Speedo Issues

[Mudboss]

Hi All
Just put 35" tyres on my GU TD42, and like expected the speedo is 10km behind my road speed. I live in SA and am trying to get the tyres engineered so the speedo must read right. I cant affort dif gears yet but what have people dont to correct your speedo.

Also im legalising the 4" lift, any information on little thing to look out for?. Got the engineer orginised.

[BigRAWesty]

If your actual speed is still behind then your right.
You can have up to 10% behind but 0% in front.

But I guess that's just a mix up and your doing 110 when gauge says 100..

So 2 things you can do. Buy a replacement gear for the box so the output is changed.

Of swap diffs to a higher ratio.
THe closer to stick ratios you can get the better the car will perform and the closer your speedo will be.

Mine on 33's is spot on $ for $.. So if your running 4.1 diffs you may up to 4.3 ratio.

[BigRAWesty]

And also good luck with the lift. That'll be the hard bit. A lot involved with it here in Sa.

You may find you'll need to upgrade the brakes to going 35's.

I did have the blokes name who does it all but is on my old phone. (Gone).
I was investigating an a 3rd anchor point in the middle row

[the evil twin]

Unless you are already on the highest number of teeth you can purchase from Mr Nissan or Wreckers the correct speedo drive cog and swap that out.
Very simple job
They make about 4 different size cogs each with an extra tooth over the previous.

32743-VB015 15 Teeth
32743-VB016 16 Teeth
32743-74P17 17 Teeth
32743-74P18 18 Teeth

[threedogs]

Dress to the right lol

[Mudboss]

Thanks fellas. i didnt know if i could just replace the speedo cog or not.Thanks for the part number, will the part number be written on the cog at all or i just count the teeth.

The engineer that im going throught is pretty posotive with the lift. he says hes dont heaps of patrols with gmv upgrades that usualy lift the car 4".will let you all know how i go.

[Mudboss]

um ok, next question. do i go up a size or down to increese the speedo reading

[liftlid]

On a gq you can adjust the speed shown at the cluster , not sure if the gu cluster has the pot though.

[BigRAWesty]

um ok, next question. do i go up a size or down to increese the speedo reading

Great question. If your replacing the gear which drives the output then down a tooth.
If your replacing the output sprocket itself then up a tooth.

I think that's right. Have never done it so only working on ratio changes.

[BigRAWesty]

Thanks fellas. i didnt know if i could just replace the speedo cog or not.Thanks for the part number, will the part number be written on the cog at all or i just count the teeth. The engineer that im going throught is pretty posotive with the lift. he says hes dont heaps of patrols with gmv upgrades that usualy lift the car 4".will let you all know how i go.

What's this blokes name and number?? See if it's the same bloke.

[Mudboss]

im going through

Philip Degenhardt MBA, BEng(Mech), MIEAust CPEng
Director & Principal Engineer



PO Box 882, BLACKWOOD SA 5051
Mob: 0407 725 261
E-Mail: pdegenhardt@motivengineering.com.au

[Mudboss]

you wouldnt happen to have a number of were i could get these cogs please

[the evil twin]

you wouldnt happen to have a number of were i could get these cogs please
Any Nissan Dealer or the Forum Spares blokes should be able to get them

Those numbers are the Nissan part #'s AFAIK

[Mudboss]

Well just to let all you boys know, I ordered a speedo cog from my local Nissan dealer, went from a 16 tooth to a 15 tooth, it brought my speedo from 110 road speed at 100, down to 105 road speed at 100. I found out that you can get a 14 tooth cog, it’s out of a tb48 auto. So gonna try that and hopefully it will correct my speedo. (Marks adaptors also do a speedo correction box for around $250).