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Discussion Starter #1
Hi

On my R34 GTR uk spec some R33 GTR vspec front and rear differentials were fitted to get a shorter final ratio.

Now the speedometer reads wrong, it will read around 25mph more.

The speedo is the standard uk spec one in MPH.

Is it possible to adjust it?

Will the GTR systems like hicas etc react in the wrong way now as the readig is not accurate?
 

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The r33 sweedo has 9 solder pads that can be linked or opened to calibrate the displayed speed, maybe the r34 has the same. What is the percentage difference in the gearing with the new final drives?

If the speedo is receiving a higher speed it will also be sending a higher speed value to the HICAS system so it will not be functioning 100% correctly. Adjusting the displayed speed on the speed will not effect the speed signal to the HICAS and so will not correct the difference. TBH if the difference is quite small it shouldn't make alot of difference. Also, adjusting the displayed speed will not correct the over reading of the odometer. I have never messed with an R34 speedo so my comments may not be correct, but IMO the R34 is likely to have a very similary system to the R33.

The PCB used on the R33 GTST, R33 GTR, UK R33GTR, Nismo R33 GTR speedos are all the same AFAIK. The adjustments are made by making or breaking links and possibly adjusting some resistor values.
 

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Discussion Starter #8
The spped sensor should be fitted on the gearbox, so basically now that the final ratio is different, it still reads the speed that it was making with the standard final ratio at the same rpm, now it's reading about 30mph more.
 
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