[bosscar]

Loud cracking/popping sound.
At first I thought I had a bad strut.  It only starts making the sound after driving for at least 15-30 minutes.  Cant get it to make the sound before driving it.  I drove it and brought a friend with me today and asked him to push down on the fender while I was underneath.  When you put a lot of weight on the left front it will keep making the noise once it starts.  I think it's coming from the coil spring.  Not the strut.  Weird.  What could be wrong?  A rock stuck under the spring?  Can I drop the arm without the use of a spring compressor?  Thanks, Jim

[TurboRay]

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Since most members PROBABLY. haven't memorized what car/truck you own, AND you haven't created a signature with that info, AND you didn't disclose it....... what vehicle are you talkin' about? Depending upon the type of suspension, front-end noises can emanate from all sorts of components (ball joints, anti-sway-bar bushings or links, inner A-arm bushings, struts, spring perches, tie-rod ends, etc., etc.! 

Aside from that....... it's doubtful that "I/we" could accurately GUESS what's causing it. Rather, I suggest crawling underneath and placing your hand on the various components while yer friend bounces the vehicle to duplicate the noise. You should be able to FEEL .the vibrations created by the noisy component(s).  <shrug>  GOOD LUCK!

[bosscar]

.
Since most members PROBABLY. haven't memorized what car/truck you own, AND you haven't created a signature with that info, AND you didn't disclose it....... what vehicle are you talkin' about? Depending upon the type of suspension, front-end noises can emanate from all sorts of components (ball joints, anti-sway-bar bushings or links, inner A-arm bushings, struts, spring perches, tie-rod ends, etc., etc.! 

Aside from that....... it's doubtful that "I/we" could accurately GUESS what's causing it. Rather, I suggest crawling underneath and placing your hand on the various components while yer friend bounces the vehicle to duplicate the noise. You should be able to FEEL .the vibrations created by the noisy component(s).  <shrug>  GOOD LUCK!

[TurboRay]

I could feel the "shock" putting my hand on the bottom of the control arm. 

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Springs don't make noise ~ unless they're "skewed", cracked, or moving around in their mounting "cups" - which is highly unlikely since they're compressed and exerting pressure against their upper & lower mounting "cups". Soooo........ feeling the "shock" (snap or pop?) by putting your hand on JUST the LCA means that the noise could be coming from the (1) LCA bushings, (2) ball joint, (3) anti-swaybar bushings or links, (4) strut, or (5) upper strut mount. 

IOW, you need to move your hand around to ALL those "joints" to pinpoint .the exact worn component(s) that is/are causing the noise. I'm gonna go out on a limb and GUESS that it's the upper strut mount (a relatively high-wear failure-prone component). Replacing it would require removal of the strut assy for replacement with a new "loaded" strut (pre-assembled with a new spring and mount) ~ OR compressing the spring on yer old strut, removing the upper mount/spring cup, and reassembly with a new mount.  OTOH, it could be ANY of those 5 items I listed above. <shrug>

[bosscar]

I could feel the "shock" putting my hand on the bottom of the control arm. 

.
Springs don't make noise ~ unless they're "skewed", cracked, or moving around in their mounting "cups" - which is highly unlikely since they're compressed and exerting pressure against their upper & lower mounting "cups". Soooo........ feeling the "shock" (snap or pop?) by putting your hand on JUST the LCA means that the noise could be coming from the (1) LCA bushings, (2) ball joint, (3) anti-swaybar bushings or links, (4) strut, or (5) upper strut mount. 

IOW, you need to move your hand around to ALL those "joints" to pinpoint .the exact worn component(s) that is/are causing the noise. I'm gonna go out on a limb and GUESS that it's the upper strut mount (a relatively high-wear failure-prone component). Replacing it would require removal of the strut assy for replacement with a new "loaded" strut (pre-assembled with a new spring and mount) ~ OR compressing the spring on yer old strut, removing the upper mount/spring cup, and reassembly with a new mount.  OTOH, it could be ANY of those 5 items I listed above. <shrug>

[dan_xr4]

The old fox body Mustang front suspension is a modified Macpherson strut. The spring and strut are separate. The front strut can be replaced without disturbing the spring.

Do you notice anything when turning the steering wheel back and forth ?

[bosscar]

The old fox body Mustang front suspension is a modified Macpherson strut. The spring and strut are separate. The front strut can be replaced without disturbing the spring.

Do you notice anything when turning the steering wheel back and forth ?

That is one of the oddities of this noise.  It doesn't make noise turning back and forth like a bad strut usually does.  At first, I thought it was probably the strut, because it only starts making noise after driving for at least 20 minutes or so.  
So I was thinking the fluid in the strut, or air building up inside, or heating up or something causing the noise to start once warmed up.  
I couldn't think of why a control arm bushing or coil spring type issue would only start making noise after driving for a while.  
But you really feel the shock to the arm when manually bouncing the suspension up and down once the noise starts.  
I'll take the strut out and see if the upper mount is causing the noise too.  
I wish Ford made the original style struts still.  I hate the aftermarket replacements.  They don't seem to fit right.