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.

[Stropp]

i have changed mine from 3.9 to 4.3 and that is good for both 33 and 35 tyres, she just revs a little higher with 33's but goes well.

[mudski]

I went from 4.3 to 4.1. Only because im using a zd gearbox, different gear ratio tothe td box, and it virtually had no first gear with 4.3s. And at 100ks it was at 2700rpm. Now it sits on around 2400rpm. Goes great with 33s and 35s.

Sent from my SM-P600 using Tapatalk

[MudRunnerTD]

i have changed mine from 3.9 to 4.3 and that is good for both 33 and 35 tyres, she just revs a little higher with 33's but goes well.

Any second thoughts Stropp? If you had your time again would you still choose 4.3s?

[AB]

Any second thoughts Stropp? If you had your time again would you still choose 4.3s? Are you asking this question for your GQ or your family tourer GU?

[Stropp]

Any second thoughts Stropp? If you had your time again would you still choose 4.3s?

4.3 are good with the 33's but if I could get the 35's engineered I would go 4.6

[MudRunnerTD]

Are you asking this question for your GQ or your family tourer GU?

Nah the GUIV for sure. Coupled with a turbo and intercooler it should be pretty peaky!

[MudRunnerTD]

4.3 are good with the 33's but if I could get the 35's engineered I would go 4.6

So your happy with the 4.3s and the33s? You would do it again rather than 4.1s?

[MB]

Quite hilly highway country for me. 4.3s powering 35's, love em! Other family truckster running 33's on 3.9's, now saving coin for 4.1's, same same ?

[Dannyboyz]

Thinking I will see how it goes on the 4.6s with 33s. Should have had them on by now but tyre joint got in the wrong rims. Anyway once I get the defect sticker off I will take it for a spin to Melbourne and see how it likes the smaller boots. If its revving too hard maybe 4.3s will be in order. With the 4.6s and the 35s it goes really well so and is an animal out the bush. Just borrowed some stock nissan rims and tyres for the roady seeings as my new ones arn't ready yet. Think 1st will be not worth it with 32s on. Probably pull Christ off the cross tho!

[MB]

G'day Danny,
I know a couple of blokes whom's be running 35-4.6. They are great scrub/mountain ratios but they may need to tow a 44 or two to Pajinka Tip ;-)

[Dannyboyz]

@ MB Yeah I hear ya mate. I'm thinking 33s on the 4.6s may be too much. But I will take it for a few runs anyway and see how it is. Looked into the taller 5th gear that marks adapers do. Thinking 1st-4th would be unreal out the scrub, windy roads ect. Shift into 5th to cruise all day. But the price turned me off pretty quick. 1250 bucks just to buy it! Then gotta fit it too!

[MB]

Apologies Danny:-(
My bad!
Ignorantly haven't read your thread properly mate!
What are you trying to achieve, touring, smashing etc....?

[Dannyboyz]

Its all good MB. I am trying to achieve a happy medium if there is such a thing. The patrol is not a daily driver. It sits in the shed awaiting camping trips. 95% of what I do with it is dragging my big camper trailer with dirt bikes up the bush. Or leave the trailer at home, load up the back and roofrack with all the stuff a family of 4 needs for a multi day drip though the vic high country. But also middle of this year my wife and I left the kids at home and took it up to the NT for our honeymoon. We had a ball and now wish to do some more touring with the kids. I was pretty happy with how it was with 4.6s and 35s but due to my recent run in with a city copper up the bush (bad combo) while minding my own business the 35s and 5 inch life have got to go. Thinking the the 4.6s with 33s will be wicked in the steep high country but when I want to unlease it on the flat parts of the country I think I will be limited to 80-90 kph in the interest of fuel economy? As a truck driver this just wont do :-)

[Stropp]

So your happy with the 4.3s and the33s? You would do it again rather than 4.1s?

Happy as mate don't think I would change them.