[david-b]

Hey everyone;
75 Monte Carlo. While driving, the speedo and fuel gauge move pretty erratically. Fuel can be at a half tank, and go from full to empty. Speedo just bounces alot, especially under acceleration. Was this common or is there something wrong and/or a fix for it? Trans is auto (if that matters)

Thanks!

[LATECH]

The speedo is likely a dry cable in need of replacement by now,cables are pretty inexpensive.
The fuel gauge is a little different. I am not sure what is used to "dampen "the movement of the fuel gauge but whatever they use it aint working now. My old 64 had a dab of light grease where the armature is suspended so as to slow the gauge needle movement or "dampen" the action.
It keeps the gauge from reacting instantly to any abrupt change in the fuel level arm (like sloshing back and forth) so as to maintain a nice steady indication.Like a shock absorber for a gauge.
Some gauges have a felt "brake" on the armature to dampen the movement.Not sure what you have. I dont work on too many clusters of that vintage anymore and didnt work on them much back then either.You might do a google search on gauges to see what you can find.
You may need to lube the speedo head bushing as well, use a spray grease to get some in the bushing and make sure the spinning pieces are clean of dirt and fuzz...whatnot as this can also cause a radical speedo. Most likely the cable is bad or going bad.

[david-b]

Thank you for the repsonse. I'll first check the speedo cable to make sure it's in there good. If it is, I'll probably just replace then. For the bushings, are you talking in the gauge itself or at the trans/cable?

And again for teh fuel gauge, I'll do some research on it, but this grease or felt... is this in the tank or at the gauge?

Sorry for the dumb questions, so used to sensors these days. And thanks again!

[LATECH]

the grease or felt is on the actual needle of the gauge itself.It slows the needle down so it doesnt swing violently when the fuel in the tank sloshes.
The bushing for the speed is in the back of the speedo. It surrounds or holds the spinner piece that the cable fits into. Chances are you just need a new cable. I would start there with the speedo.
Be sure that you dont put any tight bends or kinks in the cable when you install the new one as it can cause the speedo to be jumpy, and fail prematurely.

[david-b]

Originally Posted by latech

the grease or felt is on the actual needle of the gauge itself.It slows the needle down so it doesnt swing violently when the fuel in the tank sloshes.
The bushing for the speed is in the back of the speedo. It surrounds or holds the spinner piece that the cable fits into. Chances are you just need a new cable. I would start there with the speedo.
Be sure that you dont put any tight bends or kinks in the cable when you install the new one as it can cause the speedo to be jumpy, and fail prematurely.

Sounds good. I'll check into this. Looks like I need to drop my trans so I'll do the cable when i do that and then look into the gauges. Thanks very much.