4.6 diff versus 4.3

[dom14]

Hey guys,

What is the advantage of 4.8, 4.6 ratio H233B rear diff over 4.3?

Mine is an RB30, carby, manual with stock 4.3 diff.
I got 235/85s atm, which comes to around 32".

So, is there any advantage for me for having a 4.6(or even 4.8) diff?!

Thanx
Cheers

[Stropp]

A lot less load on the motor but a lot more revs

[nissannewby]

A lot less load on the motor but a lot more revs

Basically this. Gearing is doing the work so quicker acceleration. But one step in ratio usually adds around 200rpm at cruise speeds etc.

[dom14]

So, if I go down on ratio and install 4.11 diff on mine, I would get sluggish take offs, but better fuel economy and less revving overall?

[liftlid]

So, if I go down on ratio and install 4.11 diff on mine, I would get sluggish take offs, but better fuel economy and less revving overall?

The car could be crap off road as well.

[Rock Trol]

So, if I go down on ratio and install 4.11 diff on mine, I would get sluggish take offs, but better fuel economy and less revving overall?

Not necessarily better fuel economy because if the engine is lugging it may use more fuel to keep the speed up. Or you need to give it more berries to make it go. Depends on how much torque you have low down.

[Throbbinhood]

I'm still running 4.3s with my 35's on my rb30.. Yeah, performance suffers a little, and the biggest downfall is probably downhill in low range first, it's still quite quick, fine for most thing but some of the steep downhill bits in the high country mean I'm clutching in and just letting the brakes inch me down... Fuel economy, I've gone up 1L/100km on 35's from 31's, so would take a while for me to recoup the cost of 4.6's, which are usually 1-2k depending on condition etc. For 32's, stick with the 4.3's.

[TheFlyingBadger]

Have a look at the calculator here (http://www.nissanpatrol.com.au/forum...eed-calculator)

It'll tell you what you can expect in terms of revs at a given speed

[dom14]

I'm still running 4.3s with my 35's on my rb30.. Yeah, performance suffers a little, and the biggest downfall is probably downhill in low range first, it's still quite quick, fine for most thing but some of the steep downhill bits in the high country mean I'm clutching in and just letting the brakes inch me down... Fuel economy, I've gone up 1L/100km on 35's from 31's, so would take a while for me to recoup the cost of 4.6's, which are usually 1-2k depending on condition etc. For 32's, stick with the 4.3's.

Are you saying fuel economy improved when you went from 31" to 35"?

[TheFlyingBadger]

Are you saying fuel economy improved when you went from 31" to 35"?

no, he went up 1l/100km with the 35s. Litres per 100km, low number is good, high number is a TD42TI on 35s and 3.9 diffs. :|