropped off his Steelman ChassisEar exactly like the one stangnet33 posted. Now when I get some time I'll hopefully track this noise, and some of the others, down.

[copb8 97]

On 4/14/2017 at 8:56 PM, Ridge Runner said:

I doubt that the squeak is coming from the housing to the leafs ,more likely from the brakes or rear shackles .The ubolts keep the rear end housing from spinning ,along with the mounting pad on the housing and the locator pin in the leafs  ,no way it will spin unless the bolts are loose to the point of allowing the housing pads to skip over the pins , or the U bolts are  broken or you have to much horse power ...and that would take a whole lot .

Just to clarify my description of the issue, the creak happens for just a second on pull off. And again a second on braking. Like something was shifting. Certainly not enough to think they housing completely rotated the pins out of the locator holes. 

[copb8 97]

Did some work on this yesterday and may have narrowed down the issue. Is it possible for the rear drum brake backing plate to rotate very slightly on the axle housing if not tightened or installed correctly? Maybe it's just loose enough to rotate within the bolt holes? 

I used the microphones and it seems to point to this area although those things aren't super easy to pinpoint issues in a close area. I pulled the rear wheels and drums and tightened the 4 bolts holding the backing plate on. They weren't loose but some of them weren't that tight either. Once I did this it seemed to quieten down a significant amount but not gone altogether. 

If this is the source and tightening didn't completely eliminate it perhaps something was missed by the previous owner while assembling the car. If some of you will recall I bought the car and the front brake calipers had been installed without rubber isolator bushings and they rattled like crazy.

Thoughts?

[Midlife 814]

Aren't there pins that hold the drum brake pads off from the backing plate?  The backing plate typically gets worn in this area and needs to be ground down flat.  Of course, my memory could be waaaay off, but I remember having to do that to my 66.

[copb8 97]

Well sometimes finding the problem is 99.99% of the problem. Ending up with the car on the lift with a friend rocking it back and forth violently while I laid underneath putting my ear to everything. Turns out it was an under torqued u-bolt holding the diff to the leaf spring. Torqued the 8 bolts to spec and now the noise is gone. Duh!

Now on to the next thing. Thanks for all.

[Brian Conway 264]

Thanks for the story.  Good to know  Brian

[RPM 1,190]

Ha, good news! Thanks for providing a final answer on this thread, as many internet forum threads are never finalized. Probably should've tightened the U bolts after suspecting them back on April 10th eh?  :) 

[copb8 97]

Just now, RPM said:

Ha, good news! Thanks for providing a final answer on this thread, as many internet forum threads are never finalized. Probably should've tightened the U bolts after suspecting them back on April 10th eh?  :) 

And hence the 'duh' in my post. :-)

I hand tightened them all back then and thought I put some effort into it. I must of been fading by the time I got to the one set. Also I wasn't using a torque wrench back then. Definitely lesson learned.