Soft Left Rear? (Suspension)

DakotaR

New Member
Dec 9, 2011
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This is my first post here, so be gentle. This is also my first foray into Mustangs, too.

My girlfriend just purchased an 04 Mustang with the 3.9L and 5-speed. We got a good price on it, especially considering mileage, but it did come with a few issues. Most of them have been taken care of, but one still persists.

During take-off, heavy acceleration, or at the very end of end of a hard stop, we're getting some odd movement from the rear. I figured it may have been a bad shock on the rear, so I replaced both of them, and the problem isn't as bad, but it's still there.

I have jacked up the rear and attempted to check both rear upper and lower control arms, and I can't find any worn bushing or play in any of them. The left rear seems softer, and the feeling comes from the left rear. On take-off, it feels like it dips harder than the right, and while up to speed (around 45 mph), a quick steering input to the right makes the left dip hard, sometimes hard enough to hit the bump stop (or I assume that is what is happening... you can hear a bump and the suspension doesn't travel any lower). On braking, if you come to a quick stop, the rear almost wiggles. I am tempted to strap an old digital camera to the rear bumper and video what is going on, but I figured I'd get some input first.

Is it possible the coil spring has gotten soft? Can the upper or lower control arms go bad without any noticeable play? Could it be something else? The car was checked before we purchased, and one item on it mentioned the front sway bar links needed to be replaced. I know its a long shot, but could this cause the problem?

The only other issue I have is a shudder on take-off in 1st if you do a light take-off. I'm betting on one of the motor mounts or trans mount being the culprit, as the clutch holds firm in all gears.

I consider myself mechanically inclined, but I'm not too keen on suspension, especially 4-link.

Edit: Should probably also post that the left rear sits about 1" lower than the right.

TL, DR: 04 V6 5-speed; Left rear dips on accel, hard breaking, and quick steering inputs to right at speed (feels like it hits bump stop). Changed rear shocks; improved problem, didn't go away totally, didn't notice play in either UCA or LCA.
 
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