When driving ,my speedo needle move's up and down erratically what could cause this,also my petrol gauge only move's up to a quarter regardless how much is in the tank.The car has undergone a complete resto and the gauges were bought restored,any help would be great
Thanks

Fuel gauge is probably a sticky sender. You can take it out and hold it upside down to test the gauge, give it a shake if it's sticking. You can also take them apart to carefully clean them. The guide shaft for the float is chromed and when that starts flaking, it can make the float stick.

The speedo could be gummy internals, a weak speedo cable, or a failing angle drive (on the transmission).

On the gas gauge it sounds like your in tank float is sticking. A bit of work to remove as some disassembly is required to see inside but you should be able to tell if it is damaged and sticking. Could be bent a bit. Just be very careful with the very thin wires that are on the outside as they operate the gas light and they break quite easily

As far as the speedo it is either the cable connection is loose, the gears in the speedo, or the speedo drive unit in the transmission. Pull the cable portion off the trans not the speedo drive, and hook a drill to the end and see if it still bounces. If it does it is the cable or speedo. If not, it is in the trans.

Others may have better guidance so see what the have to say also.

Cheers.

For a quick test, you could pull the speedo and bench test it to rule it out. Install the trip odometer cable into the speedo drive and run the drill backwards.

My speedo was doing the bouncing needle dance also. It additionally would make an AWFUL noise on rare occasion that sounded as if I was fishing and the big fish was pulling out line with the drag on. Eventually the noise/vibration resulted in a the needle falling off (note, cable was still working)

I sent my speedo off to North Hollywood for a rebuild (evidently it was trying to seize up), replaced the cable and removed and inspected the cable drive from the transmission...it's flawless now