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MG Midget and Sprite Technical - Rear axle big nut torque

Anyone know what the torque setting is for the big nuts on the end of the midget axle.

Yes I know they should be FT, but anyone got a figure??

Colin
Colin Parkinson

140lbft according to the good book
mark 1500 on the road Preston Lancs

do you mean the nuts on the bearings or the pinion nut? Pinion nut is 140 lb ft but don't try to get the bearing nuts to that figure! I had to rig a securing bar to stop the innards turning when I wound the torque wrench up to 140!
David Cox

Ah, that old chestnut.

You ought to drop in more often - it's discussed at least a couple of times a year.

I can't remember if we've ever pinned it down to an exact figure, although the figure quoted for the MGB banjo axle is 180 lb/ft.
Dave O'Neill 2

from the good book in lbft


mark 1500 on the road Preston Lancs

Mark, that's the drive flange on the diff.
Dave O'Neill 2

Mark that isnt the one!!! I know the MGB is 180 and I have had special sockets made for that axle.

David 140 is probably the figure actually, and yes it is difficult to get it that tight!

Colin
Colin Parkinson

Colin, you were right first time, FT, which is about 8 white knuckles on a 2 foot breaker bar.

I'd be inclined to er on the side of what feels right for a big but thin nut with very fine threads on an axle at least 35 years old.
john payne

exactly John, needs to be qualified to 'not too FT'
David Smith

...although, the threads aren't that fine.
Dave O'Neill 2

Colin

Here's an interesting one - the MGA and 3-synchro MGB gearbox use the same nut on the first motion shaft bearing. Is there a torque figure specified for that?

Having said that, it probably wouldn't need to be as tight as a hub nut.
Dave O'Neill 2

When I replaced the pinion seal on my axle I ventured to buy a "new" nut.. fearing that the old one may in some way become damaged as I loosened it off from 140 lbft. In the end it was fine... and in fact I reused it. The "new" one seemed to be too thin, so held too few threads to be secure at said torque nor did it have a flatted face as the old one for binding snugly against the pinion. This seems to cross with the other thread about "poor parts quality". The "new" one also seemed to be made from cheddar cheese in comparison... just didn't fancy trying it... could have ended up mashing the threads and turning a simple job into one somewhat longer!
David Cox

Point taken!
Colin Parkinson

This is one of those never ending debates, into which the lack of a specific figure, has given rise to the fear factor, dictating that the nut should be 140lbft.

It doesn't need to be that tight (140lbft), and for the Spridget size axle, it's NOT quoted anywhere.

Very or f*cking tight is more than enough, but define f'ing tight.

See the most recent thread, for just one of the previous lengthy discussions. It's superbly named for easy location in the technical archives. it's called -- :)

"help on 2 areas - fuel pump set up and rear wheel" The last post was 28 September 2014.

Do you prefer stilsons on your nuts, or a home made tool. They both feature in the above thread. :)
Lawrence Slater

How tight you make it depends on past experience on whether you have had one "go" on not! It has a lock washer so only needs to hold the bearing tight enough to stop it turning.

I found that about 60 ft lbs "felt" about right.

Watch out as you tighten because the lock washer has a tiny lug that fits in a hole in the casing and the friction between the nut and washer can tear the washer free of the location. It then won't do it's job.
Graeme W

i always have mine as "pretty tight", which is one below "effing tight" and 2 below "as tight as I can get it"

I bought a socket off ebay that was exactly the right size, has to have 6 sides cos the nut's got no corners...
Rob Armstrong

I note that there is a page authored by Norm Kerr, which discusses the nut torque: http://www.ahexp.com/article/midget-rear-axle-knowledge.html

Norm says 140-150 ft. lbs. My only concern is that I once stripped the threads on the very end of an axle, using a 3/4" drive breaker bar. First time I've stripped threads in ~30 years.

I solved the problem, but worry a bit about that much torque, and agree with Graeme that it might not be necessary. I've seen photos of the disastrous consequences of this nut coming loose, but surely there's a happy medium. Really, the thing shouldn't come off with the tab washer bent up tightly around the flats.

Joel.
JM Young

Until someone suggested that it should be 140lb, everyone was happy to just whack it up tight, and probably no more than 60lbs.

Until I made a tool, I never used a torque wrench on that nut in 35 years, and never had one come loose. Then I made my tool and used a torque wrench on it, and 70lbs felt way tighter than I'd ever done it before.

That nut may well take 140, but that doesn't mean it has to be that tight. It's the size it is, because the half shaft passes through the center of it.

If it had to be 140lbs, then why don't the front hubs have to be that tight?

