Loose nut in diff

[jleyton]

Whilst rebuilding my rear end I'm taking the opportunity to fit a reinforced extension housing, as recommended by many on here.

Having removed the old extension housing, I noticed that the nyloc not on the end of the pinion shaft - which I think should be tightened to 120 ft lbs ?? - was actually slightly loose

Has anyone else experienced this and is it just a case of fitting a new nyloc and tightening correctly ? I hadn't experienced any diff problems or noises.

The nut I'm referring to is part no 159394 and is the outermost item once the extension housing has been removed.

Any help or advice would be greatly appreciated

Cheers

Julian

GRID005262.jpg

[StagnJag]

Was it a standard nyloc or the proper shorter one? The standard ones are (If I remember correctly) a bit long so the nylon bit doesn't have a great deal to grip onto. The correct ones are wider and shorter, thus the specific part number. Could that be it? All my nuts were tight!

Regards

Dave

[Goldstar]

Hi Julian,

I'm pretty sure my nut is castellated with a split pin holding it in place but looking at your RB picture it should be a nylon. No help I'm afraid. How do you get the oil seal out that surrounds it?

[jleyton]

Thanks Guys,

I'm not sure if it's the correct one - I'll have a closer look in the morning although I think the shaft looked like it came all the way through the nut and the nylon.

I also remember reading about a castellated nut there, however I think, as is often the case, nylocs replaced castellated nuts, even on the production line.

Thanks again and any other thoughts will be most welcome.

Cheers

Julian

[4x4]

I am no diff expert - but I do know what the results were of the pinion gear on my front diff moving around.
For me, the inner race of one bearing slipped on the pinion gear, ripped up the spacing shims, and allowed the bearings to loose their preload.
Stuff then started moving around that shouldn't have - the pinion gear was literally wiggling around.
Result? Trashed gears - and a big bill for a one off crown wheel and pinion set.
Now - I had taper bearings on mine - which I don't think this has.
But - think what that loose nut allows to happen.
It can allow the pinion gear to move in and out (how much will depend on how good the bearings are, and how tight they fit on the pinion gear), completely wrecking the carefully set up backlash and clearance for the gears to work nicely.
If your nut was loose (painful?) and no noise/damage was the result - I would say you've been stupendously lucky.
Castle nut, or nyloc (make sure it is shallow enough that the nylon has something to grip) - get your nut properly tight and make sure it stays that way!

My diff was rebuilt by Autogear on Canvey Island - very helpful bunch if you need to ask anything..............

[sunnystag]

I recall, but could be wrong. castellated nut= early cars with shims. whereas Nyloc=mid and late cars with collapsable spacer

[jleyton]

Thanks all.

The castellated early - nyloc late does seem to make sense.

I too thought that I had been very lucky and I just hope that replacing the nut and torquing it properly (that's going to be fun getting to 120 ) doesn't alter my previously pretty quiet diff

Has anybody else experienced this ?

Cheers

Julian

[Mike Stevens]

I recall, but could be wrong. castellated nut= early cars with shims. whereas Nyloc=mid and late cars with collapsable spacer

Exactly what I was going to say. Pipped at the post yet again!

Julian, I'm not sure about just tightening to 120 ftlbs. I thought these were tightened against the collapsable spacer checking the pinion preload. Could you be confusing it with the one on the extension housing, under the prop flange? That is a straight tighten.

The scanned manual I have here at work does say 90 - 120 ftlbs, but that's for the slotted nut and the text talks about setting it for a specific torque to move the pinion.

Hmm.

Cheers,
Mike.

[jleyton]

Hi Mike,

Thanks for your thoughts and it's a good point about the collapsible spacer, although I really could do without going through that whole rigmarole

No, it's not the one in the extension housing. It was only after I'd removed the extension housing, complete with quill shaft and the nut you're describing, that I saw this loose nyloc. In fact, the nylon has had some effect as the nut hasn't come off - I wouldn't be surprised if just 1/4 or 1/2 a turn would get it back to it's correct torque - but then there's that question about the collapsible spacer. Drat !

Cheers

Julian

[Mike Stevens]

Hi Julian,

As you've not had problems, I'd be tempted to tighten it while checking the effort required to turn the pinion (CW as well I guess). Stop tightening when you can feel a difference. What you'll be doing is changing the height that the pinion sits in the crownwheel. I think. That mainly has an effect on noise.

It really ought to be tight. I wonder why it came loose?

The scanned manual doesn't mention the nyloc type, only the castellated one. However, I also have manuals for the saloons and they also had the 2 types. I'll see if they mention what to do with the nyloc type.

Cheers,
Mike.

[jleyton]

Thanks Mike,

I'm doing a load of work on the car at the moment so it's not urgent but I'll be interested to hear what you find.

I've got about four different manuals so I'll look through all of them sometime.

Cheers

Julian

[Goldstar]

Hi Julian, are you taking the oil seal out? Mine seems to be an older, metal bodied seal, any tips on easy removal?

Cheers

PAul

[jleyton]

Hi Paul,

I'm undecided at the moment. Although I'd say it's normally good practice to change oil seals, as I had no leak there I'm tempted to leave well alone.

Thus I haven't checked on the proper way to remove it but usually you can lever them out with a screwdriver or some sort of hooked tool - even the metal cased ones. In extreme cases I've deliberately distorted the metal casing to get them out.

Sorry I can't be more help.

Cheers

Julian

[Goldstar]

Thanks Julian, that is helpful and kind of reinforces what I was thinking - hammer it is!

Paul

[4x4]

Was just thinking (anybody smell smoke?).
Perhaps the bevelling on the gears kept it bedded in the right place.
But if you'd given it some stick in reverse for any reason and got the pinion gear on the move in its bearings, then you'd have been in trouble.

Give it a good tweak and cross your fingers.


Adrian.