Speedometer Way Behind

[richcraig11]

So I just replaced my Speedometer and cable with new ones from Quadratec. My odometer works and my speedometer works but it seems about 30 mph off. It doesn't even leave 0 until I hit about 30 mph. Thoughts please?

 

[mriplaybass]

At 30mph, does the needle jump up to 30, or does it just start climbing as you go faster? Like, if you know you're doing 50, does it show 20? Is the odometer accurate? Does the needle jump around, or is it smooth and steady as it climbs? If it jumps around, you may have a binding speedometer cable or it is not fully engaged in either the speedo or the Transfer Case , possibly a stripped drive gear in the Transfer Case . If it operates smoothly, I would tend to think the speedo is defective.

 

[cglax6]

At 30mph, does the needle jump up to 30, or does it just start climbing as you go faster? Like, if you know you're doing 50, does it show 20? Is the odometer accurate? Does the needle jump around, or is it smooth and steady as it climbs? If it jumps around, you may have a binding speedometer cable or it is not fully engaged in either the speedo or the Transfer Case , possibly a stripped drive gear in the Transfer Case . If it operates smoothly, I would tend to think the speedo is defective.

Yup...

The jumpiness can be attributed by having too long of a cable...it'll get bound up if it is.

My needle doesn't go below 15mph, but catches up to what it should be after about 45mph. I don't have the desire to take the thing apart and troubleshoot, so I've been saving up for a Speedhut speedo...uses GPS instead of mechanical means. Might be an option if you can't figure it out or just don't have the time/desire to work it out.

 

[jp360cj]

Interestingly enough, I have a buddy who bought a '78 CJ5 and has had the same issue. It had a lot of work done to it by the PO including a hand built diamond plate aluminum tub, 4" lift, 33s, widetrack CJ axles with 2.72 gears (that was real fun with the T-150 3 speed), and what looked like an aftermarket speedometer. His gauges didn't work and the speedometer way off and wouldn't read more than 30-35 mph (even while traveling 70 mph down the interstate). He replaced it with another aftermarket speedo cluster thinking it would fix his issues. His gauges still don't work and the speedometer works just as poorly as the last one. Even after changing the axles to 3.54s, there was little change in the speedometer.

Both of these speedometers were actually the 72-75 style 90 mph speedometer (because apparently no one makes the correct 76-79 one). Haven't taken the time to try to diagnose it.

 

[Marsh Dweller]

Jp360cj, did your friend figure out what was wrong with his speedo? I'm having rhe same problem