Just do it up very tight, bend the tab over, and forget it.
Lawrence Slater

<< because the half shaft passes through the center of it. >>

Lawrence
I think we're all talking at cross purposes: The pinion flange nut is 14O lbft.... but the hub nut [i.e the one to which your comment refers] is never that tight...
David Cox

Hi David. I agree. Colin was asking about the hub nuts.

Others may have gotten confused. ;). Some people definitely think the hub nuts should be that tight too.
Lawrence Slater

Just to clarify this afaiu, as there still seems to be confusion right up to the end here: the value pulled out of the spridget manual of 140 lbs ft refers to the nut on the input to the diff. Not the bl**dy great nut on the end of the axle casing where the hub fits.

And while we are talking about it, remember one side is left hand thread! That's the one that seems very tight to undo! Oh, it goes the other way! (I think it's the left hand side but check it!)

Graeme W

Colin very clearly described which nuts he was asking about. Its half of the replies that have thrown confusion all over it!
Guy W

But as noted above the very similar but slightly larger MGB bearing nut is 180 lb-ft, the MGB manual definitely says so. And no, I'm not mixing it up with any other nuts!
And this is what happens if it's not tight enough ....


Paul Walbran

"And this is what happens if it's not tight enough .... "

Quite possibly.

But "tight enough", doesn't need to be anywhere near 140lbft.

Circa 60lbft has kept my hubs in place for over 35 years, and they've never come lose.

Lawrence Slater

Mine too, but I don't chuck it around like Paul's team does!
Nick and Cherry Scoop

Nor me. But I don't see why hard cornering on a track, anymore than cornering over 35 years on public roads would make the nuts unwind.

-- Unless you were driving in reverse, AND, didn't have the lock tab washers in place and bent over, AND, the outer race was seized to the inner race, AND, the inner race was loose on the axle shaft. Then I suppose the hub could unwind the nuts as it rotated anticlockwise.

Or of course you might have weak or stripped threads in either the nut, or on the axle.

I reckon they'd have to be pretty loose, or something else wrong, for the nuts to vibrate loose and off.

But since it was shown in the other thread, that a spridget axle hub nut in good condition, can take 140lbs. Go for it, even though it's just not neccessary, and you might strip the axle.
Lawrence Slater

I have had a nut come loose on the race car, although not enough for the hub to come off.

Apparently, it was not uncommon on overworked Spridgets.

In the end, I dispensed with the tab washer complete and used Loctite.
Dave O'Neill 2

No, but whacking the handbrake on at full tilt in California Cup can do it, I expect.
Nick and Cherry Scoop

Lawrence worked it out, it was in reverse. The wheel managed to jump out of the wheelarch whilst the body was lurched the other way in the middle of a turn.
The tab was done up and clamped around the nut. The nut was certainly tight, 100+ lb ft as a fair chunk of my weight was on the end of the power bar. Maybe too much, I wondered, - had the threads had been damaged, but no. Altogether a bit of a mystery. So like Dave I don't trust the tab any more and use Loctite.
Paul Walbran

Since the tab washer is pretty soft, I would imagine that applying a very high torqued loading onto it would distort the washer, and over a period of time that torque load would slacken off anyway.
A bit like what happens with head studs correctly torqued up, but onto soft putty washers. But in the case of the hub nuts, the "soft" tab washers are the correct "as factory fitted" item which rather suggests they were never intended to be torqued to quite such a high figure.
Guy W

Well that's an interesting theory. It's the nuts that get done up too tight, that eventually loosen off, and in extreme cases, the hub comes off.
Lawrence Slater

I thought that input would appeal to you, Lawrence.

I have nothing to support that theory, other than the comparison with the use of the wrong spec. washers on head studs. But it does seem to me to have a certain logic.
Guy W

It does indeed have logic Guy. The law of unintended consequences.
Lawrence Slater

Things may have improved with Loctite over the years but it is not always a suitable fix. The late Terry Sanger told of using it for retaining a suspension component some decades ago as it seemed upto the job and allowed a simpler design that would save unsprung mass, on testing after a lap or 2 the wheel/hub came off. They tried a stronger version but same result. On paper the product looked strong enough but actually had the strength but poor fatigue characteristics so due to the cyclical loading it failed quickly. I doubt this is much of an issue with the hub nut if done up properly but not everything is obvious.
David Billington

Not an MG, but the Riley 1.5 has the same hubs and locknut, which under certain circumstances can come loose - please see this clip from the St Mary's Trophy Race Part 2 in the 2014 Goodwood Revival:

https://www.youtube.com/watch?v=fa8fky7jwrE

How do you make this a live link??

