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R33 GTS-T Speedometer conversion from Km/h with speed limiter, to MP/h without speed limit.

I have posted on this subject in the past, and I was wrong about a couple of things, however I now FULLY understand what is happening and why.

The speed pulse signal is feed directly to the speedo head as a bi-polar signal from the sensor in the gearbox.
The speedometer uses this signal for the speedo reading and then CONDITIONS this signal into a square wave (at about ¼ of the original frequency), which is outputted to the rest of the cars electronics, ECU, HICAS Power steering speed sensitivity.
The good news is that the speedo head is modifiable to UK spec. if you are able to work with a soldering iron, and a lot of common sense.
THIS information may well piss off people selling converter ‘chips’ however I feel the Skyline is a special case as with the correct signals the car is MUCH nicer to drive, and feels more stable, than even with the best 5 wire converter fitted.

Firstly strip the dash out, I always remove the top steering wheel cowl then the dash trim as this avoids scratches, remove the dashboard and take it somewhere well light clean etc. split the front cover of by the plastic clips, and undo the 4 screws that hold the speedo head into the cluster, and remover the speedometer.
AT ALL TIMES BE GENTLE.
On the printed circuit board on the back of the head which you will see the foil side of, mostly at the top things are written on the pcb, and there are a set of calibration pads.

What you need to do is this, where the solder pads have ADJ 1-9 clean all pads (on mine 4+5 were joined) and join pads 6 8 and 9

Where J2 is written but no link installed join J2.

What would be the 10th adjust link is called PESL cut this link, (the solder pad is there but the pcb track is continuous), cut it and leave it as an open link.

This will get you right into the ball park, however you may need to play with the adjustment links to calibrate for your car, mine is an auto and I think its dif ratio is different to a manual, also wheel size effects things, so you may need to set up with GPS or something.
I have function generators and was able to do mine 100% accurate on the bench, but it is an easy task to add or remove links on the solder pads.
Adding a link decreases the reading, 1 buy the smallest 9 by the greatest amount, and it is incremental in a binary fashion.

This is the definitive and final answer to this question, I have today tested and tested and then tested again, this information is 100% accurate, joining J2 is what alters the conditioned signal to MPH pulses that removes the limiter, but all things should be done at once.

If anyone wants this done for them please PM me.

Andy.
P.s. If you like what you have read I have been having a hard time of late and a verbal pat on the back would be appreciated.
 
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This is very interesting information.

I removed the subframe from D4T's old car on friday and noticed a sensor reading from the front of the dif - any idea what that is reading, I thought that might be a speed sensor for the Hicas???


Simon
 

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simon said:
This is very interesting information.

I removed the subframe from D4T's old car on friday and noticed a sensor reading from the front of the dif - any idea what that is reading, I thought that might be a speed sensor for the Hicas???


Simon
Yeah Id like a definitive answer for this too. I have that sensor, but it doesnt show up on any of the fast parts diagrams. Was wondering if it was anything to do with the auto box, or possibly ABS ??

Doesnt seem to be on many cars so doubt its hicas
 
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5 days on and just to re-itterate, my car now feels perfect.
Before it was ok, but I made allowences for the car being 11 years old, you know, it felt a little unsettled at 130+, just felt a little wobbly round some corners....nothing bad, but felt like an oldish car.
Now it feels tight, more precise, I can cruise at 130 now, and brake later and turn in harder, it even feels like it understeers less at roundabouts, when I am not provoking a drift, all together the car feels well 'like new'.
Has anyone tried it yet, I'd love a bit more feedback.
Andy.
 
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I think 320kph should read high enough.....that is about 200mph!
And the signals will be right with that clock, it is only cars with electronic converter 'chips' fitted, on std speedo.
Andy.
 

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excuse my ignorance, but how does recalibrating the speedo affect how the car 'feels'?
is it to do with the hicas, cos mine feels like driving a boat on bumpy roads!
 
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M1 Gts
The speed signal is sent direct from the gearbox pick-up to the speedo.
This signal is then processed by the electronics inside the speedo to give a reading on your speedo, and also it conditions the speed signal into a nice square wave, and lowers its frequency but about 1/3-ish, this output is then called the 'speed pulse'.
The speed pulse is then outputed from the speedo to the ECU and HICAS.
The '5 wire' converters do intercept this signal, and do a fair job, but it is not the same as the speedo doing it correctly.
Please try it, I think you'll be amazed quite frankly.
 

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Mine is a '92 R32GTR that has the original 180 kph speedo, there isn't a limiter on mine as I have taken the car faster, off the gauge. Will what you are saying work on mine and will I need to replace the speedo face with one that reads in mph?
A BIG pat on the back to you for your efforts in trying to explain this to narrow brained f**kwits like me and thanks.
 

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R33GTS-T 350BHP said:
Where J2 is written but no link installed join J2.
Hi Andy

Little confused about the J2 bit....I ve attached a pic of an unmodded manual speedo unit. Was wondering if you'd be so kind as to tell me what to do with the J2 point.

:cheers:
 

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Discussion Starter #19 (Edited)
You see where it is written 'J2' and to the imeadiate left is 1 solder pad, then left a tiny bit more is the corrasponding solder pad that goes back to the chip, join these 2 pads with a long blob of solder or a tiny piece of wire, exaclty the same as 'J4' which has a '000' link installed.
OK?

Oh and good pic, thanks.
 

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R33GTS-T 350BHP said:
You see where it is written 'J2' and to the imeadiate left is 1 solder pad, then left a tiny bit more is the corrasponding solder pad that goes back to the chip, join these 2 pads with a long blob of solder or a tiny piece of wire, exaclty the same as 'J4' which has a '000' link installed.
OK?
What These two with a little bit of wire ?



And would this work for us GTT oweners :)
 
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