Tony, I have no data either way. My experience is limited, but I do not ever remember of hearing of any failures in the last 30 years or so. But I am sure they do occur. Pre load issues?
Tom
I have heard of many recalls, with GM, Ford and Jeeps all affected
The only one I was told the “cause” was Fords suffering from low quality metal in the ring & pinion gears (made in China)
If you rummage around a bit on the Internet, you will find info
Differential Unit Problems of the 2014 Cadillac CTS (carproblemzoo.com)
not something that typically makes it into the press
a lot of vehicles have front transaxles these days…some of them fail too
making stuff lighter, ie Al housing cant be helpful for long life
Well they could be junk. I am sure there are failures, but compared to the 50’s and 60’s, it just seems that differentials, as well as about every other automotive component, seem to last much longer. It seems 100,000 miles was a goal back then. Now expected.
Tom
I wouldnt say that, I have had them last over 300,000km
but also had them fail earlier
Older iron-case units such as Jag/D44, D60, Ford 9" also last a very long time
I would assume there has been improvements in production technology, but also weight and time reductions which may offset each other
In my current project, I have had to do a lot of measuring, and found the align bore of the axle carrier bearings is slightly offset, making it harder to set up the gears
Presumably there is also variations in quality control from different makers etc etc
I hope this is not too diversionary to the OPs original topic, but as he has already received copious info on that, not to mind
Of course it would. It’s the shim pack that is stopping all of the end thrust applied by the nut being tightened, being exerted on the mating components of the bearings.
The same applies with the collapsible spacer. Omit that and all of the load applied by the nut and the helix of the thread would be applied to the bearings. The bearings are only compressed an infinitesimal amount once all End Float has been taken up, they really don’t come together any significant amount once full and firm contact is made between the Cone and Cup of a Taper Roller bearing. Think about three pieces of steel plate in a stack under the ram of a press. The ram can be brought down to apply, say a one ton load. If further load is applied, say ten ton, the outer two plates don’t get any significant amount closer to each other.
If you were to put rollers between three pieces of hardened and ground plate, then apply a load, there would be a correlation between the amount of force required to push the centre plate sideways and the amount of load being applied to the three plates and two layers of rollers. Its the same principle with the torque required to rotate the Pinion Shaft.
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it matters so much that a .044" Pinion preload shim stack will not allow me to achieve correct pre-load with my 200ftlb impact wrench, (aim on this diff is 200ftlb+), but a .042 will lock it up before the nut is tight enough.
I have shims for .043, so lets hope that works
You can see the attraction of crush sleeves
Bill, I agree with all your facts- but I am still wondering… if you care to pursue the “theory.” I understand if you do not.
Getting back to the negative end play story. If, with the shim pack, one adjusts the shim pack so upon tightening the nut, one gets 0.001 inch negative play. That is, the shaft stretched and the bearings were compressed a total 0.001 inch. First, of course, am I saying that correctly???
If so, how is it different if we set up a shim pack that allows us to compress things that much by bottoming out the shim pack versus simply tightening the nut until we compress things the exact same amount? The dimensions would be all the same, the “load” on the bearings would be the same. The nut torque may not be as much since it does not reach a “hard” stop, so we secure it by what ever means, staking or what ever.
Tom
Tony, if your ultimate goal is to have a rolling torque preload, then you would be correct. But, if your ultimate goal is to have a measured “negative” end play, then the shims only need to achieve a dimensional goal, the precision of which is set by your thinnest shim. And the nut torque and rolling torque are irrelevant. Again, it depends on whether your goal is negative end play or rolling torque.
Tom
Yes, if you were to have no spacer whatsoever and did the Companion Flange nut up until the correct pre-load was achieved (this would be achieved with very little torque applied to the nut), then the nut welded to the shaft, the correct pre-load would be achieved. But how do you conveniently measure the amount of pre-load on the bearings in that scenario without some comparison to the likes of a torque figure to rotate the shaft.
Further, by having the resistance of the spacer and the shaft in tension, make the assembly more rigid.
On very large projects (physically large) I’ve worked on, the pre-load on the bearings was determined by stretch of the shaft measured with a dial indicator. The amount of end thrust being applied was calculated from the stretch measured.
Bill, thanks for all your comments. I believe that brings me around to what I believe is the goal of the preload issue.
I especially like the measuring the stretch, as that was a possibility that crossed my mind.
I wonder if another accurate possibility would be to snug the nut up lightly with a very light torque to get to 0 end play, then, by knowing the thread angle, turn the nut X amount of degrees. Thus stretching and creating the negative end play. Just like many bolts are now torqued by the degree method for better and more consistent tightening.
Or of course, simply continuing to do it as it has been done for years with success. Measuring rolling torque! 
Tom
given this Diff Pinion appears to need a .001" shim adjustment to allow me to have both my measurements in spec (pre-load inch pounds and Pinion nut tightness in foot lbs)
I would suggest it very critical to get both these things as near to perfect as possible
If not, you will loose Pinion pre-load AND the nut will work loose
If pre-load is is too tight, you WILL destroy things.
I have a Jaguar Diff with too much pre-load, and that has destroyed a bearing
also seen Jaguar and other diffs fail due imo to improper set up
The one I am working upon at the moment failed
Thomas I don’t know where you are on your differential. I should of sent you this video of Paul Cangialosi rebuilding a Jaguar differential like yours with a collapsible spacer. Paul is quite a famous guy. He owns Medatronics that used to manufacture the best 5 speed transmission for E Type.
As to an inch pound torque wrench I use the one photographed. I got it off Amazon or E Bay quite inexpensively. These things you can calibrate your self - it was quite accurate when checked. The nut on my diff was 1 1/8 so I had to use some adapters to fit it to the 1/4" drive on the torque wrench.
The Jaguar manual I have for Ser III XJ6/12 cars is very explicit - once you disturb the crushable sleeve it can’t be reused. If you remove the flange you may be able to get the old spacer out with out further dismantling. If not you will have to pull the center section out, remove the pinion and replace the spacer. It’s not particularly difficult as you will see on paul’s video. If all you do is remove the pinion and replace the collar there is no need to do the measurements Paul does.
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Thanks Terry
I’ll be into this in a few days and will review video beforehand
Thanks again