How to check a rear diff

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GrumpyGel

GrumpyGel

Well-Known Member
Posts
26,393
Location
Christchurch, New Zealand
3 years ago I managed to trash my IRD - I believe through an under inflated tyre. At the time I got a rebuild kit for the IRD and it was rebuilt good as gold - but I removed the pinion gear so it didn't drive the prop shaft.

At the time, I didn't consider the VCU or rear diff. However its been running 2WD perfectly happily since.

I'm now coming to reinstate the 4WD. I have a replacement IRD. My VCU has been lugging the forward prop around for 3 years and is absolutely stuffed (if it was not before). I have a replacement VCU and am not concerned at this point about that.

However, I'm a rather concerned about the rear diff. The events leading to the IRD being trashed would have put a lot of stress into it and I haven't examined it at all - I didn't even change the oil at the time - its probably never been changed. Once I go back to 4WD its obviously going to put a lot more stress through it than it is now so I'd like to give it a check over to see if its OK. I don't though know what to look for.

Has anyone got any pointers on what I can do to check it to see if its in a decent condition? Also any pointers on what to examine on the mounting bushes to make sure they are OK.

Ta.
 
If its a doubtfull whether I can rely on it without a full strip down (in which case I might as well get some bearings and do a rebuild), I might just swap both the IRD and diff over from my parts car. If it all goes bang, at least I can then just go back to what I have now.
 
First off, see how much pinion back lash there is.
If is only a small amount, say a few mm at the flange, then I'd move on to step two.
Step two consists of removing the rear pan and draining the oil. Do this after a drive of a few miles, to warm the oil. I undo and remove 8 of the rear pan screws. Go for a drive to warm it up, then remove the remaining screws and prise off the pan. Examine the oil for metal particulates, as you would for the IRD. There may be some bronze particulates, which is normal. Silvery flecks would indicate bearing failure and gritty chunks would be gears.
Oil should look like this.
20160417_121330.jpg

If all seems well, then it probably is fine. With the pan off, look at the gears, turning the diff slowly. You are looking for strange wear and missing bits of tooth. The unworn sections of the teeth will look mat. The working surface will be polished. If the working surface is pitted, the diff is best replaced.
If it passes the visual check. Get your fingers on the diff cage and see if it's loose. If not, see how loose the planet gears in the diff cage are. There will be some looseness however.

If you are happy. Reseal the rear pan with RTV and fit all the bolts. Fill with fresh 80w90 and forget about it for another few years.

This is what you will see under the pan.
20160417_114818.jpg
 
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As usual life gets in the way of Freelander. Only time available was basically spent procrastinating the issue.

I like to have a good understanding of what ever job I take on and I didn't really have any idea how the diff is installed. I know it has 3 mounts, but I've seen images of the mounts and they look very strange! So I wanted to get a good look. I'll be taking the diff off the parts car first - so I started with that - I can take my time procrastinate and learn while the main car is still road worthy.

So I consulted Rave and it looks simple to remove the diff - remove the prop shaft (already done to harvest the VCU), drive shafts and the 3 mounts. Then lower of a jack turning it through 90 degrees. I wanted to get a good look at what this entails, so I lifted the back of the car and put it on axle stands. I then removed the back box of the exhaust - and wham - its like a theater all opening up in front of your eyes :) With the box out of the way you have great site of the diff and how its all installed....

20170305_180559.jpg


The splashes are WD40 used on the bolt to loosen the back box. I undid it a bit - but the bolt snapped in the end.

I've often wondered where the big round "bushes" on the mounts are fixed to - where they slot into. With the box removed its obvious they go nowhere! They just sit there poking up in the air! I presume they are just dampers of some kind.

Unfortunately I didn't have time/light to do any more - but I'm happy now that maybe one afternoon in the week I can remove it. I'll drain the oil and if it looks OK it will go on the main car and be filled. I expect the oil to be good - the oil that was in the IRD was perfect. I will see if I can get a couple of seals as different shafts will be plugged into it and it probably good practice to change them. I won't bother with the pinion seal and I won't be disturbing that.
 
I am around this week, would you like me to drop in and offer an opinion/help?

I have done (in more ways than one) a few diffs in my time.
 
That would be great Tony :)

I'm busy tomorrow - hoping to get the diff off on Tuesday. So maybe after then you could come over and we can open it up and you can see what you think of it?

How was the house you looked at today?
 
BTW - in the "Differential Refit" instructions in Rave it talks about (and even has a video of) a special tool "centralising jig LRT-51-013" used to position the diff before the mounts are trightened.

Is this needed? Is it not sufficient to fix it by sight?
 
GrumpyGel said:
BTW - in the "Differential Refit" instructions in Rave it talks about (and even has a video of) a special tool "centralising jig LRT-51-013" used to position the diff before the mounts are trightened.

Is this needed? Is it not sufficient to fix it by sight?
Click to expand...

No need for a jig to mount the diff. I just make sure the bolts hold it as high as it can go. There is a small amount of slop on the mount to diff bolts.
Although it's easier to check the old diff over, before going to the work of changing it unnecessarily;)
 
GrumpyGel said:
That would be great Tony :)

I'm busy tomorrow - hoping to get the diff off on Tuesday. So maybe after then you could come over and we can open it up and you can see what you think of it?

