Monday, March 10, 2008

Maintenance: Lubricating the speedometer cable

Here's a quick, inexpensive, and easy maintenance I did this last weekend, it took all of one hour to complete from start to finish, which, is a good bang for the buck investment of time.

As mentioned on an earlier post, the speedometer of our DeLoreans are fed by the rotation of the front left wheel. That rotation is transferred through the angle drive, through a lower speedometer cable, through a "Lambda counter", through the upper cable which plugs straight into the speedometer. The cables both consist of an outer protective sheath, to an internal rotating wound wire. What this maintenance consists of is to ensure that the internal cable rotates smoothly through lubrication. If left un-lubricated, the internal cables have been know to unwind, as well as affect the speedometer reading by causing a needle bounce at low speeds.

This maintenance was on the lower cable.

The materials used were:
Brake cleaner
Cable lubricant
Lint free towel.

Easiest to lift the car up at the front (follow correct safety protocols).
Turn wheels towards right.

Undo the knurled end that plugs into the angle drive - pull straight out.

Following the cable, pull out the rubber grommet on the body.

Now going inside, just above the clutch pedal you will see the other end of the cable that plugs into the Lambda counter (basically a 30K counter). Unscrew that end and pull out, being careful not to bend the internal cable.

Push the cable out through the grommet hole and take the cable to a workspace to begin the lubrication.

(Note the cable shown has a stainless steel outer sheath, this is an aftermarket cable, not the OEM cable.)

Lay the cable as flat as possible on a table, and pull out the internal cable, note it only comes out one end, the end that went on the Lamda counter.
Clean internal cable by wiping it down to remove any gunk or residue.

Put a plastic sandwich bag at one end of the cable, and holding the cable vertical spray some brake cleaner inside.

Now slide the internal cable in and out to work the brake cleaner out, and into the bag. Repeat another time, wiping down the internal cable.

Next repeat the process, but this time with the cable lubricant, after the last time the internal cable is cleaned, leave the cable inside and you are done.

Reverse the disassembly process and you now have a well maintained spedo cable.

I generally grease the angle drive after an oil change. Note that I changed the standard grease fitting (seen on 2nd picture above, a 90 degree 7mm fitting available at PepBoys) in order to facilitate this process, when done I turn the fitting in towards the wheel.

Lubricating the upper cable is a little more involved, in that it requires the removal of the binnacle, not that difficult to do, and when you do so it is a good opportunity for an LED upgrade when you do this.

This was a simple procedure, which helps to maintain the integrity of the speedometer system. Hope this was/will be helpful to you.

UPDATE 04/16/08I got feedback from the DMC guys to be careful with lubricating the upper cable.

Apparently they've seen some cars with gummed up speedometers, from lubricated upper cables. 
Don't know if it was the lubricant used, but the lubricant that I have used above, is very, very viscous/slippery, and if you are patient enough to allow it to drain through the cable, should not cause such a build up of gunk.

Still good advice to heed.

BTW:  I had trouble finding cable lubricant locally, so I wound up ordering it from a vendor on eBay, who goes by the name of: "keyco Hardware Direct" This link should work: Click Here

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1 comment:

Tim said...

Use wheel bearing grease. Dip the cable and place it back in the housing. DON'T use any form of graphite. Tim