Differential oil seal?

Discuss mechanical problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

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.
oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Differential oil seal?

Post by oliver90owner »

PS will probably go for string and luggage spring scale option.

An even better way, than a spring weighing scale, is the string over a low friction pulley with the appropriate mass hanging vertical, it having the very constant force of gravity on it.
Declan_Burns
Minor Legend
Posts: 1956
Joined: Wed Apr 18, 2007 7:32 am
Location: Düsseldorf, Germany
MMOC Member: No

Re: Differential oil seal?

Post by Declan_Burns »

I use an in-lb beam style torque wrench. They are not that expensive. The photo shows the tooling I use on MG T-Series diffs. The in-lb torque wrench as shown in the centre of the photo.
Regards
Declan
Attachments
IMG_5213.JPG
IMG_5213.JPG (2.27 MiB) Viewed 1229 times


Regards
Declan
moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

Now ready to reassemble.
1) Which way does the pinion oil seal face IE are the lips of the seal towards the diff or propshaft?
2) Does the seal fit flush with the casing or does it sit at the diff end of the housing?
Many thanks
moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

Now ready to reassemble.
1) Which way does the pinion oil seal face IE are the lips of the seal towards the diff or propshaft?
2) Does the seal fit flush with the casing or does it sit at the diff end of the housing?
Many thanks
philthehill
Minor Maniac
Posts: 10767
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: Differential oil seal?

Post by philthehill »

The hollow/concave side of the seal faces the diff.
The seal fits flush with the end of the casing.

moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

Update, seal fitted correctly.
Torqued up pinion bolt but marks made on pinion bolt and shaft at disassembly just miles off. I assume whoever removed the oil seal torqued it up to unknown value.
So incrementally tightened bolt in initial 10 ft lb steps.
Measured the preload using electronic luggage scale and string around narrow part of diff flange. Pulled upwards and discounted value to overcome limiting friction.
Basically I can have accurate preload within limits but with only 60 ft lbs torque on bolt or accurate torque in region of 130 ftlbs but high preload in region of double the preload or more.
Question is what to do now?......
oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Differential oil seal?

Post by oliver90owner »

I would suggest you need to start the rebuild ing again - with a new crushable spacer. Crown-wheel and pinion will likely either howl loudly and/or wear rapidly if not rebuilt to specifications.
moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

Have stripped down and extracted crush washer which had to be fine chisel cut longitudinally it was so compressed on pinion shaft.
Height (crushed) is 18.77mm. the two new crush washers are 20.69 and 20.79 respectively.
Can I use one of the new crush washers and progressively tighten up to get required torque range and preload?
philthehill
Minor Maniac
Posts: 10767
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: Differential oil seal?

Post by philthehill »

So long as the pinion is positioned fore and aft as original (no spacer/packing washers removed or added and you are using the same bearings) relative to the crown wheel I see no reason that you cannot install the crush washer as you describe.

Declan_Burns
Minor Legend
Posts: 1956
Joined: Wed Apr 18, 2007 7:32 am
Location: Düsseldorf, Germany
MMOC Member: No

Re: Differential oil seal?

Post by Declan_Burns »

If you run out of crush washers :o , I still have some solid spacers here that I had made up. They are 20mm. You are welcome to have one if you cover the postage.
Regards
Declan


Regards
Declan
moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

Have now installed new crush washer, oil seal and torqued up to 132ft pounds. No shims added, seen or removed.
The preload is now high 12 occasionally 13 foot lbs on exerting a steady pull on the propshaft coupling with string and digital luggage scale. A bit looser in fact than a spare 4.2 diff I have.
Hopefully this will suffice. As warned the preload shoots up and it's dead easy to end up overloading even with smallest torque wrench increments.
Thanks for all the help - road test or redo with last remaining new crush washer?
Myrtles Man
Minor Legend
Posts: 1081
Joined: Wed May 16, 2018 10:49 pm
MMOC Member: Yes

Re: Differential oil seal?

Post by Myrtles Man »

moggiegeek wrote: Wed Nov 17, 2021 2:56 pm Have now installed new crush washer, oil seal and torqued up to 132ft pounds.
Wow! That should crush it all right! :o
philthehill
Minor Maniac
Posts: 10767
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: Differential oil seal?

Post by philthehill »

The ideal torque setting is 140lbf ft.

oliver90owner
Minor Legend
Posts: 1653
Joined: Thu May 12, 2016 6:33 am
MMOC Member: No

Re: Differential oil seal?

Post by oliver90owner »

If I were ever to do one (which I doubt - I have a spare) I would set up the diff with a crush spacer, then make a solid one to replace it. No bother, then, of needing to worry about torquing the nut to specification, in the future, if the seal needs replacing.🙂
Declan_Burns
Minor Legend
Posts: 1956
Joined: Wed Apr 18, 2007 7:32 am
Location: Düsseldorf, Germany
MMOC Member: No

Re: Differential oil seal?

Post by Declan_Burns »

Exactly!
Regards
Declan


Regards
Declan
philthehill
Minor Maniac
Posts: 10767
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: Differential oil seal?

Post by philthehill »

I would suggest that whether you have a solid spacer or crush spacer just replacing the nose seal and applying the correct torque will not effect the pre-loading on the pinion bearings. If you under torque or over torque then you will have problems.
Just replacing the seal can be made to sound complicated but it is not if care is taken with the process.

moggiegeek
Minor Fan
Posts: 268
Joined: Sun Mar 14, 2010 9:06 pm
MMOC Member: No

Re: Differential oil seal?

Post by moggiegeek »

What seems to be emerging is that ensuring the correct torque when replacing the nose seal is the most important parameter. I became more concerned with the preload and so didn't torque beyond 132 ft lbs cos the preload seemed to be whizzing up.
In retrospect I should have focussed on the torque.
However all now reinstalled and road tested and all seems good ,- no whine or howl .
And I learned a lot. Thanks to all.
Post Reply