37 lasalle speedo issues

[suchan]

My speedo was making an obscene noise and jumping all over, so I replaced the cable with a NOS unit I got off eBay. Worked fine for a while, but now it's starting to make a little noise and jump around, especially when I'm driving over 40.
What are the symptoms of a speedo needing repair? Can the speedo be causing the problem rather than the cable?

[nixiebunny]

There are two bearings inside the speedo that can cause trouble. The likely one is the tiny bearing that the needle pivot sits in - it's part of the spinning magnet assembly. Any bit of crud can cause it to stick a bit. When it sticks, then the needle jumps. The main bearing that the magnet spins in can also be worn. Mine was rather loose after 100k miles. I swapped in the assembly from a '58 Chevy, with some minor tweaks for the odometer.

It's possible to disassemble it yourself to clean and oil the bearing, but you need a steady hand and some clock-making tools. Best to leave that work to a professional if you don't have the skill set.

[tripwire]

You might also consider lubricating your speedo cable.  They dry out, get noisy and will make the needle jump.  If the cable is truly NOS it's had plenty of time to dry out sitting on the shelf all these years.

Wes in VT

[Steve Passmore]

Try loosening the knurled nuts that hold the cable to the back of the speedo. If the outer cable is too tight they can bind up the inner cable. Use very little oil as too much can wind up the cable and ruin the speedo head.  I apply some oil to a rag and pull the inner cable through it.