Differential oil seal?

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moggiegeek
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Differential oil seal?

Post by moggiegeek »

Now building up my new running gear for Moggie. Wolseley1500 rear brakes, new handbrake arrangement, konis and treated to anti tramp bars. All very beautiful with hardened half shafts. 3.9 diff.....,
Final task to fill the diff with oil. Unhappily as fast as I poured it in - it poured out of the nose of the diff housing.
What is the way forward here re replacing oil seal that I presume has given up?
philthehill
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Re: Differential oil seal?

Post by philthehill »

You need to replace the oil seal.
When you have removed the propeller shaft drive flange make sure that the flange oil seal seat is not damaged/scored. If it is scored come back on here for advice.
Use the search facility for details on how to replace the seal.
Do not over tighten the drive flange/pinion nut because if it has a crush spacer you could be effecting the pinion bearing pre-load which could lead to pinion bearing failure.

kevin s
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Re: Differential oil seal?

Post by kevin s »

On such axles I usually mark the nut and pinion shaft with a centre punch then tighten the nut up till the marks align to avoid over crushing the spacer.
oliver90owner
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Re: Differential oil seal?

Post by oliver90owner »

From ~50 years ago, I recall instructions where a crushable spacer was used to find the desired point of proper mesh. The unit was then disassembled, the crushed spacer measured, and replaced by a solid spacer. If the unit was simply dismantled for other repairs, the existing crushed spacer could simply be replaced with a same-sized solid spacer.
philthehill
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Re: Differential oil seal?

Post by philthehill »

The crush spacer is used instead of a solid spacer to increase production rates.
Once the pinion has been set relative to the crown wheel the preload on the pinion bearings can be set using the crush spacer.
With the crush spacer the pinion nut is tightened until the rotation of the pinion is stopped by a specified rotational load resistance.
The force resisting rotation is measured by a weight on a arm at a specified distance from the centre of the pinion. Once the rotational resisting force has been reached the pinion bearing preload is set and nothing more has to be done to the pinion or bearings.
The bearings must be preloaded as in use the forces acting on the bearings try to drive the bearings apart which can lead wear of the crown wheel and pinion teeth so producing axle whine.
The solid spacer in my opinion is the better spacer but it takes much more skill and time to set the pinion relative to the crown wheel and apply the pinion preload.
Last edited by philthehill on Sat Oct 30, 2021 10:27 am, edited 1 time in total.

moggiegeek
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Re: Differential oil seal?

Post by moggiegeek »

Thanks for the replies. I've been through the relevant threads and looked at the videos. I can see that the tricky bit of the operation is to manage the tightening torque in relation to the correct preload.
Not sure I have the tools to measure the preload or the experience and come to that a robust enough work bench and vice. Has anyone used places like Heathrow Transmissions to do this kind of thing or have other recommendations?
The other thing that struck me was how the oil didn't just seep out - it streamed out - is this common with seal failure?
philthehill
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Re: Differential oil seal?

Post by philthehill »

Changing the seal can be done with the differential in the axle - the diff does not have to be removed.
The job of replacing the seal is relatively easy - just do not rotate (tighten) the pinion nut more than it was when you started the job. As above mark the pinion. pinion nut and flange before undoing the nut and removing the flange - fit flange in line with the marks, tighten to bring the marks back in line. Check the nut with a torque wrench to ensure correct tightness but be careful not to overtighten past the marks.
If the oil streamed out is there a seal fitted - had the diff been partly dismantled previously to you.

moggiegeek
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Re: Differential oil seal?

Post by moggiegeek »

The Diff I think was a flea bay purchase. I haven't done any more than clean and swap into refurbed axle.
Thinking about stripping out diff from car and bolting up in old axle casing to give a bit of purchase for loosening/ tightening pinion nut and a safer working environment.
After marking up pinion shaft, nut and flange I'm planning to use an electrical impact socket tool to loosen nut.
Has anyone experience of using the ESM bearing shield they market?
win
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Re: Differential oil seal?

Post by win »

My method to check the preload on the pinion bearing is.
Wrap a piece of string 6 times round the flange shoulder, where it is approximately 2" diameter 1" radius, secured to a bolt hole.
An electronic luggage scales are attached to the string. Pull smoothly, after overcoming the initial inertia, by turning the flange by hand.
The reading should approximately 8lbs without seal fitted, or 12lbs with a seal fitted.
To remove or refit the pinion nut, I have a 3ft length of steel 2" angle, with 2 holes drilled in one end, and a circular slot cut in to allow the socket to fit.

If you can search for a previous question "DIFFERENTIAL OVERHAUL" asked by NDEVANS. It makes exhalent bedtime reading.
It is the most comprehensive description of diff overhaul I have ever seen, well done to all who contributed.

Regards Win have fun
Image
South Yorkshire
philthehill
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Re: Differential oil seal?

Post by philthehill »

https://www.morrisminorspares.com/rear- ... r-p1238342
These 'Speedy Sleeves' are a useful solution to wear on an item that has a seal rubbing against it.

moggiegeek
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Re: Differential oil seal?

