TD42, which diffs suit which tyres sizes?

[Dannyboyz]

Hey guys and gals. On the hunt for some info on diff ratios. I have a TD42 installed in my wagon which was originally a 2.8. Currently running 4.6s i believe ( standard for the 2.8 wagon? ) with 35s. So I managed to score one of those nice yellow stickers on my windscreen while just minding my own business out the bush on Saturday. I have made the heart breaking decision to bring the big gurl back within legal specs so that I can take it out on long weekends without attracting attention from the boys in blue. So 35s and 5inch lift is coming out. Insert 33s and might try squeeze a 3 inch lift through the roady. But I'm thinking that the 4.6s will make it rev too hard on the highway which is not ideal as I plan on doing some touring in the future. With the 35s it sits around 2400rpm now so I really dont take it past 100kph for long. Even when I had it in the 130 zone in NT. What I am wondering is which ratio would suit 33s? To be able to sit on 110 where the limit allows would be nice but I want it to be low enough geared for the Vic high country still too? Also what would be the easiest way to change the ratio being that I have lockers fitted in my current centers?

Thanks in advance for any input

[Touses]

Heya bloke! I'm pretty sure the bog standard centres are 4.3 for the td42, there are also 3.9s about but these might be a little too tall on the 33".

[garett]

my td42 mav has hg41 axle code so i'm guessing that stock it has 4.11 diff ratio.
sits about 2200 at 100ish on 33's

[Hodge]

Heya bloke! I'm pretty sure the bog standard centres are 4.3 for the td42, there are also 3.9s about but these might be a little too tall on the 33".

Yeah I understand later 4.2 Turbo Wagons are 3.9. Like mine. And I remember nissannewby suggesting I go to 4.11 's cause I run 33's.

[Touses]

my td42 mav has hg41 axle code so i'm guessing that stock it has 4.11 diff ratio.
sits about 2200 at 100ish on 33's

Yeah, now I've had a better look mine are HG41 as well!

[Dannyboyz]

Thanks for the replies fellas. 4.11 sounds good for 2200rpm at 100kph. Should sit nicely at around 2350 or so at 110kph then. Would I be better off chasing whole centers and getting my lockers fitted into them or just buying the crown wheel and pinions? I will be trying to sell the 4.6s so maybe it would be better to sell whole centers?

[BigRAWesty]

It really depends on what box your running also..
If your happy with the rpm atm at 100 then dropping back to a 4.3 and 33's will keep the same ratios as your 4.6 and 35's atm..

In saying that your only adding 300 ish rpm at 100 k if you keep your 4.6 diffs and go to 33's.

You'll find although it's reving more you'll use less fuel and gain a bit of torque too..

4.1 diffs as above will go past current ratios, you'll gain a few less rpm but you'll loose torque and may loose a bit of fuel efficiency..

It really is hard to predict thou as each car setup is different.
I sold my 4.6 diffs to a bloke who had a 6x4 extended chassis dual cab gq auto trans and stock 31" tyres and td42 T under the bonnet..
He struggled to get below 16 on the highway and it was a slug.
Threw the 4.6's in and dropped to 12 ish / 100k and said it's now brilliant to drive..

So it really is a mixed think..

If you like the way it is now I'd say drop to 4.3's.
If you want more poke keep the 4.6's..

[Dannyboyz]

Hmm. Thats an interesting point of view. As it is now it does 2400rmp at 100ks. Recently i took it to the NT from Vic towing a camper trailer. Not sure on the weight of the trailer but there was a bit in it. I was averaging 17lts / 100ks and put that down to revving too hard. I kept it at 100kph the whole time. But what your saying is possibly if I had of been doing 110kph it may have got better? I would have thought to sit a TD42 at 2700rpm for hours at a time would not be good?

[nissannewby]

You dont want RPM to low nor to high at crusings speeds. The TDs seem to like being between 22-2600rpm.

Nothing wrong with 2700rpm for extended periods. There is a red section on your tacho for a reason

[TimE]

I have a 2005 4.2tdi running 33s with a 3.9 diff. 2000 rpm is 95 kph, that is peak torque for my motor, towing is easy at 95 to 100 kph. Fuel usage ranges from 14.5 to 17.5 depending on the road and wind direction.