Drive Train Gearing Bible

[rodw]

Rod, Im not sure your table on VMN site is correct. It shows no change in RPM with manual diesel betwen stock and 3.7gears ? ? The table linked in the post by mmaaxx, http://www.4wheelparts.com/aux_incl/gear_ratio.html I thnk is correct. Therefore the 3.9 gears are the closest match.

So I need to find 3.9 CW and P gears from a current prado for the rear and a complete front diff assembly with 3.9 gears, or 3.9 gears and buy an ARB air locker for a Prado front. Is that correct ?

Andrew

Yes I agree with you. My table must be wrong for the Manual. I must have missed changing one formula.

Yes, the ARB front locker part number is listed in the first post and there is also a link to the ARB catalog. It lists the same part numbers for both the Prado 120 (8" gears") and the Hilux. You need the ARB RD111 for the front fr the 3.909 and 4.1 diff.

Try ringing Dennis Smith at http://www.hiluxwreckers.com.au He has not got one but he said he found a couple that were too far away for me (so might be close to you). Tell him you have been talking to Rod Webster. You now have the photos to ID the diff before you buy in my other sticky thread.

[Lancair]

I've just been quoted $1053 for front and $1053 for rear diff gears from Toyota. That's for the 3.9 set. By the time you add in $360 for the carrier or $???? for an ARB locker it works out a bloody expensive exercise. Now thinking that some 2nd hand 4.1 gears are looking good.

[GreenHilux Guy]

Check out loktup on the net. They seel Hilux front and rear gears in a 4.56 and a 4.8 I think from memory.

Im getting aset to suit my hilux lockers in the auto diesel.

they are about $400 for each end

[Hilux Max]

You can get them cheaper if you contact Just Diff in the US and get them from there direct......

http://www.justdifferentials.com/index.php?main_page=index&cPath=22_37_484&zenid=584fbfdfd45e7fb661bf995c86becc79

4.56:1 is 300 bux US and the 4.88's are 250 bux US

Note, as written in the Drivetrain Bible, the 4.56:1 fits tha factory 3.7 and below carrier on the front, the 4.8:1 requires the Prado120 front diff carrier.

I doubt that anybody would need the 4.88's unless running atleast 34'ish inch tyres and has an auto.

[Lancair]

Yeah thats fine, if your running super huge tyres. I dont plan on running anything bigger than the 32's I have on now. I also dont want to be sitting on the rev limiter at 110km/h in 5th gear
Thats why I said maybe the 4.1 set is viable, a small increase in rpm at cruise speeds but a lot cheaper to set up.

Andrew

[Hilux Max]

I agree.......

[GreenHilux Guy]

Agreed,

but thats the boat I am in with 34's going on with an auto with prepurchesd stock hilux lockers.

I think that just differential deals in replica Chinese lockers but don't quote me on that, thats ARB talk. So they might be making average gears as well for that kind of money.

[Lancair]

Just found out that the Prado 120 series, 6 speed manual TD has the 3.909 diffs. I think that model is one of the newer versions of the 120 Prado so they may be like finding hens teeth.

[Bull]

I've struck a problem (actually my diff rebuilder has struck a problem).
I want to change my front diff to 4.88 and install an Eaton Trutrac.
My car is diesel/auto so comes with the 3727:1 ratio.

We're told that the carrier needed for 4.88 is different to the factory carrier which can only support up to 4.56:1 ratios.
I purchased the Trutrac some time ago in preparation for this but left the gears purchase up to the diff workshop.
The workshop has finally got my car but now they tell me they're having trouble sourcing the gears so I called Locktup to order theirs and they were very helpful. They couldn't tell me what the difference was between the two carriers exactly so they contacted their suppliers to find out.
Apparantly the difference is in the deck height.

So now I need to order another Trutrac from Locked Drive Systems to suit the Prado.
Question is, exactly which Prado?
Because I'll need to tell them exactly which model.

[Bull]

Eaton doesn't make the Trutac for any model Prado so now I'm really screwed.

Does the current Hilux still have the previous models' 7.5" front crown wheel?

So, do I run 4.56 gears and keep the Trutrac or buy the 4.88s and a Prado selectable locker?

WTF didn't I just SAS it to start with?
Couldn't possibly have taken any longer.

[McSumWay]

Current Hilux and Prado have a 8" crown wheel.

