4.6 ratio

[TuffTD42]

Hi guys, maybe someone can explain why i come up with the following.

I swapped ratio's from 4.11's to 4.6's yesterday. I checked the rear ratio on the vehicle i was pulling it out of to make sure they were 4.6. I didn't check the front, but now I have installed them I rechecked because I didn't get the jump up in rpm at 100kph I thought I would get. Approx 2400rpm @ 100kph on 35's. From what I've read should have got around 2600rpm on 35's.

I put a piece of tape on one wheel nut & on the guard & marked the yoke. I got my oldest son to turn the wheel one revolution while I counted the revs of the yoke & got approx 4.6-4.7 turns. So the rear should be 4.625:1. We done this to the front & the front gives half, approx 2.3 revs. I am racking my brains but can't figure it out. I thought the front yoke would have to turn the same amount of revs as the rear?

As I'm not the smartest cooky:icon_bonk: maybe someone can point out why the front turns half as much as the rear.

cheers Jono.

[MudRunnerTD]

I am not sure there TuffTD42, i like your measuring trick though ;)

on a side note the measurement you get on the front is exactly half what you are expecting to get so is a division of 4.6 and there is some logic there. If it was 2.15 on that logic it would be 4.3s and so on.???

If the car they came out of was a runner and you did not mix up the fronts when you took your other one out then i dont think you should do your head in mate, it will likely be the output from the Transfer and by design.

If in doubt take it to the dirt and put it in 4x4 and you will not get more than 3m without knowing your answer mate. Gently!

[TuffTD42]

Cheers mate. The front gets half of the rear @ 2.3 approx.

[gq4200]

Front is an open diff you need to keep one wheel on the ground while doing this test. With LSD rear you need both off the ground. Other thing is try driving in 4wd. If the front ratio is different to the rear you will know quick smart as it will be doing all sorts of nasty things.

[the evil twin]

snip...now I have installed them I rechecked because I didn't get the jump up in rpm at 100kph I thought I would get. Approx 2400rpm @ 100kph on 35's. From what I've read should have got around 2600rpm on 35's.



Were you using your speedo or GPS to check the 100 KPH revs? If it was your speedo there is your problem as the "revs per 100" won't be affected by the diff ratio as the speedo pick up is in the Gearbox. You could put 10:1 in the diffs and the RPM versus Speedo will still be the same. All you have done is changed your speedo versus actual error as you will actually be doing about 40 KPH.
If you used a GPS then something else is suss if you still have the same revs


Front is an open diff you need to keep one wheel on the ground while doing this test. With LSD rear you need both off the ground. Other thing is try driving in 4wd. If the front ratio is different to the rear you will know quick smart as it will be doing all sorts of nasty things.

Agree 100%... try the same test again but with someone holding the other front wheel or with only one front wheel jacked up

[YNOT]

Front is an open diff you need to keep one wheel on the ground while doing this test. With LSD rear you need both off the ground. Other thing is try driving in 4wd. If the front ratio is different to the rear you will know quick smart as it will be doing all sorts of nasty things.


Were you using your speedo or GPS to check the 100 KPH revs? If it was your speedo there is your problem as the "revs per 100" won't be affected by the diff ratio as the speedo pick up is in the Gearbox. You could put 10:1 in the diffs and the RPM versus Speedo will still be the same. All you have done is changed your speedo versus actual error as you will actually be doing about 40 KPH.
If you used a GPS then something else is suss if you still have the same revs



Agree 100%... try the same test again but with someone holding the other front wheel or with only one front wheel jacked up

This is how he got the incorrect reading. By turning one front wheel while the other is being held stationary the diff side gear is able to rotate the sun gears meaning the diff pinion only rotates half as far as it otherwise would. He needs to have the vehicle on the ground and push it forward in a straight line so both front wheels rotate together.

Tony

[the evil twin]

Hiya Tony,

Yeah, pretty much gotta be eh... and I reckon the reason the revs didn't change at 100 KPH between the 4.1's and the 4.6's is that the 100 KPH was off the Speedo

[patch697]

Hiya Tony,

Yeah, pretty much gotta be eh... and I reckon the reason the revs didn't change at 100 KPH between the 4.1's and the 4.6's is that the 100 KPH was off the Speedo

Yep agree with ET here......

No change in the speedo/ tacho relationship would only be he's not changed the speedo drive to mach he's new diff/tyre combo.

[portal pat]

2400 at 100kph on 35s would be right with 4.6s old mate. I have 35s with 5.0 diff ratio (i.e. 4.11x 1.22 portal hub reduction = 5.01:1) and I get 2650 at 100kph. So you are on the money and should be loving it!

[iht2670]

Yep agree with ET here......

No change in the speedo/ tacho relationship would only be he's not changed the speedo drive to mach he's new diff/tyre combo.

