Diff Ratio TJ

[Trots]

I need some info regarding new ratios for my 02 tj, 4 inch on 33's, ARB front locker fitted no rear locker. Would 4:56 be the go? What is the effect on acceleration and fuel consumption? I have just moved to melbourne, who should I get to do the job?

[krankieone]

Talk to Tony(TW on forum) at USA 4X4

[Chief]

or we could get some answers on the board, so future generations can use the search feature and find the information they're looking for..

and also it might be relevent for other people who may be looking at upgrading diffs.

[Tropey]

I would go the 4.56. Your going to need a new carrier for the rear aswell so you may aswell put the locker in as they act as the carrier. You've already got the compressor so that saves you a little bit. And Tony at USA 4x4 is your go.

[Trots]

Thanks for the info, does anyone know about the fuel consumption?

[Tropey]

would be marginally better than stock ratios... at a guess I would say maybe 20-30km's per tank. But you have a bit more pick and go in the vehicle so suddenly your foot becomes heavier... then no more extra km's ;)

[Dan96XJ]

check to see if your front locker is compatible with new ratios, otherwise you may need a new one their too?

[Ben]

would be marginally better than stock ratio

Has anyone actually measured it? I've always wondered if the fact that you're rolling bigger tyres, you're lifted, you're heavier, etc all pretty much negates any fuel saving??

[Tropey]

Ben, I did a rough comparison (no science to it though) and over the first 4 or 5 tanks I got about an extra 20km. I then lost track of it all.

[Ando_13]

Assuming you have stock gearing ATM (3.07), you will need new carriers front and rear if you want to go 4.11 (if never going larger than 33's ever) and 4.56 (will suit you for 33s up to 35s). The stock carriers in the front do a split at 3.54 (somewhere near that on the front) and 3.73 (or thereabouts in the rear). Therefore both ends need new carrier, which in turn causes you to have to replace your fron ARB air locker as it acts as the carrier (as mentioned by Tropey for the rear) and thus has a different part no. to the ARB air locker required for the 4.11 or 4.56. Going to get expensive real fast!

I personally went for 4.56 with Air lockers front and rear (I'm still on 31s, cash drain from that set back plans by 2 yrs!!!), I did this so that I didn't have to go thru the process again, I simply wanted Air Lockers then realised the whole ration thing.

So you have a couple of choices:
a. just re-gear upto the maximum that your current carriers will handle
b. buy new carriers front and rear and buy a lockrite or similar locker, and install 4.11s or 4.56 (
c. go the whole hog and buy ARB air lockers front and rear that suit 4.11/4.56 ratio and throw in 4.11/4.56 into each pumpkin

I'd say that you would want to put in at least 4.11s, and obviously recommend 4.56 (as thats what I have), or if you plan going rediculously large tyres get 4.88s.

JMHO!

[Wooders]

LOl someone should ask what transmission does it have ;)

[Ando_13]

Yep great point Wooden One, my post refers to 5 Speed Manual, D30 front (3.07 stock), D44 rear (3.07 stock).

Forgot about the Auto trans having different ratios from stock, and don't know about the new 6 speed manual.

[Trots]

5 Speed manual, so it looks like Im up for a bit, Do you think it is worth it?

[Tropey]

Do you think it is worth it?
is a pig pink ??? (before it plays in the mud ;) )
you wont know your truck afterwards !!!

[Wooders]

As Ando said for a maximum of 33" tyres + 5spd man, i'd probably recommend 4.11.
Also the 4.11 is available in a thick set for you can keep the current LSD in the rear and save on lockers etc....but naturally if you go offroad heap you really should consider the lockers ;)

[Fud]

Personally I would go 4.56. Better acceleration, better decent control, better crawl ratio, less strain on clutch, gearbox, transfer case and driveshafts and it gives you the ability to upgrade to 35s down the track.

[JEEP1]

i agree with FUD

[ike]

ive been looking into doing this same mod... and have done my shopping around...... your looking at around $3500..... not a pretty figure i know...
im tryin 2 save up to do it. im also running 33s and am getin fed up with the gutless power

[Bear TJ]

What sort of RPM do they sit on @ 100km/h with 33" and 4.11's? And can you pull up hills in 5th OK? I think that's the setup I'd like to go with but would like to go for a drive in one first.

[Chad_TJ]

So does thick cut 4.11's mean that you dont need to replace the carriers front and rear?

[monte]

So does thick cut 4.11's mean that you dont need to replace the carriers front and rear?



You dont have to replace your rear,but you do have to make the holes in your existing carrier a little larger for the bigger bolts that the crown wheel takes.
It is the same rear crown and pinion (thick set) that the rubicon has as standard.

[MattW]

Before deciding what to buy from other peoples opinions see if you can take a couple of TJ's for a spin around the block with the different gearing and come up with your own opinion. You will be much happier with your choice then and be able to make a better informed decision.

[monte]

Also are you planing on towing a camper or a trailer,(extra weight)?.

[4b4fun]

I have just had 4.56 fitted to my TJ (02 manual on 33's) and it was the best mod i have had done. I was tossing up between 4.11 and 4.56 and glad of the choice of 4.56. Its awsome on the freeway and pulls up most hills in 5th. I think the lower ratios were betta suited to me because i have some heavy bar work and tend to carry alot of campgear quite often, and it pushes the weight much beta. I am not running lockers and have the thick cut gear in the back, with original LSD, and bought a new carrier for the front. All up with new seals and bearings including wheel bearings and including fitting the price was $3200...... I hope this is some help to you...

[Jeeps]

How do the RPM's sit at 100klm in 5th?

[4b4fun]

hard to tell cause i'm still waiting on a spedo gear but at 100k's it about 2500rpm.

