Another bouncing speedometer head question

[tampabronco]

I've changed the cable and fittings in the transfer case and greased both sides of the cable. I've noticed the needle movement is wobbly and thinking it's got to be the speedometer heads at this point. Can I replace just the heads and keep the face of the speedometer?

 

[dsenatore]

I've changed the cable and fittings in the transfer case and greased both sides of the cable. I've noticed the needle movement is wobbly and thinking it's got to be the speedometer heads at this point. Can I replace just the heads and keep the face of the speedometer?

Hi tamapabronco,
I'm not totally sure but I don't think you can separate the speedo head from the face. Tom's sells the head/face so that may be your best bet.
https://tomsoffroad.com/parts/66-77-ford-bronco-speedometer-head
Good Luck,
David

 

[BRONCITIS74]

Before you get too carried away, change your speedo cable. That's what I did to mine and it cured the problem. Hope that works for you.

 

[tampabronco]

Hi tamapabronco,
I'm not totally sure but I don't think you can separate the speedo head from the face. Tom's sells the head/face so that may be your best bet.
https://tomsoffroad.com/parts/66-77-ford-bronco-speedometer-head
Good Luck,
David

I had mine reconditioned a few years ago and customized with a "76" on the face of the speedometer. Wanted to keep what I have and replace the heads

 

[DirtDonk]

When you changed the cable did you replace just the core, or did you replace the entire assembly?

One thing I always do when I have a bouncy speedometer is play around with the tension of the coupler at the speedometer itself.
Is yours a snap in, or one with the screw on collar?

If the screw on type, loosen it just a bit so that it’s still attached but just barely.
See if anything changes.

 

[tampabronco]

When you changed the cable did you replace just the core, or did you replace the entire assembly?

One thing I always do when I have a bouncy speedometer is play around with the tension of the coupler at the speedometer itself.
Is yours a snap in, or one with the screw on collar?

If the screw on type, loosen it just a bit so that it’s still attached but just barely.
See if anything changes.

It's a screw in. I replaced the cable and plastic gear piece in the transfer case.

 

[DirtDonk]

Yeah you mentioned replacing the cable. I was just trying to clarify whether you simply inserted a new drive cable (the inside piece only) or replaced the entire assembly, including drive cable and outer jacket/sleeve.
Sometimes people replace just the cable and reuse the outer jacket which can be damaged from age and use as well.
This would cause similar symptoms even with a new drive cable.

But since we generically call the entire assembly the “cable“ it’s harder to discern just what was replaced.

 

[sprdv1]

It's a screw in. I replaced the cable and plastic gear piece in the transfer case.

but still no go huh

 

[sprdv1]

But since we generically call the entire assembly the “cable“ it’s harder to discern just what was replaced.

definitely can be confusing...

 

[chris-nc]

When you changed the cable did you replace just the core, or did you replace the entire assembly?

One thing I always do when I have a bouncy speedometer is play around with the tension of the coupler at the speedometer itself.
Is yours a snap in, or one with the screw on collar?

If the screw on type, loosen it just a bit so that it’s still attached but just barely.
See if anything changes.

I hadn't thought that having the coupler too tight at the speedometer could cause the bounce. I read this thread this morning, loosened mine up just a touch and went for a drive this evening, and it cleared right up! Thanks!

 

[DirtDonk]

Great! I can’t explain the dynamics of what exactly is going on, but I’ve run into it a time or two so it is definitely something to think about.

If your loose threaded collar ends up vibrating even looser over time, you’ll probably hear it in the form of a tinny rattle as you drive. A couple of things to be done about that.
One you could use some sort of a mild silicone or even a low pressure thread locker to keep it in its loosened position without it falling off. Or you could just leave it loose all the way if the cable allows that.
Some installations have the cable actually under tension to the point where it will literally hold itself in place. In those situations you can leave the collar completely loose.

 

[lars]

Cable routing matters too. My speedometer bounced for years, especially at low speed. Eventually drove me crazy. Replaced cable (entire thing, core plus housing), no change. I even bought a new speedometer unit. No improvement, and it was wildly inaccurate so I put the ancient original back in. Finally I removed the cable, tried to route it with the largest radius bends possible, and removed all clamps, zip ties and other constraints. That was it. In my enthusiasm for constraining the cable from flopping around, I had created the problem.

 

[tampabronco]

Great! I can’t explain the dynamics of what exactly is going on, but I’ve run into it a time or two so it is definitely something to think about.

If your loose threaded collar ends up vibrating even looser over time, you’ll probably hear it in the form of a tinny rattle as you drive. A couple of things to be done about that.
One you could use some sort of a mild silicone or even a low pressure thread locker to keep it in its loosened position without it falling off. Or you could just leave it loose all the way if the cable allows that.
Some installations have the cable actually under tension to the point where it will literally hold itself in place. In those situations you can leave the collar completely loose.

I loosened at the speedometer and still bounced.... How tight at the transfer case? I will keep tinkering and see if I fix it

 

[DirtDonk]

I’ve never seen changing the tension at the transfer case do anything. I think it needs to remain tight to keep that little plastic gear correctly engaged.
Of course, a little half-turn test is probably worth a try, but before that even just take it out and see what condition your new gear is in.
If it’s already buggered then there was a problem in the transfer case end, or something binding and that’s what’s causing the bouncing.

Usually if it bounces immediately after replacing all those parts though it’s not a problem with the gear but still something else.
And even though the cable is the most common culprit it’s not unheard of for the actual spirometer to lose its tension.
There’s some pretty fine adjustments in those things when they’re put together and they can get old and floppy.

What happens when you tap the glass with your finger? If you’re just sitting there and you tap the glass does the needle bounce easily?
If so then it’s lost most or all of its dampening.

 

[sprdv1]

I loosened at the speedometer and still bounced.... How tight at the transfer case? I will keep tinkering and see if I fix it

definitely not over tightened..

 

[sprdv1]

Cable routing matters too. My speedometer bounced for years, especially at low speed. Eventually drove me crazy. Replaced cable (entire thing, core plus housing), no change. I even bought a new speedometer unit. No improvement, and it was wildly inaccurate so I put the ancient original back in. Finally I removed the cable, tried to route it with the largest radius bends possible, and removed all clamps, zip ties and other constraints. That was it. In my enthusiasm for constraining the cable from flopping around, I had created the problem.

good learning experience..