I've been inspired by Clokkers old thread about retrofitting a different set of car clocks to the FC dash.

I want to go about it in a slightly different way and have a few ideas, but before I start pulling stuff apart I just want to confirm that the circuitry on the back of the clocks / dials is simply to make those work, and doesn't control any other systems?

I have no intention of touching the switches and buttons, just dials and gauges.

 

I believe the only important thing is the alt light because its tied into the charging system

 

Thanks.
Is the alt-light on the main dash, or the idiot cluster? I can't recall right now and the cluster is up in the loft.

That should make things easier anyway.

 

The CHARGE light is in the warning cluster.

 

Thanks that's good to know. Last question, I assume that the Cruise control must get a speed signal from the clocks, even though the speedo is mechanically driven?

 

I ran my car for years without the idiot lights (I had gauges there instead) and my cruise worked. The instrument cluster (with speedo, etc) outputs a VSS signal that feeds into the cruise computer, the warning cluster will have no effect on it.

 

I was planning on using a different speedometer using an electric gearbox sensor for the VSS. I would assume that whatever VSS the standard clocks put out, given the age of them, it will be different from whatever I install.
So the cruise control likely won't work.

 

After swapping the driven gear for the stock FC part, the VSS from a FD will bolt right on.
Not sure if it's compatible with the FC cruise module, but it's possible.

 

Thanks! I gleaned that from your thread. I believe someone later found one that was a direct fit. I have it bookmarked somewhere. I'm sure some would say its more effort than its worth, but I'm not a huge fan of the stock appearance.
I have in mind adding the gauges that people stick on top of the dashboard (which looks ugly and bolted on to my eye) into the cluster itself.
Or should I say a different cluster that I'll build using stand alone gauges, which should allow me save space for example with a combined oil pressure / oil temp etc.
The only real difficulty I think will be the fuel gauge, but if I can't make that work then I have a few senders for boat fuel tanks knocking about the garage, one of them should work with a universal gauge suitably calibrated.

 

Personally, I've long thought that anything not directly in front of your eyes (which means the gauge cluster, basically) is useless except as bling.
If you have time to scan all over the cockpit for info, you're not going very fast and why do you need gauges?

Having run both gauges together, I wouldn't worry too much about oil temp, at least not from a display standpoint.
Sure, it would be useful to datalog and study later, but in practise the oil temp follows along with water temp pretty consistently (albeit more slowly) and you can extrapolate the oil temp from the water temp and oil pressure if you're bored. More useful would be a warning light that could be ignored till necessary.
The FC fuel gauge is hopeless but the one from a Miata is completely standalone and easily adapted to a standard gauge housing.
I probably have a few spares, if you'd like.
This approach has the decided advantage of leaving the stock tank bulkhead completely untouched, which, if everything is working, is a good thing.

One nice thing about the FC wiring is the short patch loom between the firewall harness and the cluster, which means that most of your wiring mods can be done outside of the car.

 

All invaluable info, thanks.

Starting in reverse order.
It looks like I'll be going for the Miata / MX5 fuel option then. As we have thousands of them rusting away every year in the UK its probably more economical for me to source it locally, but thanks for the offer.

Oil temp as you say is not a critical gauge to have, although I have noticed on the only other car that I actually had such a gauge on that when running hard it would often be much higher than the water temp. However that could be down to the fact water temperature gauges on most cars after 1990 have 3 modes, 'Cold' / 'OK' / 'OVERHEATING' with no variation at normal temps.

However, I'd still like the gauge there anyway, to me its part of owning a sportier car is to have the info there, even if most the time its not used. I realise this makes no sense from a purely function only perspective, but then neither does owning / restoring a 30 year old car.

Regarding the VSS signal, I'm inclined to give it a try with whatever signal the FD sensor puts out, after all the cruise control doesn't need to know the actual speed, just if its the same, increasing or decreasing.