Richard
Richard Wale

Remove the 's' from 'https'

http://www.youtube.com/watch?v=fa8fky7jwrE

That would be this one...


Dave O'Neill 2

We had this on the Morris - identical set up - at Rockingham this year. An odd gentle clunk as I threw it into the hairpin, so I pitted. Could see nothing wrong so put it down to locking a wheel or the LSD working. Two corners later, Wheel, hub and half shaft exit stage left. The little inner tab had sheared off, see pic. (Hard to see, as it's almost gone,!) In my view the tab needs to be more robust, but the nut has to allow movement for it to start going.
I say keep the tab washer and tighten well, B tight, seems right at about 140 lbft. I have a homemade tool about 18" long which can be held in place with a wheel spacer and the wheel nuts. I believe the BMC tool had a socket with a strap using the studs to hold it in place. I now add loctite too!


A Cross

Wow... sold me. I'll double check mine when I'm done fooling around with the disc brake conversion, which I hope won't be long!
JM Young

Yes, I use both Loctite and the locktab now :-)
Paul Walbran

Andy

The BMC tool had a spigot that located inside the axle tube. It was also double-ended - A-series one end and B-series the other.


Dave O'Neill 2

Speaking about the RH side, for the LH side read the opposite :---

The inner race of the rear hub bearing is, and is supposed to be, a tight fit on the axle. Even if it wasn't tight, if it revolved, it would do so in a clockwise direction. The same direction that would tighten the nut further.

The outer race is, and is supposed to be, a tight fit in the hub. It revolves around the inner race in a clockwise direction if travelling forwards. Even if there was sufficient friction between the outer and the inner, it would tend to move the inner in a clockwise direction too. Again in the same direction that the nut tightens.

If the outer seized to the inner, that too would tend to rotate the inner in a clockwise direction, and tend to tighten the nut.

So how does the nut undo?

The front hub nut is only done up to circa 50lbft. The split pin is for extra safety. The same forces apply; Heat, vibration, cornering forces. If the 50lbft is sufficient for the fronts, why should the rears need to be almost 300% tighter?

The must be something wrong on the rear hubs in the first instance, if the nuts are coming off, it seems to me.

So what are the candidates?

If the tabbed lock washer is being compressed, as some suggest, in hard cornering, then that implies that the inner bearing must be a 'loose' fit on the axle, thereby allowing it to 'rock', and eventually slide back and forth, and damage the washer. So maybe that's the problem for those who've had the problem?

Or maybe too much heat? Maybe the constant heat cycling on track cars, causes the washer to degrade to the extent that it allows the nut to undo. Why would there be too much heat?

Maybe the washers used by the those that have the problem, are in some way inferior to the originals used?

Or maybe the extra forces on the hub on track cars, given enough time, are the cause.

But so far, I seem to recall only ONE instance of a road going Spridget shedding it's hub in the fashion described for track cars. I think that was on here a little while ago.

The cars with these axles have been around for a very long time. In that time, very few people will have had a 140lbt torque wrench. Very few people would even know what it feels like to pull 140lbft on that nut, and no way of gauging if they had.

Add to which, the manuals don't give a torque wrench setting for the Spridget size axle, and many if not most people would have simply followed the guidance of Haynes, when doing that nut up 'tight'.

Add to which, most people on here, including Norm and others who previously only did the nut to around 50lbft, have never had their hubs come off.

So why now, after all these years of no problems worth the mention, are we all supposed to accept that the nut should be 140lbft.

On a road car, it doesn't need to be. If it needs to be on a track car, then the "mystery", that Paul talked of needs to be explained.

Interestingly, the Riley in the video, snapped the inner end of it's half shaft. Now I wonder if that's what led to the hub coming off, rather than the other way around. I think that would make more sense, and would imply that something was wrong with the hub.

On all the cited track examples of hubs coming off, did they ALL snap the inner end off the hlaf shaft?

If you fit a new correct spec bearing into a decent rear hub, and the inner is a good interference fit on the axle, -- until you insert the half shaft you can rock the hub outer bearing on the inner, due to the internal clearance of the complete bearing. When you insert the hub, as long as you have good bearings in the diff the rocking at the hub is removed almost entirely, as they work effectively as a pair.

Perhaps if there was too much internal clearance in the hub bearings to begin with, that would stress the half shaft sufficiently to cause a break?



