Complex Speedo And Tacho Question

[ydawak]

Hello SAU

I have an idea. It seems pretty simple, but as all simple things, its complex in nature.

I have a vl calais turbo and i want to change the internals of the dash with the GTR skyline dash internals to make the vl a 300km/h and 9'000rpm dash. Now the difficult part is that i want to use the same face of the VL dash and get it re-numbered to match the factory style look (but obviuosly with the skyline numbers) and to get the needles tuned to the same ratio of the new gauges. (i hope that makes sense)

So i need to find out a few things:

The specifications for the electrical signals from the rpm and speed signal for the two cars (or at least the skyline one - while im here)

And to see if they are then compatible

I have tried to do a search on here but the main things i am findiing is the wiring diagrams and so forth, not the actual signal specs and so forth.

Now before the comments start coming in about why not go aftermarket - well everyone has that!

I appreciate any help given.

Regards - Ben

[zoomzoom]

Why bother with factory internals - if you are going to change the dial face anyways? You cant "tune" the sensitivity and response of the air core driver. To do that you need to build your own like I did: http://www.sau.com.au/forums/topic/455121-tachometer-fix/

Moreso, it would be beneficial to look into microcontrollers in order to bend the signal to calibrate it to the dial face. Otherwise you will probably end up with inaccuracy at either the low or high end of the dial.

If you want to make something custom, you are going to need flexibility.

[jiffo]

Is this a single cam Rb30 setup or has it had an engine/box swap?

[ydawak]

Jiffo - sorry i should have mentioned this.

I will be using a 26/30 engine with the normal MX7 gearbox from the vl turbo.

I did have a long troll around the interweb and find out some things i needed to know. I stumbled upon a dude from NZ that made an rpm signal converter for a vl. If i understood it correctly it changes the gtr 5 volt 6 pulse rpm signal to a single pulse 12 volt signal. Or maybe the other way around, i dont have the web page open in front of me right now.

There was also another dude called Grant that used to work in Sixworks in Newcastle who made some kit for this kind of thing, but that forum info was from 2003 i have sent the guy an e-mail but not heard anything yet.

The reason i want the thing to look factory is just because of personal taste. I want something unique and not just normal autometer guages in a box

zoomzoom - your dash looks pretty neat. i like what you've done. Once again, while surfing the web i found out that you can also recalibrate the vl speedo to 240km/h (its no 300 but its something different) I will post up the links i have found when i get home today and see what you guys think about them.

I do appreciate the response. thought provoking.

[ydawak]

http://www.gweeds.net/RBModule/rbmodule.html

here is the link...

here is the face, its something like what im thinking of...

The beauty of printing your own dials means you can do what you want with them here are some pictures of the prints I used

I surrounded the gauges with carbon fibre stick on film. The GSR of course stands for Guido Seevens Racing. The Speedo has been roughly recalibrated so that it matches with the speedo drive out of the Nissan gearbox (My 100k is where a standard commodores 80k is) And the top end brought up from 200 to 240. The rev counter has been extended to 9 grand (tho the motor is limited at 6800rpm). The whole lot was printed on high quality white paper with a colour photocopier. The paper was then stuck to 0.5mm thick white Polystryrene sheet behind which I stuck 2 layers of blue cellophane so that the dash has a blue glow at night. This is to be replaced by Electro Luminescent sheet which will give it the Indiglo type effect. The gauges will then be printed on transparencies. The satellite switches and boost gauge have been illuminated with blue LED's

[jiffo]

So you'll be using the VL speedo and tacho, just with a different fascia?

Speedo would be working at present?

VL tacho will work from the Rb25/30 ecu with the 10c pull-up resistor circuit.

One of my boys chopped up his dash to fit a boost gauge. Was a long time ago now.

Car was actually a VB but with VL interior and Rb20.

[ydawak]

Hey Jiffo

Yes the speedo works at present. as does the tacho.

I don't imagine it makes a difference that its an 26/30 not 25/30 - the ecu pins should be the same.

your mate has a nice setup there.

the fascia will be different. My original question was, whether its possible to have a different internal mechanisms behind the fascia (ie. 300km/h from gtr nismo dash). However through some lucky surfing and finding out some info from some friends it seems that maybe that doesn't even need to be done.

[zoomzoom]

When you say internal mechanism, do you mean just the circuitry? The air core dial itself shouldn't need to be changed if it has sin+ sin- cos+ cos- connections. Its just that whatever combination of dial angle and frequency will differ between circuits.

[ydawak]

When you say internal mechanism, do you mean just the circuitry? The air core dial itself shouldn't need to be changed if it has sin+ sin- cos+ cos- connections. Its just that whatever combination of dial angle and frequency will differ between circuits.

As i am not very knowledgeable in the circuitry of the internal dash components and i am not claiming that i know exactly how they work , i can only attempt to describe what i mean. I will do this with the best paint skillz that i have. I hope this helps to explain 2 things. 1) that i am a moron that doesnt understand dash circuitry and 2) that the thing im wondering is if you can change is, the thing behind the fascia (which controls the speedo pin/dail).

[zoomzoom]

Righto. Well I think you're referring to the air core gauge. Think of it like a motor. The angle of the motor for a given frequency is determined by the circuitry, and that is where I think you need to be concerned. The air core mechanism itself shouldn't need to be replaced, and will save you time and fabrication.

For example, my tacho stopped working, but it was the circuitry and the ECU signal. There's not much to break in the gauge itself, its just copper windings. I built a new gauge driver circuit, plugged it into the existing gauge and it works again.

[ydawak]

Thanks zoomzoom

very helpful and informative. I will look into it some more at a later point. There are plenty of things that i can do in the mean time but i get what your saying with respect to the air core gauge