Speedometer Needle Bouncing

[DT1]

So, I'm working out the last of the bugs after restoring the 72. The last item is the speedometer. I noticed on the test ride a ticking sound. Sort of like a pebble was stuck in the tire tread. Then I noticed the speedometer needle was bouncing quite a bit. This has happened with other vehicles I've had and the fix is to either lube the cable or replace it. I figured that the cable was one of the only parts I didn't replace so I ordered a new cable from Summit Racing. When I got it, I was surprised at the cable length. My original cable was 62 inches long and this new one from Summit is 120 inches long. Really? What kind of vehicle takes a 120 inch cable? This is the only cable that Summit has for my application so I figured I'd creatively route it, being careful not to make any sharp turns to avoid any kinks. I also pre-lubed it before I installed it. After it was all finished, I took the truck on the road. No change at all. Still ticking and bouncing. What else but the cable would cause this?

[sick472]

The plastic gear in the transmission could be your culprit. OR would you suspect the speedometer? Too tight of a bend in the cable housing could do that too.

[Myoldtruck]

I would disconnect the new cable from the trans, insert the cable into the tip of a battery drill and run it. Does the cable still make noise and does the needle in the dash spin up to a certain speed without problems. If it does work ok, I would look at the gear reduction box if your trans has one, that goes between the speedo cable and the trans itself. I did away with mine because of similar problems, my speedo is off by 5% after 50mph until I get it fixed. After you pulled the old speedo cable out, what did you find wrong with that. If it wasnt broke it just needs a good cleaning and oiling.

[Keystone_Hate]

You can always hit up Motion-Pro. You can send them darn near any clutch, speedo or brake cable and they can replicate it. I've had them do clutch cables for motorcycles and they are top quality.

[rockyrivermark]

I changed the cable and speedo gears and needle still bouncing around.
Found out it's often the magnets in the speedo gauge itself.
Mark

[Barnfind46]

I bought a speedo cable from Summit and it was too short. I exchanged it for one that was 72". I think it was for an "A" body Chevelle. Had to have the screw on ends. A little long but still worked.