Lawrence Slater

That last bit should read ---

When you insert the 'HALF SHAFT', as long as you have good bearings in the diff the rocking at the hub is removed almost entirely, as they work effectively as a pair.
Lawrence Slater

The lock tab distortion could be because you apply F*ing torque to the nut. 140 lbft could impart enough turning force on the lock washer to distort the tab and allow it to come out of its location slot. Would you check whether this has happened? Would you notice it? If I applied 140 lbft to this nut I would probably end up in a fuzzy incident due to the strain (on my body, not the nut).

So A. Cross, can you be sure the bent tab was caused by the forces due to driving the car or the force used to do up the nut?

Rob
Rob aka MG Moneypit

Dave, thanks, I knew I'd seen that tool before!

Lawrence, I agree the back/forward erosion might wreck the tab, due to a loose fitting bearing or, as Rob suggests, rotation of the washer as its being tightened, which is perhaps an argument for NOT going too tight (earlier threads have commented that the BMC tool is manual, and would only achieve around 50lbft). Critically important is to check it very carefully before replacing the half shaft.

But, Lawrence, no sign of halfshaft breakage on the Riley, and not on ours. Has anyone broken a Peter May shaft? We re-used it, after a lot of filing the damage back into shape, hammering what was left of the nut on the stripped-thread axle and welding it on! Wrecked the oil seal so oily back brakes, but completed a 45 minute two driver race, second in class.
Andy
A Cross

Rob: I made the same comment about the tab earlier. It's a crappy little half moon which engages in a hole in the casing. If I recall, if you leave the half moon untouched, it is very difficult to actually get the washer on the shaft so there is a tendency to bend it up slightly anyway. If the nut is overtightened, it can drag the washer around with it, shear off or bend the tab and then the nut is not locked securely.

If the lock washer is actually locking the nut correctly, it can't come off.
Graeme W

I don't think the theory too much torque dragging the washer and shearing it holds up. Our tab was intact, and I have never noticed any tendency for the tab washer to drag. The theory also overlooks the torque spec for the very similar B series is definitely listed as 180 lb-ft. Which, BTW, is easily achieved with a spanner of the form of the BMC tool as the cross shaft (scaling it off the approx 2" size of the hex) is about the same length as your average power bar.

As for the quality of the tab washer, they are mild steel as they have always been, since tab washers need to be or they won't bend over properly. I do wonder about the shape of the tab though and whether it differs from the original, but that's one thing that I can't recall.
Paul Walbran

It happened to me once Paul. I had an axle casing on which the thread stripped at about 90 ft lbs and the lock washer had come out of the location too. I finished up replacing the casing (the po had used a standard axle with wire wheels!) but as a consequence got very nervous about incurring similar damage on the replacement.

I remember at the time being mislead by the "140" figure and posted a similar thread here. The impression I have of the results was that there was a much more "oooh... be careful... not that tight" feeling than there is currently. We all base our comments on our own experiences and mine is based on that sickening feeling you get when you feel a thread going!
Graeme W

Just had a quick rake through the archives. The impression I have is that opinion is as divided then as it is now (probably because it is the same contributors). It seems enough wheels haven't fallen off yet to cause any ingluence on posters' views.

I'm sure this is a topic which has come up again and again over the years and will continue to do so. A bit like front wheel bearings!
Graeme W

Andy. The commentator says the half shaft is snapped on the Riley, -- "like a carrot" I think is the phrase he used. I down loaded a still, and it looks snapped to me.

But if yours didn't snap, and the only damage is the tab washer, then maybe the nut too tight theory, holds for yours, whilst Paul's remains unsolved.

graeme. From what I can tell scanning the archives, it was only in the last couple of years that the 140lbft insistance has come up. And it's only 140, because as you say, people keep mistakenly quoting the diff pinion nut. That's the first reason. The 2nd reason is that Norm introduced the concept of how much a thread that size can actually take, and from that concluded that 140 is quite reasonable.

And finally, the MGB hub nut is now quoted as being a good reason to go to 140 on a Spridget. But I still argue that is irrelevant.

There isn't a solitary original BMC publication that states a 140 torque figure for a Spridget sized axle hub nut. Not in the Spridget manuals, or the Morris Minor manuals, or in the A40 manuals, or the A30 manuals.

I simply do not believe that in all the years that BMC were producing these axles, that at some point, they wouldn't have noticed the ommision of a critical torque figure in at least one of their w/shop manuals, and at least put out a service bulletin, which would have spread to mechanics in at least a few non bmc garages, and eventually become common knowledge.

In all the manuals, they suggest the use of the offical tool for the rear hub. And in the same manuals they list a torque wrench rated to 140lbft, but don't suggest it's use for the rear hubs.

They go into detail about the thickness of the paper gasket between the shaft flange the hub face, and yet, don't bother to mention torquing the hub nuts.

