When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
1965 roadster corvette my speedometer works sometimes BUT sometimes 1. it doesn't work at all 2. it bounces 3 it gives incorrect speed reading 4. it works perfectly
any suggestions ? before I start tearing into all ....Thanks
It's possible that the casing that the cable is in, is gunked up with crud and causes the issues you describe. It could also be the head unit is failing, requiring removal and repair. Dennis
This is a common problem with 65's with a 4 speed. In 65, the speedo bullet was moved to the pass. side of the trans. and was pointed slightly downwards. This new position allowed trans. fluid to wick up the cable and into the speedo head causing your problems. In 66, GM added an additional seal to the speedo bullet to prevent this. The solution is to repair the speedo,. clean the cable and install a newer bullet. Here's a pic. of one of my 65's that had this issue. You can see where the trans. fluid had wicked up and even spilled out of the cable.
Wasn't aware of the transmission wicking but that certainly could internally gunk up a speedometer. According to a 1967 AC Delco Bullention on speedometers, their procedure is to remove, clean, inspect and relub or replace the cable and clean the speedometer head. Erratic needle movements are normally associated with binding cables, partially seized or seizing bushing/1st worm gear shaft, dirty speed cups/jewels, and/or 2d/3d worm gear wear. No readings whatsoever would most likely be a separated solder joint of the speed cup and its needle stem. Sounds like your speedo needs a good inspection and cleaning even if you fix the transmission end.
Speedometer Problems
Dennis
