HELP - spinning/grinding/buzzing noise??? (speedometer cable)

[ashooter]

My guess is it may be a speedometer cable, but here's what happened:

It's about 35 degrees F this morning, and I live in a VERY dry climate... if that matters. I took off down the highway this morning and as I accelerated up to about 60 mph, all of a sudden this "spinning/grinding/buzzing" noise sounded like it started coming from roughly where the tac is located in (or behind) the instrument panel in front of the steering wheel. I immediately slowed down and pulled over to the side of the road. As I decelerated, the pitch and "speed" of the noise decreased, until it completely stopped at about 10mph. Kinda sounds like "buzuzuzuzzuzzuzzzuzzzuzzzzuzzzzuzzzzzz" as it slows down as the truck decelerates. About the same "pitch" as a ticked off bumble bee.

On the way back home, as I would accelerate up to about 15mph, the noise would start, then when I dropped down to about 10mph it would stop. The speedo or tac needles don't bounce or wobble or anything like that. Everything appears normal.

When stopped, I put the truck in neutral and revved the engine - no noise. When rolling, I put the truck in neutral and the noise doesn't change, except as related to the speed the truck is rolling. It definitely has to do with the speed of the truck, NOT the speed of the engine. And it definitely sounds like it's coming from somewhere in or behind the instrument panel.

Any ideas???


thanks.

 

[Romer]

Do you have an FSM? Key thing would be to see if the cable is mechanical going into the speedometer, the later 80's is an electronic signal.

Could you be hearing a noise from the engine bay? Notice anything with the hood up?

It shouldn't be that hard to take apart the dash and get the instrument cluster out to see what the cable looks like and inspect. Then you could also drive it to help pinpoint it further.

Sorry, not much help

 

[motorsargeT]

It may be the cable. I changed mine without pulling the dash very easily, although it would be way easier to pull the dash. unfortuanately you are probably going to have to pull the cluster to diagnose it anyway. It might be worth trying to lube the cable as the new cable cost me about $125.00 5 years ago. Also is it possible a relay is turning on/off at a high frequency? unlikely but possible.

Also the speedo in mine was changed by my father-in-law back in 95 or 96 for a noise. I replaced the cable because it broke clean off at the transfer.

 

[CJF]

Very easy on a 91-92 to temporarily disconnect the speedo cable from the speed sensor/speedo gear down at the transfer case. I can't *think* of any reason why doing this for a short drive would hurt anything; it definitely would tell you whether the speedo cable is in fact the issue.

Curtis

 

[ashooter]

Very easy on a 91-92 to temporarily disconnect the speedo cable from the speed sensor/speedo gear down at the transfer case. I can't *think* of any reason why doing this for a short drive would hurt anything; it definitely would tell you whether the speedo cable is in fact the issue.

Curtis

I can't find sh*t in my FSM or Haynes manual about the speedo cable, other than the FSM says check for "unusual noise"...

Can you describe where the cable is and how to disconnect it?

BTW - looks like pulling the dash etc to get to the cable from the top side would be a booger!

 

[ashooter]

It may be the cable. I changed mine without pulling the dash very easily, although it would be way easier to pull the dash. unfortuanately you are probably going to have to pull the cluster to diagnose it anyway. It might be worth trying to lube the cable as the new cable cost me about $125.00 5 years ago. Also is it possible a relay is turning on/off at a high frequency? unlikely but possible.

Also the speedo in mine was changed by my father-in-law back in 95 or 96 for a noise. I replaced the cable because it broke clean off at the transfer.

How do you lube it?

Also, you said you changed your cable without pulling the dash "very easily"... Any tips? I have no idea where to start and the FSM is not a lot of help, other than giving you half-assed instructions on pulling the whole dash.

 

[ashooter]

Okay, is this the speedo cable where it connects to the transfer case?

Whatever it is, it's loose right where my finger's pointing, where it connects to the TCase.

Suggestions? Observations? Past experiences???

 

[KliersLC]

That looks like the speedo cable. You could try tightening it first, but I'd just take it off and see if that helps--use pliers on the round nut.

Lubing the cable should be done from the top side--pull the dash and disconnect both ends. Spray lube of choice and rotate cable until it starts to make its way out the bottom end. It will take a bit.

