Fox T-Bird/Cougar Forums  

Poly can be used in the front control arms with minimal increase in harshness and without any squeaking. The key is in the installation. Front poly bushings can induce a lot of harshness because of their design (at least the design of Energy Suspension bushings). The sleeves of the Energy Suspension front control arm bushing are shorter than the bushings. If you install the front bushings as they come, the k-member clamps down on the faces of the bushing when the bolt is tightened. Because the mass of the bushing has to go somewhere, it attempts to expand in the shell. (See Figs. 1 and 2)

The ends of the bushing are now clamped against the k-member and the perimeter of the bushing is pre-loaded in the shell. As a results, the control arm/bushing can't pivot or flex as needed. This is where the majority of complaints of queaks and harshness comes from with poly bushings in the front control arms.

The key to minimizing harshness and elimintating squeaking is to trim the end of the bushings so that the k-member clamps on the sleeve and not the face of each bushing. The end without the  is the one that is trimmed. I use a hacksaw to trim them. By tpuppies the bushing, a clearance is provided between the bushing and the k-member (See Fig. 3).

The  of the front and rear bushings keeps the front arms from moving front-to-rear relative to the k-member. The control arm cannot shift forward because of the  of the front bushing and it cannot move rearward because of the  of the rear bushing.

The result of this install technique is no squeaking and a ride that's nearly as smooth as with rubber bushings. I've used this install techique on SVO Mustangs, Fox-Body Mustangs and SN-95 Mustangs with excellent results.

Give it a try! You'll like the results.