Rear Diff seal

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01 Nov 2012 11:43 #1 by dandjcr
dandjcr created the topic: Rear Diff seal
Forum Home > OKA Maintenance > Rear Diff seal

Tony Lee
Member
Posts: 539
Not sure whether it was the fine sand coming across the Simpson, or perhaps the 147 mud-soup bog-holes coming down the Birdsville Highway, but the end result is that the rear diff pinion seal is leaking more than it is sealing.

The diff service manual promises instant death for anyone who even looks at one of their diffs without first buying 67 different special tools and a surgeons' gown and mask - but the OKA service manual, being somewhat more pragmatic, in the section on drive shafts, merely says to get the pinion yolk off, just unscrew the pinion nut.

My question is, since that seems to requires nothing more than a 1 5/16 socket and strong arms, can the seal be then prised out, things cleaned up a bit and then a new seal put back, the yolk replaced if not scored and then the nut done back up to the 200-odd ft-lbs specified in the manual -- all without requiring any special tools and with a reasonable chance of success.

Also, does the seal require any sealant between it and the outer recess. Manual doesn't mention it, but lots of these sorts of things are not in the manual because they are regarded as good practice.


Why don't they fit a seal protector like on the front of the transfer case???

Also need to put new brake pads on the rear wheels. Rotors will naturally be so scored they should be machined, but that isn't going to happen here at Beltana Station so guess they are going to wear pretty fast.. Garage in Birdsville ran out of brake pads for normal 4WDs because the grey sticky sandy mud on the Eyre Creek detour (about 4km of water-filled deep ruts) ripped hell out of pads and discs. Obviously didn't do mine any good either. Alternators and starters also had a very high failure rate.

--
Tony

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September 25, 2010 at 8:10 PM Flag Quote & Reply

Peter_n_Margaret
Member
Posts: 198
1. Although I have not done it myself, I have had a couple replaced and I reckon it is as simple as you propose,
2. If it is scored it will leak again soon. Add a Speedie Sleeve for a better result.
3. I now have a seal protector after replacing a couple of seals. No leakers since.
4. Just whack in a new set of pads.

Cheers,
Peter

--
Cheers Peter, OKA196 Motorhome. www.oka4wd.com/xt196.htm



September 25, 2010 at 8:53 PM Flag Quote & Reply

Peter & Sandra James Oka 374
Member
Posts: 412
Tony, what you say is correct with a couple of addendum's
1/ When you remove the tailshaft, before you touch the nut, mark the end of the pinion shaft, the nut and yoke all in line with a centre punch and white paint or similar.
2/ Undo the nut, remove the yoke and repair/replace as you said taking time to clean up the yoke seal surface, fit a speedy sleeve if it is badly scored. Also fill the V on the seal with multipurpose grease before putting the yoke back in, helps lube it on initial contact.
3/ refit the yoke to the pinion shaft, lining up the marks, then refit the nut and only tighten until the marks are lined up. The reason for doing it this way is that upon initial setup when new the diff preload would have been set correctly with new bearings. When you refit with old bearings as you are doing if you retighten to 200ft/lbs you will overload the used bearing leading to failure. Also diffs quite oiften have a crushable spacer on the pinion shaft to allow that initial preload to be set, crushing it futher is not good.
Slingers to protect the front of the seal to fit the yoke are available.
Another special tool you can make at home is a length of heavy angle iron drilled to fit the uni bolt holes which can be used to jam the pinion to stop it turning while removing and refitting the pinion nut. You may need to V one side for clearance on the nut.
Peter
September 26, 2010 at 6:57 AM Flag Quote & Reply

Tony Lee
Member
Posts: 539
"1/ When you remove the tailshaft, before you touch the nut, mark the end of the pinion shaft, the nut and yoke all in line with a centre punch and white paint or similar."

