Author Topic: Bouncing speedometer needle.. (Read 10293 times)

toytuff · « **on:** October 17, 2011, 04:06:56 pm »

I did a search but really could not find a definite answer. My needle bounces above 40 mph on the 1973 CB 350 F.

Could this be the gear at the front wheel or in the speedo itself?

Thanks in advance.

tt

MCRider · « **Reply #1 on:** October 17, 2011, 04:11:30 pm »

Not likely. Usually its the instrument.

Though you can check the drive and the cable.

usually its the instrument.

They can be disassemcled and lubed. Patience of Job. I had one repaired by a speedo place once. A 68CB77, but its all the same to those guys.

toytuff · « **Reply #2 on:** October 17, 2011, 04:12:40 pm »

Quote from: MCRider on October 17, 2011, 04:11:30 pm

Not likely. Usually its the instrument.

Though you can check the drive and the cable.

usually its the instrument.

They can be disassemcled and lubed. Patience of Job. I had one repaired by a speedo place once. A 68CB77, but its all the same to those guys.

Thanks for the reply. I forgot to mention the cable is new.

tt

MaaseyRacer · « **Reply #3 on:** June 19, 2012, 11:08:00 am »

I am bringing this topic back from the dead. I am having the exact same issue with my 1968 CL350. Did you ever find a solution?

MCRider · « **Reply #4 on:** June 19, 2012, 11:19:18 am »

Quote from: MaaseyRacer on June 19, 2012, 11:08:00 am

I am bringing this topic back from the dead. I am having the exact same issue with my 1968 CL350. Did you ever find a solution?

There's not much to it, that's why the thread is so short.

Cable, or instrument. Disconnect the cable from the instrument, spin the front wheel and see if it turns.

If so, its the clock. They can be disassemled and lubed/repaired. Either DIY or send it out.

onepieceatatime · « **Reply #5 on:** June 19, 2012, 11:31:05 am »

The cable can spin but still be causing the problem. Pull the inner cable out from the outer, and check the inner for rust and stiffness. Also make sure it is lubed. If it is rusty, stiff in places, or not properly lubed it can catch on the outer cable and cause the needle to jump.

MCRider · « **Reply #6 on:** June 19, 2012, 11:36:29 am »

Quote from: onepieceatatime on June 19, 2012, 11:31:05 am

The cable can spin but still be causing the problem. Pull the inner cable out from the outer, and check the inner for rust and stiffness. Also make sure it is lubed. If it is rusty, stiff in places, or not properly lubed it can catch on the outer cable and cause the needle to jump.

Yes, my bad, you are correct.

Xnavylfr · « **Reply #7 on:** June 19, 2012, 01:18:27 pm »

Disconnect the cable from the speedo and wheel then pull the inner cable, clean it off with WD40 and rag then apply a coating of grease and reinstall the inner cable and hook it up to the speedo, hook an eletric drill( preferablly reversable) to the bottom of the cable and spin it with the drill, if it was the cable then you shouldn't have the jump, if it's still there you have a bad speedo (need lubed internally)

Xnavylfr(CHUCK)

flybox1 · « **Reply #8 on:** June 19, 2012, 01:51:00 pm »

to internally clean the gunk out of your speedo and tach w/o disassembling, remove the back plate, housing, and bulbs, fill it 1/4 full with Denatured Alcohol Solvent, shake, dont stir, drain. repeat.
let it dry overnight or in the sun.
relube , and reinstall.

DJ_AX · « **Reply #9 on:** June 19, 2012, 02:08:25 pm »

Quote from: flybox1 on June 19, 2012, 01:51:00 pm

to internally clean the gunk out of your speedo and tach w/o disassembling, remove the back plate, housing, and bulbs, fill it 1/4 full with Denatured Alcohol Solvent, shake, dont stir, drain. repeat.
let it dry overnight or in the sun.

Sounds good but then wouldn't you want to lube it as well?

