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Diff Ratios?

HarroVX

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hey guys, can anyone actually explain to me what the #### diff ratios are all about?
ive been told about them before but not in detail.
 

Cameron P

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its the ration between the pinion teeth (forget the technical term) and the crown wheel teeth. if you mark one tooth on the pinion and turned it the whole way around the crown wheel you will get the ratio

someone correct me if im wrong :p
 

Kernal

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Just think about it like this. The usual standard diff ratio on a commodore is 3.08 - 1
Now think of that as first gear on a mountain bike. You have to peddle hard to get it moving right??
Now put the bike in a higher gear, say 4th. Its a lot easier to get it moving yeh? you dont have to work as hard.

Now if you put a higher diff gear in your commodore (correct term is taller and shorter but its easier to understand like this), say 4.11, your car wont have to work as hard to get moving.

The gears go up in these increments; Standard is 3.08 and 3.46, upgrades are 3.73, 3.89 and 4.11. the higher you go the less your car has to work to get moving therefore you will have faster acceleration, however, the higher you go, the less your top speed will be.

Although diff gears wont affect you ET's much, it will make a difference in your 60 footers as it helps you get out of the hole.

If you mostly drive in the city/suburbs i would recommend 4.11, you wont look back. But if you do quite a bit of freeway/highway driving maybe 3.46 or 3.73. However i stll went 4.11 and havent look back.
Why? you ask. Because the higher the diff gear the more you'll be revving at freeway speeds 100kmph. But if you can put up with drone (if your exhaust system has drone), and dont mind paying $5 extra in petrol a week go 4.11, either way you wont regret it.
 

Mirkz

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what's the usual cost to rebuild a diff or fit new diff gears? (I'm not sure if this is one in the same???)
 

Brett_jjj

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Just think about it like this. The usual standard diff ratio on a commodore is 3.08 - 1
Now think of that as first gear on a mountain bike. You have to peddle hard to get it moving right??
Now put the bike in a higher gear, say 4th. Its a lot easier to get it moving yeh? you dont have to work as hard.

Now if you put a higher diff gear in your commodore (correct term is taller and shorter but its easier to understand like this), say 4.11, your car wont have to work as hard to get moving.

The gears go up in these increments; Standard is 3.08 and 3.46, upgrades are 3.73, 3.89 and 4.11. the higher you go the less your car has to work to get moving therefore you will have faster acceleration, however, the higher you go, the less your top speed will be.

Although diff gears wont affect you ET's much, it will make a difference in your 60 footers as it helps you get out of the hole.

If you mostly drive in the city/suburbs i would recommend 4.11, you wont look back. But if you do quite a bit of freeway/highway driving maybe 3.46 or 3.73. However i stll went 4.11 and havent look back.
Why? you ask. Because the higher the diff gear the more you'll be revving at freeway speeds 100kmph. But if you can put up with drone (if your exhaust system has drone), and dont mind paying $5 extra in petrol a week go 4.11, either way you wont regret it.
Its actually the other way around ,the lower the diff ratio,the higher the engine will rev on the highway.The 4.11 gears are actually lower than 3.08 gears,not higher.The higher the number,the lower the ratio.
 

Cameron P

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wpn.. what revs are you sitting on doing 100km/h?

and what gearbox do you have?
 

Mirkz

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I was always under the impression higher diff ratio, the higher revs at fwy driving...

Edit: duuh huurrrr just read the rest of the post :/
 

Brett_jjj

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The higher the diff gearing is,the lower the engine will rev at highway speeds,but it also makes the car sluggish to get going off the line ,and slow to pick up speed.This is why people fit lower gears,like instead of 3.08:1 ratio,they will fit a lower ratio of 3.5:1,this makes the car way better off the line,and gives better pickup,but it will be reving harder at highway speeds with the lower diff gears fitted.
 

Paul13pp

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I used to have a 2.78 diff and a commodore 5 spd box in a HR ute.
She was a real cruizer on the highway. hardly any rev's.

Can you get ratios like that for VS's?
I know the one in it is a 3.08 but it would be more ecconomical on the highway with something like a 2.78.
It is not like there is a lack of takeoff power.
I'd hate to have 4.11 ratio with the engine reving its tits off at 110 klm/h wering everything out faster and using more fuel.
 

VUte89

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So do any of you know if the LSD in the vu has a different ratio to the non LSD in a vx sedan
 
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