I wonder why?

Could it be that the rear hubs don't have to be done up any more than simply good and tight? Which amounts to what pretty much most people were doing them to until fairly recently. Cira 50/60lbft.


Lawrence Slater

Lawrence, I was watching the St Mary's Trophy Race from Goodwood (Riley) live on t'internet, and vaguely remember the 'snapped like a carrot' comment from the commentator. I can't, for the life of me, imagine how he could see the halfshaft from where he was.

I can only assume that he believed that the wheel and halfshaft had come adrift because the halfshaft had broken.

The MGB workshop manual lists at least three torque wrenches in the 'tools' section. One of them is rated to around 225 lbs/ft IIRC.

I don't see why the MGB hub nut is irrelevant, as the axles were more than likely engineered by the same engineers.
Dave O'Neill 2

Commentators frequently get it wrong! I remember once we had an address to our clubnite by the TVNZ motorsport commentator of the time, and what he basically said was that if you don't know exactly what's happening then make it up as that's better than ignoring it :-)

The halfshaft may or may not have snapped, and I agree that if it did break then the wobble could exacerbate things, but there's no way in the world the commentator could have known one way or the other as all he'd have to go on was whether the halfshaft was an inch or so shorter than normal from that distance on the spur of the moment. Though I note that this is obviously a commentry dubbed on after the event so maybe he had the good oil on what ahppened by then. Or had the wool pulled over his eyes, I remember that when Chevettes did the WRC round out here and failed, the official version was electrical problems whereas those on the scene saw breakage in the camshafts or their drive.

To me, it looks as though there is still spline on the end of the halfshaft.

And it didn't really matter, the main thing was that something had indeed broken and that's all most viewer apart from our eclectic lot would need.
Paul Walbran

But that wasn't a live commentary was it? It was post event judging by his remarks being mostly in past tense. So I assumed he was privy to the state of the halfshaft. But I agree, even expanded it's a bit hard to tell what state the spline is in. Although the end does look deformed to me at the least. Perhaps not suprising though as it bounced around a fair bit.

But anyway, great seeing all those oldies hacking around though.

" ---- and that's all most viewer apart from our eclectic lot would need." Need to what? Tighten the hub nut to 140? Why?

Even a non-racer like me knows that race cars are subject to extra requirements for fastenings for belt and braces safety, that road cars simply don't need. And the very few examples of hubs coming off, seem to be limited to race cars. So I just don't see the need to tighten to a 'guessed at' torque figure.

Hi Dave. Yes, and the Spridget manual also lists another torque wrench too. But the point is that Spridgets aren't MGBs.

So the hub nut on an MGB is 180. There may be other higher torque figures on the MGB, for nuts the same size that are also present on Spridgets. And if the nut in question was checked in Norms fasteners guide, it may be that you could do that nut tighter on a Spridget too. But does that mean that you have to?


And to repeat myself, there is no mention in any official manual with a Spridget sized axle, that the hub nut should be torqued to 140, or something less than 180. And to repeat myself again, it's simply not credible that for the entire duration that these were produced, nobody noticed that a critical safety value was missing from all of those official manuals.

I think it's entirely reasonable to assume therefore, that the hub nuts do not need to be 140, given that most peope have never had the hub come off, and that most nuts are done (hitherto) to only circa 50/60lbft.

I also think, given that some people, Graeme for one, have experienced stripped threads when trying to get the nut that tight, that you shouldn't go to 140 for a good reason.

Yup, it's an engine breather/front wheel bearing type issue. lol. But at least with the front wheel bearings, it's a clear cut issue of the wrong spec bearing.
Lawrence Slater

Lawrence, Lawrence, Lawrence,

You are the only one who keeps going over and over and over this.

There is no number in the Midget manual, that is unfortunate, because you seem to have become obsessed with that fact.

In this thread, and in the other threads, many, many people have explained that rear axles very similar to ours have torque values quoted, and they are useful as a reference to help guide us to making a wise choice in our case.

Also, you have been shown the calculations for how a torque is decided, based on the thread size and materials used. That calculation shows this nut can allow a torque of well over the numbers being discussed. Remember that the torque of a fastener is like a clamp holding things together. A too low torque will not be able to resist the loads in the joint and the nut can move, leading to loss of torque.

Good fastener design includes determining the minimum necessary torque to avoid that, and calculating the maximum torque the fastener can withstand to make sure it won't strip during assembly, and then mass production uses a range between those two. It is too bad BMC didn't publish these calculations to satisfy you, but no manufacturer ever does. However, the second one is based on straight forward mathematics and as we showed you is easily recalculated.

