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cam_champion said:
3.0L and 4.2L have the same gearbox, the 2.8 is different. I think the 2.8 is all alloy?

Sorry - forgot about the 2.8. I should have said for the 3.0L TD and 4.2L TD. I belive the 2.8 TD is the same box as a Skyline - but don't quote me on that.
 

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Im in the same boat as some of the other, 4.2t with a factory fitted 15 tooth gear, i need to drop to 14, but as said above there different, any other news?

I spoke to my nissan dealer, he has all the parts on his screen but cant view the differences
 

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ok, so I'm confused.

When my speedo says I'm travelling at 100km, I'm actually doing 110km, so I'm 10% out.

I'm not 100% sure how many teeth my sprocket has, but lets say it has 17 (It's a 2001 GU Wagon 4.2TD), so 10% of that is 1.7, so do I get a sprocket with 16 teeth, or 15 teeth? do I round up or down? :)
 

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waveriders said:
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.
I fitted one of these around 12 months ago....takes about 1/2 to fit, & has two settings which are both adjustable. ie you can set it up for 2 different tyre sizes & change between them at the flick of a switch.

Very easy to calibrate with a GPS.
 

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its a shopping trolley
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ok, heres a curve ball...................after fitting the 285/75/16 BFG muds to my truck, the speedo now reads spot on to the GPS, HOWEVER odometer is out by about 8%???????????????????
 

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Discussion Starter #27
Pinion Gear

uneekwahn said:
ok, so I'm confused.

When my speedo says I'm travelling at 100km, I'm actually doing 110km, so I'm 10% out.

I'm not 100% sure how many teeth my sprocket has, but lets say it has 17 (It's a 2001 GU Wagon 4.2TD), so 10% of that is 1.7, so do I get a sprocket with 16 teeth, or 15 teeth? do I round up or down? :)
If your gear has 17 teeth and your speedo is reading Below the actual speed then you need to subtract teeth.

So 10% is 1.7 teeth.. You can either get (if available) a gear with 16 teeth - that will still read slightly below your actual speed or a gear with 15 teeth which will cause your speedo to read higher (by a small %) then actual speed.

Personally I would prefer it to read higher so I remain within legal speeds.

Unfortunately it cannot always be spot on but it will be a lot more accurate.

I have a chart from Blackburn Nissan in Melbourne which shows all the different vehicles but only the parts for a 3.0L (which I have).I am sure if you give Wayne at Blackburn a call they can help you with the correct part.

Regards

Marc
 

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cam_champion said:
ok, heres a curve ball...................after fitting the 285/75/16 BFG muds to my truck, the speedo now reads spot on to the GPS, HOWEVER odometer is out by about 8%???????????????????
Hi cam_champion, I have had trouble with my GPS as well, I have checked it on the h/way 5k markers and a police radar and my speedo was right on the money - GPS was out!

Another way is to test it with the RPM and 1:1 gear on the highway, you first measure the distance from the center of the rear wheel to the ground in meters eg. .42m, double it and multiply it by 3.1416 - this will give you the circumference in meters eg. 2.6389m.

You then divide the 2.6389m by the diff ratio (eg. 4.1) and multiply it by the rpm you want to test at (say 2000rpm), you then multiply this again by 60 to get meters per hour - in this case - 2.6389/4.1 x 2000 x 60 = 77236mph (77.236kmph).

At 2000rpm in 1:1 gear your speed will be 77kmph, you can now check your speedo and your GPS.

Cheers,
Whitie
 

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whitie said:
Hi cam_champion, I have had trouble with my GPS as well, I have checked it on the h/way 5k markers and a police radar and my speedo was right on the money - GPS was out!

Another way is to test it with the RPM and 1:1 gear on the highway, you first measure the distance from the center of the rear wheel to the ground in meters eg. .42m, double it and multiply it by 3.1416 - this will give you the circumference in meters eg. 2.6389m.

You then divide the 2.6389m by the diff ratio (eg. 4.1) and multiply it by the rpm you want to test at (say 2000rpm), you then multiply this again by 60 to get meters per hour - in this case - 2.6389/4.1 x 2000 x 60 = 77236mph (77.236kmph).

