4.6 diff ratios?? is it worth it?

[full-boost]

hi guys, ive got an 89 GQ 4.2 turbo diesel. ive got standard diff ratios (4.1 i think) and 33" tyres.
im wondering, will i feel a difference if i change the diff ratios to 4.6? how will i feel the difference? is it worth it? does it have much of an effect on fuel economy?
for aprox $210 i can get the crown wheel and pinnion, is this enough?
thanks guys!!

[bru21]

i run 36" tyres on road and they are not big enough for the speedo to read correctly. i had 3.9's standard. it reads about 8% more than the correct speed

[jessie928]

4.6's are to high for you

you need 4.3's

Jes

[Big Red Toy]

depends what you want to do!

Your running 33's so obviously nothing to extreme these days... So i'd leave it as you are, i run 4.11 with 35's & mines turbo diesel also & its actually quite a good ratio i have found for what i need

If your planning on doing comps then yeah go for it but only if your going bigger tyres


If you feel your struggling to turn the 33's, then your motor is shagged Goodluck with it

Cheers
Andrew

[sudso]

Just about everyone I know that has standard size tyres on their GQ tell me there speedo is already about 10 kays over what they're actually doing so 33's would probably even it out.

I've got 35's and the speedo is only about 10 kays under. (tested with GPS) That's with 4.11 gears

At the actual 110 kmh in 5th gear my engine is doing 2200rpm which is nice and cruisy for a 4.2D with a turbo

cheers

[sudso]

Just about everyone I know that has standard size tyres on their GQ tell me there speedo is already about 10 kays over what they're actually doing so 33's would probably even it out.

I've got 35's and the speedo is only about 10 kays under. (tested with GPS) That's with 4.11 gears

At the actual 110 kmh in 5th gear my engine is doing 2200rpm which is nice and cruisy for a 4.2D with a turbo

cheers

[bogged]

4.6's are to high for you

you need 4.3's

Jes

thats the way I went with my GQ and it was perfect with 33's.

[Beastmavster]

Well you can probably sell them for more than that but it will be useless to you on 33's.

4.1 or 4.3 would be best. I'm on 4.1 and 33"s and very happy with it.

[beretta]

I run 34's with a TD42 (gutless) and 4.10's and it really isn't that much of a difference, even in the slow crawling stuff, if anything it probably makes you keep a little more momentum.

My personal opinion, I wouldn't waste your money or time, unless your going to go to 35's or 36's, then it would definately be worth it.

By the way you can only get the front crown wheel and pinion for $210 the rear will be a LOT more expensive, more like at least three times that....

[Mkdude]

i run 35-36's on my gq, diesel(non turbo) and its slow, can anyone suggest a ratio,,, its manual

[sudso]

i run 35-36's on my gq, diesel(non turbo) and its slow, can anyone suggest a ratio,,, its manual

4.3 or 4.6?
How much do you want it to rev at highway cruising?
With those size tyres I'd say you do more off road though.

[full-boost]

when these tyres are stuffed, im getting between 35" - 40". most likely 37"-39". but i dont want it to be a screamer on the hwy (high reving). we will do an around australia tour in it in a few years (when bubs is bigger, only 7 months at the moment), as well as the weekend work we do at the moment!

[Mkdude]

high revs on the freeway dont worry me too much, but i dont want them too high.... my last car was a worked vk with 4.11's and 3spd auto lol.. and i dont a fair bit of hwy driving

[beretta]

Mate if you are seriously considering changing to 37-39's you should be looking at 4.88's, not 4.6's.

[bogged]

when these tyres are stuffed, im getting between 35" - 40". most likely 37"-39". but i dont want it to be a screamer on the hwy (high reving). we will do an around australia tour in it in a few years (when bubs is bigger, only 7 months at the moment), as well as the weekend work we do at the moment!

so your going to be touring on 37-39inch tires?

[Freakazoid]

I am running 35's with standard petrol engine and transmission and it is just OK on the pavement. I am going to be upgrading to a VH45 and hopefully with it a 6 speed box. The problem is that the 1st gear on the 6 speed box is 3.9 vs GQ's 4.55 The V8 should have enough power to push the car on the pavement. For offroad though, will it be better to change diff ratio's or put a double transfer case in?

[Big Red Toy]

yeah i think touring on 37"+ tyres is a bit crazy...

