gu patrol diff ratio?

okay have a 2000 gu 4.2td right now i'm running 33's with original rear diff and speedo is out 10kms at 100kmh. looking to put on 35's and change the pinion in the gearbox but what is the best diff ratio to have?

I wouldn't think 33s would throw the speedo out 10ks are you sure the diff ratios havnt been changed previously?

Would be cheaper just to change the speedo adapter. ..



I tapped that app...

If a manual more than likely 4.1:1, if auto 3.9. There should be a silver placard under the bonnet that will give you an axle code. The last numbers of the code will be the ratio. Eg mine says hg41, meaning mine has a diff ratio of 4.1:1. If you can jack the rear of the car up with the front wheels chocked, mark a reference point on the tail shaft and turn one of the rear tyres one compete revolution while counting how many times the tail shaft rotates will give you your ratio.

cheers guys don't know if the diff has been changed. will have a look today. i'm guessing that its out by 10km at 100 only from my hema it says i'm doing 110 and my speedo says 100. its a manual was my dads before he passed.

Quote:

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Originally Posted by Parksy

If a manual more than likely 4.1:1, if auto 3.9. There should be a silver placard under the bonnet that will give you an axle code. The last numbers of the code will be the ratio. Eg mine says hg41, meaning mine has a diff ratio of 4.1:1. If you can jack the rear of the car up with the front wheels chocked, mark a reference point on the tail shaft and turn one of the rear tyres one compete revolution while counting how many times the tail shaft rotates will give you your ratio.

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Didn't know this....... Thanks
Scotty

mines a 42td 01 gu manual on the compliance plate says hg39

I had a 99 model 4.2 gu running 305 70 16 (33s) the speedo was spot on, I guessing you may have different ratios already installed no longer have the 4.2 so I cant check the compliance plate

compliance plate is HG39 havn't got under it yet to check the revolutions due to work.

You have 3.9:1. Same as my GUIV. I have run 35s without too much trouble mate.

I put 35"s on a 98 GU TI with 3.9's and it didnt have the talk to push them. Changed to 4.6's and now it feels like its got more power than it had with the standard tyres and 3.9's but the speedo is way out. Thats in a guttless petrol though.