Rattling noise in my passenger side rear end?

[ShootsHeScores!]

What a pain in the a**. I've had this rattle in my rear end for two years now and three mechanics have failed to correct it!

First of all I'll tell you about my car. It's an 89' 5.0 coupe with 49,000 miles. My problem started a few months after I installed a set of 3:73's and an FRPP Aluminum Driveshaft. The gears and driveshaft were installed over 2 years ago right around the 37,000 mile mark on the ticker.

Secondly I'll explain the noise. It sounds like it comes from my passenger side rear end. It only occurs over smaller road imperfections. Large bumps or potholes it doesn't happen at all. Put it this way; it gets real annoying when driving down a dirt road. It also occurs during a launch. It doesn't even have to be a hard launch. It's more of a thumping than a ticking sound, but the thump is not a very deep thump (explaining a noise can be almost impossible but that's the best I can describe it).

Thirdly I'll tell you what I have done to fix the problem. I took my Stang to the local Firestone repair place. They told me it was my upper shocks. So they replaced them and as soon as I turned out of the driveway I turned right back in. They checked everything out again (I even got under the hoist and started tugging and pulling on parts) and decided to remove the new upper shocks and put my old one's back on and gave me my money back. Then I took my car back to Alternative Auto, where I had my 3:73's installed the previous year, to get everything checked out and make sure that wasn't the problem. The gears checked out and they then told me they were too busy to chase down a rattle. So unhappily I took my car home and did nothing till the following year(today). The third mechanic told me that it was probably the quad shocks. He tugged on them and they did make a slight noise that resembled my problem. So I ordered a pair of Bilsteins and they were bolted up today. SAME PROBLEM. The Bilstein quad shocks did nothing toward the elimination of my phantom rattle. I'm taking it back tomorrow to the same guy.

Has anyone else experienced this problem with their fox-body. What could this be?

 

[_jb_]

Yeah I have a problem like that in my car, but very seldom. I sounds like it comes from the passenger rear tire/quarter panel/exhaust pipe. It sounds almost like a backfire to me, except without that high pitched gun sound. I have stock 2.73s and like I said, it only happens like maybe once every two weeks or so.

 

[Legendary]

Sounds like your torque box is ripped. I had both of mines go in my last mustang. Loud music cured the problem for me.

 

[dude5l]

Did they replace the strut insulators when they did the rear struts?

 

[ShootsHeScores!]

Sounds like your torque box is ripped. I had both of mines go in my last mustang. Loud music cured the problem for me.

What is the torque box and where is it located? I'm taking my car back in the morning and would like to suggest that to my mechanic.

 

[time only]

What is the torque box and where is it located? I'm taking my car back in the morning and would like to suggest that to my mechanic.

Put your car on floor jacks and follow the lower control arm back to where it is bolted on to the chassis of your Mustang,the thin hollow metal box thing is the torque box and it is only held together by some light spot welds from the factory,it will twist and crack at the seams after a few hard launch with a high power 5 speed car.

k.

 

[90mustangGT]

I had something similar. Check all the bushings. I just did my upper controll arms and I couldn't see it when they wereon but once off I could see two of the bushings were split. You have low milege but it is still old rubber in there. Your tq boxes could be ripped, but I would say most likley its in the bushings.

 

[bunnk]

I feel for ya man I too have a phantom rattle in the rear end of my car, except its the kind that gets worse with loud music! I hope you figure this thing out!

 

[HISSIN50]

ill toss one out from left field. make sure the flange that is on the fuel filler hose is attached to the tank. if not, it rattles around on the filler pipe. makes a nice metallic clinking noise.

 

[ShootsHeScores!]

I have good news!!! I returned my car the next day to my mechanic and the problem has been 86ed! It turns out the mounting plate for my upper shock was busted. A quick fix and now I feel like I'm driving a new car. The suspension even handles better and its quiet as a mouse. It's a bummer i paid $150 for a new set of quad shocks that I didn't really need. It's okay though, because when I can afford it someday I'll slap some Bilstein's all the way around and that will be one less set I'll have to buy.