speedometer bounce
Melting Slicks
Joined: Aug 2001
Posts: 3,039
Likes: 121
From: Wichita KS
Re: speedometer bounce (jetech)
jetech,
It shouldn't bounce, sounds like the cable needs lubrication.
Does the car have cruise control? If so, you can disconnect (and lubricate)the speedometer cables at the cruise control sending unit. Cruise control sending unit is on the driver's side sort of tucked under the master cylinder. There will be one long) cable from the transmission going into the sending unit and another (short) cable from the sending unit that goes through the firewall and connects to the speedometer.
Twisting the cable that runs from the sending unit into the speedometer should be EASY, if not, then lack of lubrication might be causing it to bind. You might try to dribble some "Dri Slide" (graphite in a light oil) into the cable ends between the wire cable and its sheath.
The cable that runs from the transmission up to the sending unit will not "spin" if you try to twist it as it is connected to a gear in the transmission. The binding might also be caused by this cable.
Some post recommend using lithum grease on the cables. On my 1980, you can remove the wire from the sheath, on the transmission to sending unit cable, by pulling on it. In this way you can lubricate the cable. You will have to "play with it a little" to get it to reengage the transmission gear but it isn't difficult. The cable running from the sending unit through the firewall to the speedometer won't (shouldn't) pull out.
I just pour some dri-slide into the sheaths of both cables and let it flow down.
You might check to see that the cable connections at the transmission and speedometer have not worked loose.
The sending unit might also be a problem. I have not had one of those apart (yet) $$.
It shouldn't bounce, sounds like the cable needs lubrication.
Does the car have cruise control? If so, you can disconnect (and lubricate)the speedometer cables at the cruise control sending unit. Cruise control sending unit is on the driver's side sort of tucked under the master cylinder. There will be one long) cable from the transmission going into the sending unit and another (short) cable from the sending unit that goes through the firewall and connects to the speedometer.
Twisting the cable that runs from the sending unit into the speedometer should be EASY, if not, then lack of lubrication might be causing it to bind. You might try to dribble some "Dri Slide" (graphite in a light oil) into the cable ends between the wire cable and its sheath.
The cable that runs from the transmission up to the sending unit will not "spin" if you try to twist it as it is connected to a gear in the transmission. The binding might also be caused by this cable.
Some post recommend using lithum grease on the cables. On my 1980, you can remove the wire from the sheath, on the transmission to sending unit cable, by pulling on it. In this way you can lubricate the cable. You will have to "play with it a little" to get it to reengage the transmission gear but it isn't difficult. The cable running from the sending unit through the firewall to the speedometer won't (shouldn't) pull out.
I just pour some dri-slide into the sheaths of both cables and let it flow down.
You might check to see that the cable connections at the transmission and speedometer have not worked loose.
The sending unit might also be a problem. I have not had one of those apart (yet) $$.
Instructor
Joined: Nov 2002
Posts: 119
Likes: 1
From: Aberdeen NC
Re: speedometer bounce (jetech)
I've got a '78 with a speedometer that bounces all over the place and at will. Some days it is perfectly well behaved, others it never stays in one place for more than a nanosecond! Had it lubricated and it's been somewhat better. but still acts up at will. Makes an awful screeching racket sometimes too. I'm planning to just replace the whole thing as lubrication didn't take care of it. I understand this was a problem common among late 70s models. Good luck.
