Speedometer Needle Bouncing

[scott_1200]

Hi!

I too have the bouncing speedometer needle.  I read in the threads here that you might be able to fix it with some dimethecone, but I never found the exact instructions. So I ordered some dimethecone from Amazon and then tore apart the speedo.  Here's what I found:

The fluid in the speedo had leaked out and collected into two drops, one at the reservoir bottom and one at the bottom of the magnetic pickup. It appears that the fluid didn't dry out, but worked it's way out of the seal at the top and drained down the bottom of the parts.  If this fluid is providing some kind of dampening, then the needle and the reservoir should not be coupled together so that the fluid can provide the friction necessary to drive the needle.  

After I tore the speedometer apart, I found that the needle shaft is firmly connected to the reservoir with no slack or movement to suggest that the fluid was acting to dampen the needle.  I also noticed that the fluid droplet didn't easily move as you rotated the needle.  This would place the droplet at about 90 degrees when the needle is reading highway speeds (which is where it bounces the most). I am now thinking that the spring isn't enough to compensate for the extra weight of the two droplets (now at 90 degrees) and causes the needle to bounce around while the spring tries to keep it steady.  I also am thinking that the reservoir is there only to provide some rotational weight to properly balance against the spring force.  If this is true, then adding the equivalent weight to the shaft would do the trick and remove the bounce from the needle without the need to replace the fluid.  Although, the fluid may provide a slight sloshing effect that dampens the needle.

Also, to replace the fluid, you would have to either remove the needle, face and support bracket to get to the seal. Or you would have to manually rotate the reservoir (since the only access is from the bottom) to then drill a hole (so that the hole is at the top when not moving) to inject more fluid and then seal up the hole.  If you go with the first option, you will have to also recalibrate the speedo.  If you go with the second option, you have to guess to the amount of fluid to add and also risk drilling too far into the reservoir.  A speedo repair shop would do option one and is probably the best choice.  Has anyone ever torn the reservoir apart to see what's inside and what the fluid is for?

I cleaned up the fluid droplets with some alcohol and q-tips and put everything back together.  I also haven't added any weights or extra fluid.  I just cleaned up the leaking fluid.  I haven't ridden the bike yet and will post back with the results.  If I still get the bounce, I may try adding some weight to the outside of the reservoir or the shaft.  

Here's some pics:
https://picasaweb.google.com/113153371481528835695/FJ12001989#5718415675180692562
https://picasaweb.google.com/113153371481528835695/FJ12001989#5718415475192183122

The bike:
https://picasaweb.google.com/lh/myphotos

Scotty

[SlowOldGuy]

Dimethecone is for a bouncing FUEL gauge.

A bouncing speedometer is usually the cable or drive mechanism.

DavidR.

[scott_1200]

I guess I didn't catch that in the other threads.  At least I now have a lifetime supply.  If it's not needed for the speedo, then what is the fluid that I saw in the speedo and what is it's purpose?

Thanks!!
Scotty

[FJmonkey]

I guess I didn't catch that in the other threads.  At least I now have a lifetime supply.  If it's not needed for the speedo, then what is the fluid that I saw in the speedo and what is it's purpose?

Thanks!!
Scotty

Lube maybe?

[andyb]

You can also use dimethicone for a bouncing tach, I understand.

A bouncy speedo is usually just a matter of using a mildly heavy grease on the cable that drives it.  It's a big spring, and needs a heavyish lubricant to help dampen the movement a bit.

[scott_1200]

I finally got to ride the bike again today and no bouncing needle, Yaaaaa!  But I got bad news.  The motor was making a bad mechanical noise while at highway speeds.  It sounded like something bouncing around in the engine. It didn't do it at idle or at lower speeds. At first I thought it was the speedo cable going out, because it was mostly coming from the instrument cluster. But then the motor started to loose power and then it died.  I had to get a tow back home.  I guess I'm going to have to take the head off to be absolutely sure. My best guess is a broken valve and/or piston.

Scotty

[baldy3853]

Scotty
On my 2nd trip to Phillip Island for the Aussie motoGP had stopped in to my brothers place to collect him before heading further south and said to him that my speedo was playing up, his suggestion was to look at the cable, mine was bouncing more then a 1st night bride on a her new husbands dick.
when we pulled the cable out it looked ok but on closer inspection it was broken on the bottom and a little dry, replaced it with a new cable, pulled the wheel off also and found the speedo drive was also a little dry, repacked it with grease after cleaning out crap that was in it.
All good for the most part until the return trip speedo stopped working  ended up getting a ticket on the way home for being 8k's over the limit  when I got home found the bloody speedo drive had seized up
Just a thought for u to keep in mind could be a combination of all thise things you said.
Baldy

[scott_1200]

Thank you for heads up on the speedo drive.  I've repacked the drive and cleaned, inspected and lubed the cable. I was going to replace the cable and speedo drive if the needle was still bouncing during the ride.  I guess the problem was the two droplets of fluid that was counter balancing the spring and causing the bouncing. Once I cleaned the fluid off the speedo innerds, the spring could work as it was intended and it didn't have to fight against the additional weight of the droplets.

The engine is now my man concern as it appears it will need a complete overhaul.  Might not be riding again for another year while I get the engine fixed up as money and time permits. :>(

Scotty

[cgoochce]

Hi, I'm new to FJowners.com but may have some useful information as i have the same problem on a FJ i purchased a few months ago. I disconnected the cable from the wheel and connected it to a two speed drill, you will have to push the cable up to insure its seated in the speedometer housing. Spin the drill slowly and watch as the needle on the speedometer moves, watch as you speed up the drill. I did this and did not see the speedometer needle bounce. this leeds me to believe the cable and speedometer is working, and that the speedometer gear on the front wheel is the problem. Rather than pull that off and repack it i chose to just purchase a new one. i will however need to clean and lubricate the cable. Any suggestions on the type lub to use?

[Arnie]

Either white lithium or moly grease works well on the speedo cable.

Arnie