KNOCKING from the rear of the 67 Newport

[Scoopy G]

Hello fellas (and fell-ettes),

I've got some knocking in the rear of the "67 Newport. I got 'er up on the lift, and cinched down the rear shocks, and that helped. Funny, the shocks would not move at all by hand, but I tightened them down and that made a bit of difference. STILL, I got some knocking back there when going over bumps. I think it's the rear leaf spring bushing? Here are some photos, the first photo is the driver's side, and it looks kinda pushed rearward. Second photo is the passenger side. The bumping noise seems to be coming from the left side.

Any suggestions? Source for bushing kit? Cheers from Tampa.........Rich

 

[Big_John]

Anybody locked in the trunk?

If not that, check the tailpipes.

 

[Scoopy G]

Thanks John. The exhaust setup is a bit interesting, but to my knowledge, everything is tight back there.

 

[CBODY67]

Check the shock bushings, too. The leaf spring bushings usually are not an issue . . . if they were, the car would track funny when one wheel hit a bump one the other one did not, for example. IF the rear tail pipe has been changed, OR has been "muffler shop made", that can be an issue, too, as it is very near the top of the shock where it goes over the axle.

Enjoy!
CBODY67

 

[Mr C]

When it happened to me it was the bushings on the rear shocks...

 

[Scoopy G]

Thanks Mr. C,

The shocks are new, so the bushings are in good shape. I'll check the exhaust system again. The funny thing is that I can't replicate the noise when I bounce the car by hand.

 

[CBODY67]

The shocks might be new, but are the upper bolts tight to spec? Was the car on a body contact lift when they were installed or on a drive-on lift? This can be important (which we didn't worry about back then) in that the bolts on any suspension bushing need to be torqued with the car at factory ride height rather than with the suspension extended to its full travel. If they were tightened in the extended position, the bushing will have a pre-load on it when the car is on the ground, which can affect long-term durability of the bushing. By observation, a more minor thing, but something to consider, fwiw. The other thing is, as we discovered with Monroe Magnum shocks on GM pickups (where they were popular in the 1990s) is that if the upper bolt is not tightened and stays that way, the slightly loose bolt will enlarge the mounting hole it is in, which makes noise and complicates things in the future.

On the rear shocks, the upper mounts might be ok to be tight with the suspension in the extended position, but the lower attachments can be left slightly loose when initially mounting them, but then fully tighten the attachment with the rear wheels on the ground (or in that position) as the lower mounts will see more movement as the suspension contracts and extends in normal use.

Remember, too, that as the rear suspension compresses, the shock body will move outward and can more easily contact an exhaust pipe that is not configured correctly (which makes OEM replacements better), by observation.

My parents took their '72 Newport to a local "bend it" muffler shop (back in the 1980s) and got the rear tail pipe replaced. Rattles happened. I looked under it and saw what was happening and ordered a Walker OEM replacement pipe for it. With it in the correct position, no more knocking back there and plenty of clearance for the rear shocks to work.

Also check the condition of the exhaust system hanger which should be at the rear muffler joint. That and the rear hanger are the main hangers on the single exhaust system. Duals usually have the hanger that is at the top of the bend over the axle, plus that rear mount at the back of the frame rail. All of the hangers should have an equal amount of weight they support.

Just some observations and experiences,
CBODY67

 

[ricks_RR]

shack bushings maybe

 

[Scoopy G]

Seems like the shackle bushings are indeed the culprit.

 

[xxcarguy]

Anybody locked in the trunk?

If not that, check the tailpipes.

My first thought!