Series 3 how often does your rear transfer axel (shaft) brakes or twists?

Thanks a million times for your replies.
However since the mechanic has his heart set on charging me a full day's work for taking the front diff out and counting the gears I really appreciate if one of you explained step by step what to do. The explanation went over my own head and can not explain it clearly enough for this dimwit mechanic.
really appreciate your knowledge (to the tune of 9 hours of my mechanic's fee )

If you drove it with different ratio diffs in 4 wheel drive the truck would jump about like a dog with the meanest flea in the west. I know this because we mistakenly put the wrong diff in a mates trials truck last year .
There is no need to remove the front to know what ratio it is. Print off the count the turns explanation above to show him ?

Jack one wheel up, high range, neutral, FWH locked (if you have them. Paint mark on the prop. Turn the wheel and coun't EXACTLY how many turns the prop does. It will half the amount with both wheels turning because of the diff. Do front and back. Use the ratios in the posts above and also note that it is more accurate to turn it more times (again eg 10 as above).
If your problem is mis-matched diffs then you should never ahve a problem unless you drive in 4WD. Is there any relashionship between the breakages and using FWD or low range? If you put the yellow knob down in high range does it come back up when you change to low range and back to high? This "should" show its coming out of 4WD, if the yellow knob stays down there's a good chance its stuck in 4wd which also overloads the half shafts

If you have missmatched front/rear diff ratios you have been lucky to only break halfshafts. It usually buggers up the gearbox.....

Well I had problems with rear dif. In fact in 6 years I have changed 3 although they were all used (could not find new locally). This time also it had developed a lot of play (loose smaller gear). May be we have finally found out why. I will try it tomorrow. Thanks everybody for your advice especially for the method to test.

That's a lot of diffs to get through, someone mentioned earlier about checking if the axle case is straight, probably worth a look.

Which end is twisting diff or hub? Is it always the same end?
If hub end what are the splines like in the flanges?

Up to now I don't think anyone has asked if you use the parking/handbrake correctly. Never apply it if the vehicle is still moving even slightly, there is an awful lot of torque generated from the road wheel. My MOT test station always use the old Tapley meter when testing 4x4 vehicles.

I know you are right, but I still managed to drive 2 miles with mine on, the smell made me realise something was wrong!

Driving from stop with handbrake on will only load the engine applying it whilst driving will shock load the half shafts due to the momentum of the vehicle.

rob1miles said:

I know you are right, but I still managed to drive 2 miles with mine on, the smell made me realise something was wrong!

Click to expand...

I did this twice in a day and prob much further than 2 mile , thought the clutch was burning out , now need to sort the handbrake for mot!

Blackburn as far as my memory serves it is usually the longer shaft and the thing just twists almost 90 degrees in the middle of grooves at the end.

Thanks for your replies. I tried the suggested counting test three times with front driver tire jacked up, neutral, locked and high range (red knob pushed forward). For exactly 10 turn of that tire the prop rotated 23.5 times. So this must indicate a 47-10 gear ratio (meaning 4:7:1) Is that correct ? If yes then the back diff we installed is correct.
Still the mystery of why so many twisted shafts remains. It must be poor quality of metal used and my driving.