Author Topic: Breaking axles.  (Read 2363 times)

Red Rocket

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Breaking axles.
« on: October 31, 2012, 09:50:58 AM »
I have made this a topic of its own because you all need to see it if you are going to use these trucks off road.
The actual engagement of the front-wheel drive, in low range, is the very last part of the backward stick movement
When driving over rough ground and especially down hill, front to rear movement of the engine/cab/transfer case causes the selector to disengage the front wheels.
This is not a problem if there is no great load on anything but, if you begin to climb or mount some obstacle, all the load will be only on the rear axle.
You should make it a habit to declutch momentarily and heave back on the Hi/Low lever before climbing or driving into a bog or going into any situation where thetractive load is going to increase.

I bought two Mk3 from the army that had axle breakages. One of them wouldn't go 100 metres without slipping out of 4WD and then out of low altogether. I bought it with one axle broken and both axles out. I fitted a new axle and the old unbroken axle and fixed the transfer case problem by swapping the winch drive shaft for the front-wheel-drive shaft. The old axle broke at the flange a few years later. Five years, thousands of kilometres of use on the  wildest tracks in Australia later, I found the broken off end of the original snapped axle, lying in the bottom of the diff housing! The crown-wheel had started contacting it and causing noises.
The other truck broke its old axle on the bitumen!

Since then, by employing the habit suggested above, no axles have been broken. I have insisted that my drivers religously do this and it has paid off.
You will never take your truck anywhere tougher than where mine have been.
Red Rocket.

Offline Mick_Marsh

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Re: Breaking axles.
« Reply #1 on: October 31, 2012, 12:49:01 PM »
REMLR # 310, MVCA # 364, 101 Club # 2188, MHG #101
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Offline Alien

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Re: Breaking axles.
« Reply #2 on: October 31, 2012, 06:19:47 PM »
Some interesting reading Red Rocket.
It's these little tricks we can all learn from.

I may be a little stupid, but I thought the air switch on the gear lever locks the front drive??  At least I'm sure it does on my truck.  (6BB1 Isuzu/Isuzu 5sp box)
I beleive the switch is to go from 2-High to 4-High.
My understanding is 4-Low is on the lever as described above.

Offline Bluebell One-eight

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Re: Breaking axles.
« Reply #3 on: December 14, 2012, 01:51:23 AM »
This is one of those traps for the unwary! There are two common causes. The first is that during a vehicle rebuild or replacement of the transfer the case has been replaced by one from a 6X6. This was esentially the same as the 4X4 but low range could be selected without front wheel drive. It was meant to disengage when the load came off the gears (lifting off throttle or declutching). That didn't always happen as the linkages got stiff with time. If this type of case is fitted then the trigger MUST be activated to engage front wheel drive. The second cause is that as the rocket pointed out the front drive only happens in the last bit of lever travel. The selector rod for low range has to bottom in its travel then the front drive linkage pivots at the fwd selector rod and moves the front drive dog into the engaged position. If the splines on the dog don't line up and it stays in 2wd but in low range, and the torque multiplication does the rest. Climb under the truck and have someone work the lever and you will see how it happens. The way to ensure front axle drive is engaged every time select low with the truck moving, it only needs to be roling slowly. It can be double declutched at speed but the ratio change is 2.5 :1 about double the difference between gears in the main box and that has to be alowed for.