In this article we’re going to learn what is required to perfect the 5.0 Mustang’s launch from the starting line. In the first installment we covered the tires. For the second installment we’re going to talk about suspension modifications, you can make to get you down the quarter mile quicker and faster.
The 5.0 Mustang uses a non-parallel 4 link rear suspension. Unlike the parallel 4 link suspension used on Pro-Stock racecars and other full on racecars. Ford used the non-parallel design from the factory as a cost saving measure, because it requires less parts to function, saving production costs. But like any cost saving measure, compromises are involved.
A parallel 4 link suspension requires either a panhard bar or a watts link to keep the reared centered in the car body. The 5.0 Mustang’s angled suspension arms keep the reared centered, without using any additional hardware. By using a combination of short control arms, and long control arms, both with different angles, the potential for suspension binding is very high. Ford compensated (compromised) for this by making the control arm bushings out of a soft rubber compound, that has some give to it.
Anyone who has drag raced their 5.0 Mustang knows all about wheel hop and fishtailing that these cars are notorious for. So the first thing that needs changing is the rear control arms. Ideally the car should use a control arm like the Mega-Bite Sr. which has Heim joint rod ends, to eliminate suspension slop and prevent binding. They also have the added benefit of being adjustable for length, allowing you to center your tires in the wheel well openings. It also will allow you to adjust the pinion down angle, to further adapt launch characteristics. This one suspension modification alone should make a noticeable improvement in your cars starting line antics. No more wheel hop or fishtailing, and much easier to keep in a straight line down track.
The next suspension modification that needs to be remedied is a change to an adjustable shock absorber. If funds are low you could get by with a 50/50 rear shock, and either a 70/30 or 90/10 front strut. But if funds permit, you’ll be much better off in the long run with an adjustable shock/struts. Quality products are available from companies like Competition Engineering, AFCO, Koni and others. Having the ability to adjust your shock settings gives you the flexibility to adapt to future mods in the power department. If you’re like most 5.0 Mustang racers you’ll be adding more and more power to your car as time goes by. What works for your launch at one power level, may prove totally wrong with 50-100 more hp in your engine.
If your street/strip car is more strip than street. More aggressive suspension mods can be performed. Items such as Eibach’s Drag spring set allow for much better weight transfer upon launch. Removing the front anti-sway bar is also another way to loosen up the front end for better launch at the drag strip. It’s also very heavy, and removing it will shave a few pounds off the front end weight of the already nose heavy 5.0 Mustang. Stock weight bias is typically around 57/43 stock, which means 57% of the cars weight is on the front wheels. Not exactly conducive to great traction, which is why I will be addressing redistributing some of that weight in a future article.
For now I would not recommend removing the rear anti sway bar from the car. It serves a purpose, that being to help keep the rear end of your 5.0 Mustang from torquing over to the passenger side when launching. As you add more power to the car a change to an aftermarket anti sway bar or even a double bar system may be in order. But the factory rear bar will take you deep into the 11 second range and perform admirably.
Aluminum Caster/Camber plates are another worthwhile suspension mod. Caster/Camber plates are made by Steeda and others. These devices replace the flimsy factory part, Replacing the rubber bushing upper strut mount, with a much more precise ball bearing, and allow you to add additional caster to the front end alignment. Adding caster to a drag race 5.0 Mustang helps you keep the car centered in your lane and adds stability at the top end. Adjusting your alignment to provide 5-7 degrees caster will help tremendously in keeping you going straight ahead.
Replacing the factory tie-rod ends with an aftermarket bump-steer kit is another trick that will work very well for keeping you from running off the racing surface. Bump steer is the change in toe-in that your 5.0 Mustang experiences when the front end rises and falls. From the factory the Ford Mustang usually has a bit of bump steer built in. Once you start changing things it only gets worse. These pieces will need to be installed at a chassis shop, but are well worth the expense, for the stability your car will receive from them.