Thanks. Good to remind me although it is one of the 'good practice' things I actually do. I remember doing it on the bigrig when I mistakenly thought pinion seal replacement was a job I could do. Bent (borrowed) 1" Sidchrome bar and lots of effort later, I gave it up. Should have read the manual which stated quite clearly that required torque was 900ft-lbs. Bit beyond a backyard job. That's one of the things I appreciate about the OKA - all the torques are within my feeble capabilities AND a suitable torque wrench is within my feeble financial reach too.

Thanks also Peter. I'll get Paul to find a seal guard when he sends the replacements for the spares I carry hoping never to use them. and stick that on too.


Hmmm while I've got the tailshaft off one end, I might take it off the other end and see if there is any good reason why the handbrake barely holds on level ground and then only when there is no wind blowing.
--
Tony

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September 26, 2010 at 7:41 AM Flag Quote & Reply

Dandj
Member
Posts: 367
Tony, I replaced the rear diff seal a year ago (from Paul Nott). I borrowed an electric rattle gun to remove and replace the (new) pinion nut. I bolted a steel bar across the yoke (leaving room for the socket) and jammed it against the concrete to reduce the shock load on the bearings and pinion.

While I was at it, I had the yoke (and the front shaft one) modified by Paul Nott to use U-bolts to hold the UJs rather than those flimsy straps. Much stronger and after 20,000 km, no more diff leaks.

I also modified my handbrake to make it more effective, see our home page for details.

Regards.
--
David and Janet Ribbans, Oka 148

September 26, 2010 at 9:20 AM Flag Quote & Reply

joseph baz
Member
Posts: 331
Peter & Sandra James Oka 374 at September 26, 2010 at 6:57 AM
Tony, what you say is correct with a couple of addendum's
1/ When you remove the tailshaft, before you touch the nut, mark the end of the pinion shaft, the nut and yoke all in line with a centre punch and white paint or similar.
2/ Undo the nut, remove the yoke and repair/replace as you said taking time to clean up the yoke seal surface, fit a speedy sleeve if it is badly scored. Also fill the V on the seal with multipurpose grease before putting the yoke back in, helps lube it on initial contact.
3/ refit the yoke to the pinion shaft, lining up the marks, then refit the nut and only tighten until the marks are lined up. The reason for doing it this way is that upon initial setup when new the diff preload would have been set correctly with new bearings. When you refit with old bearings as you are doing if you retighten to 200ft/lbs you will overload the used bearing leading to failure. Also diffs quite oiften have a crushable spacer on the pinion shaft to allow that initial preload to be set, crushing it futher is not good.
Slingers to protect the front of the seal to fit the yoke are available.
Another special tool you can make at home is a length of heavy angle iron drilled to fit the uni bolt holes which can be used to jam the pinion to stop it turning while removing and refitting the pinion nut. You may need to V one side for clearance on the nut.
Peter
Sorry to disagree guys,the problem with torqueying the nut to the original mark is that you don't know what the original torque was,the DANA 70 pinion preload is adjusted by shimms between the pinion bearings,what you have to be careful if you remove the outer bearing to make sure that no shimms are attached to the bearing and end up in the washing tin,that will be the only way that you can alter the preload in that model diff pinion,if for some strange reason you have a crush sleeve you should be replacing it as the sleeves are a single use,if you can find the old style slingers they are a lot better as the flange is much wider and covers the whole seal area rather than just the lip
Cheers,Joe
September 26, 2010 at 12:36 PM Flag Quote & Reply

Tony Lee
Member
Posts: 539
Hmmmm! I started this exercise by reading all relevant sections of the diff service manual and anything slightly pertinant in the OKA Service manual. I ended up a little puzzled so posted here.

I was relieved when my puzzlement seemed to have no basis, but now after several more posts, I am totally confused.

Crush Washers?? Don't remember reading about them so maybe an XT OKA doesn't have them and we can forget about them OR it does have them and my service manuals are inaccurate. A crucial consideration or red herring?? I don't know.

