Hi all. Today my rear n/s halfshaft decided it would like to leave. Fortunately caught it before it went.
Question is how could it leave? Shaft appears complete and seen worse splines. Currently trying to get into diff but being foiled by 3 bolts at moment.
Next question, what am I likely to find in there and how will I fix it?
Any helpful advice really appreciated, I can do engines but gearboxes and leccy are a scary mystery to me.

Did the flange bolts all come out ? It is unlikely there is anything to do in the diff its self as the shaft you say is good.

Yes, I've had this problem. The halfshaft floats outward until the splines are no longer engaged and you come to a stop, despite the speedo registering a healthy 100 mph. They come out because there's not much holding them in. When they decide to drift outwards they push the little plastic cap off and away they go. When brand new there's enough meat on them to provide a little bit of a shoulder just inside the drive flange so as to make this unlikely, but a little bit of wear means that, despite the splines looking OK-ish, they can come out a bit like that Aston Martin in Goldfinger. Unlike Goldfinger, in real life if they happen to hit anyone they're more likely to result in a lawsuit than any romantic interest, I'm afraid. I always use those aftermarket drive flanges with a screw on cap rather than the push on plastic one. That way you can put a bit of oil inside and help the splines last a bit longer too.

Oh, and I should mention that the diff is probably fine. Unless it's especially noisy or rough you don't really need to take it apart. It might appreciate a change of oil though, as this is a blind spot a lot of people have. I've changed axle oil on my own and friends' Land Rovers that looks as if it's been in there since the vehicle was new.

Thanks for that. Worried though that I can turn the shaft when its pushed right in. Will leave it in one piece for now and just renew the shaft to see how that goes.
Unless of course anyone has any other advice to give on the subject.

I suppose it's possible that the splines are worn out, but at the diff end they live in the same oil as the diff so don't really wear out. If the car's jacked up and the handbrake is off and the gearbox is in neutral, don't forget that the motion could be going anywhere. Another wheel could be turning, or it could be going up through the gearbox itself. If the splines are jumping, you'd usually feel it as being fairly notchy. Also don't forget, the halfshaft sometimes needs a bit of jigging around and rotating with gentle pressure to get it into the diff - are you sure it's fully seated?

Diff mechanisms can fail, of course, but they're usually fairly long lived unless you do a lot of competition driving with a highly tuned engine.

tottot said:

Did the flange bolts all come out ? It is unlikely there is anything to do in the diff its self as the shaft you say is good.

Click to expand...

Yup, Mr Dewalt wheeched them out with surprisingly little bother.