Broken Rear Half-Shaft

[Paul_Driver]

Well I've got a replacement half shaft from Stef, but it is slightly different from the broken one and doesn't seem to fit.

They are the same length and I'm pretty sure it's from an 80, but there appear to be two differences.

1. The grooved area that fits into the diff is shorter; instead of being about 4", it is nearer 2"

2. The bolt holes look like they take cone washers, but mine are flat.

Also when I insert the shaft into the axle it won't engage the with diff. It should click in easily shouldn't it? Or is there a knack to it?

 

[Chris]

Paul, I can't answer all of that, but in terms of there being a knack, I think you;ll find that there is something to do with the diff lock. I know that Jon can tell you the full story, but I believe that it needs to be locked first or it won't go in. IIRC you must lock the diff before you take the shaft out.

That's all I can tell you mate.

Chris

 

[BobMurphy]

IIRC you must lock the diff before you take the shaft out.
Chris

Is the broken half shaft on the same side of the diff as the diff locker ?? (I didn't see any reference to 'side' in this thread, but I may have missed it).

If it isn't, then I'm guessing the diff lock won't be an issue (I don't know much about 80s ).

Are the splines the same (spacing) on the old & new shafts ?? I know LandRovers changed the splines during their development and wondered if Toyota had done the same.

Bob.

 

[Jon Wildsmith]

I assumed from the picture that we were looking at the long (passenger) side shaft but maybe the camera has played tricks on me? No need to mess with the locker on the long side but on the short (drivers) side you'd have been advised to engage the difflock before removing the shaft.

I think if you look closer at yours Paul there will either be cone washers or something wrong with it as there should be cone washers.

When the shaft reaches the diff it is usually a bit low especialy doing the long side and needs the inner end raising for it to engage and you may also need to rotate it very slightly for the splines to align.

 

[callum]

Sounds like you've been sent a shaft from an axle without a locker. Shafts from axles lockers have a longer spline on one side.

 

[Paul_Driver]

He's sent me an import

Jon, I didn't lock the diff and to be honest it didn't even cross my mind - it doesn't work anyway!

As I look down the axle with a torch, I can see that there is a pin across the tube, in the vicinity of the diff. Is this what is preventing me from getting the half-shaft to engage?

If so is there an easy workaround?

Definitely not cone washers, nor any way to use them. The washer and the bolt holes are flat.

 

[Jon Wildsmith]

Are you saying the shaft you've been sent can't take cone washers, that's what it sounds like but that isn't what you said up above?

Are you working on the drivers side or the passenger side?

The diff centre has pinions in it, so you'll see a pin in the middle of the diff.

If you're working on the short (drivers) side then you need the longer splines, end of.

 

[Roger Fairclough]

The fully floating rear hubs on the 80 series must be set up with a pre-load. This effectively means that the hub unit is in a state of tension and there will not be any movement at the wheel rim.

If the hub is loose the half shaft will be constantly bent, straightened and then bent again as the shaft rotates and the vehicle moves. The faster you drive, the faster the period of bending and straightening. This will induce fatigue cracks in the metal, localised heating and eventual failure. Toyota do not make bearings. They buy them in from a reputable supplier like Koyo. Other makers, such as Timken, are as good if not better.

The hub must be removed and ckecked for damage. If OK, re-fit and set the pre-load as per spec. When done, I suggest a dial gauge to check the hub flange is running true would be a good idea.

Roger

 

[Paul_Driver]

Yes Jon, I'm working on the drivers side and Stef is sending another half-shaft.

Having taken a closer look, you are right about cone washers. Mine we still in place afterall.

Roger, thanks for the advice but I must confess to not really understanding it.

 

[frank rabbets]

Just forget about the cause and build everything up with new bits and as per manual and it will be fine. Like my friend with wrecked E type engine with brocken inlet valve...impossible as they do not trail open like an exhaust valve and don't get hot or hit by a piston. No wear or seizure in the guide or valve stem etc. Just one of those things. Tempting and satisfying to find a cause but when I've done one mental circuit I give up now.

With regard to the location of the wheel bearing if it is centred in the mid plane of the wheel the weight of the car should keep the bearing vertical even with wear [yes/no?] unless you had spacers on or were cornering on a track.

I've had loads of brocken half shafts for no apparent reason with rear drive cars. They used to break off at the splined end . In the good old days the splines were cut very deep.Unfortunately all stressed metal breaks in the end.

Frank

 

[Dave Docwra]

Just forget about the cause and build everything up with new bits and as per manual and it will be fine. Like my friend with wrecked E type engine with brocken inlet valve...impossible as they do not trail open like an exhaust valve and don't get hot or hit by a piston. No wear or seizure in the guide or valve stem etc. Just one of those things.

Frank

Sorry I do not understand this quote..

