Fact or Myth

Steve, you say 'with the exception of the 78 /79 series gearbox'. I'm led to believe the problem with these models was in vehicles built pre Sept 2003.
I have no personal knowledge on this, but I am very interested in getting the 'real' facts. As I have posted on another thread (thanks for your response on that thread - great rig your parents have), I am considering a 79 Series as a replacement for my Hilux.

Can you or anyone else confirm that, if there was a gearbox problem in the 79 Series, it was resloved for vehicles built after Sept 2003.

Mate had the 100 diesel and did the gearbox 3 times, once was Toyota dealers fault.

Steve,
I know many people who have broken front diffs, and occasionally rears and some of them two or three times. Most have happened in the High Country. Its a different sort of 4wding than the Top End. Lots of steep climbs, lifting and dropping wheels etc - spinning wheels and they drop and the diff goes crunch.

And like you say, the other LandCruiser boxes - H55F and H150F were better than the R151F that you've had the dramas with. Interestingly enough, the Prado owners don't have issues with this box. Lighter vehicle and doesn't get power upgrades like 1Hz.

I have driven nothing except cruisers (toooo many to count) for the last 7 years some which never saw a bitumen road.
I have had a cracked rear diff housing on my 75 camper and a cracked front housing (I think they werent spcific) on a 99 79 series
No g box, diff ot TC failures that I saw first hand

Steve ,

A member , Richard H , was telling me that he smashed his front diff the other day on his 100 TD . He was going up a steep track , a front wheel lifted and then came down and bingo .

He is getting a new diff and a front difflock to ease the problem in the future .

Cheers ,

Willie .

Steve I had no serious driveline problems at all with my 1989 diesel Troopcarrier or 1991 diesel 80 series despite carrying heavy loads on remote ouback trips, towing big trailers & giving them a flogging up the high country on plenty of low 1st hills. (A few competitions included) Only exception was the troopy's seal between gearbox & transfer leaked pumping gear oil accross & I believe some early 80's had the syncro upgraded as it grated 1st to 2nd.
The main problems started with my 2000 diesel 105 series. 4 blown front diffs over a 60,000km period! All done in low 1st going forwards, no more than 2000 revs with a heavily loaded vehicle & over sized tyres (285's). Usual deal is lifting a front wheel over a rock ledge, wheel spins then diff breaks as it suddenly regains traction. With my model there is no doubt the front diff is weak as each was replaced under warrenty no questions asked. Dealer said it wasn't common but apprentice said he had seen 6 others in their workshop that year! Know of 3 others 1st hand blowing them in similar circumstances.
Although the diffs strength is pretty border line they can be upgraded with an ARB locker and when set up correctly not have any issues. Most repeat breakages IMHO are from poor dealer fitment.
Cheers Craig............

I know of a few FRONT WHEEL DRIVE 78/79's around these parts - usually with a trubo upgrade as well......
I think something to do with the 10ton of "gooseneck" boom spray hanging of the 5th wheel on the tray :-)

Sort of goes like this - booting down the paddock, do a cloverleaf turn and head up hill accelerating hard - instant FWD cruiser! LOL!

A popular 4WD mag that comes out monthly was doing a comparison with other models and blew a front diff on an IFS during a test a coupla years back.
I was under the impression that the IFS was the one to watch RE blowing diffs, especially when in reverse.


Shane

Steve, I have a 2000 Solid front axle and I did mine in a few years ago. I was coming down a steep hill in low first and hit a large rock which blew the front tyre causing the rock to pick up and am into the base of the front guard behind the wheel. With low engaged, the jambed rock is stopping the wheel from turning and I'm driving against it. Peeled off several teeth off the crown wheel. Fortunately, the insurance company paid for the damages.
I also know of one of our club members with a 2004 IFS did his front diff during some training. He first noticed the "noise" coming down a sand dune. It could have happened earlier possibly.

steve
mate in 100 rigid front did front diff twice-nothing spectacular just manouvering on incline to be able to tow another vehicle-vehicle has seen plenty of off road action in vic high country and driver certainly didnt give the vehicle any favours if you no what i mean.
i have 100td ifs and notice when on bitumen,and an incline and turning left i get wheelskip from front when accelerating from standing start-to me this is major potential for breaking front diff-never occurred in 80 series
cheers

fozzy

Hi Steve, I have driven Tojos from FJ45s,HJ 47s & HZJ75s over the last 30 years clocking up over 600,000km & never had problems with diffs both front & rear. In the early model Tojos the only problem I had with transmission was the layshaft idler bearing going in the transferbox due to the chrome face hardening on the shaft wearing away. Never a problem with the gearbox end.
Since I bought the 75 series Troopy the only problem I have had was a similar case as with the earlier model & the 5th gear output shaft seal allowing oil to transfer into the gearbox. I changed the gearbox/transferbox 150,000km ago & replaced it with one out of a 100 series (98 model) & have never had a problem. I run Castrol VMX-M 80W gear oil & do a gearbox/transfer-diff oil change every 25,000km

Steve...(didn't think much of Jabiru...lol) but I blew my R151f gear box some years ago...about 100k.....fifth gear and the connecting shaft BUT no problems with either front or rear diffs ( I get the serviced regularly and the oil is clean)...Toyota does a special on those boxes ( wonder why) and so I had a new gearbox and "beefed up output shaft" put in..about $3500 from memory for them both, labour and other parts extra...so far touch wood all O.K....BUT now I will not tow in fifth gear.

My son has done two front diffs on his 80 series..... and doing nothing particularly spectacular at the time.
And a mate of his has done a diff AND gearbox.
There is truth in it.

Hi Steve

Only seen one diff go , but also 3 CV joints in 78/79 (they go with a bang).

In two of cases it was muddy rutted track and a spining wheel which came down.

Track really didn't seem that hard , and I followed thru in Patrol ok.

These cars generally lack articulation and I think this contributes to and already marginal situation.

When a gear box fails ' while doing nothing in particular ' it is often the final result of a fatigue crack at the base of a gear tooth growing to the point where the tooth breaks off and general destruction follows . The fatigue crack can be started by normal stress at the base of a gear tooth being concentrated by a stress riser such as a machining fault giving rise to a microscopic sharp groove in what shoul be a smooth radius . If a gear is to light for the job , or overloaded, the likelyhood of a crack developing is multiplied . The crack will grow over a period of about 150 hours or more , depending on gear revs and the number of teeth on the gear wheel [ ie how many times the tooth is loaded ] . 150 hours multiplied by an average speed of 75 km/hr gives failure 11,250 km after the crack is started . While the crack is growing , the box will vibrate each time the weakening tooth flexes under load , and metal chips will be shed into the oil . Examination of chips in drained oil on a filter can be used to predict failure . Spectographic oil analysis and vibration monitoring is justified on more expensive or critical gearboxes .

Well I was getting towed along a track by an 80 series and the front diff on it broke, a tooth or two off the crown wheel. Still kept going just no front drive. He was on 285's with the small yota pumpkins and me on 265's with the big Nissan pumpkins I was bound to get stuck. I believe wazza has more info.