How was the house you looked at today?
Click to expand...

Great, give me a PM when you are ready for me.

House was good, our second viewing. Interesting place, a bit of a mess inside with superficial damage but all good otherwise. Putting in a cheeky offer today. Emailed the Real Estate agent with my plan and she is happy to submit it to the vendor.
 
Tony Reeves said:
Great, give me a PM when you are ready for me.
Click to expand...
Will do :)
Tony Reeves said:
House was good, our second viewing. Interesting place, a bit of a mess inside with superficial damage but all good otherwise. Putting in a cheeky offer today. Emailed the Real Estate agent with my plan and she is happy to submit it to the vendor.
Click to expand...
As you say "superficial damage" I take it that its in North Canterbury/Marlborough?
 
GrumpyGel said:
As you say "superficial damage" I take it that its in North Canterbury/Marlborough?
Click to expand...

Greta Valley. It suffered a little in the Canterbury quakes, but at the time EQC said it was pre-existing and the owner did not bother to get it reviewed, or fixed. So we get a good house that needs little more than a repaint and a little gib-stocking.

Got a neat double garage and workshop.
 
Tony Reeves said:
Greta Valley. It suffered a little in the Canterbury quakes, but at the time EQC said it was pre-existing and the owner did not bother to get it reviewed, or fixed. So we get a good house that needs little more than a repaint and a little gib-stocking.

Got a neat double garage and workshop.
Click to expand...
Nice place :)

Lovely area, not to far from the city, closeish to the shops in Amberley, close to the cafes of Cheviot, close to the wines of Waipara, close to good fishing in Motunau, close to the Salmon in the Hurunui, close to skiing at Lyford, an hour from Kaikoura and Hanmer. Perfect :)

Room for a lodger? :)
 
Nodge68 said:
No need for a jig to mount the diff. I just make sure the bolts hold it as high as it can go. There is a small amount of slop on the mount to diff bolts.
Although it's easier to check the old diff over, before going to the work of changing it unnecessarily;)
Click to expand...
To be honest, it doesn't 'look' like to much work to remove/swap diffs over.

I got another couple of hours to work on the car this evening, to remove the diff from the parts car. Rave says to remove the drive shafts, however in the oil seal replacement section, it describes removing the bolts securing the 3 suspension arms and pull back the hub which allows the shaft to be popped out of the diff. So, after cracking the 6 bolts on the diff mounts, I've released the suspension arms on both sides and it was dead easy; a squirt of WD40 and the bolts and bushes all came out allowing the hubs to move back a bit. However, I've popped the shafts out of the diff but they do not go back far enough to extract them completely! I'm confused. The combo of strut and hand brake cable isn't allowing the hub back far enough.

So maybe you are right! But I've set my goal of completely swapping out the transmission (IRD/VCU/diff) - in doing this, if anything goes wrong I can put back the current ones that have been perfectly reliable.
 
Yesterday I spent another hour on retrieving the parts diff. An hour of pain and frustration - all due to my misunderstandings!

As I couldn't get the shafts out of the diff - I thought that maybe the diff could be shifted sideways a bit to get them out. This was confirmed by Austen on an old thread. So I thought I'd remove the diff mounts to give it a bit of room. Each mount has the big bolt going through it, so picked one to start with and got the socket on the nut. Geepers it was hard going. Lots of heaving, lost skin and swear words and I still hadn't got the nut off when I had to finish up.

So at this point, I'd failed to get the shafts out and failed miserably to remove 1 nut.

Coming back to it today, I thought I'd check the hand brake cables again as the clip Rave said to losen I didn't have on the car - but of course I did and I'd missed them. 10mm spanner, off the come and out pops the drive shafts. Easy when you don't cock it up.

So back to 'harvesting' the mounts. I finally managed to get that nut off, but didn't fancy the same agro with the other 2. Thought I'd try putting the socket on the bolt end. Out they popped nice and quick - the nuts are captive, welded to the brackets! Easy when you don't cock it up. The front mount though is completely shagged.

So with the shafts out and mounts harvested I lowered the diff on the trolley jack and Bob's your uncle!

Still time for 1 last Grumpy cock-up! I moved the diff to the garage, placing it on the floor nice and level so no oil spills out. Put all the bolts back on the suspension, tidy up all my tools, back into the garage to find diff sitting in a big puddle of oil! Bugger.

At least the oil looks nice and black :)
 
Seems like a lot of work, if you are doing it unnecessarily GG. I'm betting the original diff is perfectly serviceable. They are pretty robust little units. ;)
 
Nodge68 said:
Seems like a lot of work, if you are doing it unnecessarily GG. I'm betting the original diff is perfectly serviceable. They are pretty robust little units. ;)
Click to expand...
I'm sure you're right Nodge :) But this Freelander has been so good as a 2WD I don't really want to start fiddling with it - I even went to have a look at another 4WD L Series to run as a 2nd/3rd car yesterday - but don't tell Mrs Grumpy! So if anything goes wrong - I want to be able to put it back exactly as it is :)
 
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