Speedo gauge jumping

[DeMartini]

My speedo gauge jumps when I drive my car. Before I changed the speedo cable and plastic gears it used to go up smoothly and go down in the same manner. When I first drove the car after the new parts installed the gauge didn't move at all. I removed the plastic gear that slides on the speedo cable and noticed two of the teeth were deformed. I cleaned the teeth and re installed the gear into the transmission. The needle still did not move. I placed the original part, which is starting to crack, back and the gauge needle work perfectly.
I placed another after market plastic gear and the same thing happen. The needle didn't move and the plastic gear got deformed. Please note that I purchased a gear with the correct colour, number of teeth and going in the correct direction.
I finally installed a new Ford plastic speedo end gear and during the test drive the gauge jumped up in small segment when I accelerated and the same thing when the car slowed down. Then I placed the original plastic gear, which is cracking, back in and the needle started also to jump unlike before with this gear.
Has any one had this problem before? Please note I have a four speed top loader and an Ford original gauge cluster.

[hybrid]

So the drive gear is OK now. No more deformation?
It sounds like either something is slipping, or something is grabbing the cable and making it stop until it has enough force to move again (this could have also caused gear damage if the plastic was overly soft).

First I would double check that the cable is properly in the back of the gauge in case it's slipping there.
Also make sure your cable run is as smooth as possible. Why did you change the speedo cable if it was OK?
Where did you get the replacement cable from?

[DeMartini]

Thanks for the reply! The drive gear has no deformities now. I purchased the new cable from Mustang Unlimited out of the US. The plastic gears were from National Parts Depo. The reason why I changed the cable was that the cable that came in the car, when I purchased it, was not correct for the year and it came in two parts rather than one length cable. Plus some rubber was melted off from it for being to close the the exhaust.
I will check the connection where it meets to the back of the gauges. Thanks again.

[hybrid]

No probs.
You can also put the car up on stands and pull the cable out of the back of the cluster.
Put it in gear and watch the cable inner to see if it's running smooth.

[DeMartini]

Hi Hybrid,
I re-lubricated the cable with some lithium grease and that solved the problem. The needed is now nice and smooth and the plastic gear works well. Thanks for talking and enjoy your car!

[hybrid]

Good to hear it's sorted.