Speedometer Bounces Around

[Mark_Bialzik1 (Mark Bialzik)]

My speedometer bounces around. In my 1950’s GM cars this indicated that the speedometer cable needed lubrication. Is this also true of the 1965 MKII? If so or not, what should I do?

Thanks.

[Andrew_Waugh]

Speedometer fluctuation

If you have the instrument out then you can check if the problem is in the instrument itself. Take a 3" piece of solid copper wire such as used for house wiring (14, 12 Ga will do), strip and fold one end over to give a double section about 1/2" long. Flatten the folded end so that it will fit diagonally into the square at the back of the speedo. Put the other end in your cordless drill and run it (slowly at first, to make sure you’ve got the direction right). If the needle doesn’t bounce (and …

[John_Quilter (John Quilter - PayPal donor)]

@Mark_Bialzik1

My speedometer bounces around. In my 1950’s GM cars this indicated that the speedometer cable needed lubrication. Is this also true of the 1965 MKII? If so or not, what should I do?

In my experience with 53 years of ownership of a 3.8S a fluctuating speedometer needle is an indication that the speedo cable is worn. When this happens the cable winds up and unwinds in rapid sequence causing the needle to fluctuate. I doubt that just lubrication of the cable will cure your issue but you can give it a try. You might be able to simply have a new inner cable made up using the old one as a pattern for length and rethread that into the outer casing with proper lubricant. Ensure there are no sharp bends in the routing of the cable casing as these promote inner cable wear and the issue you are experiencing. For many years my MOD 3.8S was running with no 90 degree angle drive at the gearbox end and this resulted in the cable making a large bend in its routing to the engine bay and to the fascia instrument. Once I fitted an angle drive to the overdrive that greatly improved the cable routing and periodic wear out of the inner cable was greatly reduced