S4 Gas Gauge Float.
 

So, I had this idea the other day. It's nothing major, but it'd be a nice little mod/ feature to add to my S4 cluster. The S5 gauge holds the gas level even when the car's off. The S4 just goes back to 'E' whenever you shut the car down. Is it possible to make this little S5 feature work in the S4?

, Simon

It would be a neat feature. The tank level sender signal is the same for S4/S5 so the only difference is the dial motor. The only real question is will the S5 gas dial motor mount to a s4 cluster? You wouldn't want to swap out the temp/gas combo gauge since the s4 has the linear temp gauge.

Maybe Clokker can chime in with some insight since he holds the world record for most gauge cluster exploratory surgeries.

Haha ya, I always see clokker's gauge cluster adventures. I have no intention of putting the actual S5 gauge unit in there because it'd look extremely out of place. I just thought it'd be kind of a cool feature. A small function, but it could be a nice addition.

If the sending unit is more or less the same, maybe it's in the circuitry. That'd be in over my head to say the least.

If the geometry worked out, putting the gauge and swapping the S4 face back onto the S5 gauge unit could be an option. But I'm not familiar with the differences in mounting, etc on S4 vs. S5, as I have never owned an S5.

The wiring for the fuel gauge is identical between S4/S5, so any differences in behavior will come down to either the gauge circuitry (on the "motherboard") or the windings that actually motivate the needle.
The FC's four subgauges are paired on plates that holds the dial faces, act as a light diffuser and mount the "motors/windings".
I have no idea whether the S4/5 windings share mounting points...I'd suspect they do and if so, that'd be the first (and pretty much only) thing I'd try.

im all for new things, but is this even worth the effort?

I like it because I don't DD my FC and can't remember how much gas is in the tank. This would make it easier to check the gas gauge from outside the car, rather than as I'm starting the car. Also, my gauge usually reads 1/8~1/4 tank lower when I first start the car, so an S5 gauge would keep the reading more accurate.

Whether it's worth it or not depends on how much work the swap ends up being.

Ya, this was just an idea more or less. In 25 years, people have modded what seems like everything on these cars so I was just seeing if it had been done. I'll have to get an S5 gauge and mess around with it I guess. I have a spare S4 cluster I can test on also. I'll keep you guys posted if I figure it out.