Been chasing a noise for a while now. Sounds like its coming from right in front of me, maybe drivers side wheel. Its not that (probably). It typically comes on after driving for a few miles, and is tied to ground speed (not engine speed). Its like a tick tick/ chirp chirp. Applying brakes or clutch has no effect. Once it starts, it keeps on until the truck has sat for awhile.

Started by changing the wheel bearings. I inspected the brakes while I was in there and everything was fine. I later got to trying to time count the number of chirps at low speed on a dirt road. So in second gear I'm getting what seems like 3 or 4 in about 10 feet. Maybe that's 3.55 chirps in the distance of a wheel, I think. So I start thinking a bad u joint. No big deal. So I have changed all three u joints. Still there, but maybe its taking longer before it starts making the noise.

Tonight I was back on the dirt road moving my head all over the cab to see if my ears could give me a eureka - Not really, as it still sound like its coming from right in front of me. I stick my head out the window and I cant hear the sound out there, even at low speed, despite it being obviously there inside. I moved my head toward the gauge cluster and it seems like its coming from right there.

The only thing moving back there is the speedo cable. So - my question - can I just pull the cluster and squirt some oil down that tube with the cable in it? The speedo has always been a little bouncy at low speed, no issues when driving though.

Is just changing the cable a pain in the rear? I'd imagine there are worse things I could parts cannon at if this wasn't the problem. But I would prefer a simpler route.

 

Yes you can lube the cable. Have you pulled the cluster before? It's a little involved the first time you do it.

1. Pull the battery cable

2. Pull out the headlight switch ****

3. Reach up behind the dash at the headlight switch, find the little button and push it to pull the **** and shaft out of the switch

4. Use a hook tool to pull the wiper **** off

5. Pull the little shroud off around the column next to the cluster.

6. Take the string loose to the PRND21 indicator

7. Take the screws loose to the cluster

8. Pull the cluster forward as far as you can, and reach your hand behind it and grab the white plastic piece on the end of the speedo cable

9. Push the white plastic piece to the side and it will release the cable from the cluster. Then you can lube it.

The speedo itself has a bushing that can go dry and cause a noise and needle jumping also.

 

Thanks Franklin - yeah I've had that cluster out several times.

When it comes to the speedo cable - can I pull it out, lube it, then feed it back through? IIRC, its attached to a gear at the transmission. I know I disconnected the gear-end with I did the clutch, but I really don't know how the whole thing works or if its at all modular. I saw a youtube video of a guy just pulling the cable out through the sheath on a 70's F series and then fishing it back in, but I'm a bit shy to try without knowing if that is a good idea.

 

No problem doing it like that.

Does your truck have speed (aka cruise) control? If so, there’s a speed sensor in the middle of the cable run. Instead of one long cable, it’s actually two shorter cables joined end-to-end in the middle at the sensor. If you pull out the cable from the top, you’ll only get the upper half. If the noise is in the lower half, the easiest access is from the transmission.

Are you aware of how to release the cable sheath from the back of the speedometer? There’s a plastic clip you push to the side. If not familiar with this, it’s not obvious at first, especially working by Braille. I can post more details if needed.

 

Thanks for the info - Yeah, fortunately/unfortunately I have had the cluster out quite a few times now. I should be good on the cable removal, although I can say I've never found that part to be especially easy, lol.

 

I being lazy would pull the cluster and not the inner cable and just squirt a lot of ATF down inside the outer cable and call it good.
Dave -----

 

Found this from the related threads below,
https://www.ford-trucks.com/forums/1...r-noise-2.html

 

I should also say my cable is only 6 years old so I think my noise and bouncing needle is the head it's self not the cable.
But being lazy and not wanting to pull the cluster, then I got to fit the 1 blinking LED light, I just let it all be.
An old truck needs to have some noise and quirks
Dave ----

 

HAHA - I agree with that. This was just driving me crazy, and at first I really thought I had a real safety/mechanical issue.

So - I pulled the cluster and used some needle nose pliers to pull the cable out of the sheath ( it came out surprisingly easy for any future people who are contemplating this and have never dealt with a speedometer cable). I greased it up with some white lithium, slid it back down in, reinstalled the cluster, and proceeded to drive around for essentially 90 minutes. No noise.

Am I mad that I spend $150 and 3 or 4 hours (at least) on stuff that I didn't really need. Sort of. But at least I know that stuff should be GTG for many more years now. And that's like 1 hour of shop time nowadays, and who knows if they would have diagnosed a speedo cable (I didn't even know that was a possibility until I narrowed it to behind the cluster and did googling). It was loud enough and tied to output shaft speed that I had many incorrect theories.

The whole fix took less than 40 minutes, and I had to find that can of lithium grease somewhere in my camper.

Thank you everyone for your advice!