Yes this would be correct.

Steve.

[Big Red]

As the others have said above ... the rear LSD wil turn both wheels but the open front will only turn one wheel unless you have a diff lock.

there is two ratios of 4.6 that fit the rear H233B
4.625 out of GQ/GU and 4.636 out of Navara

also 4.625 out of MK in the H260 diff

[Bigrig]

As the others have said above ... the rear LSD wil turn both wheels but the open front will only turn one wheel unless you have a diff lock.

there is two ratios of 4.6 that fit the rear H233B
4.625 out of GQ/GU and 4.636 out of Navara

also 4.625 out of MK in the H260 diff

I thought all standard diffs were either 3.9:1 or 4.1:1 ??? Marks do 4.325's and 4.625's (or something close to those numbers) as aftermarket upgrades.

Not with you boss, bit I'm a simple critter, so let me know what path you mean as I'm a bit confused as the diff ratio wouldn't have much to do with the operation of the LSD (so I thought, and seriously happy to be wrong mate). Does the slowing of the wheels with the reduction ratio assist the LSD? I've thought about getting the diffs swapped, but not for that reason. Be interested to know more.

[Big Red]

the GQ and GU 2.8 Turbo Diesels both had 4.625 diff ratios

the GQ 3.0 petrol had a 4.3 ratio

not sure what you mean by your post, the diff ratios don't make any noticable difference to LSD operation.

If you jack the car up so wheels are off the ground, car in neutral, 2WD, front hubs locked in.

turn one of the rear wheels and the other rear wheel will turn the same direction with an LSD.
turn one of the front wheels and the other front wheel will probably turn backwards with tailshaft stopped due to the open diff ... stop the other wheel from turning and the tailshaft will turn at half the normal speed it would if it had an LSD

[Bigrig]

the GQ and GU 2.8 Turbo Diesels both had 4.625 diff ratios

the GQ 3.0 petrol had a 4.3 ratio

not sure what you mean by your post, the diff ratios don't make any noticable difference to LSD operation.

If you jack the car up so wheels are off the ground, car in neutral, 2WD, front hubs locked in.

turn one of the rear wheels and the other rear wheel will turn the same direction with an LSD.
turn one of the front wheels and the other front wheel will probably turn backwards with tailshaft stopped due to the open diff ... stop the other wheel from turning and the tailshaft will turn at half the normal speed it would if it had an LSD

Sorry boss - I thought you were suggesting that the diff ratios made a difference to the LSD - not the case obviously. All good!!

That said, I still was not aware of standard patrols coming out with anything greater than a 4.1 to 1 diff ratio .. That was news to me, and no doubt, others. 4.625 is a huge diff ratio and the first I've heard of possible candidates for swapping out mine rather than buying gears from Marks. I'll be sussing that out more as I'm thinking of swapping mine out for 4.3's at least to get some oommmfff off the mark after having installed 33" tyres and the new turbo ...

Thanks for the info, and something for me to follow up on to hopefully avoid spending too many $$$ on after market gear ...

[Big Red]

if you want 4.3's ... check the 3.0 turbo diesel GU's as well ... some of them had the H233B small diff with 4.3 and they would be more common.

just check the plate and look for HG43 [this is my wagon with HG39 diffs, it has 3.9 ratios

HG = H233B diff small one]
HH= H260 diff [big one]

39 = 3.9 ratio
41 = 4.1
43 = 4.3
46 = 4.6

http://www.nissanpatrol.com.au/forums/images/imported/2012/02/44.jpg

[Big Red]

just for interest sake ... this is the plate on my MK

it has the 4.6 ratio H260 big rear diff

http://www.nissanpatrol.com.au/forums/images/imported/2012/02/45.jpg

[Bigrig]

if you want 4.3's ... check the 3.0 turbo diesel GU's as well ... some of them had the H233B small diff with 4.3 and they would be more common.

just check the plate and look for HG43 [this is my wagon with HG39 diffs, it has 3.9 ratios

HG = H233B diff small one]
HH= H260 diff [big one]

39 = 3.9 ratio
41 = 4.1
43 = 4.3
46 = 4.6

http://www.nissanpatrol.com.au/forums/images/imported/2012/02/44.jpg

Thanks mate - I will be doing just that - perfect timing too as it saves looking into after market gears that are somewhat pricey!!!

[patrolone]

Thanks mate - I will be doing just that - perfect timing too as it saves looking into after market gears that are somewhat pricey!!!

Hi,
I took this photo this morning.
It's a '96 gq y60 rd28t but I don't find the reference you talked about almost a year ago.
Anyway according to the informations I got mine gq has h233b front and rear with 4,625 ratio.

Agree?

Thanks
Andrea

[patrolone]

I forgot to post the photo.

[patrolone]

nobody know?