Rear end popping

[PKFIRE]

I've read through the years about rear end popping on IRS cobras but not sure if they have found a solution to the problem. Maybe I'm missing some information. Mine has gotten worst through the years where now I can here it while I drive. I checked the torque specs from the TSB today and did not resolve my issue. Is Going to a new MM irs bushing the answer? Any info would be much appreciated.

BTW this is the pop when the suspension is offset. Example leaving the driveway or going over a bump.

 

[FNCLOWN]

mine does this as well, i have bushings on order also the irs bolts were supposed to be 14mm from the factory but many terminators left with 12mm bolts in the irs subframe allowing a litte too much play. i'm going to try those tricks first and if nothing then i'll go solid.

 

[PKFIRE]

I purchased the 14mm bolts from Ford. Since I have to drop the cat back I may just want to put in the MM bushings which I haven't ordered yet. Let me know how everything turns out.

Is the sound in your car coming from the upper shock mount in the back? I'm not 100% positive but for how loud it is I assume it's right there.

 

[mu22stang]

Have you ever greased your tie-rods? 03-04s come with grease fittings and it's good to hit these with some chassis grease every oil change. Motorcraft part # is ESA M1C 92A if you wanna pay out the butt, otherwise a good chassis grease will do the trick. Hit the fronts while you're at it.

 

[PKFIRE]

I never greased the tie rods. I wonder if I can get a how to.

 

[Digital]

If you know what a grease port looks like it should take you like 3 seconds to figure it out.

 

[Juruense]

Also there is a TSB about the rear swaybar and shock mounts. I just had the stealership perform that TSB on my car and it really tightened up the rear. They only charged $46 to do it. The TSB issue can also cause popping.

 

[PKFIRE]

Also there is a TSB about the rear swaybar and shock mounts. I just had the stealership perform that TSB on my car and it really tightened up the rear. They only charged $46 to do it. The TSB issue can also cause popping.

I've had this done and I check all the torque specs from this TSB over the weekend. Everything was right at or above what it asked for.

 

[mu22stang]

Also there is a TSB about the rear swaybar and shock mounts. I just had the stealership perform that TSB on my car and it really tightened up the rear. They only charged $46 to do it. The TSB issue can also cause popping.

What's the name and/or TSB number for this?

 

[PKFIRE]

TSB 03-9-5 Suspension - Clunk Or Pop Noise From Rear Suspension - Mustang Cobra Only

--------------------------------------------------------------------------------

FORD:
1999-2003 MUSTANG

ISSUE:

Some 1999-2003 Mustang Cobra vehicles may exhibit a "popping" type noise while turning into or out of an incline, such as turning into a driveway, at low speeds (below 15 mph (25 km/h). The steeper the incline the more noticeable the noise will be. This may be caused by the lateral movement of the stabilizer bar or one or more of the fasteners shown in Figures 1-3, that may not be tightened within the required torque specifications.
ACTION:
TSB 03-09-05

Inspect and torque all of the fasteners listed for the proper torque. Refer to the following Service Information for details.
SERVICE INFORMATION



Raise vehicle on hoist and verify torque at the following components and locations:
Stabilizer bar bracket bolts (both sides) - 42.8 ± 3.7 Lb-ft. (58 ± 5 N-m)
Stabilizer bar collar bolts (both sides) - 6.6 ± 1.0 Lb-ft. (9 ± 1.4 N-m)
Lower shock bolts (both sides) - 98.1 ± 14.8 Lb-ft. (133 ± 20 N-m)
Upper control arm bushing bolts (both sides) - 66.4 ± 10.0 Lb-ft. (90 ± 13.5 N-m)
Stabilizer bar link bolts (both sides) - 35.0 ± 5.3 Lb-ft. (47.5 ± 7.2 N-m)

If you go to the dealer they'll print out a 3 page paper with drawings to help out where to tighten and how much for.

 

[mu22stang]

I appreciate this. I'll hit them today for good measure.

 

[JetmechF16]

May be a dumb question, but does the car still have to be in warranty to have a TSB performed?

