87 chevy spedometer issue

[87ChevyMan]

Hello my fellow c10 brethren. I've got an 87 chevy c10 and my spedometer has been making a chirpping sound since I bought it a year ago. The needle doesnt flail around like a spedo cable that's going out typically does. I took the cable off and looked at the ends and compared it to a new cable, and everything looks fine. I also noticed that at speeds between 65-70 mph a slapping/tapping noise consistently occurs directly under the driver side floor pan, but not at higher or lower speeds. Dont know if its related to spedo problem, but it feels like its in the same general area as the cable where it is held to the bottom of the cab en route to the transmission. The spedometer makes the chirpping noise at all speeds and increases in frequency relative to speed. Has anyone faced a similar problem?

[joel]

My 86 silverado does the exact same thing.  I was going to probably replace the cable, I don't really know what is making the noise, but it is aggravating.

[1979C20]

If there is a kink in the speedo cable sheathing, it may cause a tick. You could look to make sure there are no sharp bends or corners that could kink it, or even try lubing it with something like White lithium spray grease, an oil that wont evaporate(WD40 evaporates). and if it still ticks, the square hole that the speedo cable goes in may be hogged out on either the trans side or the speedo side, and the cable might not be spinning with the gear and when the gear comes around, it hits the cable and ticks and turns the cable.

[DnStClr]

Autozone carries the cable for under $20. Figure on an hour or so to replace it. There should be 2 clamps- one on the firewall and a 2nd right at the transmission- a tube the cable goes thru. Reaching up behind the dash with one hand to unplug the cable from the speedometer is a bit tricky and takes some time.

[1979C20]

I found it easier to reach up under the dash and press down the clip on the back of the gauge cluster, and have someone pull on the speedo cable from the engine bay to get it out. Then to put it back in, reach up behind the dash and line it up and have someone push the speedo cable in. there's one 9/16ths bolt that holds the cable to the firewall. Its straight below the brake booster at the bottom of the vertical part of the firewall. I don't know if there's a second one.

[bake74]

If there is a kink in the speedo cable sheathing, it may cause a tick.

     I would say this is your problem, or a combo of the sheath and cable itself, as DnSTCLr stated, they are relatively cheap, that more than likely will solve your issue.

[txchainsawgogi]

with motorcycles i always find that the end of the speedo cable (usually a square shaped piece of metal) starts rounding off and causing noise or showing the speed drop/jump while cruising.