Speedometer going nuts

[PatS]

I think I have a problem. I was out on a 200 miles drive yesterday in my '70 SRL. On the freeway going about 70 mph (speedometer said 75 but it always reads high). I looked down the needle was bouncing between 120 and 140. I can see if a gear in the meter or cable broke it would register low but high. This is a new one for me. Any suggestions?

Thanks,

Pat

[Habitat.pat]

The Speedo cable may need lubrication or it could be the grease in the speedometer is needing replacing - not an easy job.

Peace,
Pat

[Bwk2000]

Either end may have also come loose. Worth checking the gauge and trans connections.

[Erock311]

I had the same problem w/my 66- can't remember if it was speedo or tach, its the same repair. Remove the head and where the cable screws on (past the threads) on mine, there was a small cup plug. I removed it with an EZ out or similar tool. Under that plug is a passage to the speedo/tach shaft. There was grease in there, but it had turned to "wax", wouldn't lube any more. Use a small screwdriver (or similar tool) and scoop out as much of the old grease as possible. Look down in the hole where the plug was ,I think you should see the shaft turning when it is moved. Regrease w/new grease (don't over pack) just put in a little at a time and work it into the shaft. A lite grease is best, I used a product called "Magalube G" a teflon grease. Put the cup plug back in and reinstall, it should stay in, if not, you might have to gently "stake" it in place to hold it. Hope this works for you , I did both heads on mine,no problems