Speedo Bounce

Just fitted a new speedo drive and cable , now the needle bounces a lot around the dial sometimes, any thoughts....?

If you can get a variable speed electric drill on the end of the cable and see if the needle moves normally in that situation (drill may have to be reversed, possibly), assuming the speedo is fine it's usually cable routing or lubrication. In an ideal world there would be a smooth cable run and no cable deflection.. sadly not possible with the rear wheel bouncing up and down. And pattern parts should be avoided..

Yeah, mine just makes suggestions till I hit 50, 55 then steadies. My speedo was rebuilt, new cable, original drive.

Try and keep the cable as straight as possible

Make sure the cable is lubricated.

Does the new drive unit require greasing out of the box? I think I heard somewhere in these forum threads that it. does, no or little grease present from factory.

Does it bounce on a level road or when going over bumps or slight changes in the road. Sometimes the way the cable is routed or tied down will cause the movement of the swingarm to cause the needle to fluctuate.

It's possible that the speedometer cable within its housing is too long thereby causing the cable to bind within the speedometer head. Or the speedometer drive does not allow the cable to push in as far as the original one thereby getting the same results.

Peter Joe

manx850 said:

Just fitted a new speedo drive and cable , now the needle bounces a lot around the dial sometimes, any thoughts....?

Click to expand...

Yes,... I modified my bike for NON-commando wheels. When I did that, the brake on the rear moved to the timing side, which meant I had to remove the speedogearbox from the rear wheel.

I always had a little bit of bounce in my speedo when it was driven by the rear wheel, and like you, I wondered why. With my modification, I had to reverse the guts of the speedo gear box, so I could drive it off the front wheel on the primary side. Yes, I'm crazy,... After I made the switch, the speedo no longer bounces at all. I attribute this to 2 things.

1)The speedo cable is a nice gentle arc upward to the speedometer so it spins consistantly without a "pinch point"

2) I cleaned the hell out of the speedo gear box drive and regreased it with the rocker box oil that Jim Comstock recommended for some other application. (I can't remember atm) When I can hear the cable whirring a bit after a few weeks of riding, I give it another pump of oil. ( I did change the weird pyramid shaped grease nipple on the speedo gear box to a standard grease nipple to make pumping the oil into the gearbox easier)

You should remove, clean, and regrease your speedometer gearbox, to eliminate a "sticky" gearbox as the cause of your pulsing at the speedometer needle. After all the needle is showing you what the cable is doing, which is pulsing because it's getting un-equal resistance as it rotates... sounds like the gearbox to me.... especially if the cable is new.

o0norton0o said:

Yes,... I modified my bike for NON-commando wheels. When I did that, the brake on the rear moved to the timing side, which meant I had to remove the speedogearbox from the rear wheel.

I always had a little bit of bounce in my speedo when it was driven by the rear wheel, and like you, I wondered why. With my modification, I had to reverse the guts of the speedo gear box, so I could drive it off the front wheel on the primary side. Yes, I'm crazy,... After I made the switch, the speedo no longer bounces at all. I attribute this to 2 things.

1)The speedo cable is a nice gentle arc upward to the speedometer so it spins consistantly without a "pinch point"

2) I cleaned the hell out of the speedo gear box drive and regreased it with the rocker box oil that Jim Comstock recommended for some other application. (I can't remember atm) When I can hear the cable whirring a bit after a few weeks of riding, I give it another pump of oil. ( I did change the weird pyramid shaped grease nipple on the speedo gear box to a standard grease nipple to make pumping the oil into the gearbox easier)

You should remove, cleane and regrease your speedometer gearbox, to eliminate a "sticky" gearbox as the cause of your pulsing at the speedometer needle. After all the needle is showing you what the cable is doing, which is pulsing because it's getting un-equal resistance as it rotates... sounds like the gearbox to me....

Click to expand...

My setup is similar to yours
I fitted apprilia wheels to my commando and I moved the Speedo drive to the front wheel
I had a special cable made up that is very straight (IE no where near as curved as running from the back wheel)
The result is a perfectly smooth accurate Smith's speedo from one that used to jump around

baz said:

My setup is similar to yours
I fitted apprilia wheels to my commando and I moved the Speedo drive to the front wheel
I had a special cable made up that is very straight (IE no where near as curved as running from the back wheel)
The result is a perfectly smooth accurate Smith's speedo from one that used to jump around

Click to expand...

No good when you're popping wheelies, though

manx850 said:

Just fitted a new speedo drive and cable , now the needle bounces a lot around the dial sometimes, any thoughts....?

Click to expand...

The inner cable has a little thrust washer pressed on to the end that usually goes to the speedo. Sometimes this thrust washer is pressed on in the wrong position. The cable protrudes too far into the speedo or the drive mechanism. If you still have the old inner check one against the other, or even use it if its okay.
Slacken off the outer cable nut and see if it improves the speedo. I currently run a small spacer at the speedo end, you could try moving the spacer or cutting the cable to length but beware if you cut too much off the cable may unravel.
Dave

EstuaryBoy said:

No good when you're popping wheelies, though

Click to expand...

No its fine
I usually reach down and spin the wheel by hand!
It's remarkably accurate