A fix to your speedo issues

[Mudboss]

Well after much research I’ve found out that to correct your speedo, I replaced my speedo cog from a 16 tooth to a 15 tooth for $50. But the 14 tooth cog is a different setup. It dropped my speedo by 5km. You can buy a marks adaptors Speedo correction kit for around $240. But I’ve found a speedo correction kit from Jaycar for $50. Looks like a bit of set up work and I haven’t fitted it yet. I’ll let you all know.

[outback]

Well after much research I’ve found out that to correct your speedo, I replaced my speedo cog from a 16 tooth to a 15 tooth for $50. But the 14 tooth cog is a different setup. It dropped my speedo by 5km. You can buy a marks adaptors Speedo correction kit for around $240. But I’ve found a speedo correction kit from Jaycar for $50. Looks like a bit of set up work and I haven’t fitted it yet. I’ll let you all know.

If you have to drop from the standard black cog to the 14 tooth one you have BIG problems with the computer and its software.
Are you running standard 17" rims and tyres?

[my third 256]

i drive off the gps no mucking around and it has speed alert sound when you are speeding

[tracemul7]

Interested to see how this goes ......

We're about 108km/h when speedo reads 100km/h ..... resulted in a very expensive ticket a few weeks ago
Been using speedo from GPS but found it fluctuates a lot, so hard to be efficiently driving close to the limit, without risk of throwing more money away.

[mjr350]

you got done for 8km over? Cop must have been having a bad day.

[tracemul7]

It was before we realised it was 8km over .... must have been doing about 7km over, as got done for 15km over ..... sad times!
Although it was from her radar in her moving vehicle against our moving vehicle .... i do wonder about the accuracy.

[Mudboss]

My 03 patrol is allowable +/- 10% but anything made after that is -10% only. I had to drop my speedo because im running 35" tyres now LEGAL, engineer signed off on it the other day.

You can drop down to a 15 tooth speedo cog, but ill let you know how this Jaycar speedo correction kit goes once i fitted it.

[mudski]

I've had this snip cut and paste into a info word doc I keep on my pc. I can't remember where I got it from but this is what it says....

The standard pinion speedometer gear on a 3.0L GU Manual has 17 teeth and in my case my speedo is reading 6% below the actual speed.

So to calculate the correct gear:
Standard Gear = 17 Teeth
Speedo Error = 6% Below
6% of 17 = 1.02
Number of teeth Required = 16 (17-1)

Of course if your speedo is reading higher then the actual speed then you need to add teeth.

[my third 256]

found this chart in one of the threads
Thanks to ET for the table, this the pinion gears table for speedo correction at the gearbox.

Diff ratio Tyre size Speedo gear (pinion) Part Number 32703 - 31G 17
Change last 2 digits (in boldface) for gear you need using the table below.

Be aware that is manuf spec so speedo will probably overread slightly IE at 100KPH GPS the speedo will possibly be 103 maybe 104 KPH as req'd by ADR's

Your diff ratio will be on the vehicle build plate

3.9:1 Ratio
TyrePinion
31 16
33 15
35 14
37 13

4.11:1 Ratio
31 17
33 16
35 15
37 14

4.375:1 Ratio
31 18
33 17
35 16
37 15

4.625:1 Ratio
31 19
33 18
35 17
37 16
which is in this thread
http://www.nissanpatrol.com.au/forum...orrection+gear

[janderson]

My 03 patrol is allowable +/- 10% but anything made after that is -10% only. I had to drop my speedo because im running 35" tyres now LEGAL, engineer signed off on it the other day.

You can drop down to a 15 tooth speedo cog, but ill let you know how this Jaycar speedo correction kit goes once i fitted it.

VicRoads Customer Service commented on your Wall post.

VicRoads Customer Service wrote: "Hi Jeff – ADR 18/02 specifies for vehicles manufactured after January 1995 must have a speedometer that indicates the actual vehicle speed, for all speeds above 40 km/h, to an accuracy of ± 10 per cent. If your speedometer isn’t accurate you can speak to your manufacture regarding calibration or to a VASS engineer as well. Regards - Nathan"