 

[xenodragon]

May be a dumb question, but does the car still have to be in warranty to have a TSB performed?

Depends on the dealer. The one I went to did it for me and I was out of warranty. They performed some other checks as well, and didnt charge me a dime.

However it still didnt fix the issue...i gave up

 

[PKFIRE]

I went ahead and installed the 14mm bolts in place of the 12mm bolts this weekend. This didn't eliminate the sound. The sound is almost like it's coming from the top of the irs passanger strut. It pops driving down the road when there is little imperfections. Any idea what else I should look at?

 

[notfastenuf]

I'll chime in since I had a similar problem start yesterday. I installed some wheel studs / spacer over the weekend. Two days of fine driving, now I have a popping sound that appears to be coming from the body, narrowed it down to the RIGHT REAR. Pops over decent pot holes and bumps in the road, also hard lefts.

I can push down on the right rear panel on top and usually get it to pop now. I thought shock at first, but I'm new to the IRS so hopefully I can get around to checking the torque specs PKFIRE listed.

Kinda frustrating - if it's not one thing it's another. :rolling:

 

[SVT32VDOHC]

I did the bolts. I got my left side in with the exhaust in place, but the right side exhaust needed to be dropped. I just couldn't get it started. MY advice......drop both sides of the exhaust, makes it much easier. I was on a hoist too. If you drop the exhaust you might as well do the diff bushings and brace while you are under there. 3 birds, 1 stone.

 

[exdeath]

Pull the carpet out of the trunk and grab hold of the upper shock mount as you reproduce the pop sound and see if you can feel it shifting.

There is a lot of rubber that wears fast and gets loose on these cars from the factory. Strut and shock upper mount donuts are a source of a lot of clunking and popping noises at low speeds over bumps, as are sway bar bushings and spring isolators (spring being metal to metal contact shifting around and popping in the perch when the rubber is all crumbled away). For example I had a clunk in the front when going over speed bumps unevenly, it was the left sway bar chassis bushing that was completely crumbled away at the top, allowing the sway bar to push through and bang into the chassis instead of twisting. Pretty much need to go over everything where there is a metal-rubber interface.

If you can't find the source right away you may need to get under the car on a drive on lift and start muscling things with a big pry bar. If the shock mount feels sturdy and isn't shifting or causing the noise, start placing the palm of your hand at various places in the trunk and see if you can feel sheet metal popping as you have someone produce the sound for you.

Apparently another source of popping in the rear is a seam on the inner quarter panel in the trunk that has a sloppy weld that can be loose and pop as the sheet metal shifts under load. I've not encountered this personally though, all my noises have come from metal-rubber-metal points and can be solved with urethane bushings or solid mounts.

 

[PKFIRE]

I found it! Thanks for the post! I put the car on jack stands and took off both wheels. I placed a jack under the passanger rear A-arm. Since the pop happens when the springs load and unload. I was able to recreate the sound by jacking up under the spring. This pop sound resonated in the trunk. I thought it was the upper shock mount. So I removed the shock. Then I compressed the spring again. Noise was still present. Anyway after checking different spots I had a second person jack the car up while I was in the trunk.

In the photo below is spot welded sheet of metal that under this load was deflecting and causing the popping sounds. I just bent it a bit and the noise went away.

 

[notfastenuf]

I found it! Thanks for the post! I put the car on jack stands and took off both wheels. I placed a jack under the passanger rear A-arm. Since the pop happens when the springs load and unload. I was able to recreate the sound by jacking up under the spring. This pop sound resonated in the trunk. I thought it was the upper shock mount. So I removed the shock. Then I compressed the spring again. Noise was still present. Anyway after checking different spots I had a second person jack the car up while I was in the trunk.

In the photo below is spot welded sheet of metal that under this load was deflecting and causing the popping sounds. I just bent it a bit and the noise went away.

What are the chances - that was it on mine. Same piece. WTF. Thanks dude. :banana:

 

[PKFIRE]

What are the chances - that was it on mine. Same piece. WTF. Thanks dude. :banana:

Kind of odd right but a cheep fix? Good thing that it worked for you. :thumbsup: