Shakey Speedometer Question

[billkrz]

Finally installed a new Mopar speedometer cable in my 1968 GTS (340-727). The speedometer is wild! It oscillates back and forth a good 20-30mph and sometimes will read with the car sitting at a stop. Odometer seems ok. I did not lube the cable as it was brand new Mopar from the dealer.
Now the car was sitting for about 20+ years without a cable in the hot sun.
Any (easy) suggestions? I really don't want to pull the cluster out again (I did this to fix all of the guages and it wasn't fun).
Thanks, Bill

 

[Longgone]

Usually that`s the sign of a cable that`s in need of a grease job but since your cable is new it`s likely in the speedometer. The same old grease gets hard and sticky and makes the speedometer move erratically. Without removing the speedometer I don`t know how effective you can be but what you want to do is get some fresh grease into the the back of the speedometer drive.

 

[player1up]

The needle doesn't really touch anything inside the housing, it has a drum with magnetic fingers that ride on the outside. As the cable spins the fingers, the drum will get pulled clockwise...unless the fingers hit or rub the drum, then you will see a swing to the right and then a fall as the fingers get too far away to "pull" the drum..... I got the chance to look at the inner workings of an....."altered" speedo from a 72. ok so someone tried to roll it back...scratches on the far left mile drum really a shame because the face looks pretty good. AND there is a little metal scraper that gets lowered onto the wheel if you try to roll it the wrong way.

long story short... you will probably need to pull the speedo to check the clearance inside use a drill with the old cable to spin it and you'll see. you might even be able to hear it hitting with the gauge still in the dash. it will sound like something scraping a bell.

and the wife says my head is full of useless information..

 

[66dartgt]

I agree, with playr 1 up. What Ive seen is junk get stuck in between the arms and the drum, the drum or arms are magnetic and bits of metal sometimes finds its way in between there causing the erratic operation.