[cj5350]

I second the 4.56 with 33's and 5 speed. Next set will be 4.88

[accept]

97 TJ manual had stock gears with 33's and f/r ARB lockers.
Changed to 4.88's and DID NOT need to change lockers/carriers as many people and businesses had told me.
also new gears (precision gear) were thicker ie. stronger than originals.
So you don't need to change carriers/lockers to go the bigger set.
And go 4.88 , you won't regret it and gives ability to change to bigger tyres in future
without changing expensive ratios again !
at 100km/h reads 2600rpm (speedo gear not changed yet tho)
Got gears thru suburban but could probably did up part numbers if you need $1300
and got fitted locally, with no problems or tricks for $1000
Hope this helps

[jammy jeep]

4.56's are excellent with 33's. The TJ drives like a 'normal' car on the highway and is excellent offroad. Best mod I ever did. Sits at 2500rpm at 110kms and uses around 16l/100kms, or just under. This is a 5spd manual.

[MR EXTREME JEEP]

97 TJ manual had stock gears with 33's and f/r ARB lockers.
Changed to 4.88's and DID NOT need to change lockers/carriers as many people and businesses had told me.
also new gears (precision gear) were thicker ie. stronger than originals.
So you don't need to change carriers/lockers to go the bigger set.
And go 4.88 , you won't regret it and gives ability to change to bigger tyres in future
without changing expensive ratios again !
at 100km/h reads 2600rpm (speedo gear not changed yet tho)
Got gears thru suburban but could probably did up part numbers if you need $1300
and got fitted locally, with no problems or tricks for $1000
Hope this helps

If I understand this correctly that goes against what everyone is saying on this thread. The carriers are good only up to certain gearing. When you go to a 4:11 or 4:56 you have to change your carriers, and lockers (if you have them)

[Wooders]

As Ando said for a maximum of 33" tyres + 5spd man, i'd probably recommend 4.11.
Also the 4.11 is available in a thick set for you can keep the current LSD in the rear and save on lockers etc....but naturally if you go offroad heap you really should consider the lockers

Ok I don't run 33"s myself - so I'll conceed the majority preference for 4.56....
But the thick set I meantion above is to retain the stock carrier/LSD.
HOWEVER I would NOT call then stocker than stock. The deeper the ratio (ie the higher the resultant number) the smaller the actual teeth......
3.07 is infact a fair bit strong than 4.1/4.56/4.88......I'll snap a comparison pic tonight for anyone that doubts me ;)

[Laz]

4.88's 5th gear 110 Klm 2900 rpm

Round town I get about 17 L/100 K's (had 16.2 a couple of times)

I tow between 85 & 95 klm using 4th & 5th, with a 16' Jayco weighing in at 1200 Kg's (yes it's legal to tow that much - ask Jammy if you need details) I get ~20L/100.

Given I never made it to 35" tyres and love my 32"mtr's I would have done 4.56's.. (but i can do STOOOPID stuff with my gearing - which btw seems pretty identical to a 3.0L TD patrol)

[accept]

Mr Extreme Jeep,

Correct. Everything people were telling me was wrong. Had lockers with original 3.07 gears and DID retain them when i went to 4.88 !! Opposite of what people and shops were telling we. So it is doable.

[MR EXTREME JEEP]

Jeez I bet there has been more than one person that has gone out and bought new lokkas when they have done ratios. Or like myself have not done a rear lokka cause I am waiting to do the ratios...

[Blackpearl]

Just saw my Jeep offroadin (on video)
and both front wheels are spinin.
there is contact on both wheels.
i thought the 65th only had single set up in front?
jeep is new and standard.
What ratios and diff types are in the 65th, :?:

[Wooders]

Mr Extreme Jeep,

Correct. Everything people were telling me was wrong. Had lockers with original 3.07 gears and DID retain them when i went to 4.88 !! Opposite of what people and shops were telling we. So it is doable.

Well really to be fair:
Thick gears are a relatively new addition to the market - go back a few years and they weren't available.
And it's also a matter of what available - As agents for Randy's R&P, I can get Thick ratios to 5.38 to suit a Dana44. But they don't currently have any thick gears past 3.73 for the Dana30.
Also in some instances spacers are used to allow the thin crown wheel to be used and unless notified otherwise you probably wouldn't even know.....Although it's not a good practise as the bolts are more prone to loosening.

[LEXX]

Mr Extreme Jeep,

Correct. Everything people were telling me was wrong. Had lockers with original 3.07 gears and DID retain them when i went to 4.88 !! Opposite of what people and shops were telling we. So it is doable.

What sort of lockers are you running, air or mechanical?

And yes it is doable but not advisable.

[accept]

Lexx,
ARB Air lockers.
Why would you say "doable but not advisable" ?????

Doing this way is exactly same as changing gears whenever you do it, except this way you get the thicker gearsets, bummer ! ha

(quietly..... or did you get caught out earlier and don't wanna admit it...shhh)

[MR EXTREME JEEP]

Ok So just to clear things up for people like me who like to keep things simple.
I can put a set of 4:56 ratios in my front D30 fit a lokka (arb air) and not change the carrier.? Wich would save me a feww hundred buckaroonies.

[sir_camel]

ARB locker acts as a carrier. SO yes. ARB in d30 will negate the need for a carrier.

[Wooders]

ARB Air lockers.
Doing this way is exactly same as changing gears whenever you do it, except this way you get the thicker gearsets, bummer ! ha


Perhaps I didn't make myself clear above - the "Thick" set gears offer SFA strength benefit over "Thin" sets. The teeth size and material determine the strength.
Also the main reason to run thiock gears is to retain the standard rear LSD - however if you are fitting an ARB locker anyway a thick set offers you nothing.
Lastly in some cases the thick gears are more expensive......but again this is offset if you don't need a new Lsd/locker.