[Ron Sutton]

Originally Posted by DBasher

Ron I'm sure we are talking about the same car. I didn't want to mention the shop name or the company of the TA because I only had part of the information.

So if properly set up, are they silky smooth? No more or less vibration and noise transmitted up under the driver?

In most cases the type of rear suspension doesn't have any effect on NVH (Nosise/Vibration/Harshness). NVH comes from a LOT of different sources, from front control arm bushings, motor & trans mounts, steering, etc. The NVH that comes from rear suspensions is more of a function of the rod ends, joints or bushing type chosen. There are exceptions.

Leaf springs have a lot of harmonic noise going on, because they are doing three jobs ... rear axle side control, suspension link & spring. When driven hard, they "can" create some ugly harmonics that are counter productive to smoothness & grip. But during street cruising those loads are there.

Torque Arms that mount to the trans mount "may" or "may not" transmit some of the transmission/driveshaft NVH through the car. But that depends on the mounting method.

Otherwise 3-links, 4-links, Torque Arms, etc are going to be similar in NVH. I believe the decision for each car owner ... is where do your priorities lie. If the car is more of a driver/crusier ... a variety of non-metal bushings will offer less NVH. If the car is meant to be a serious performer, zero friction rod ends & monoballs will allow the suspension to much quicker reacting & produces substantially more grip. It is a compromise either way & a choice for each car guy/gal to make for themselves.

Don't confuse NVH with ride quality or handling/grip. Ride quality is primarily influenced by spring rate, sway bar rate & shock vavling ... and secondarily by suspension bushings.

Someone read my Track Handling Thread & thought I wasn't a fan of Torque Arms ... which is not exactly accurate. Because I'm a racer, tuner & looking for every edge ... I run offset 3-links in race & track cars whenever possible. Frankly, decoupled/offset 3-links if I can. This is the fastest, most tunable rear suspension.

But for multi-purpose cars, street G-machines, true Pro-Touring cars that will be street driven a lot, the Torque Arm is a great rear suspension choice. You don't have to cut up the rear floor. You can keep your rear seat. Most designs put the pick up point 45-50"+/- ahead of the rear axle CL. As mentioned above, that puts the pick up point far enough ahead to avoid problems from too much anti-squat. All in all, a great performing rear suspension.

Make sense?