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Discussion Starter #1
I've had a mysterious "clunk" coming from the rear of the car since I first went to the track a year ago (I was dumping the clutch at 4k on slicks and it puts down 400 ft/lbs of torque at the wheels). There was no clunk before that day, and that was the first time the car had ever been to the track. Since that time I've replaced my rear end, so I'm fairly certain it's not that.

The clunk doesn't happen if I accelerate very slowly, but besides that, if I get into the gas even the slightest bit, it clunks. It clunks from a dead stop, and also between gears if it'm hammering on it. It sounds and feels similar to a heavy object loose in the bed of the truck and each time you hit the gas, the heavy object rolls back and hits the tailgate.

Someone recently said it's probably the control arms ripping the torque boxes out. I've taken a bunch of pics underneath the car, so I'm hoping someone here that knows what they're looking for can help determine if it's the torque boxes.

Here's a link to ALL of my Mustang pics, as well as some of the more applicable ones posted below.















 

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You don't happen to have spherical bushings do you?

Either way someone more knowledgeable will chin in but it looks to me like your torque boxes are fine. It's hard tell from your pictures (for me anyway) but when my buddy ripped the torque boxes out of his fox they literally ripped out and one control arm was on the ground.

If your making 400ft/lb rwtq then even if they are okay it might not be a bad idea to get them reinforced or at least welded up




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look alot better than mine what do the uppers look like?
 

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Discussion Starter #5
Nice to see that my throttle body bracket pics made into your collection, lol.
hahaha. Oh yeah man, hope you don't mind. If I see something that I might need to know later, or that I like and might want to do later, I snag the pic. You never know how long it'll be hosted on imageshack or something, so it's safer to snag it and store it somewhere to use later...
 

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Not at all, that's what I put it out there for. Glad someone else liked my idea, though I'm sure I'm not the first to think of it. None of my stuff is trade secret, lol. Though what I would like to know is how you get your wife to help you? Mine could care less how it gets to what it is, just wants to go to the dragstrip. But then again, I don't really take an interest in her show horse either, hahahahaha.
 

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Anyone taking thier Mustang to the track should weld thier torque boxes. They are held in place with nothing but a few spot welds from the factory. All that twisting, pushing, and pulling during a hard launch will eventually tear those spot welds right out. The better you hook the worse it gets. If any are pulling away or have pulled away, they need immediate attention.

Check all torque boxes, the u-joints, control arm bolts, shock bolts, anything that can work loose. Check the mufflers. If they are working loose they can hit the frame from time to time. Rock the back of the car side to side and listen for any odd noises there to.
 

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Hey danno, Is that your car that has the cowl gauge pods ? If so, do you like it ? Im thinking of getting one some day
 

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The torque boxes look fine. Your car is clean underneith. I would grind down those bubble gum welds on the subframes and re weld them or have it done. Before joining the forum I wasn't aware that the Foxbody torque boxes are prone to tearing out. Pushrod metioned it to me and then Faststang suggested the Wild Rides Battle Boxes and I got them. ($76) Installed them in last month. I have the steps on my build thread. I would plan on getting them if you are going to continue to run slicks. I'm going from the ground up, I don't want to F up the chassis.
 

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More likely the upper torqe boxes than the lower. Take ou the back seat and you can see if the spot welds are ripped out. Also check your trans crossmember, sounds like the tube has rusted through or broken loose. Nice looking car undrneath and I love those ca you have, verify rhose bushings are still good as well.
 

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i have had a ''clunk'' driver side, that sounds simmilar to what you described ever sinse i did upper/lower arms. my best guess is because i put on cheep sve arms with non-sperical bushings. i have a vert so they are more prone to noise, clunks, ect.. your tq boxes look fine. your subs where welded with a flux core welder, it's preety hard to weld under a car with one. those hot ass pieces of slag burning the **** out of ya and all lol! you should grind those down a little and have it redone. they prolly had a cheep 70-90 amp welder. i doubt it had good penitration.
 

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Discussion Starter #16
Wonderful responses everyone, thanks! I think I figured it out...

Those sub frame connectors are scary....
Yes they are - they've since been ground down and re-welded. I didn't know any better when I bought the car. Ya live and learn!

I didn't know u could JB weld sub-frame connectors?? J/k
You might or might not be surprised with how many times I've heard that joke. It's all good. :)

Hey danno, Is that your car that has the cowl gauge pods ? If so, do you like it ? Im thinking of getting one some day
Actually no, it's not. I snagged that pic somewhere because I'd also like to do it and I had never seen it before, so wanted to get a picture to remind me of it later.

Check all torque boxes, the u-joints, control arm bolts, shock bolts, anything that can work loose. Check the mufflers. If they are working loose they can hit the frame from time to time. Rock the back of the car side to side and listen for any odd noises there to.
Thanks - this is exactly what I did, and I found the issue: here's a link to a 10 second video of the rear upper control arms. We took a crow bar and used it to simulate a load on the rear and sure enough, there's a lot of movement in them.
https://picasaweb.google.com/104039...hkey=Gv1sRgCLyOjbe14pXiMw#5820338833709618914
 

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Discussion Starter #18
ok, so I called Summit to find the right replacement bushing, and they can't seem to find a part for what I need - they said it didn't exist. I called Lakewood and they claim the bushing is part of the control arm and that it can't be replaced without buying a whole new control arm. This sounds like BS to me considering what the current one on the car looks like. However....

I found this on Summit, and based on THIS DESIGN, I would agree that it can't be replaced, but this thing doesn't look like the one on my car.

What are the going opinions on "nice uppers"? The car is 90% a street car, but it only sees 2k of miles per year, so take "street car" with a grain of sand. The rest of the mileage is drag racing, so I'd prefer something with good results at the track, even if the car will ride like **** on the street. The street mileage is mostly groceries, local car shows, etc.
 

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Adjustable with spherical bushings. They ride a little harsh but I actually don't mind it.


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