Mystery pop

[critter]

I as out for more of an extended drive this afternoon. My goodness, what a difference having the front suspension reworked and adding low profile tires on bigger wheels has made. This thing sticks its nose into a turn and it feels like it's just dragging me and the rear end along for the ride.

But, there's always a but, I now notice that the occasional "pop" I'd get from the rear end is doing it in every turn that I take with speed. I suspect that it's due to worn out suspension back there and I have new springs/shackles on order but I'm curious if there might be another cause. Anyone ever experience anything like this before? Opinions on what might be causing my pop? Whatever it is is physical because I can feel it through the floor when it happens.

FYI, at the suggestion of Mary Pozzi, I pulled the rear sway bar a while back and the pop is still there so it's not that.

1974 Trans Am
8.5 inch rear end with 3.42 gears (formerly 3.08)
Converted drums to Pontiac/Caddy rear disk
All bushing are polygraphite (I know, but back then eveyone said do it...)
CE subframe connectors, welded at the front, bolt in at front spring eye in the back.

[exwestracer]

I as out for more of an extended drive this afternoon. My goodness, what a difference having the front suspension reworked and adding low profile tires on bigger wheels has made. This thing sticks its nose into a turn and it feels like it's just dragging me and the rear end along for the ride.

But, there's always a but, I now notice that the occasional "pop" I'd get from the rear end is doing it in every turn that I take with speed. I suspect that it's due to worn out suspension back there and I have new springs/shackles on order but I'm curious if there might be another cause. Anyone ever experience anything like this before? Opinions on what might be causing my pop? Whatever it is is physical because I can feel it through the floor when it happens.

FYI, at the suggestion of Mary Pozzi, I pulled the rear sway bar a while back and the pop is still there so it's not that.

1974 Trans Am
8.5 inch rear end with 3.42 gears (formerly 3.08)
Converted drums to Pontiac/Caddy rear disk
All bushing are polygraphite (I know, but back then eveyone said do it...)
CE subframe connectors, welded at the front, bolt in at front spring eye in the back.

What sort of diff does it have in the rear end? And do you hear it in both left and right turns?

[critter]

It's the stock posi and yes, both left and right.

[exwestracer]

It's the stock posi and yes, both left and right.

Hate to say this, but I think it's in the diff....

[critter]

I could believe that. As far as I know it's never been rebuilt. What makes you think that's the problem?

[exwestracer]

Just the fact that it does the same thing in both directions... if it were a suspension component, it would be very unlikely (not impossible) that it would make the same noise regardless of which side was loaded.

[Norm Peterson]

CE subframe connectors, . . . . bolt in at front spring eye in the back.
Check those bolted connections for tightness and evidence of movement. Just the taking up of bolt to hole clearance can make for a clunk or pop.


Norm

[critter]

You're the second to suggest a nut/bolt check. I can do that easily enough Of course the new springs will replace all that stuff so I'm hoping that's what it is.

Another suggestion was not enough anti-slip additive in the differential fluid. I can't see that causing a pop though, Especially since this seems to happen when the weight transfers from one side to the other.

[John Wright]

may not be this in your case but I'll mention it just in case.....

I had a mystery noise like that one time and I found a muffler clamp too close to the leaf spring and it would pop when it slid over/under the edge of the leaf.

[critter]

I'm going to crawl under there Tuesday night and do some poking around. I have to be out of town this evening so no sleuthing tonight. I suspect I'm going to find that it's tied to the rear suspension being worn out just like the front was.

[Skip Fix]

All bushing are polygraphite (I know, but back then eveyone said do it...)

Poly front eye and shackle bushings?? Mine us to really pop even when I jacked the car up.

[critter]

Yes, Skip. Remember when everyone said polygraphite was the wave of the future? All of the benefits of urethane with none of the squeaks! Horsepucky! :) :) :)

Live and learn.

[Skip Fix]

I do! I'd rather go rubber than those binding POS. I'll stay with steel or Del a lums in front end. My new drag car I just used rubber in the shackles as it has aluminum in the front(Cal Tracs).

I have a full set of GW front spring eye and shackles I bought years ago But I do think there needs to be some movement so it doesn't bind so when I use them I'll probably put a spherical in the front.

[critter]

I may have found it. One of the three bolts that hold the front spring eye pocket to the body spun freely when I checked it for tightness. This is also one of the 2 mounting bolts for the CE subframe connectors I installed umpteen years ago. Looking at the wear marks it appears that loose bolt was allowing the subframe connector to twist and move. I Helicoiled it and will try to get it to pull tight tomorrow night after the Loc-tite has seasoned. If not, Mr. Welder may get the call.