I feel like I'm missing something. After replacing the speedo switch in my B2 due to violent gauge spiking all was good for about a month. Then over the last few days the speedo spiked all the way up a couple times and now today it's reading really high speeds, with the gauge fully maxed out on the expressway. Not much spiking, a little wavering, basically just reading way too high. I'd think it was just a bad cable cable except I've been fighting the same issue with my motorcycle. Brand new tach cable fixed the spiking but now if I turn the handlebars (which bends the line) it still spikes violently. It's a new cable so I just don't understand it. I do feed ordinary engine oil into the cables and smear bearing grease on each end before installing, maybe that's my problem. Is there a specific oil/lube I should be using? The other thing I'm trying to understand is how it would read high? I think I understand the spiking: the inner cable gets caught, builds pressure, and lets go causing the gauge to spike. But how is the gauge reading high without much spiking? Doesn't make sense to me and I'm hoping someone can shed some light. Tonight I'll check the cable for kinks and re-oil, just seems like there's something I'm missing because I keep having this problem.

Josh

 

Most cables call for grafite as lube.

 

Ditto on using graphite for cable lubrication, or graphite oil.
If you investigate the (inner) cable and it's OK, check the cable housing.
If both those check OK, then suspect an grounding issue. Bad grounds can cause the instruments to act wierd. Check both the battery cables (both ends) and the instrument grounds.

 

Thank you both for the replies. I wasn't aware of the graphite at all. My local Autozone didn't have any graphite lube, only dry powder, so I ended up with this product that's at least a 'dry' substance.
LIQUID WRENCH Dry Lubricant, Aerosol, 5.5 Oz. - Penetrants and Lubricants - 12U394|L506 - Grainger Industrial Supply
So far the gauge is working well but time will tell. If the problem comes back I'll seek out some graphite.

 

I guess I don't understand chemistry at all. That stuff contains "Boron Nitride", which I understand is supposed to be used to apply extremely hard coatings. But Liquid Wrench is using it as a dry lubricant???