Ford's Focus RS World Rally Car, driven by Markko Mrtin, on its way to victory in Finland. Markko became only the third non-Nordic driver to win the Rally in its 53-year history. A large portion of the Focus RS WRC's success is attributed to suspension. H&R made the Focus RS World Rally Car's springs from the same wire it uses to make basic Sport springs for a GTI and every suspension application in between.
Ford's Focus RS World Rally Car, driven by Markko Mrtin, on its way to victory in Finland.
H&R is always looking at the market, looking for new product opportunities and ways to improve existing products. H&R's biggest news is the new spring wire it uses, 54SiCr6. It is more expensive than the older, already high-quality material and is available only from Muhr and Bender KG, the world's largest producer of springs and spring wire. You haven't heard of Muhr and Bender because it only manufactures for O.E. customers. H&R's conversion required that it completely change most of its tooling. Certain parts of the coiling machines were changed, and the knife to cut the wire is very different. The shot peening operation was modified, and there were a few other, "non-dramatic" changes in the process.
The advantage of the new material is that it's stronger, with a strength of roughly 290,000 psi. H&R engineers can work the wire harder, stressing it more, without yield, or sagging. That allows thinner wire and fewer coils to be used for a given spring length and rate, reducing weight by about 20 percent for most springs and providing more travel before coil bind. All new spring designs take advantage of the new wire material, and as older applications are scheduled for a production cycle, they are being redesigned as well.
The SiCr material can't beat the performance of titanium in every application, but can be worked so hard that it can often come close enough. In any case, the price of titanium is still too high-even at the WRC level, the price of Ti alloy springs is a deterrent.
Joachim Frettlh, H&R's Manager of Spring Development and Motorsports, said that steel gives the best flexibility in production and design. H&R stocks spring wire from 0.3 to 32mm, in 0.25mm diameter steps. With Ti alloy wire, the inventory costs would be too high to do that. Fewer diameters could be stocked, and larger wire would have to be drawn down when a different diameter was needed. That would add more machinery, more process to monitor for quality, and more cost. H&R says that reduced costs with good quality in the future may make Ti a possibility for certain applications, but not now. H&R believes its spring material is the best available, and uses the same stock for a basic Sport spring as for the springs on the WRC Ford Focus RS.