 

[Ecoman]

Sorry Frank but I don't agree with your statement. A conscientious mechanic will always try and find a cause for failure of a key component. In leymans terms its called preventative maintainance or doing the job properly. Its a bit like changing a brake disc without fitting new pads or only changing one shock absorber. I had a Landy once that had been repaired by a right cowboy and when he replaced a broken half shaft he left big chunks of metal in the axle tube. This ended up causing damage to the new shaft and casing. I ended up needing a complete axle rebuild with a new case. If the job had been done properly the first time I would not have had to spend half my holiday in a hire car and ended up cutting the trip short as the cost of repairs wiped out my spending money. It saves time and expense in the long run. Also if the axle tube has the same grooves as the broken shaft then it could also fail so investigation into its condition also needs to be carried out.

Just my twa penneth

 

[Rob]

Like my friend with wrecked E type engine with brocken inlet valve...impossible as they do not trail open like an exhaust valve and don't get hot or hit by a piston. No wear or seizure in the guide or valve stem etc. Just one of those things. Tempting and satisfying to find a cause but when I've done one mental circuit I give up now.

Clearly it is possible as the valve broke. Also you should Google material fatigue

 

[frank rabbets]

Hi; What a fuss!
Dave
I always try and find out what went wrong. In 1963 I was forced to work on cars because they kept breaking but I had to get to work. My point was that whenyou stratr going round in circles it's time to move on.

Eco
What part of the quote didn't you get? How a valve train works or that the whole thing was jusu off topic.

I had a Morriss Minor. the crankshaft broke. No point in trying to solve that , it just got tired. Every weekend was a constant maintainance battle. We take it for granted now that nothing mechanical breaks;it's always electrical. I'm afraid the good old days are not yet gone.

Re; the halfshaft design. Surely with a flange on the halfshaft it is designed strong enough to keep the wheel upright. that is what I was tought. If you were to tow the LC around for 50,000 miles without the halfshaft in the bearings would fail? Any thoughts?

Frank

 

[Dave Docwra]

Hi Frank, when I start going round in circles with a problem, I try to seek advice as I clearly do not understand the fault or what caused it.

Plenty of mechanical failures still going on in the motor trade, just most of them can not be repaired any longer.

Morris Minor was that a three bearing crank shaft.

I feel very lucky that I was never forced to work on vehicles.

I am sure if you protected the bearings from the elements, i.e fitted the cut of flange back onto the hub you could tow it around for well in excess of 50,000 miles, at the end of the day I believe the
rear bearings are the same part as the front wheel bearings, if you think about running it with bearings out of adjustment it would cause the shaft to flex constantly until it got to the point where
fatigue would play its part & it would break.

 

[Rob]

Re; the halfshaft design. Surely with a flange on the halfshaft it is designed strong enough to keep the wheel upright. that is what I was tought. If you were to tow the LC around for 50,000 miles without the halfshaft in the bearings would fail? Any thoughts?

The reason Mr T. put a flange on the end of the shaft is to reduce the amount of components, in order to reduce machining and assembly costs (no drive flange means no splines on the end of the shaft). If the flange was used to keep the wheel upright then you would need a bearing on the output end around the shaft itself, so it does not rub against the axle casing. I understand that the semi floating axle has that arrangement and in that case the hub and the drive flange are essentially the same thing to keep the wheel perpendicular to the shaft.

I don't think we are going around in circles, most of us agree that it was the wheel bearings whether it was wear or incorrect preload.

 

[frank rabbets]

OK

I think the preload is to prevent rear wheel steering? Is that correct?

Frank

 

[Rob]

Yeah you could put it that way

 

[frank rabbets]

The Morris was a 998cc 3 bearing crank. Car was 1956 split screen. I was fed up with 803cc engine big ends going so I bought a 998cc. I already had a 3 inch diameter aircraft oil pressure gauge fitted due to paranoia. On installing the engine with a 998 gearbox and differential I confidently set out on my epic 1967 expediton from Cheltenham...............to Manchester.
Half way there a feeling of superiority gradually established itself whilst I smiled at my rock steady oil gauge reading a healthy 65 psi. To my horror and in front of my eyes the gauge dropped to 0 psi. I decided to get as far back home as possible hoping not to have to push the car far. No breakdown cover for pansies in those days. Men were men and girls were men. Much to my amazement I got home!! Anyway the crank had brocken clean across the front web at right angles and was turning the timing chain as if nothing was wrong. I was tempted to put the sump back on and run it like that but bought a Gold Seal half engine from BMC. Delivered by a BMC parts van. I think the cost was £14 part ex. They took a cheque!! Back on the road in 5 days.

Frank

 

[Roger Fairclough]

Yes Jon, I'm working on the drivers side and Stef is sending another half-shaft.

Having taken a closer look, you are right about cone washers. Mine we still in place afterall.

Roger, thanks for the advice but I must confess to not really understanding it.

If you bend a straightened out paper clip it will quickly heat up at the bend. This is caused by the metal being crushed on one face and stretched on the opposite side. Eventually the clip will snap. This is a fatigue fracture. This is what happened to your half shaft, except it was being bent by the shaft being out off alignment. Because the bearings were loose and the flanged end is fixed to the wheel, any movement of the wheel as it goes round a bend creates a bending force on the shaft. This it is not designed to accept. End result is that the shaft suffers fatigue and fractures.

Roger