LC Front diffs!

We saw one gettin towed into Woods Point by a rusty old MK about ~2yrs ago..

The front end was banging badly as it went past, but why he didnt just remove the front driveshaft is beyond me.

Dude was just 'doing a firetrail' according to the owner when we asked on UHF... But that could mean anything to different people.

Lots had issues originally with lockers causing problems..

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"But in general bush usage, is one likely to blow a front diff? "

You SHOULD be ok, but then anything can happen, you could have a Friday car and be a nightmare from day 1, or have a Wednesday car, and never have an issue.

luck of the draw

I have "heard" that the front diff is the same as a Hilux but with a reverse cut on the teeth of the crown wheel. the failures I have been told of occurred while be snatched in reverse.

Like most of these stories, I heard it from a bloke who met a bloke etc.

Bilbo,
As usual, Truckies right on the moolar......
I'd love to know why you went from a Nissan to a Toyota (not trying to be a smartass). I could understand it if your Nissan had been a Series II GU 3.0 litre jobbie. You'd be hard pressed to break the drive-train of a Nissan under most circumstances, but certainly from what you describe as your planned travels, you'd have been okay.
Is your 100 series the independant front suspension model or the beam axle (just curious as I don't believe one is necessarily STRONGER than the other, just that the beam axle has better articulation)?
I would reckon you SHOULD be okay, but don't stray too far from civilisation IMHO.
Good luck on your travels.

Guys,

Just to expand this topic slightly, I am led to understand that the front diff on the 120 Prado is the same as the 100 series. Can anyone confirm this? If this is the case then this thread has obviously got some possible implications for me as well.

Steven

Driven as they should be Bilbo I cant see a problem as there are thousands of them out there and only a couple on this forum blown up. Misuse would have to play a part there somewhere.

Most of the Yota's which break their diffs are ones which reverse under load. ie: trying to reverse back up a hill.
When you compare a Yota crown wheel with other 4x4s particularly Nissan and Pajero in the cross section (width) they do not have the meat in them compared to either. This is why you never hear of Patrols or Pajero's ever breaking crownwheel/pinion assemblies. CV joints? yes but never crown/pinion.
Whereas Yota's will shear teeth off the crownwheel.
Just be aware of what type of load you are putting on your front diff, particularly in reverse.
Regards Andrew.

I have questioned my local ARB store on the size of the front diff of the 100 series and was told that the live axle vehicles (105 series?) had the hilux rear diff and the IFS 100s had a smaller diff again. A member of our 4WD Club works for a diff/gearbox specialist and he says there is no shortage of work replacing 100 series front diffs, amongst other things.

I personally know of two that have blown front diffs - one was snatching in reverse in 4WD Low and the other was reversing a heavy caravan back up a slope in 4WD Low. I would not class either situation as extreme but reasonably routine and that's what the owners said as well.

Don't know about the Prado 120 front diffs but I am told that they have been beefed up after the problems with earlier models - the 90 series?

Larry

Gday everyone
The front diff in a 80/105 is the same size as a lux rear (or front for that matter)
The teeth on them are reverse cut and the pinion comes in on the top of the diff.
This means that the front lands of the teeth are cut straight and are driven on when going forward. The problem is when reversing, the back part of the teeth are cut at 45 deg, so transmitting power through them in reverse puts pressure on the gear teeth to move appart. Add to this that the weight of the cruiser is infront of the diff when reversing (as opposed to the rear diff reversing with the weight behind it) there is less chance of the front wheels breaking traction.
The design of the front hemisphere is not that helpful either, with two windows in it to put the gears in the middle and only one pin through the two sungears. If you put alot of pressure on the ring and pinion drive gears when one of those windows in the hemi is under them, there will be very little resistance to the teeth spreading appart. Putting an Air locker from ARB in there helps strengthern the setup because it has 4 pinions in the hemi and it is solid all round. This doesnt stop breakages however, just reduces them.
On outerlimits4x4 they talk about putting a GQ ctr in the 80 diff to get a strong setup....
Just be aware that if you need to reverse out of a tricky situation, use care, and resist putting the right foot down all the way, take a turfor
Andew

Thanks for the replies, guys. It seems that most diffs are blown as result of misuse. As Pesty says, If you use it as it was designed you shouldn't have a problem. But some are blown simply by trying to recover from a "situation" or reversing a van up a hill. The latter is not a good advert for the much vaunted Toyota Landcruiser. In a way, I'm happy that I kept my Ford Maverick ute for the rough stuff. But the Cruiser will carry me in comfort around "Oz" with odd offroad trip I suppose.

The other comments about "take a Tirfor with you", whilst they may be valid seem to speak volumes about the problem. If one can't reverse out of a "tricky" situation under the vehicles own power without worrying about bursting a diff, then it's a sad world. After all what's a 4WD for, if not for getting through (forwards or backwards) "tricky situations"?. Might as well buy a Commodore and a big Tirfor Hand Winch??

I wish Nissan would come out with 6 cylinder, turbo diesel that compares with the Cruiser. The TD42 is a great old engine but being an push rod motor, one can only do so much with it even with a turbo. Don't even mention 4 cylinder diesels, thanks.

Bilbo

Bilbo,

A friend of mine broke his and he really looks after it, treats it like a baby... Toyota replaced the whole front axle under warranty.

Another one broke while doing a stall start on a driver training session, basically it was pulling forward when he let it stall to simulate a real stall and it went bang...

None of the ones I know were the IFS ones.... Both were live axle petrol models

Will

Mines IFS, turbo diesel. I like Roachie's idea about the Chev diesel transplant - simple but lotsa grunt.

I know my old Mav ute like the back of my hand, and other to a major engine block type breakdown, I know I can get it going one way or another. The "electronics" on new motors like the Cruiser etc, really do worry me in a "far away bush" situation. Ah, well, I'm stuck with now and I've still got the Mav if all else fails. My missus wanted me to sell the old ute but that truck was my home for a long time and I'll keep it till it either rusts away or I'm dead. Other than that I'll give it to a museum to show what a real bush truck used to be like!

Bilbo

Oh what a feeling! Toyota!
The unbreakables , over two tonnes & fitted with a Hilux diff in front on the 80
and still cant get it right in the front with the later ones.
Diffs have been around for years & many with 2wd cars have had to back trailers & vans up a steep slope & done other unmentionables with them without trouble.
In 4wd you have the load spread over 2 axles so there is no excuse for breakages
unless they are horribly abused.