At 2000rpm in 1:1 gear your speed will be 77kmph, you can now check your speedo and your GPS.

thanks whitie
what would we do without your calculus skills;)
mine is about 10% according to GPS so keen to test this out.
vince
 

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VinceGU05 said:
thanks whitie
what would we do without your calculus skills;)
mine is about 10% according to GPS so keen to test this out.
vince
Share the calculus man! - that's my motto :) , let us know how you go with it Vince :bigthumb:, be interesting to read if your GPS is out too?

Cheers,
Whitie
 

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As a matter of interest I have a 4.2 GU 4 ST with 285/75/16 tyres (Dick Cepek FCIIs on 16" steel rims), fitted the speedo pinion part no. 32743-VB015 15 tooth today and the speedo is now spot on according to the GPS.

This thread was a great help, thanks guys.
 

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The Bear
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Gee you techies are cool, I used to do it the old way, spot of paint on the tyre, roll forward, and measure between the front or rear edges of the spots on the road to get an EXACT rolling circumference, then calculate the gearing/rpm, of course now days I would use a couple of simple formulae's in an excel spreadsheet for every RPM between 40 and 110kph. Easy to do for every gear too, but 3,4,5 are prob the most important. 3 columns, 8 lines.

You would only need to extract the most important RPM/speed figures out of that, like 40, 50, 60, 70, 80, 90, 100, 110.

Nah, GPS is easier, and neater. Anybody who really actually navigates with GPS truly appreciates how accurate it is nowdays.

Whitie, I think maybe your GPS initial set-up might be wrong, not a criticism, just a thought.

Problem with using RADAR/LIDAR against GPS is that RADAR/LIDAR is virtually an instantenous measurement, where GPS updates every 1/2 -1 second plus whatever you have set-up as the refresh, and averages over time and is accurate that way.

You look at a RADAR/LIDAR vehicle speed (unobserved by the target) over time and it fluctuates as well, sometimes wildly, especially with motor vehicles because there are so many variables/human intervention/road surface/wind etc.

sorry for hijack, just thinking out loud on this issue.
 

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allananicol said:
Whitie, I think maybe your GPS initial set-up might be wrong, not a criticism, just a thought.

Problem with using RADAR/LIDAR against GPS is that RADAR/LIDAR is virtually an instantenous measurement, where GPS updates every 1/2 -1 second plus whatever you have set-up as the refresh, and averages over time and is accurate that way.

You look at a RADAR/LIDAR vehicle speed (unobserved by the target) over time and it fluctuates as well, sometimes wildly, especially with motor vehicles because there are so many variables/human intervention/road surface/wind etc.

sorry for hijack, just thinking out loud on this issue.
Thanks for the headsup allananicol but I think that it is the GPS - only a cheapy bought some time ago and there is nothing to set up on it.

Cheers,
Whitie
 

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Marcus I have bigger tyres on my Navara and has thrown the speedo out by 4km's.

The gearbox in my Navara is a 30 series box, same housing as the GU ZD30, TD42 gearbox. Just weaker gear set, are the gears available for the Navara.

Cheers Dave.
 

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Bump, got a mate with a Navara, looking to fix speedo after tyre change, can we get gears for the speedo drive like patrols?
 

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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.
The GQ's have an adjustment screw concealed behind a plug on the back of the speedo. You can get 10% adjustment either way because of all the different tyre options that GQ's came out with: 31" to 32.5". Probably preset at factory with corresponding tyres.
I dont know if the GU's have it.
cheers
 

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Discussion Starter #38
Navara

Hello Dave

Its been a while since I looked at this but I would recommend calling the folks at Blackburn 4x4 (Melbourne)

Most dealers didnt even know what I was talking about when I asked for the speedo gear but the guys at Blackburn knew exactly what I wanted and the correct part #.

http://www.blackburn4x4.com.au/

Regards

Marc
 

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Mty GPS is an HP iPAQ 5765. It runs TomTom and also OziExplorer. The built in GPS antennae takes ages to find the satellites and lock onto them and then I usually end up with 4, maybe 5 satellites.

I purchased an external antennae, when it is connected it takes about 15 to 20 seconds to find a dozen satellites and lock onto them.

Does having more satellites make the GPS more accurate? My gut feeling is that the GPS seems to respond better / more quickly to changes when more satellites available. The external antennae is certainly better in narrow city streets and on very overcast days where the built in one would sometimes lose communication with the satellites.
 
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