Others have posted experiences where the nut has come loose. Unfortunately, since each case was not forensically analyzed, there is not enough data to prove exactly why it came loose each time, but, being a nut, it does indicate that lack of torque on the nut to withstand the forces it was subjected to was most likely a factor.


Now, in your case, you have been using your car for many years, without trouble, with an unknown torque on that nut. Probably your torque is in the 60 ~ 100 ft lbs, if I recall correctly what you figured it was, in a previous thread on this subject.

Others have been using somewhere between 100 ~ 180 ft lbs. Still others have used very low torque and relied entirely on the tab washer to hold it. Graeme had an unfortunate outcome, his threads stripped. We don't know why it happened, but we do know all of these other things.

The thread calculation shows that healthy threads can survive 900 ft lbs (because this is a really large thread). This calculation assumed the softest grade 3 steel, and included consideration that the nut is only 1/4" thick.


OK, you have been fine for a long time with whichever torque your car happens to have on it.

Let's all agree the nut can come loose. Applying enough torque to the nut is wise to prevent it, as is using a locking washer and even lock-tite maybe for severe applications.

Modern cars are not designed this way because too much is riding on just one thread. Modern cars use 4 or 5 smaller studs to do this job instead.


Norm
Norm Kerr

Norm, Norm, Norm, Norm, Norm.

You obviously have a problem noticing all the other people discussing this, and you do hate to have your 'expertise' questioned don't you. And, not me not me old bean. I didn't start the thread.

Hands up those who've done their rear Spridget rear hub nut to 180lbft then? Norm says you are all out there somewhere.

No, not obsessed Norm. Just pointing out a very relevant fact, about what ISN'T in a whole range of pertinent official BMC workshop manuals. Whereas, you are obsessed with the potential of a nut to stand a large torque, when it isn't necessary to employ one. But fair enough, you like your nuts tight. ;).

And allow me correct your unreliable memory, of what I said about my rear hub nut tightness in a previous thread.

I'll quote myself if I may.
-----------------------------
"I knocked up my rear hub nut removal tool today. Took about an hour. Looks very crude I have to admit, but it's also very effective, and that's what counts.

6mm plate and a 3/4 af bolt head.

I've had the LH rear hub and back plate off my Sprite. So I used it first to tighten the hub without a torque wrench. I just used an extended T bar, which is little longer than the length of my Stilsons handle. Did the nut up to what I reckon is tight enough, -- and felt the same as using my stilsons, and then a little bit more. I wouldn't have wanted to go more than that I reckoned.

Then I put the torque wrench on it set at 55lbft. Click.
60lbft, click.
65lbft, click.
70lbft, moved a tad, and click.

Ok, I admit, using my stilsons I might possibly have been achieving more than the 50lbft I reckoned earlier. But not much, if at all."
------------------------------------------

So as you can see, I've been driving around for a very long time with my rear hub nut at around 55lbft, and never had a problem. Likewise have many, many, many, other people.

Yes, "others", as you put it, have reported an experience of the hub coming off. But so far that amounts to only a couple or five, and those were on race tracks. Let's be generous and say a half dozen or 10. Out of how many who've NEVER had a problem is that? And how many on the road? In how many years?

And I really hate to embarrass you with MY memory, of what YOU said, in a previous thread Norm. But I will anyway. ;)

Now what was it you were saying back in November 2010? Let me think.

Ah yes, Allow me to quote you Norm.
-----------------------

"I've heard as low as 40.

I used 45 on mine.

Have also heard of folks stripping their axle housing when they went too far, so I would definitely not go above 60. 45 "felt" like plenty.

As David pointed out, the lock tab holds things, so "fully snug" is enough (funny that the factory never bothered to define it though).

Norm Kerr"

----------------------------------

And then you took a trip to Damascus and had a conversion, when someone called Tore, said a bloke from Brown and Gammons, said it should be 140. – (How did he know that for sure then?), -- and further told you about the MGA guru who said it was similar in size to an MGA rear axle.

You were so impressed with the "math" that you rushed off and retorqued your rear nuts. Even though until then, you were blissfully riding along with your nuts quite loose at 45lbft, and not had a problem at all.

What? How tight? Yes that's right 45, and you Norm, "would definitely not go above 60. 45 "felt" like plenty."

That says it all Norm. Someone told a story to frighten the children, and you've been telling it ever since. A few tenuous links, and you decide it’s a new "fact", to be ignored at your peril, written in blood, and spread like a crusade.

Yes Norm dear. We all agree that the nut should be tight enough. Obviously.

