When I reach 60mph, my speedometer needle will pulsate (no severe bouncing). The cable is lubed with liquid graphite...any clues to what may be causing this? Since it has a 223 with a 3.92 rear, maybe it's not used to going 60! Thanks.

 

If you pull the speedo out, there is a hole on the back of the unit, just inside the threads for the cable, for lubing the bushing inside. That might help. I'd use 3-in-1 or another light oil, not grahite since it could get thrown around.

 

I had a the same problem with mine. After I put in the 289/C4. It seems that if the cable has any sharp angles on it's way from the dash to the tranny, the drive cable seems to twist inside the cable and when that twist gets to the speedo, there is a quicker spinning action when that tension is released causing the speedo to read faster for a moment and then back to normal for a moment. That causes the up and down movement of the needle. I was able to route the cable so it has a very gentle curve when it exits the firewall and as it comes into the tranny. That seems to solve the problem. I don't think it was the speed, I've been up to 80 in mine, speedo fine. Me HAPPY

 

Thanks. On the 53-55 dash panels, can just the speedometer be removed or do I need to remove the entire cluster?

 

when I did mine i pulled the whole cluster. had to give the whole speedo assembly a real good cleaning then the 3 in 1 oil as recomended above. when pulling your cluster remember to DISCONNECT THE BATTERY. if you have original wiring the breakers on the left side of the cluster are LIVE even with the ignition off and VERY EASY to short against the metal dash.

 

first thing I'd check is to pull the speedo cable off the back of the speedometer. Twist the brass **** of the speedo several revolutions and feel for any binding.
The bind could be in the cable as mentioned before, or.. it could be in the speedo gears.
When I recently pulled mine apart, I noticed a very strong bind in the gears that would have created a similar problem to yours... (if mine was actually running... lol)
I oiled up my gears a bit, but the problem was still there. I even ran it for a bit with my drill... and that barely cleared it up. I realized the driven worm gear off the cable/drive gear was pushing aside (just a little play inside the box) and creating friction. A tiny, well placed C-clip took care of that.

Hopefully in your case it's just the cable. But regardless, check the speedo -drive. You don't want to not fix the issue... or fry another cable because of a stuck speedo.

 

Probably a bad ground!

 

LOL! I wish it was that simple! I may just try replacing the cabel with a new one and see what happens. I also have a tube of Sil-Glyde from NAPA that is supposed to be good lube for cables.

 

Use a white lithium grease to lube the inner cable. Grease the lower 1/2 ONLY enough that it has a visible coating on it. the grease will work itself up the rest of the cable over the next couple hundred miles without coming out the top into the speedometer head. Dry lubes and silicon lubes are not suitable for this application. A new inner cable may include a packet of suitable amount of lube.Check outer jacket for tight bends or kinks, especially at the tranny and head ends, the last 3 or 4 inches should be straight into the connector.

 

Lubing the speedo cable took care of the big bounce, but it still took pulling the cluster and cleaning the speedo head before the needle held steady and the whole mess stopped whining. Why only do half the job iffin you're takin the time to fix on it?