As for preload. My understanding is that it is done by adding shims and then (I presume), putting the yolk on WITHOUT the seal, tightening the nut up to 150 to 250 ft lbs (or whatever the actual range specified is), measuring the torque required to rotate the pinion and undoing the nut, removing the yolk and adding or subtracting shims and repeating the process until it is correct. THEN, wouldn't the last step be undo the nut, remove the yolk, insert the seal, put the yolk back on and then do the nut up tight enough to firmly compress any shims. By my reading, this is achieved by doing the nut up "pretty tight with a large tolerance" and there is no mention of any torque having to be exact.

Therfore, in my case, if I remove the yolk and prise the seal out and clean up any muck that got past the seal (possibly even to the extent of withdrawing the outside bearing AND being VERY careful not to lose any shim washers - or even change the order they were in), can't I just put all the bearing and shim washer bits back in their correct place, add a new seal and then put the yolk back on and do the nut back up " pretty tight with a large tolerance" as specified then won't it be exactly what the bloke who did it in the first place did, so it should be still correct.???????

Or have I got it all a***-up and maybe I should just remove the rear tailshaft and both rear axle halfshafts so the diff doesn't do anything and finish the trip in front wheel drive and get an expert to fix the problem.
--
Tony

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September 26, 2010 at 10:40 PM Flag Quote & Reply

joseph baz
Member
Posts: 331
You're right,if you haven't removed any shimms from the pack it's all sweet to re assemble and torque the nut as per the specs,the pre load measurements are done at the diff setting up,a seal replacement is a very straight forward procedure,make sure that you lubricate between the lips with a bit of grease.
Cheers Joe
September 26, 2010 at 10:57 PM Flag Quote & Reply

Tony Lee
Member
Posts: 539
I'll give it a go.

"make sure that you lubricate between the lips with a bit of grease."

Yes, apparently works wonders ;-)))

If you hear a loud diff-type howling coming out of the north Flinders Ranges, you will know I messed it up.

Next question - well, not a question perhaps, but why don't they fit a drain plug to these diffs - especially when they say it needs draining EVERY day when operation in deep water. Every other vehicle I've ever owned has diff drain plugs. Never used them, but now that I should use them, haven't got them
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Tony

picasaweb.google.com/114611728110254134379

September 26, 2010 at 11:11 PM Flag Quote & Reply

joseph baz
Member
Posts: 331
It's basically to get lazy people to check the diff internals,I welded a nut in my cover and regularly check the level,if the diff isn't noisy is no need to remove the cover(in my opinion),what you did it's fine and should be no probs,just one little point,the diff nut torque is to be done up at 260 ft lb it's in the very last page of the Spicer maintenance manual
Happy travel!!
Joe
September 26, 2010 at 11:25 PM Flag Quote & Reply

joseph baz
Member
Posts: 331
I should clarify,I welded a 1/2" nut at the bottom of the cover so I can drain a bit of the oil and check for water,metal or impurities.
Cheers
September 26, 2010 at 11:41 PM Flag Quote & Reply

Hal Harvey
Site Owner
Posts: 510
While you're on the drain plug subject, there is an alternative if you want to keep adding to that shopping list Tony. I replaced the Dana covers with aluminium Mag-Hytec ones, which have magnetic drain plugs along with O-ring seals, a dipstick complete with high and low marks and a magnetic insert, and a temperature sending port. And a bit more capacity.


-

The second one isn't mine, it's just for the purpose of illustration. The real thing has the O-ring groove incorporated like the Dana 60 one illustrated below...

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Hal

September 27, 2010 at 1:02 AM Flag Quote & Reply

Peter_n_Margaret
Member
Posts: 198
Diffs don't need draining if you have them vented properly.
I drain mine anually. Never had water in a diff.
Front wheel bearings are mich more problematic for water ingress.

Cheers,
Peter
--
Cheers Peter, OKA196 Motorhome. www.oka4wd.com/xt196.htm



September 27, 2010 at 6:21 AM Flag Quote & Reply

Tony Lee
Member
Posts: 539
"While you're on the drain plug subject, there is an alternative if you want to keep adding to that shopping list Tony. I replaced the Dana covers with aluminium Mag-Hytec ones, which have magnetic drain plugs along with O-ring seals, a dipstick complete with high and low marks and a magnetic insert, and a temperature sending port. And a bit more capacity."

