The Mazda Miata has a compact and sporty design that has made it a very popular choice for the foreign car enthusiast. The Miata has a high performance engine and a small, aerodynamic body that allows quick acceleration, great handling and increased fuel economy. Noises often heard from the dash cluster location, such as a squeaking or scraping sound point to one main culprit -- the speedometer cable. Speedometers cables routinely dry out inside their protective sheathes, causing friction and erratic speedometer needle fluctuations. The Miata owner can replace his cable, or choose to lubricate it. Lubricating the Miata speedometer cable requires some basic tools and few steps to complete the procedure.
Set your transmission shift selector in park or neutral, according to your vehicle's design. Open the hood and disconnect the black, negative battery cable with a socket. Raise the front of the vehicle with a floor jack and place two jack stands underneath both sides of the chassis. Lift the rear of the vehicle and place two jack stands under opposite ends of the chassis. Open the driver's door. Use a screwdriver to remove the two screws that hold the plastic plenum cover to the underside of the dashboard.
Use a screwdriver to remove the screws from the plastic cover over the dashboard cluster. Direct a shop light so you can see the back of the pod cluster where the speedometer attaches to the socket. You will see a plastic tang that holds the speedometer head to the socket on the pod cluster. Reach your hand up from underneath the dashboard and squeeze the plastic tang. Pull the speedometer cable out of the pod cluster.
Go to the underside of the vehicle and locate the speedometer cable where it enters the transmission housing. Use channel locks to unscrew the ring nut that holds the cable to the cable drive gear head. Pull the cable out. Move upward toward the engine and locate the two cable hangers. Unclasp both cable hanger snaps by hand and pull the cable away. Move to the engine compartment of the vehicle.
Look for the cable next to the firewall, between the engine. To remove the snap on the third cable hanger, disconnect the vacuum line at the manifold fitting with a screwdriver. This vacuum line runs from the manifold to the brake booster. Reach your hand down and unsnap the third cable hanger. Locate where the cable enters the dashboard. Pull the rubber dust boot cover off the cable. Use your fingers to pinch the two ends of the cable socket together and twist the cable out of the firewall hole.
Pull the speedometer cable from the engine. Support the cable in an upright position between cans or wood blocks. The side up that came out of the pod cluster should be in the dashboard. Use wax paper to form a funnel around the top of the cable sheath. Use duct tape to seal it. Pour a small amount of 10W motor oil into the funnel opening and let it sit for 24 hrs, or when the oil can be seen seeping from the other end of the cable.
Wipe the cable heads dry at both ends with a rag. Insert the cable through the firewall hole. Go underneath the dash and push the cable back into the cluster pod socket, by depressing the plastic tang. Move to the engine compartment and snap the cable socket back into the firewall, then push the rubber dust boot back on. Route the cable through the top cable hanger mount and snap it into place. Push the cable down to the floor.
Go underneath the vehicle and route the cable next to the two bottom cable hanger mounts, but do not snap the hangers yet. Run the cable end up to the transmission and insert the cable inside the transmission. Turn the cable end so the tooth fits in the drive gear socket. Screw on the ring nut by hand and tighten it with channel locks. Go back and snap the cable into the hangers by hand.
Move to the engine compartment and reattach the vacuum line to the intake manifold. Reconnect the negative battery cable with a socket. Use the floor jack to raise the vehicle and remove the jack stands. Lower the vehicle to the ground. Replace the top plastic dash cover and tighten the screws with a screwdriver. Replace the underside dash cover and tighten the screws with a screwdriver. Test drive the vehicle and note the speedometer operation. It should function with no noise.
