Speedometer bounce

[Billy]

My speedometer needle started bouncing like mad the other day and then stopped working altogether.  Took a look at the cable and followed it to the tranny where it connects.  It was very loose and I pulled the rod out with the plastic gear on it just to take a look.

 

i wanted to make sure I did this correctly.  Forgive me for not knowing the exact terminology.  The plastic gear that goes into the tranny has the number “55” on it.  I looked up which way I need to line up the numbers on the actual part that the rod slides into and has the big nut on it.  I aligned it to the “39-45”.  I have 27 inch tires.  After I put everything together my speedometer works again but I want to make sure It’s accurate.  

 

Thanks

[HOrnbrod]

The speedo gear's position in the housing is determined by the number of teeth on the gear. There is no speedo  gear with 55 teeth, so I don't know what the number on your gear means. 

 

See THIS thread. It will tell you exactly how to properly align your speedo gear.

[dvitha]

The alignment is to make sure it spins right without crushing gear (not moving) or not being in contact (not moving). If you changed tire sizes or gears you would change the whole gear. normally if it bouncing around a good lube in the cable, meaning it is drying out and getting resistance.

[Billy]

Thanks a lot for that link, just what I needed.  So I need to actually sit there and count the teeth?

[Eagle]

4 minutes ago, Billy said:

Thanks a lot for that link, just what I needed.  So I need to actually sit there and count the teeth?

 

Unfortunately, yes.

[HOrnbrod]

To calibrate the speedometer, you need to calculate the correct tooth count for the speedo gear based on tire size and rear axle ratio using the tables on the link. It's all explained there.

[Billy]

Well I have a little maintenance to do tomorrow.  I’ll post some photography.  Thanks all, trying to avoid any speeding tickets 

[Jeep Driver]

My speedo bounced from 0-40mph, beyond that it was good. I swapped out my cable, set the gear, made no difference. 

Others have reported the bouncing too, I've yet to read that a new cable solved the problem. 

 

Could be the gear, could be the cable, could be the speedo itself. 

[jason.cook.52206]

I installed a brand new speedo cable. It bounces like crazy. I have heard to add lube into the cable. Does anybody know if it matters what type?

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[lcoutback]

With all the old Chevy pick-ups I've owned, I used a light coating of bearing grease.  It stays in place and holds up to heat.   In those cases, I would disconnect the speedo cable from both ends, pull the cable out and shoot a copious amount of brake cleaner down the cable sheath to clean it out. (put the lower end of the cable into a bucket or something to catch the mess)  Then I would dab bearing grease in the palm of my hand as if I was going to pack a bearing, and drag the cable through.  Again, a LIGHT coating the length of the cable, then put everything back together.  Of course, I always made a mess doing this but it works on old chevys.

 

Are my redneck roots showing? 

[HOrnbrod]

3 hours ago, jason.cook.52206 said:

I installed a brand new speedo cable. It bounces like crazy. I have heard to add lube into the cable. Does anybody know if it matters what type?

 

I use this on all mechanical cables. Doesn't gum up, lasts forever, and easy to apply into the sheath with the needle. Great stuff. 

 

https://www.amazon.com/Bike-Aid-Drislide-Multi-Purpose-Lubricant-Liquid-oz/dp/B001F2Y25G

 

[ParadiseMJ]

Don't know if you have the cable operated or electric, but, on the cable driven model, the end in the transfer case has a little square end, which must be seated in the end of the gear.  If the cable was ever pulled on that "key" could come loose...or even break.  Check out the tips of each end of the cable.  If it jumped before and it's not working now the cable could have broken.

[Eagle]

Also, try to route the cable without any kinks or tight curves. Tight curves create points where the cable can bind up, and that results in the needle jumping.