But there is no proven good reason, to tighten it to 140lbft, and precious little, if any, evidence, that all those like me -- AND YOU, -- who've been doing the nut to circa 50lbft, have had in the past, or are going to have in the future, a problem if they continue to do it to circa 50LBFT.




Lawrence Slater

Somewhere at the start of this thread it said it was similar to the nut on the MGB Banjo axle.

So, I had a look on the Moss website but couldn't find this nut.

Usually, when a f**cking great torque is mentioned it's because both sides of the car use RH threads instead of LH and RH threads and the high torque is very necessary on one side.

But, can someone point me to the nut on the MGB Banjo axle that requires this humungous torque?

Rob
Rob aka MG Moneypit

Rob

I've just looked at the Moss site and the nut doesn't appear in the diagram. It is, however, in the list - item no. 10, LH and RH.

I'm guessing it was originally depicted near the end of the axle casing, but that also appears to have been edited out of the diagram.


Dave O'Neill 2

Also, the relevant figure from the WSM


Dave O'Neill 2

Ooooh, here's a better pic - MGA axle...


Dave O'Neill 2

Dave,
The axle bearing nut is shown on the Moss paper catalogues for the Sprite /Midget, which has the illustration with the outer casing, similar to that MGA illustration. Moss also frequently add a short paragraph about an item or about assembly if there is something of note, but I don't see anything added regarding this nut.

Which "WSM" did that table come from? I have two facsimile copies, one for the Frogeye and one for later cars. Neither quote a figure. In fact neither even suggest using the workshop spanner 18G 152 to tighten the nut - only to undo it! It just says that the bearing should be "Drifted onto the axle" with a different workshop tool 18G 134.

I also have several editions of Haynes (though I wouldn't necessarily rely on these for absolute correctness) Including A30/ A35. None quote a figure. The only printed reference that I can find for it is in Grahaeme Bristow's book, Restoring Sprites & Midgets" where he quotes just 45 Ft/lbs.

For many years accepted workshop garages from the thousands of small rural and side-street garages was to tighten those nuts with a cold chisel. By current standards this looks ham-fisted, but in the '50s and '60s this would be how experienced time-served mechanics would have done it, without a qualm.
Guy W

And they are very similar to the A series axle, just as thin but a little bigger in diameter and the nut is octagonal not hexagonal. And like the A series, there is a LH and a RH thread.

Paul Walbran

Well its pretty clear that the use of a very large nut isn't especially that way so that it can be torqued up tight, but just because the axle shaft has to fit through the middle of it!

The fact that given this size and the consequential length of contact surface of the thread means that, as Norm has calculated, it will take a very high torque, doesn't automatically mean that it has to be tightened to that extreme. To be fair, I don't think Norm means that either.

The fact that the workshop manual says that the bearing needs to be "Drifted on" certainly implies that the bearing is located firmly by an interference fit on the casing. Or at least a very close tolerance or slight taper. If this is the case, then the nut and lockwasher need to be tight to stop the bearing from working its way loose, but not necessarily acting on the bearing to hold it in position by clamping force alone, as the interference fit will take care of that.

If one uses a standard 18" breaker bar and a socket, then it is very easy to get up to somewhere around the 180 ft/lbs mark just with a strung "grunt" pull on the bar. That is what I would call tight or "F**ng tight" and will continue to be about right for me. Anything more brutal like the use of extended levers, scaffold poles etc would be quite unnecessary and risks damaging threads and 50 year old axle tubes (they rust thin and become quite delicate. OTOH, 45 ft lbs just doesn't seem enough, ~~ its barely more than finger tight!
Guy W

45lbft finger tight Guy? Try it and report back. lol.

You stole my thunder Guy. I too was going to write that Moss have annotations in their parts books, about important or otherwise noteworthy issues regarding fitment of the bits they supply.

It's in their interests I would think, not the least to prevent them being sued for not advising their customers about correct fitment. So the fact that it's not their, supports the ommision from all the other w/s manuals that don't mention it either.

And I agree with you about the chisel. That's how a mechanic first advised me to tighten mine all those years ago. I preferred stilsons. As you say it was common practice, and if it had led to nuts coming loose, and hubs falling off, word would have gone around pretty quickly, and a torque figure would have become common knowledge.

I don't dispute the MGB axle figure, it's there. I've got a download myself. But so what? Who knows, maybe THAT is the abberation. Maybe the MGB figure is wrong. People often remark that these WS manuals can't be trusted. I'm not saying it is wrong. But it could be.

Anyway. Why does any of this this matter? People, often without previous experience, come on here and ask for advice. It does them no favour to exaggerate or invent risk, where little or none actually exists.