Gee Hal, I'm just a poor pensioner who finds filling up the tank bad enough without trying to keep up with the tycoons. Still, I'm encouraged that this particular mod is 101% functional and not at all concerned with adding bling.
Didn't notice any iPod dock and speakers mounted on the diff to keep you entertained while polishing the cover after each outing :-))).

Yes, I'm just jealous.
--
Tony

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September 27, 2010 at 8:06 AM Flag Quote & Reply

OKAPETE .......... Peter and Sharon Furlong.
Member
Posts: 33
Just thought I'd put my two bobs worth in here also, seeing as we talking diffs,(applicable to F & R but rear usually doing the distance quicker) It is recommended that every 40,000 kms you retorque the crown wheel bolts, as they can loosen and/or break over time, in fact even better is to ensure or upgrade them from grade 8 to higher grade 12 or cat bolts. The recommended torque setting is 120 lb ft, (163 Nm). I have heard it said that this is the reason there is no drain plug, to ensure that as the cover has to come off to change diff oil, that you check the crown wheel bolts at the same time. cheers pete.
September 27, 2010 at 10:55 AM Flag Quote & Reply

Tony Lee
Member
Posts: 539
Peter_n_Margaret at September 25, 2010 at 8:53 PM
1. Although I have not done it myself, I have had a couple replaced and I reckon it is as simple as you propose,
2. If it is scored it will leak again soon. Add a Speedie Sleeve for a better result.
3. I now have a seal protector after replacing a couple of seals. No leakers since.
4. Just whack in a new set of pads.

Cheers,
Peter

Peter - and others,
I asked Robin to send me a shaft protector for the rear diff but he reckons they are no longer available. Any suggestions where I might source one - assuming they are still available.

Fitting a speedy sleeve if I need to - assume they have to be glued on somehow. Is the adhesive supplied in a kit. Alternatively I have some of that good red silicon used by mechanics. Would that work??


--
Tony

picasaweb.google.com/114611728110254134379

October 2, 2010 at 8:36 AM Flag Quote & Reply

joseph baz
Member
Posts: 331
Tony, if the yoke is badly grooved the correct way is to clean the metal well,fill the grooves with a compound ( i use DEVCO) file it smooth and then press the speedy sleeve,you can use Loctite (bearing and shaft retainer) you can leave the flange on or tear it and welah! its done as far as the yoke slingers,Spicer(and others) decided their are no longer needed but they make a big diference with de durability of the seal,I'm going to make some enquires to get some made,i let you know the outcome
joe
October 2, 2010 at 10:36 AM Flag Quote & Reply

dingo
Member
Posts: 14
Hi Tony lea,
I have done the seal replacement twice in the last two years. Could someone post a pic of the protector sleave!

First I did this job on the road side, its real easy and the seal has some rubber to self seal onto the housing. Just got to buthcher the old seal out with a screwdriver. The pinion pre load should be via shims in all the big DANA's, crushable washers arn't a great idea with big diffs (there not a great idea.).
A realy neat tool to help with ths job is one of the 12v KC impact guns about $100 from your local 4x4 shop. thease are not rattle guns but a propper impact gun ( I know their plastic and chinese, trust me!). With ear plugs and time they will undo anything on an OKA that is undoable. I use it for wheel nuts, transfer case and diff pinion nuts. You just have to get comfy and spend 20 minutes or so pulling the little tiny trigger repeatedly. It is also much safer than swinging great big bars etc under a truck where you have little room.

Another great fitters allronder tool that every OKA owner should have is a nut splitter. A good tool shop should have one for under $30. It clamps over the nut then as you tighten it up it swells the nut out (poor discription) which will loosen big old ceased nuts that hold body/chassis together. Once you get the hang of it you will be able to judge how much to winder her up with out doing permenat damage to the nut. Or keep winding and it will crack the nut in half.
Tim.
October 2, 2010 at 11:17 AM

David and Janet Ribbans - Oka 148
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