Erratic Speedometer

[madtrout]

Just thought I'd post a recent experience with an erratic speedometer on a CB77. The needle was fluctuating wildly above 40 mph. The speedo had been serviced by Foreign Speedo Repair of San Diego about 5 years ago. I disassembled the speedometer, checked the little spring and drove it directly with a drill motor set to reverse and used a small tap with a square head to drive the speedo. Checked out smooth and perfect. Reinstalled the speedometer in the headlight shell. Next I cleaned the cable and replaced the "O" ring in the lower end of the cable. The "O" ring was falling apart, and I speculate that the cable could not seat properly. Spun the cable with the drill motor and all was still good. Last step was to remove the screw in the top of the speedometer gear drive attached to the front wheel and gave it a shot of lithium grease. Took it for a ride and everything is good again. My lesson learned was not to immediately blame the speedometer for erratic motion. There is a long chain of events leading to that pesky needle. Cheers, Mark

[G-Man]

The erratic motion is caused as the cable 'winds up' and releases against excessive friction in the cable or speedo. Much easier to check the cable first.

Glad you got your problem fixed.

G

[madtrout]

Actually, the cable was quite well lubricated and free spinning even before cleaning. I think that the degraded O ring allowed the cable to be fastened too tightly onto the attachment point at the speedo gear. Mark

[rzgkane]

Is it possible to completely remove the cable from the housing? I used to fix old Buick Regal speedo bounce that way and I'm wondering if these bikes are susceptible to that same technique.

Just thought I'd post a recent experience with an erratic speedometer on a CB77. The needle was fluctuating wildly above 40 mph. The speedo had been serviced by Foreign Speedo Repair of San Diego about 5 years ago. I disassembled the speedometer, checked the little spring and drove it directly with a drill motor set to reverse and used a small tap with a square head to drive the speedo. Checked out smooth and perfect. Reinstalled the speedometer in the headlight shell. Next I cleaned the cable and replaced the "O" ring in the lower end of the cable. The "O" ring was falling apart, and I speculate that the cable could not seat properly. Spun the cable with the drill motor and all was still good. Last step was to remove the screw in the top of the speedometer gear drive attached to the front wheel and gave it a shot of lithium grease. Took it for a ride and everything is good again. My lesson learned was not to immediately blame the speedometer for erratic motion. There is a long chain of events leading to that pesky needle. Cheers, Mark

[madtrout]

The cable slides right out, lower end first. Mark

[rzgkane]

The cable slides right out, lower end first. Mark

I'm confused (not a first) by what you mean when you say "lower end first." Are you saying that you unscrew the cable from the wheel gear and slide the actual cable out of the housing from that end?

[madtrout]

Exactly
But I was just informed that my post ened up in tbe CA forum by mistake. This relates to a CB77. Mark