My speedo acts a little funny now over 75mph...
and my Tach is a little jumpy all over...
Hoped it might just be the cables but fresh ones are just the same.
Of course last year when I got the bike, the oily droplets on the inside of the lens indicated cables weren't the problem to begin with.

flybox1 · « **Reply #10 on:** June 19, 2012, 02:35:11 pm »

absolutely!
previous post amended.

cookindaddy · « **Reply #11 on:** June 19, 2012, 03:01:55 pm »

Shaken, not stirred huh? Is that a James Bond thing?

MaaseyRacer · « **Reply #12 on:** June 19, 2012, 04:35:15 pm »

Cable is NOS three days old and reoiled today. Sounds like I need to clean the speedo itself. From what I have seen alcohol will remove the paint on the clock. That scares me.

This bike has 4,100 miles on it all original, anyone else have any success with the alcohol without damaging the paint on the speedo face?

2wheels · « **Reply #13 on:** June 19, 2012, 04:39:38 pm »

fly
I have the bouncing needles too. 2 questions.
How much has to be taken apart before dunking in alcohol. I know the bulbs have to come out.
Exactly how would I relube?, If the speedometer is not fully opened?
This process needs pictures.

ADW · « **Reply #14 on:** June 19, 2012, 05:11:17 pm »

Quote from: 2wheels on June 19, 2012, 04:39:38 pm

This process needs pictures.

VIDEO OF TEARING DOWN AND REASSEMBLING GAGE http://forums.sohc4.net/index.php?topic=88193.0

HOW TO DISASSEMBLE SPEEDOS http://www.salocal.com/sohc/tech/speedo/spedo1.htm

HOW TO GET GAGE NEEDLE OFF http://www.cb750cafe.com/bikes.php?cat=14&id=53

You're welcome.

cookindaddy · « **Reply #15 on:** June 19, 2012, 05:30:44 pm »

The first video is excellent, second link also, the third link does not work for me.

To answer your question 2wheels " Exactly how would I relube?, If the speedometer is not fully opened?" I think you can't. You have to open it. Did you watch the first video? It's not a big deal. Buy a spare speedo off ebay to practice on?

Lots on here about gauge disassemble. I think we all do it sometime.

Did we say thank you ADW?

Old Scrambler · « **Reply #16 on:** June 19, 2012, 05:47:16 pm »

Very good advice and video.......I'll add two things........never store the clocks on their faces or the faces will get stained........I have solved a wagging speedo by spraying (1-full second) Dupont Teflon with Graphite into the cable gear area with the clock on the bike. Not perfect but works most of the time........and no stains

MaaseyRacer · « **Reply #17 on:** June 20, 2012, 09:03:42 am »

I will try the silicon/teflon spray today. I would love to avoid building a custom jig to do one speedometer, but if I cannot get it going I will open the gauge this weekend.

flybox1 · « **Reply #18 on:** June 20, 2012, 09:20:00 am »

Denatured Alcohol Solvent will not ruin clock faces.
I cleaned my original 350F gauges like this a few times with no problems. I only removed the gauges from their backing plates, and pulled the bulbs out. (thanks to motobunny for this cleaning tip) I only needed to clean and relube my cable after this to get the bouncing to a minimum. I didnt want to have to mess with prying off the chrome ring to get inside.
Dust can easily get in there and gum things up. I recently rebuilt my K8 gauges. There was a dead bee inside one of them. WTF? My gauges were sealed and had never been opened.

ADW · « **Reply #19 on:** June 23, 2012, 07:39:38 am »

Quote from: cookindaddy on June 19, 2012, 05:30:44 pm

To answer your question 2wheels " Exactly how would I relube?, If the speedometer is not fully opened?" I think you can't. You have to open it.

Agreed, you do have to open it. For what it's worth, I opened and cleaned and relubed my speedo with no real improvement, so sometimes it works, sometimes it doesn't. Luckily I found a used one that worked well.

2wheels · « **Reply #20 on:** June 24, 2012, 07:43:14 am »

There were some excellent pictures of the speedo or maybe tach internals. But I cannot find them.
I like the idea of dipping the lower part of the speedo in alcohol. It would certainly clean some of the dirt out.
But the pictures would help to see what would happen inside.

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Author Topic: Bouncing speedometer needle.. (Read 10293 times)