Have you noticed a sticky, black fluid on the ground under the front of your Mk2 300ZX (1900-1996)? On close examination does it look as if the leak is coming from the front of one or both of your tension/compression rods? The standard explanation for such evidence is that the leak originated above the rod, fell on the rod and thus onto the deck. However, in the case we are reviewing, the source of the liquid is far more elegant.
In the never ending quest to reduce the transfer of road noise, vibration and harshness to the driver, the engineers at Nissan came up with a pretty clever idea. The job of the tension/compression rod is to laterally secure the control arm to the chassis. The rod is bolted directly to the control arm but secured to the chassis with the aid of a rubber bushing or bushings. Think of it as a motor mount for your front suspension. In the case of the 300, the bushing appears to be the standard model and although the exterior looks like the old standby, it is filled with a gel-like material. These fluid filled mounts do a much more effective job of energy absorption than the solid rubber units ever could. Yes, I can hear my performance minded readers asking "doesn't that fluid filled mount make the front suspension kind of sloppy?" Remember, the fluid filled mount is built for comfort, not speed.
OK, have you been paying attention? By now we can see that the source of the leak is a ruptured tension/compression rod bushing. The very high stress level that the rod is subjected to will eventually cause cracks to appear in the rubber exterior allowing the fluid to escape. What is the fix? Nissan does not supply the bushings separately so we have to replace the complete rod.
Relax, it isn't the engine.
Michael McGinnis
Banzai Motorworks
