MXA TEAM TESTED: DSP TITANIUM SHOCK SPRING

On Dec 1, 2011

WHAT IS IT? A shock spring that will save one pound on the weight of your bike.

WHAT’S IT COST? $419.99 (plus $10.50 shipping).

CONTACT? www.dsp-racing.com or (661) 618-2644.

WHAT’S IT DO? You don’t have to be sold on the benefits of titanium shock springs. Every factory team runs them. They save one pound over a steel shock spring. Titanium has a fatigue life that blows steel out of the water. Titanium has a lower torsional modulus than steel, which makes it more “springy.” A titanium spring has a larger wire diameter with fewer coils, which allows for more free space between coils than a comparable steel spring.

If there is a downside to titanium, it is expense. Since titanium starts as ore rutile or ilmenite and must be processed at elevated temperatures, it is a very control-sensitive procedure. Any mistakes in the smelting of titanium alloys can result in oxygen embrittlement or worse. The extra steps and intensive safeguards result in a motorcycle shock spring that costs four times more than a conventional steel spring. Instead of $80, a Ti spring costs over $400.

For the money, you get a spring that has these four pluses:

(1) It is lighter by about 30 percent.
(2) The reduction in coils offers more shock travel before coil binding.
(3) Titanium, thanks to its modulus of elasticity, refuses to take a set.
(4) The reduction in unsprung weight pays dividends in the reduction of inertia during movement (it is easier to get started and easier to stop).

WHAT STANDS OUT? Here’s a list of things that stand out with the DSP titanium shock spring.

(1) Feel. A titanium shock spring is more responsive than a steel spring. It has a deader feel on compression and a livelier feel on rebound. Every test rider believed that this translated into improved traction?especially in braking bumps.

(2) Unsprung weight. Saving one pound of unsprung weight is an enormous technical coup (getting a pound off the wheels, swingarm or linkage is very expensive). The reduction in unsprung weight reduces the mass and inertia generated by movement of the suspension system. A lighter suspension system is easier to control without having to rely on overly stiff damping. Unfortunately, only half of the weight of a shock spring is considered unsprung. Thus the one-pound savings in weight only translates into a half-pound savings in unsprung weight.

(3) Spring rate. There are two issues with the spring rates of titanium shock springs: (1) You can’t trust the spring rate written on most titanium shock springs. In many cases, a 5.4 will test out as a 5.2. The good news is that when we tested the 5.3 Honda CRF450 spring from DSP, it tested as a 5.3 (it was confusing that the spring had 5.4 printed on it, but DSP tests every spring and hand writes the actual rate on it in pen).

(4) Typically, you can drop one spring rate when you switch from steel to titanium coils. This is because of the extra springiness of the metal alloy (thus a 5.2 Ti spring can be as stiff as a 5.4 steel spring).

WHAT’S THE SQUAWK? The price is out of this world.

For an AMA Pro, millionaire or hardcore wannabe, this is a five-star shock spring. However, most of us aren’t that fast, rich or full of ourselves. For the average guy, a Ti shock spring is a luxury?a very expensive one.