Speedometer jumping around help

michiganpat said

yeah, car is a '76, standard dash. tires are a little bigger than stock out back and brand new (originally came with D78-14, 25.5" tall, went to 225/70R14, 26.4" tall), so I'd expect it to be a bit low (like the odometer is acting)

if I change the speedo pinion gear to get that "correct", then I assume it will throw the odometer off even worse, since they're both driven off that gear. any advice on what to lube the speedometer with?

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Your odometer is probably fine. It works on a simple gear driven system. So if it works at all, there's not much to go wrong. On the other hand, the speedometer works by a magnetic field produced by spinning magnets. These fail, and need repairing or replacement. So much so that reproductions are available. Since yours has made that noise, I suspect it's badly wounded or terminal.

There are a couple avenues to take. The least expensive is to remove the speedo, inspect the drum (post pictures here on FABO for input) lube and reinstall. Lube can be a very small amount of light oil on the bushing or graphite lube. You'll find opinions differ on which to use. Move the needle on it's spindle to correct the MPH reading. Get the correct pinion gear for your tire size and rear gear ratio. See chart below.

You can try disassembly, repair, and reassembly yourself. Unless you start buying expensive parts, you're still on the inexpensive side. This would normally take some experience and expertise, but you may be able to find repair info.

You can send it out to a speedo repair shop. Start a thread asking for recommendations as to where to send it.

Buy a reproduction or NOS. Maybe the most expensive. The repops are close to $400.