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Discussion Starter #1 (Edited)
Hello All

This will be of interest to anyone who has changed their tyres to non standard Diameter.

I changed my standard tyres to 275/70/17's and this caused the speedo to read under by 6%.

I investigated fitting an electronic switch to convert the signal but having had a Jeep before and changing tyres and gears a few times I wanted to correct the problem at the SOURCE and not the dash display.

After almost NINE months I finally found the part numbers and a big thanks go to :D Wayne at Blackburn Nissan 4x4 :D for getting this for me.

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.

The following part numbers are needed to order the correct gear:

32743-VB015 15 Teeth
32743-VB016 16 Teeth
32743-74P17 17 Teeth
32743-74P18 18 Teeth
Cost approx $50.

Again - Thanks to Blackburn Nissan 4x4 for this information.

To install the gear:
I have documented the steps in a series of pictures below.

1) Locate the pinion speedo gear Housing - just next to the Handbrake Drum at the rear of the gearbox.

2) Using a 10mm socket - remove the screw on the side of the housing and
slowly pull the housing out. Warning - you will lose about a cup of gear oil
so place a bucket under the gear box. Dont worry - it will run out and stop
after about 10 seconds

3) Remove the old gear (Black in Picture)
The gear is held on by a C-Clip which uses tiny holes. I just used a
screw driver to remove it.

4) Put the new gear on the spindle (Yellow) and re-attach the C-Clip

5) Push the gear housing back into the gear box. It will need a slight tap to
reseat the O-Ring. And screw in the bolt (dont over tighten).

Took the car for a drive and it is reading almost 100% accurate with the GPS.

This is the best $50 I have spent on my car.

PS: In case you are wondering - I did top up the gear box oil.

Happy new year and regards

Marc
 

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Tanks said:
I thought the Gu's have a Halleffect magnetic pick ?
in english please tanks, not techie:doh:

is this just a magnet that spins on a shaft with an electronic pick up? like a basic cruise control system? i thought that would have been to course?

also i thought a cable and gear type speedo drive is a bit 1980's
 

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ZD30 Out - L77 In!
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They do have a Hall Generator! A Hall effect generator is just a coil of wire that spins inside a magnetic iron stator or the reverse, a magnetic or soft iron core that spins inside a coil of wire.
Regardless of its construction, the faster you spin it, the higher the voltage output. Your speedo is simply a voltmeter that reads the voltage after its calibrated.
Marc is right, this is the best way to calibrate your speedo, but not always the most accurate. Sometimes you just can’t get the right gear to be spot on, but you can get close. This is how we use to do it when speedo’s were cable driven.
 

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Someone should Make this a Sticky - good work

Ive been wondering if id ever find those part # if i had to - good work
 

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Discussion Starter #7
Hello Mr Nismo

The chart I have has a mixture of all different Models.

The important thing is that the part "looks" the same as the one in the original picture.

http://www.patrol4x4.com/forum/attachment.php?attachmentid=1330&d=1166182986

Best thing to do is to get under the car and remove the gear and have a look. It will spill about a cup of oil so be prepared.

The gear dimensions are:

Total Length 44mm
Length of Teeth section: 26mm
Diameter: 20mm approx.

If the gear you have is different send me a picture and I will get the correct part # for you.

Regards

Marc
 

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Discussion Starter #10 (Edited)
Fitting Speedo pinion

I am sure any Nissan dealer can fit this... They just dont seem to care and couldnt be bothered finding the part number. If its not off your original VIN number they are not interested.

I went to the dealer I bought the car off and they "Swore" that this fix was not possible.. Having owned three 4WD's now and having put bigger tyres on all of them and having changed speedo gears on them I KNOW it's possible you just have to find the right part number.

I persisted and finally found someone who was prepared to look beyond their nose (Blackburn 4x4) and gave me a list of all the part numbers and the corresponding teeth.

Seriously - fitting it is a piece of cake and takes 5 minutes.. plus a little oil.

Just follow the pictures and you cant go wrong.

Marc
 

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fix for 2 different size tyres

another option though it costs more though if you have 2 sets or tyres it might help

http://www.marks4wd.com/products/tyre_match_box/speedo-correction.html

it's a box that sets the speedo depending on the tyre size. looking at the pictures it's run from a couple of wires. do you think there would be a problem moving the box or installing it in a overhead console. (just a consideration)
 

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hi i just thought i'd let you know i have a 99/td42t which has a factory pinion cog of 15teeth. i went and ordered the 14t part off your number but this part comes on a shaft not just a cog held on with a circlip. i think all the others would be fine as i had a look at their parts diagram on their system( 15- 18).
unfortunately i don't think i can calibrate my speedo the same way.
 

