— the kind that include a length of core cable, sometimes a choice of
drive end, and a tiny tool to crimp the ends after you have cut the new
core to its proper length. I can’t say that you might not get lucky – I once
had one of these kits work for almost a whole month – but, the problem
is that no matter how carefully you measure, using your old broken core
as a guide, you will usually end up cutting the new core cable either a
tad too short or a bit too long. If too short, the new core either won’t
work at all, or will only work in fits and jerks, causing the speedometer
needle to flick and bounce all over the face as the cable core ends slip in
and out of their respective drives. If it’s too long, the core will bind
within its housing, also causing the speedometer needle to flick and
bounce all over. This could damage the speedometer head by putting too
much lateral thrust on its drive mechanism.
A much better fix is to simply order a complete NOS speedometer
drive cable, inner and outer, from a reputable parts dealer. Alternatively,
you could take your old cable to a shop that specializes in such things
and have a new assembly made. You might even be better off doing the
latter because, other than lack of proper lubrication, the most common
cause of speedometer drive cable breakage is a sharp bend.
Unless you’re a complete purist, here’s a chance to improve your
vehicle if its cable travels through sharp bends. Figure out how much
more cable would be needed to eliminate any sharp bends and have your
new cable custom built to that length. Some re-routing will probably be
necessary, but you will often find better routes for the cable than the
original designers chose. The important factors are to keep the bends as
gradual as possible, avoid contact with moving parts (such as drive
shafts, shift linkages and foot pedals) and sources of heat (such as
exhaust pipes and manifolds).
Whether the unit is NOS or custom-built, thoroughly clean the inner
core and housing cable with the solvent of your choice — brake or
electric motor cleaner in spray cans works fine, as does starting fluid.
Make sure the housing is dry inside before installing the core cable.
There are graphite lubricants specially designed for speedometer and
tachometer drive cables, but I prefer a light wheel bearing grease, such
as disk brake grease. Using grease that’s too stiff may cause problems in
cold weather.
Coat the inner core with grease as you feed it into the outer housing,
singke
(singke)
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