The surface of the fuel, oil pressure and clock gauges in my 240z have some scratch and i have decided to paint them before installing them on my car. Has anyone done this before? I believe the faces of these gauges are made of plastic. What will be the restoration procedure? Should i use sanding paper first and then use a can of flat black spray? What about the interior of the gauge will it help if i paint it in White color so when i install the leds it lights up much better?

The gauge faces are thin-gauge sheet-metal stampings. They're one-piece (full-disc) stampings for the speedo, tach and clock; two-piece (two half-discs) for the other two. IIRC, the half-disc stampings can be removed without taking off the gauge needles. The full-disc stampings require removing the gauge needle first (Blue showed an interesting technique to achieve this by using a pair of spoons as levers).

You may want to think twice about attempting a refurb using a rattle can. It would be nearly impossible to mask off the white gauge markings. If you have only a few minor scratches to fix, I suggest you use multiple coats of thinned-down flat black modeller's paint (Testors or similar) applied with a very fine-tip artist's brush (and a very steady hand). I wouldn't touch the gauge face with sandpaper, either before or after.

The topic of painting the inside of the gauge 'cans' with gloss-white paint has been covered well in another thread somewhere on this site (use the 'Search' bar). Brush-on paint will be fine. Mine already had factory-applied white paint, although the coverage wasn't complete and the paint had yellowed a bit. EZ job.

Choice of replacement light bulbs for the Z gauges is debatable. Many have switched to LED's and are happy with these. MSA has recently introduced higher-wattage replacement incandescents and these look promising. The trick is to make sure that you don't buy a higher-wattage bulb that has the correct bayonet fitting but has a glass bulb that's too long (these won't fit inside the green-plastic bulb shroud that's mounted on the inside of the bulb housing). Perhaps someone who's bought the new MSA bulbs can comment on their effectiveness and fit.

One thing you didn't mention is cleaning up the clear plastic gauge covers. These are just clear acrylic plastic discs and they respond well to power buffing (Dremel tool) with a liquid plastic cleaner. They're easy to remove in the case of the speedo and tach, but very challenging in the case of the 3 small gauges.

In the two small twin-gauges, they are held in place by a stamped-metal shroud which fits over tiny plastic pins. The shroud was locked down at the factory by melting the ends of the pins to form nubs. You'll need to grind off these nubs in order to remove the shroud and the clear-plastic disc. Unfortunately, this means that when you go to re-fit the disc and shroud, the remaining pin length is only long enough to locate the shroud. There's nothing left that you can re-melt. Instead, you'll need to drill a (tiny) hole down into each of the pins and then use (tiny) self-tapping screws with (tiny) flat washers to hold the shroud in place. A visit to your local model train shop should provide the necessary screws and washers. Be careful when drilling into the pins - if you go too far, the drill exits through the front of the bezel and you will now have visible 'air conditioning' holes.

Getting the clear plastic face out of the clock is another challenge. Instead of using melted-over locating pins, the clock's clear-plastic face is glued onto a narrow ledge molded into the inside the black plastic gauge bezel. While the disc can be removed successfully, you'll need to be very careful or else you'll either crack the disc or splinter the glued edge. The disc comes out with the centre time adjustment knob captive. When re-installing, this disc needs to be glued back in place and the glue job has to be strong enough to withstand the pressure of you pushing on the time adjust knob when you go to set the clock time. If you get this wrong, the disc will come loose and may bend the clock hands (or worse).

Overall, if any of your gauges are in really bad shape, I'd suggest that you just get a used replacement unit (lots of them around).

Hope this helps.

On 8/16/2014 at 8:29 AM, Namerow said:

The gauge faces are thin-gauge sheet-metal stampings. They're one-piece (full-disc) stampings for the speedo, tach and clock; two-piece (two half-discs) for the other two. IIRC, the half-disc stampings can be removed without taking off the gauge needles. The full-disc stampings require removing the gauge needle first (Blue showed an interesting technique to achieve this by using a pair of spoons as levers).

You may want to think twice about attempting a refurb using a rattle can. It would be nearly impossible to mask off the white gauge markings. If you have only a few minor scratches to fix, I suggest you use multiple coats of thinned-down flat black modeller's paint (Testors or similar) applied with a very fine-tip artist's brush (and a very steady hand). I wouldn't touch the gauge face with sandpaper, either before or after.

The topic of painting the inside of the gauge 'cans' with gloss-white paint has been covered well in another thread somewhere on this site (use the 'Search' bar). Brush-on paint will be fine. Mine already had factory-applied white paint, although the coverage wasn't complete and the paint had yellowed a bit. EZ job.

Choice of replacement light bulbs for the Z gauges is debatable. Many have switched to LED's and are happy with these. MSA has recently introduced higher-wattage replacement incandescents and these look promising. The trick is to make sure that you don't buy a higher-wattage bulb that has the correct bayonet fitting but has a glass bulb that's too long (these won't fit inside the green-plastic bulb shroud that's mounted on the inside of the bulb housing). Perhaps someone who's bought the new MSA bulbs can comment on their effectiveness and fit.

One thing you didn't mention is cleaning up the clear plastic gauge covers. These are just clear acrylic plastic discs and they respond well to power buffing (Dremel tool) with a liquid plastic cleaner. They're easy to remove in the case of the speedo and tach, but very challenging in the case of the 3 small gauges.

In the two small twin-gauges, they are held in place by a stamped-metal shroud which fits over tiny plastic pins. The shroud was locked down at the factory by melting the ends of the pins to form nubs. You'll need to grind off these nubs in order to remove the shroud and the clear-plastic disc. Unfortunately, this means that when you go to re-fit the disc and shroud, the remaining pin length is only long enough to locate the shroud. There's nothing left that you can re-melt. Instead, you'll need to drill a (tiny) hole down into each of the pins and then use (tiny) self-tapping screws with (tiny) flat washers to hold the shroud in place. A visit to your local model train shop should provide the necessary screws and washers. Be careful when drilling into the pins - if you go too far, the drill exits through the front of the bezel and you will now have visible 'air conditioning' holes.

Getting the clear plastic face out of the clock is another challenge. Instead of using melted-over locating pins, the clock's clear-plastic face is glued onto a narrow ledge molded into the inside the black plastic gauge bezel. While the disc can be removed successfully, you'll need to be very careful or else you'll either crack the disc or splinter the glued edge. The disc comes out with the centre time adjustment knob captive. When re-installing, this disc needs to be glued back in place and the glue job has to be strong enough to withstand the pressure of you pushing on the time adjust knob when you go to set the clock time. If you get this wrong, the disc will come loose and may bend the clock hands (or worse).

Overall, if any of your gauges are in really bad shape, I'd suggest that you just get a used replacement unit (lots of them around).

Hope this helps.

the glue on the clear plastic lens on my ahmeter / fuel gauge went off. Apparently the electrician at the shop pressed on the lens and now it is all over the place. Should i use hot glue to glue it back or whats the correct procedure? I also need to know which black matte paint should i use to retouch the enclosure. 

Not hot glue and no super glue (Cyancrylate)!

So what do you recommend to salvage this Ammeter /fuel gauge? Can i fix this without pulling the instrument out? 

Sounds like you need to remove it at this point.

Remove and how do i paste or fasten the plastic lens back?