Firstly, torque wrenches ain't cheap, and most people who own Spridgets, won't have one that goes to 140lbft, let alone an accurate one, in which 140lbft is in it's range, rather than at the top of it's range. This means if persuaded by the 180 brigade, they have to go out an spend dosh to hire or purchase an expensive tool for which they have no other need. When instead, they would have been perfectly safe doing what countless others have done before them for the last 60 or 70 years. Use a chisel, an adjustable wrench, or an adapted bench vice.

Secondly. If the 180 people have their say without challenge, it will become a "FACT", that the rear hub nut MUST be done to AT LEAST 140lbft, else you risk the life of others and yourself. even of there is NO evidence to support this. As a result, not being able to judge for themselves what 140lbft feels like, if using a long bar, they might go well over that figure and strip the axle/nut threads. But even if they do splash out on 140 torque wrench, they run the risk of stripping the threads on their axle.

These aren't new axles. Sure MAYBE they can take it. But where can you buy a new axle if you trash yours? Look at the hassle in finding a good 2nd hand one. So you get one, and again go to 140, and again you strip a thread. Who on here, who have told people that they must go to 140 to be safe, will pay for the replacement axle?

Will I take responsibility for telling people what I tell them? Yup I will. For road use, do the nut as per Haynes and you won't have a problem.

Lawrence Slater

I totally agree, Lawrence. And would add that as well as not exaggerating or inventing risk, it is also wrong to add layers of complication to simple basic tasks. Doing so is likely to put new owners off the idea of attempting jobs themselves and thinking that it all has to be left to the "professionals".
Faced with either having to buy an expensive torque wrench, or having to pay high garage fees, any new owner is going to think twice about tackling the simple job of replacing a rear wheel bearing. Or oil seal. Or brake backplate. One of the joys of these cars is their simplicity, low cost and easy maintenance. They are, to me at least, a grown-up's replacement for a meccano set!
Guy W

I, for one, have never advocated tightening the rear hub nut to 180 or even 140 lbs/ft. What I have done is said that I don't know the figure, because it doesn't appear in print and no-one has been able to categorically say what it should be.

I have, however, quoted the MGB figure for comparison.

Personally, I have never used a torque wrench on the hub nut, only a socket with a 2-foot (ish) bar and a good heave. FT.

In the past, I have also recounted the tale of dismantling an A30 rear axle and struggling to undo the LH hub nut. I didn't appreciate that it WASN'T a lefthand thread, so was actually trying to tighten it.
Having spent a long time heaving on a long bar, it eventually moved a very small amount. If it had only been tightened to 50 or 60lbs/ft, I'm sure I would have moved it much more easily. The tab washer appeared to have a 'factory' bend, so I'm convinced it had been very tight from day 1. How did they manage to bend them so neatly?
Dave O'Neill 2

"How did they manage to bend them so neatly?"

Very gently, I reckon, with a lever, and then a toffee hammer and flat bar to finish it off. That's how I recently made a pucker job on my Midget. I re-used the original washer, and bent it in a different position.

They must have had a special tool, I can't see them taking as long as I took over it.

Could this 'thread' be 'stretched' to 100, before being 'stripped' of any meaning, and becoming useless? LOL.
Lawrence Slater

Surely 140 posts Lawrence!
Graeme W

I am always amused by the footnote on this web page with the instruction to "click here" to get rid of all the superfluous information.

It doesn't seem to work as I would hope!
Guy W

Ha ha. Very good. :). 180 if your also darts player Graeme. ;).

Which superflous information would you like to see removed Guy? Don't answer that. LOL.
Lawrence Slater

why cant you just use locktite 270 or similar on the nut if you dont want it coming undone
mark 1500 on the road Preston Lancs

270? Any advance on 270? ;).
Lawrence Slater

Tack weld?
Graeme W

609. It's only problem is the effort undoing it again. And in cleaning the thread out after assembly.
And it's quite thin in viscosity so will get places you don't want it to if you aren't careful. But it works a treat if you want to lock a thread properly. Which we do, following the incident in our piccie above.

David's note re loctite & fatigue is correct where it is being used as a retaining glue on an assembly subject to vibration etc, but for threads it works a treat.
Paul Walbran

Is that the strongest loctite there is?
Lawrence Slater

i think 276 is the strongest 60mn needs heating up to take apart i think 609 is for retaining bearings.
http://tds.henkel.com/tds5/docs/276-EN.PDF
mark 1500 on the road Preston Lancs

This thread was discussed between 26/10/2014 and 04/11/2014

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