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Hey guys just wondering if anyone has done this on a TD42 GU?

I'm thinking of going up a tyre size and would like to keep the speedo acurate.
 

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Did this on my 2003 4.2TDi last night - speedo is dead on with 285/75/16s now.

FWIW - I have some extra info - the standard drive in my truck is 16 teeth (I checked with the dealer by VIN and then confirmed it by pulling it out and counting the teeth). I went down to a 15 tooth drive sprocket. The part #s that are listed in this thread are for the two Diesel varients, the TB powered Patrols have different part #s. The 14 tooth gear that someone refered to is for the petrol powered varient, the smallest gear that is available for the Diesels is 15 teeth (thats not to say you couldn't make a 14 tooth one fit with a bit of work, but its is different and not a straight swap).

The gear was $66 from my local dealer and the change over took about 5 minutes from start to finish - the hardest part was getting to the electrical plug on top of the box so I could take the whole unit out and do it on the bench rather then stuffing around with it under the truck.



PS the amount of oil you loose is significantly less then a cup, more like 20 - 50ml
 

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Top marks to Wayne at Blackburn Nissan!

Is he one of the sales people there?

When I went in to look at the Patrols, a sales person (with an office cubicle decorated with numerous sales awards) dealt with me. He was professional, very courteous and tried his best to help me with my technical queries.
 

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Discussion Starter #16
Glad this helped

TCM said:
Did this on my 2003 4.2TDi last night - speedo is dead on with 285/75/16s now.

FWIW - I have some extra info - the standard drive in my truck is 16 teeth (I checked with the dealer by VIN and then confirmed it by pulling it out and counting the teeth). I went down to a 15 tooth drive sprocket. The part #s that are listed in this thread are for the two Diesel varients, the TB powered Patrols have different part #s. The 14 tooth gear that someone refered to is for the petrol powered varient, the smallest gear that is available for the Diesels is 15 teeth (thats not to say you couldn't make a 14 tooth one fit with a bit of work, but its is different and not a straight swap).

The gear was $66 from my local dealer and the change over took about 5 minutes from start to finish - the hardest part was getting to the electrical plug on top of the box so I could take the whole unit out and do it on the bench rather then stuffing around with it under the truck.
Hello TCM

Glad that this thread helped. If you do happen to find any more part numbers and the corresponding vehicle let me know and I will add it to the thread.

I am not sure what Wayne at Blackburn Nissan's title is but he worked in the service division.

Regards

Marc
 

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For those in and around the ACT the bloke I dealt with was Ben at Lennock Phillip.

he was very helpfull.
 

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TCM said:
Did this on my 2003 4.2TDi last night - speedo is dead on with 285/75/16s now.

FWIW - I have some extra info - the standard drive in my truck is 16 teeth (I checked with the dealer by VIN and then confirmed it by pulling it out and counting the teeth). I went down to a 15 tooth drive sprocket. The part #s that are listed in this thread are for the two Diesel varients, the TB powered Patrols have different part #s. The 14 tooth gear that someone refered to is for the petrol powered varient, the smallest gear that is available for the Diesels is 15 teeth (thats not to say you couldn't make a 14 tooth one fit with a bit of work, but its is different and not a straight swap).

The gear was $66 from my local dealer and the change over took about 5 minutes from start to finish - the hardest part was getting to the electrical plug on top of the box so I could take the whole unit out and do it on the bench rather then stuffing around with it under the truck.



PS the amount of oil you loose is significantly less then a cup, more like 20 - 50ml
So, I guess I'm up the creek if I want to correct my speedo, as I have 315/75R16 tyres (35") and if yours is spot on with 15 teeth (the minimum size cog), I would need either a 14 or 13 tooth version, which doesn't exist.

Hmmmm, might have to investigate a bit more into it.
 

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Roachie said:
So, I guess I'm up the creek if I want to correct my speedo, as I have 315/75R16 tyres (35") and if yours is spot on with 15 teeth (the minimum size cog), I would need either a 14 or 13 tooth version, which doesn't exist.
Hmmmm, might have to investigate a bit more into it.
Easiest way is to fir the correction box that you can get from Marks Adaptors in Melbourne takes a bit longer but you can get your speedo correct.
 

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. The part #s that are listed in this thread are for the two Diesel varients, the TB powered Patrols have different part #s.


BUT THERE ARE 3 DIELSEL VARIANTS?

3.0
2.8
4.2

SO WHICH 2 ARE THE PART NUMBERS FOR?
 
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