The big difference here is in the general format of each suspension. 4 link and torque arm systems each have their high points. A well executed torque arm system (which the Speedtech system looks like it is) should offer very precise, predicatable handling. They`re known for being very benign, no suprises with torque arm systems as a rule. They`ve got very good roll steer characteristics and mild pinion angle change. The long panhard bar should do a good job of laterally locating the rear with precision and you`ll have only a small amount of roll center migration. That`s all good stuff. Like anything it also has some limitations, it`s got very limited anti squat (usually under 70%) and your side view swing arm length (SVSA) is going to be quite long and non adjustable, that puts the IC far forward and it is non adjustable for height. What does that mean? It means that it shoudl work well for handling but it`s not a great drag race suspension. If you`ve got big horsepower you may have a hard time putting it down with a torque arm system unless you build the rest of the cars suspension around it to compensate. If you`re on this forum you probably don`t want to do that because that will greatly compromise handling. We`ve been working with Spohn Performance for years, they`ve built some of the quickest torque arm cars in the country, but those cars don`t do anything else but go fast in a straight line. IMO torque arms make good street or road race suspensions but they`re not as good as some other systems for harnessing horsepower.
An adjustable 4 link like the G-Link is a multi tasker. This system has enough adjustment in it out of the box to make it whatever you want it to be. Will it corner as well as a purpose build road race 3 link? No but it`ll be darn close. Will it hook as hard as a dedicated drag race 4 link? Maybe not, but it`ll be darn close there too. The adjustability of this format lets you span a really wide range of performance applications and dial it in to what you want ,when you want. In a mainly handling application you`d set it up with the lower links level at ride height and the uppers as well for minimal roll steer and very neutral handling. At the drags you`s move the rear of the upper links up and the rear of the lower links down, dramatically shortening the SVSA length and pringing the rear IC to where it would be on a purpose built drag race 4 link. This package can run anti squat percentages of over 150%. That`ll create less desirable handling (although it will still be pretty good) but it`ll plant big power like a drag car. For a high horse power ProTouring car you`d likely run it set somewhere in between, probably lower links level to promote good roll steer and the upper links slightly raised at the rear (not so much that we raise the RC too high) to gain a healthy dose of anti squat as well. The G-Link also offers sway bar and mini tub options. I`m particularly fond of the frame mounted adj. rate rear swaybar which lets you dial the handling balance in without having to mess with spring rates and ride quality. Set at its firmest setting it also makes a very passable drag bar for making the car launch nice and level. The multiple arm mounting locations also allows you to achieve various different formats at different ride heights. Many link conversion suspension are only adjustable so that you can set different wieght cars up at the one and only ride height where the suspension performs properly.
Ride quality with either system is controlled by spring rate and shock settings and again, is what ever you want it to be. That`s one of the coolest things about these coil over, link rear suspensions. I think you`d be happy with either one but one may fit your particular goals better than the other depending on what those goals are. Mark SC&C
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