Broken Rear Half-Shaft

[Paul_Driver]

It's been a while, hello everyone.

My rear half-shaft broke over the weekend and I thought I'd post a photo as it seems fairly exceptional to me. My thanks to Julian Voelcker of http://www.overland-cruisers.co.uk for talking me through the problem so far.

The break is so clean you could think it been cut with a fine tooth sawn. I should say also that when I got the truck jacked up, there was a slight amount of play in the wheel bearing, may be 1-2mm worth.

Of interest is that in there are grooves around shaft suggesting wear and heat, and Julian suggests that this might be down to the wheel bearing

Presumably the next challenge will be getting the rest of the half-shaft out. I guess I have to take the diff cover off try to push it out from there.

Any thoughts on a good procedure for this?

 

[karl webster]

If i remember right,the rear half shafts slide out quite easy.

I would have a look from the hole into the axle where the half shaft goes in. It may be hanging out anyway.

You may be able to get it out with some messing around.

Taking the diff out would allow you to make sure there isnt any bits in there etc etc.

Karl

 

[Paul_Driver]

And here's the other half. Julian suggested a strong telescopic magnet to remove it.

Again lots of wear

 

[Chris]

Rob might have a suggestion or two about the mechanism of failure there. Academic I know - the point is getting it fixed. But interesting nonetheless.

X-Eng make such a magnetic device for hapless LR owners who do this on a regular basis so it seems.

Chris

 

[BRE Fabrications LTD]

What were you doing when it broke?

 

[Chris]

Hopefully not about 70 mph!

Come on Ryan, you could weld that!

Chris

 

[Paul_Driver]

You know what, I wasn't doing a lot!

I had just had to winch out of a fairly steep stream crossing, which was a surprise to me as I know damn well that the truck has done harder things at Lincomb Farm.

When this happened I was on a bit of an incline, but nothing that it shouldn't have been able to breeze.

Does any body know what a replacement would cost? I was thinking of calling Sef tomorrow?

 

[Rob]

It is difficult to say what the failure mode of the shaft is without close up pics of the fracture surfaces, but one thing is clear the bearings definitely contributed/caused the failure. Play in the bearings could result in the half shaft rubbing against the stub axle bore which would generate a considerable amount of heat. It seems likely this happened in your case due to the marks on the half shaft, and because of this I would consider replacing the stub axle and beaings as well. You have no idea if the stub axle is still concentric (temperature related creep), or has enough material left on it (due to the shaft wearing it away). I would definitely replace the bearings seeing as they are relatively cheap.

Karl may have a shaft as well, so PM him as well.

 

[Mark Whiteside]

If the wheel bearing movement is only about 1-2mm
IMHO i think it is highly unlikely to cause this sort of thing
it is a rear half shaft so if i recall correctly there is no stub axle just a axle tube
What i can see from the pictures i can not see a lot of heat build up ie blueing
If you cant find a lot wrong with the bearings i would be looking farther afield
ie something broken up in the diff and travelled up the axle tube
My 2 cents worth

 

[Paul_Driver]

Interesting.

I drained the diff and there was no debris or swarf of any kind although the oil was pretty black if that means anything

 

[Jon Wildsmith]

was the 1-2mm wheel bearing play measured with the wheel on or at the bare hub?

 

[Paul_Driver]

Hi Jon, yes good question. I'm talking with the wheel on, right at the tread edge of the tyre. I'll double check the measurement tomorrow as I didn't use a ruler. Only to say that it was noticeable but pretty slight.

 

[Mark Whiteside]

Reading back through the posts now
Me thinks
Alot of wheel spin and the tyres got grip suddenly causing the shaft to break
And did you drive home like it? (which would explain the rub marks)
Or am i barking up the wrong tree

 

[Paul_Driver]

I was driving on the farm where I live, I did drive home but that only took 5 minutes.

You've got me thinking though and upon reflection, I did have a wheel bearing failure (same wheel) over a year ago and I drove home on that occasion, so that is most likely what did it. The mechanic that did the repair didn't mention anything about the half-shaft, so I can't say whether the damage occurred before the repair or after. He obviously didn't nip up the new wheel bearings properly either.

I'll put a new half-shaft in and drive it for a few weeks then take another look, to see if there is any return of the wearing.

 

[Rob]

If the wear marks were caused on the drive home I would expect there to be localised wear near the fracture surface like on the input side of the shaft above and none on the other part as oysters held in place by the hub. I can't see how you would get wear on both apart from if the shaft buckled before failure which would cause localised wear on.both. This is clearly not the case so that is why I recommend further investigation.

Mark, this is a fully floating axle which does have a removable stub axle. If it bearings did not cause this then the only other thing that could cause this is a bent axle casing or stub axle. Either way further investigation is needed. The blueing of the metal is only a surface reaction and if it was rubbing it would have wiped it off. Also its unlikely you will see discolouration on the unmachined sections of the shaft as the shaft was cast.

Paul, if the bearings were replaced last year, where cheap bearings used or Toyota bearings used? It is not uncommon for cheap bearings to fail that quickly, especially if they weren't tightened properly. That is why I would recheck the wheel play after the shaft was removed as the shaft could have been limiting wheel play if the stub axle has deformed.

Sent from my HTC Desrire using Tapatalk

 

[Jon Wildsmith]

I suspect you'll find the play in the wheel bearings and the state of them is worse than your initial checks suggested? Could that failure be a combination of fatigue and twist i.e. fatigued weakened due to severe wheel bearing play to the point where it simply twisted off. The shaft ends look a lot like the ends of sheared bolts to me

Did you remove the shaft end and then drive it some more before pulling the remainder of the shaft? There is an oil retainer ring at about the right depth to cause that scoring but as Rob points out why are both parts scored.

 

[Paul_Driver]

Thanks, this is all great advice.

I've ordered a half-shaft from Stef, so when it arrives I'll take the bearings out and have a good look over.

The bearing that was fitted last year was genuine Toyota. No I didn't remove the shaft end before driving home.

I'll post some close up pictures a bit later

 

[Mark Whiteside]

Rob
I know the front axle has a removable stub axle,but i did think the rear was a fixed tube
Maybe when i had mine apart i did not look hard enough
I know you are a mechanical engineer and could baffle me with tech stuff
But Over the years i have seen many bearing failures of all sorts
And i have seen various cast parts got hot and showing signs of blueing
Not saying always though

 

[Rob]

Mark, I was not attempting to baffle you with technical stuff I was only suggesting that if there is no discolouration you should not assume that there hasn't been any adverse heat build up. I see we both agree that this is the case. I have just checked on toyodiy and yes you are right, there is no separate stub axle and it is part of the axle casing itself. Even if there are no signs of discolouration one thing is clear, the half shaft was rubbing on the inside of the axle casing before it failed and I would expect the bore of the axle casing to look very similar to the shaft which warrants further investigation. If you just replace the bearings and shaft without checking the axle casing, it could fail at any time resulting in a 3 wheeled landcuirser

 

[Mark Whiteside]

As you said Rob
i also would advise further investigation