Saturday 12 January 2013

Ticking speedometer fix

When a cable-driven speedometer needle starts to make small jumps and clicking noises it’s usually the result of a “dry” or unlubricated cable. This is especially evident on cold mornings. If it’s not addressed the cable will eventually break. Such was the case recently with my Subaru - on cold mornings at low speeds, the speedometer would tick incessantly and jump around by a few km/h at a time. Thankfully it’s a relatively easy job to pull it out and fix it.






Impreza speedometer cables can apparently be either a one- or two-piece assembly. On the JDM models such as mine it is a two-piece. This doesn’t make much of a difference for the lubrication procedure.

The cable attaches to the transmission on the right hand side. With the car jacked up on stands it is somewhat accessible from the underside of the car. Here’s what it looks like if you were under the car with your feet pointed at the trunk:



If your car isn’t too dirty, it’s easily identifiable by the orange rubber cover, pictured above (already pulled back from the cable end). Under the rubber is a brown plastic piece that can be threaded out of the transmission by hand (probably). Be careful though - I have heard of this plastic being brittle and breaking off in the transmission!

Once it’s disconnected from the transmission it can either be lubricated in place or it can be pulled up to the engine bay for easier access. I hate working under cars, so I pulled it up topside. Be careful not to bend it too sharply if you do this or you will damage the cable.

With the cable pulled up you can clearly see the two parts of the cable.



There is a second orange rubber boot on the second cable connection, and it is again pictured as already pulled back, exposing the connection. You can also see the brown plastic transmission connector. The small wire clip can be popped off with a screwdriver (don’t lose it!) and then the cables will pull apart.



Lithium grease in a spray can seems to be the lube of choice for speedometer cables, and so that’s what I used. The small cable section is a bit harder to lubricate but I sprayed both ends of the cable and tried to get as much as possible into the cable housing.

The upper, longer cable section is much easier to lubricate. It can actually be pulled right out of the housing.



I cleaned it off with a clean rag and then liberally sprayed it with lithium grease. I then sprayed some more grease into the cable housing and reinserted the cable, making sure it rotated freely. The two cable sections were then rejoined and threaded back down to the transmission.

On my car, the seal for the transmission side of the cable was falling apart so I slathered it with a little bit of black RTV silicone. A new seal would be a better idea, but I just wanted to get the car back together ASAP.



For me, reconnecting the cable to the transmission was the trickiest part of the whole procedure. Getting that brown connector aligned and threaded in was just a pain in the ass! I ended up removing the intercooler and threading it in while looking down from the top (rather than lying under the car), so I could see it more easily and had better access. Many four-letter words were shouted during this process.

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