Speedometer jumping

[Cohammer]

Went to town today drove about ten miles , watching speed ran 55 mph all the way. Got back in my bronco headed home the speedometer just swung back and fourth from 30 to 50 nonstop never screen one just swing like a clock no matter of the speed . Thanks for any help in advance.

 

[jckkys]

I've had that a couple times. It seemed the cable binds and releases, so I remove and clean the inner cable and used carb cleaner to flush out the outer cable. Then lubricate with lithium grease or graphite lube made for speedometer cables. This fix lasts many years.

 

[half cab]

This option came standard on early Broncos only thing is it doesn't kick in until 40 k or 40 yrs ..which ever comes first.

I used Bel-Ray MC cable lube on mine after cleaning.