 

[CJF]

Okay, is this the speedo cable where it connects to the transfer case?

Whatever it is, it's loose right where my finger's pointing, where it connects to the TCase.

Suggestions? Observations? Past experiences???

That's it. The speedo gear (and its housing) is what's actually going into the t-case. Next is the speed sensor, then the speedo cable connected to that. The connections between the gear and the sensor, and the sensor and the cable, should be tight. On the other hand, the speedo gear housing is only held in place by that little hex head bolt in your picture and a little metal "key". It's not necessarily possible to get that connection tight enough to keep you from being able to wiggle/rotate the gear housing a bit.

For your test drive, disconnect the cable from the sensor. Oh, and if that oil leak/weep bothers you, just replace the o-ring on the speedo gear housing.

Curtis

 

[ashooter]

Thanks guys.

I disconnected the speedo cable and drove the truck up to about 35mph+/- and got no noise.

The kicker is that I reconnected it and drove the truck again, and got no noise!

I don't know what happened. That buzzing noise was VERY sudden this morning, not a gradual thing at all. Something must have gotten out of whack. Seems normal now, though. Maybe it had something to do with the cold? It was low 30's this morning, but mid 60's now.

Wierd.

 

[KliersLC]

I had the same problem in my 81 mini, and cold definitely made it worse. I'd lube it before it happens again and you snap the cable.

 

[ashooter]

I had the same problem in my 81 mini, and cold definitely made it worse. I'd lube it before it happens again and you snap the cable.

Only way to lube it is to pull the dang dash apart to get at it from the top, right?

I looked in the FSM and it looks like that would be a GIANT pain in the butt. Any tips on an "easy" way to lube that speedo cable?

 

[jonheld]

You're not paying attention. Curtis already told you what to do. Unscrew the large knurled knob at the transfer case end. grab the inner cable with a needle nose and simply pull the cable out of the sheath. It will come right out and is about 4 feet long. Clean it and lube it up with your favorite lube and thread it back into the sheath. Rotate it while pushing to get it to seat correctly at the speedo.

 

[ashooter]

You're not paying attention. Curtis already told you what to do. Unscrew the large knurled knob at the transfer case end. grab the inner cable with a needle nose and simply pull the cable out of the sheath. It will come right out and is about 4 feet long. Clean it and lube it up with your favorite lube and thread it back into the sheath. Rotate it while pushing to get it to seat correctly at the speedo.

You can do all that from the bottom? Does it just "plug in" on the speedometer end the same way it plugs in on the T-case end? I figured I'd have to unbolt or unscrew something on the back side of the instrument panel in order to get at the cable on the top side.

I thought CJF was just suggesting I unscrew the cable from the t-case to see if it was in fact the cable making all the racket.

 

[CJF]

I thought CJF was just suggesting I unscrew the cable from the t-case to see if it was in fact the cable making all the racket.

In fairness, that is all I was suggesting. I wasn't aware one could simply pull the cable out of its sheath at the t-case without any fiddling at the other end.

Curtis

 

[jonheld]

Then I retract the "not paying attention" comment. Shooting from the hip again...

The inner "spring like" cable is easily removed from the transfer case end of the speedo cable sheath. I've done this a bunch of times on mine and need to do it again. The cold weather squeak is usually the speedo cable. Just remember to keep spinning it when R/R. It makes it a bit easier. Both ends of the inner cable have a flatblade that keys into the respective spinny thing at each end. Easy in, easy out.

It is a PITA to replace the entire speedo cable assembly, the most annoying part is replacing the new one behind the speedo itself. Not impossible, but there will be blood involved.

 

[ashooter]

Here's a pic of the cable I pulled out. It's got the brass thing on the T-case end and a squared off end on the speedo end. Am I missing something???

 

[k1w1t1m]

No you're not missing anything. Now clean it and lube it and reinstall.

 

[ashooter]

So it's not supposed to have a brass thingamjig on both ends? Cool. I'll wipe it, lube it, and slap it back in there and see what happens.

 

[Lka1988]

My 63 bug used to do that. I ended up disconnecting the cable....*cough*