[Bull]

Well now I'm starting to question their knowledge.
They told me today they only have 2 models for the Hilux front, 8" live axle and 7.5" IFS.
Nothing listed for any model Prado because "they don't sell Prado's in the USA so Eaton doesn't bother with them".
I thought if I dealt direct with the Aust. agent I would get the right product.......


Can anyone tell me what part no. Trutrac I need?
The one I have is a 911A342

[Hilux Max]

bull, get them to give you the part to suit the front of an FJ CRUISE or current tacoma.

its the same as the prado.

also, locktup deal with just diffs in the usa, contact them yourself direct and save some cash.

the prado120 carrier you need is for 3.9:1 gears and higher, including 4.88 which lockdup sell.

thry also sell a "thick cut" 4.56 gears to suit the 3.7:1 factory hilux carrier so you dont need to replace it to run the lockdup items.

[Bull]

Thanks Max, but I doubt Just Diffs has much knowledge on whats under our Hilux?
I'd like to pursue these 4.88s if I can. 4.56 will be a last resort.

After much searching I found this-: http://www.eaton.com/ecm/groups/public/ ... 128302.pdf
which adds to my confusion as it lists the FJ alongside the Landcruiser. As in same part no.
That can't be right can it?
Is the 8" front diff in the post-1990 Landcruiser the same as an FJ Cruiser/Forerunner?

Can anyone confirm that our Hilux front diff has 4 pinions (instead of 2)?
And also that the axles are 30 spline (instead of 27)?
Or at least tell me who I can ring that knows this stuff inside-out?

[Hilux Max]

current hilux has 30 splines and is an 8" clam shell front diff.....post 1990 landcruisers had an 8" front diff too but totaly different.

just diffs would know, they sell those kits internationally for hilux owners and they ARE the same front diffs as taco's and fj cruisers except the carrier on the hilux is different because we run 3.7 gear whilst they run 3.9 or 4.1 depending on drivetrain package.


you 4.88's will be fine for the hilux, the rear is a bolt on fit as its the same as previous gen hilux rear diffs, the front you will need either a Prado 120 carrier or a front diff locker (that the C & P gears bolt on to) to suit the Prado 120 (because they came with 3.9 gears and higher)

in regards to the eaton pdf file you are reading it incorrectly......

there is NO front listing for the FJ only a rear which is part no - 913A610
and this is listed on its own....even thou on that chart it is "grouped" with the landcruisers that is only because the FJ is technically called a " landcruiser FJ" the same as a "landcruiser Prado" is.

hope that helps you clear things up...there is only one option/item listed for your hilux there and its the rear with the part number listed above.

[Bull]

I've sent Just Diffs an email so I'll wait and see what they come up with.

They list a Trutrac for LC front but not for FJ/Taco/Hilux.

[Hilux Max]

I've sent Just Diffs an email so I'll wait and see what they come up with.

They list a Trutrac for LC front but not for FJ/Taco/Hilux.

correct, only a selectable locker works on our front ends like an ARB for example.

[rodw]

Bull, my understanding is that for the 3.909 and up you need the Prado 120 dif carrier (with the exception of the JD's 4.556 thick cut gears). By buying the ARB diff lock, you don't need a carrier as the locker replaces the carrier with it's own.

I have a Prado 120 diff centre (carrier) here that I could ship up to you. The reason for this is that I purchased a Prado 120 front diff and stuck an ARB locker in. Send me a PM/email if you want it, make an offer.. That should allow you to fit up the 4.88 crown wheel and pinion.... Max can confirm.

The problem you have is that the SR does not have ADD or freewheeling hubs so the locker will be engaged all the time. That is probably why there is no Truetrac listing so you may have to run the ARB one. ARB Part number is in the Drive Train bible (RD111 from memory), but check the bible or the ARB catalog linked on the bible.

[Hilux Max]

i confirm....what he said x2!

[Bull]

Thanks for the offer Rod, and Max for clarifying things.

I spoke with my workshop this afternoon and made sure they understood that even though the 4.88 will not fit on the stock carrier, all was not lost and to go ahead and start on the rear.
Then I rang my old mate at ARB Townsville and ordered an air-locker. So now I get to see the dramas that I've been hearing about for years with leaking o-rings and ripped out airlines.
I would have preferred to try a Pro-Locker but they're still not ready.
Needing to change carriers anyway, choosing a locker over an open Prado carrier was a no-brainer.

Perhaps the Drive Train Bible could be edited to reflect that, at this time, the only available traction aids for our Hilux front diff is the ARB Air-Locker and various auto-lockers. That's it.
Oh, and clean up all this chit-chat.