Maybe swap your diff ratios back to 4.11 & put some 33's on to tour with

[jessie928]

i run 35-36's on my gq, diesel(non turbo) and its slow, can anyone suggest a ratio,,, its manual

you have 4.1's already. with 33's you will need 4.3's and with 35/6's you need 4.6's to bring the speedo ( torque band) back to factory

Jes

[jessie928]

i run 35-36's on my gq, diesel(non turbo) and its slow, can anyone suggest a ratio,,, its manual

4.3 or 4.6?
How much do you want it to rev at highway cruising?
With those size tyres I'd say you do more off road though.

its got nothing to do with revving on the freeway. for the car to cruise comfortably, it has to be at a RPM where the motor is not labouring or to high in the torque band

you want the car at 100-110km/h to be sitting where teh torque that the engine produces is strong so it can pull the weight and battle the wind resistance with its best compromise.

ratio's to gigh and you will be wasting fuyel for no reason and reving the engine more than it needs

Ratio's to low and you will find that the car will not pull very well at the speed you wanto be cruising at, you will be forever changing down gears on slight inclines, and speeding up to much so the car cruises comfortably.

adjust the ratio's in yoru diffs for higway use, if you want better offroad performance get a set of transfer gears.

you will use heaps more fuel if the ratio's are wrong ( either way)


Jes

[weeman]

for 33's even 35's i wouldnt go 4.6

I have 4.6 in my GU and running 315/75/16 and contemplating going back to 4.3 or 4.1. It just over revs at 130 it sits on 3 grand which shits me when your heading up north.

I'm doing a turbo upgrade so i'll have the power so thats why i'm contemplating going back to 4.1 as a mate of mine has some complete centres.

But also may try and swap my 4.6 with someone with 4.3 and cash adjustments...

But i would go 4.3 unless your doing comps then you when you dont care about fuel and want gearing go the 4.6's.

[jessie928]

for 33's even 35's i wouldnt go 4.6

I have 4.6 in my GU and running 315/75/16 and contemplating going back to 4.3 or 4.1. It just over revs at 130 it sits on 3 grand which shits me when your heading up north.

I'm doing a turbo upgrade so i'll have the power so thats why i'm contemplating going back to 4.1 as a mate of mine has some complete centres.

But also may try and swap my 4.6 with someone with 4.3 and cash adjustments...

But i would go 4.3 unless your doing comps then you when you dont care about fuel and want gearing go the 4.6's.

it all depends on what your truck has from standard. With the right ratio, it will bring back your truck with larger wheels back to standard gearing. A turbo will compound the problem because it will always be on a higher amount of boost at cruising. You donot want your turbo on boost 100% of the time.

for instance.

If you have 3.9's ( tb42 auto)

with 33's you need 4.1's
with 35's you need 4.3's
with 37/38's you need 4.6's
( that said the tb42 auto revs a little low when cruising from standard, so going up a ratio will bring it on par with a manual with 4.1's)

if you have 4.1's TD42 aand TB42 manual

33's you need 4.3's
35's you need 4.6's

if you have 4.3 ( 3l petrol )

33's you need 4.6's
35's you need aftermarket 4.8's

BUT, i have found that the 3l petrol is quite happy to stay a ratio under the optimum, so if you have 35's it will be ok on d road with 4.6's


if you have a 2.8Td with 4.6's standard,

you can oly go aftermarket to 4.8's for tyre size increases. ideally you need 4.8's for 33's

JEs




Jes

[weeman]

well mine is a factory turbo diesel, orginally with the 3.9.

However as you know the utes with the same motor came out with 4.1.

And i think at 3000rpm my turbo would be borderline near on full boost which is annoying.

when i had 3.9 it was ok just sluggish.

[Dee]

I have 2000 GU 3.0TD auto..

4.3's (i think).

What sort of cash adjustment were u thinking for a swap weeman?

[weeman]

I have 2000 GU 3.0TD auto..

4.3's (i think).

What sort of cash adjustment were u thinking for a swap weeman?

i dont know, a mate just did his with someone with a new 3L and got a $1000 nice low km.

i'll see how i go might try and find somone local with a 3L

[bogged]

dont know, a mate just did his with someone with a new 3L and got a $1000 nice low km.

Your mate did very very well out of the deal.. no way I'd pay that sort of coin for straight swap 1 ratio for another, or did I read it wrong.

What ratios would my 2.8TD GQ have, and would 33's be OK?

compliance plate on the firewall... look for HGXX XX is the ratio (HG41 - 4.1's)

[weeman]

dont know, a mate just did his with someone with a new 3L and got a $1000 nice low km.

Your mate did very very well out of the deal.. no way I'd pay that sort of coin for straight swap 1 ratio for another, or did I read it wrong.

What ratios would my 2.8TD GQ have, and would 33's be OK?

compliance plate on the firewall... look for HGXX XX is the ratio (HG41 - 4.1's)

Yeap they swapped his 4.6 his 4.6 had done a bit of work as well... So for the guy's 4.3 out of an 05-06 GU 3L and got his 4.3 centres and $1000 cash.