Going to poly isolators will gain you some height. Maybe ~1/4"+??
Urethane rear spring isolators, 1979-04 Mustang
The best,
and the correct, way is to go with
MM adj rear lower control arms.
HD Adj. Rear Lower Control Arms, 1979-98, with swaybar mount
Heavy Duty Adjustable Rear Lower Control Arms, with Swaybar Mount, 1979-98
$379.95
Item # MMRLCA-2
Manufacturer: Maximum Motorsports
The easy adjustment of MM's Adjustable Control Arms allows raising the rear ride height by up to 2 inches, or lowering it as much as 1 inch. A heavy-duty weight-jack bolt, similar to those used in NASCAR, makes this possible. The spring perch design allows easy ride height changes, with the car still on the ground. Road racers and autocrossers can set not only the ride height, but also corner weights, for optimum handling. A car can be fully loaded up with gear for a road trip, and then have the rear ride height adjusted back up to normal, to avoid bottoming out. These control arms are available with mounts for a factory-style rear swaybar, or without any swaybar mounts, for use with MM's Adjustable Rear Swaybar.
The MM Heavy-Duty Rear Lower Control Arms utilize specially designed 3-piece urethane bushings at the chassis end. These bushings have a hard center section to prevent fore and aft deflection, and softer outer sections to allow the angular motion necessary to prevent bind. This design, with softer outer urethane sections, prevents torque-box damage due to binding of the lower control arms. At the axle end, we use a high quality PTFE-lined spherical bearing to precisely locate the rear axle. Unlike the other bushing types listed above, a spherical bearing allows freedom of motion for both pivoting and angularity. As with our 3-piece urethane bushings, this freedom of motion improves handling over other styles of bushings, and prevents damage to chassis components.
We place the 3-piece urethane bushing at the chassis end, rather than at the axle end, for two reasons. First, this reduces the amount of noise, vibration, and harshness (NVH) that is transmitted into the chassis. Second, because the spring is mounted to the control arm and the chassis, it is best to keep the control arm and chassis from getting too far out of line with each other. If the spherical bearing is placed at the chassis end of the control arm and the urethane at the axle end, the control arm will tend to stay in alignment with the axle. This would cause the spring to arc sideways with body roll, and change the effective wheel rate.
Note: I said,
MM.
Go with ANYTHING ELSE, and don't come crying to me when the POS cr*p breaks and you and your car go flying off a cliff.
On the other hand, I make almost 7 figures a year off of life insurances of people that buy that GMS, and other cr*p. So, if you do but that other cr*p, let me know. Why work when I can profit from people that got sucked, screwed, and fools?