Post by moggiegeek »

Thanks for the advice and knowledge. Have now stripped out the leaking differential unit. Noticed that the fresh oil in the diff when drained appears to have tiny flakes 1mm at most of a gold colour and even tinier specks of the same colour. Could it be steel fragments coloured by the oil?
Might I be looking at bronze from a bearing? And if so which one has bronze components?
Declan_Burns
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Re: Differential oil seal?

Post by Declan_Burns »

If the wrong oil (GL5) was used it can attack yellow metal such as thrust washers or brass bearing cages which are sometimes used on angular contact bearings as fitted to the carrier. I would only use a GL4 grade hypoid oil.
Regards
Declan


Regards
Declan
frostythor
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Re: Differential oil seal?

Post by frostythor »

I have recently completed a rebuild on my diff, new pinon bearing and crush spacer, like you I faced the problem of setting the preload, first I found the pinion torque was 135-140ftlbs, and the preload was 11-13 in lbs, so that's 12ilbs at 1 in or 1lbs at 12 inch, dont forget to take in the weight of the 12 inch arm, I place the diff in my vice, so I put a bolt in the flange the place a spanner at on the bolt, the measured from the centre of the flange to the ring at the end of the bolt added a welding rod hook the calculated the weight of water in empty plastic milk container I would need to achieve the required preload, so setting the spanner at the horizontal I started to torque up the pinion nut in stages, of 90 ftlbs, then 10 lflbs, taking the socket off to see if the milk bottle fell, at about 130, the drop had slowed down so bit more needed before the arm stayed horizontal, it felt nice and snug and turn very smoothly, so I am happy with the result
diff preload.jpg
diff preload.jpg (50.66 KiB) Viewed 1521 times
oliver90owner
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Re: Differential oil seal?

Post by oliver90owner »

Frostythor,

The flaw in your method is the mass of the spanner-attachment-arm-thingy - the force due to the weight of the arm will depend on the distance from the fulcrum (centre point of the diff shaft.) and where that mass is acting along the arm.

The simple (and obvious) remedy would be to place an identical spanner-attachment-arm-thingy exactly diametrically opposite to the one in use, thereby equalising the effect of the unknown mass distribution, thereby exactly canceling those extra, unwanted forces.

Unless your spanner-attachment-arm-thingy was of negligible mass (weightless, to you) I suspect your setting was just a bit off. How much, I have no idea, of course - it would depend on the mass of the spanner-attachment-arm-thingy and where that mass was distributed along its length.
frostythor
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Re: Differential oil seal?

Post by frostythor »

the Spanner was 1/2 in to 7/16ths, about 7 inch long the weight of the spanner was negligible, as i loaded the water container with a calculated weight of the lower preload setting, to allow for that, I can understand what your saying and in a perfect world I would agree with you but we are not dealing in rocket science, but in very old Morris Minor tech so a few grams either way is acceptable

the drawing was just to show the simple method of achieving a good result
oliver90owner
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Re: Differential oil seal?

Post by oliver90owner »

Even 100g at 150mm is considerable, not anywhere near ‘negligible’ in my book. That would be 200g at the old unit of a foot. I still consider not taking the spanner into consideration is a flaw. The setting of a differental is not something to ‘just get close’. The tolerance quoted is less than ±10% of the mean value of 12lb.inch. Get it right - it is simple enough to do that, without being sloppy or guessing with the setting.

Clearly the longer the spanner, the less mass required at the end. That could mean an even larger moment being supplied by the spanner. Even a GCSE student, carrying out a science experiment would try to eliminate errors if they were expecting a good result.

Nor do we know how large the spanner might be, employed by an inexperienced person. So play safe and use a balanced system is my advice. If a job is worth doing, it is worth doing properly.
frostythor
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Re: Differential oil seal?

Post by frostythor »

I very much doubt they were that precise during the build, as the torque setting is 135-140ftlbs and the preload is 11-13ftlbs , so like I have already said, if you set you weight on the lower preload, it would still give a good result against the crush tube, and even if the spanner was 200 gram. it spread over a distance of 7 ins not at 7 inch, so if that was the case and the complete weight of the spanner was included in your calculation, then the spanner plus 11 would result in a preload of 11.4inlbs , well under the max of 13
Last edited by frostythor on Tue Nov 09, 2021 7:15 pm, edited 1 time in total.
kevin s
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Re: Differential oil seal?

Post by kevin s »

The way I used to do it on similar ford diffs was with the spanner vertical so the weight was negligible and a spring balance, that said after a couple you get a feel for it and end up just doing it by feel.
moggiegeek
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Re: Differential oil seal?

Post by moggiegeek »

Have now now marked and removed pinion nut, lock washer and flange to reveal NO oilseal.
The prop shaft flange bearing surface polished up easily so no need for a protective shield. Noticed that the outer pinion bearing cage is a bit distorted on one side - see photo. It doesn't seem to affect the smooth action of the bearing.
Feel inclined to reassemble and test..... Advice??
PS will probably go for string and luggage spring scale option.
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moggiegeek
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Re: Differential oil seal?

Post by moggiegeek »

As a PPS it is clearly a mg midget differential,outer pinion bearing is a timkin taper roller bearing.
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