[locomotivebreath]

Anyone ever see a speedo go bad ? Took the GTO out today and twice , the speed starting howling loud ! Almost like a belt squealing and the needle pegged out . Any ideas ?

[ts3189]

Disconnect cable before speedo needle breaks off once that happens it can’t be rebuilt.

[steve25]

The cable is telling you it needs to be lubed.

The speedo pegs itself because of the release of energy when the cable fully hangs up and then bust free again which then spins the end of the cable at the Speedo faster then the car is actually moving.

And yes either don’t drive the car until you lube it up, or disconnect it at the trans or the dash.

[locomotivebreath]

What do I use for lube ? Graphite or a gun oil ? Or just get a new cable .

[PunchT37]

Originally Posted by locomotivebreath

What do I use for lube ? Graphite or a gun oil ? Or just get a new cable .

White lithium grease, I have used in the past.

[1968GTO421]

Originally Posted by PunchT37

White lithium grease, I have used in the past.

I, too, have used the white lithium grease on older cars speedo cables since the 1960's. Has worked well for me over the years.

[steve25]

In times of old repair shops had a adapter that screwed right on at the trans end let the repair guy use a grease gun to re- lube the cable.

If you use the white grease you can only spray it up in the dash side so it better work it’s way down.

[Goatracer1]

Pull the inner core out of the outside sleeve of the cable and use your fingers to lube the whole length of the inner cable core. If this doesn't help it is time to have your speedometer rebuilt. Bob's Speedometer is one of the places that will do it.

[locomotivebreath]

Thanks everyone. - I’ve put 400 miles on this build and and have a few quirks . I’m dreading having to go under the dash !

[PDC]

I squirted Royal Purple ‘Max Film’ down the cable sleeve from the gauge end and just let it gradually run down into the cable. Re-attached and all quiet / all good after that.

[steve25]

It can be tuff getting up in there.
If you have a Bucket seat you might want to remove it and make the easier but longer.

Anyway you might find some change under the seat .

[HWYSTR455]

You can do it from the bottom too, take the end off the trans, and pull the whole cable out of the casing. You can then spray a rag with lith, and feed it thru the rage as you push it back into the casing.

If the end isn't cooperating going back into the speedo you will know, the last inch or so won't go all the way back into the casing. Don't force it, but you can try to push the casing into the car to change it's angle, and wiggle the cable in that last little bit.

While you have it out, you can also check for damage. If it's got any pieces of 'wire' sticking out, in time, it will eat the casing, tho it may already have.

If it's boogered, you need a new cable, and I recommend getting a new casing as well.


.

[pfilean]

Way back when, all the parts stores used to have speedo cable lube on one of those boards on the wall behind the counter with 12 or so little bottles of lube. You were supposed to take off the cable at the speedo head and put the bottle over the end and let the lube work its way down the cable. Was kind of an oil and graphite mix. Worked but could be a little messy. And that was back when you could feel your way to the cable up under the dash. More modern cars are a lot harder to get access. At one time I think GM had a lube that was like a thin petroleum jelly. Had to pull the cable out of the liner from the top end and smear the lube on the cable. Still kind of messy getting that long floppy cable back in the liner with lube all over it, And the white lithium works probably the same. But you gotta do what you gotta do.

[Singleton]

https://www.ebay.com/itm/11349552996...Bk9SR5L9is7_Yg

[Ram Air IV Jack]

Originally Posted by pfilean

Way back when, all the parts stores used to have speedo cable lube on one of those boards on the wall behind the counter with 12 or so little bottles of lube. You were supposed to take off the cable at the speedo head and put the bottle over the end and let the lube work its way down the cable. Was kind of an oil and graphite mix. Worked but could be a little messy. And that was back when you could feel your way to the cable up under the dash. More modern cars are a lot harder to get access. At one time I think GM had a lube that was like a thin petroleum jelly. Had to pull the cable out of the liner from the top end and smear the lube on the cable. Still kind of messy getting that long floppy cable back in the liner with lube all over it, And the white lithium works probably the same. But you gotta do what you gotta do.

I lubed my 69 GTO years back by pulling the cable out of the casing from the speedometer. Wiped it down with brake clean and lubed it with a speedometer lube from a local auto parts store. Got the cable right back in with little effort. I remember those auto parts ads about dumping the lube over the cable at the speedometer end and letting the lube flow into the cable. The problem with that idea is my service manual recommends NOT to lube the cable within 12 inches of the speedometer head. That is the way I lubed my cable. GM recommends not to get any lube in the speedometer head so be careful here!!