Speedo Question - Jumping from 35 to 70

[Daytona Guy]

I just put on my speedo cable. I took it for a drive and my speedo jumps from 35 to 70 in a second. It would be nice if it did that when i hammered it, but that is not the case. From seventy it climbs incrementally faster but smooth. It also makes noise only after it jumps to worp speed. What is going on?

[KMPX2]

Did you clean & lube the steel cable? Sounds like is is sticking this is a common problem

[8WHEELER]

How many miles are on it? that can be a factor, I had to replace one of mine 6yrs ago same thing drove be crazzy. Bought a new cable problem solved I h0ave over 200k on the car so I was not unhappy it wore out. But sometime's they can be fixed with some lube or light oil.

Dan

[Just 6T9 CHGR]

Its your speedo head itself going bad.....same thing happened to me.  Thought it was the cable but it turned out to be the head itself....

[Charger_Fan]

A good way to test the speedo head is to spin it with a variable speed drill...I think counter clockwise.

[Nacho-RT74]

Do you have nitro on your car ?
j/k

[my73charger]

Speedo head?  I am having the same issue, where is the speedo head located?

[Paul G]

Its your speedo head itself going bad.....same thing happened to me. Thought it was the cable but it turned out to be the head itself....

Me too. I had the speedo rebuilt and no more jumping. First I replaced the cable. But that didnt fix it. Rebuilding the speedo fixed it. It has precision bearings in it that wear out. When they wear the roating magnet touches the speedo movement causing the jumping. I had it rebuilt at Auto Instruments. Gentry was a forum sponsor on the old forum.

[Just 6T9 CHGR]

Speedo head? I am having the same issue, where is the speedo head located?

Its the actual gearing behind the speedo needle.....basically the speedometer assy