Monday, February 23, 2015

Differential Stripdown

<This post is part of the 'Winter Project 2014/15 - (Gearbox Refurb)' project>

With the engine block pushed to one side for a while, I need to get to work on getting the transmission sorted out. I have been buying a selection of engines over the last year and have three gearboxes to choose from, two of which have diffs.

Each of the gearboxes has its own good and bad points, so I decided to cherry pick the best bits from each and build a new gearbox out of those parts. That way I get the best of all three and also learn about gearboxes in with the deal, starting with the diff.

First thing is to separate the differential housing from the gearbox and that starts with the two output shaft covers at either side...

Bolts out.
And away.

Now to the main housing, I started by tapping back the locking tabs and taking out the bolts.

Tap the tabs back.
Take the bolts out.

I found a good place to lever the housing off without damaging the soft aluminium surface.
Wedge, wiggle and...
it's free!!

Now that the diff unit is free, I can start to take it to pieces and check out what state it's in. Also to assess what, if any new parts I might need to buy.

After lifting the innards out, and removing the shim, I removed the bearings with a bearing puller. As I found out later on, it's not really necessary to remove the bearings to strip the unit down.

Shim, shimmeny!

With all the bearings removed, I started to tap back the lock tabs on the main crown wheel so the bolts could be removed. The bolts were very tight, but holding the diff in a vice, I was able to undo the bolts with a breaker bar.

With all the bolts out, the crown wheel could be separated.

Now the tricky bit, removing the small locking pin that locks the differential main shaft in place. It was incredibly difficult to knock out, but I managed it using an old masonry drill bit that fit in the hole precisely. Luckily the pin came out before the drill bit was too destroyed.

Once it was out, the shaft could come out along with the planetary gears and their thrust washers, plus a few other bits.

Sliding the output shafts from their housings, there is a fibre washer to remove. I almost missed it as it was stuck in place with oil.

Once both diffs were fully stripped down, I was able to examine all the parts and pick out the best bits from each, arranging them in a way that satisfied my peculiar need for regularity and order.

Once all the parts were checked over I could see there were a few items that were knackered in both diffs so I will need to buy new ones.

On the shopping list is:
One new shaft as both were worn and rough

One new planetary wheel as three were damaged on the interior surface.

Two new copper thingies as they should always be replaced as a matter of course.

I also may need some new shims for when I come to rebuild the unit and also some new fibre washers. Also it goes without saying that we need new gaskets and oils seals, but for now, everything needs cleaning ready for re-assembly.

In fact, here it is all dirty and grimy...

And before you can say, bish bash,bosh, It's all clean and new looking just like that! If only it were that quick!!

It's amazing what a bit of diesel and elbow grease can achieve. Hmm 'Diesel & Elbow Grease'! That would be a great name for a band! Anyway, nonsense aside, that's been my journey into the wonderful world of the differential, and very interesting it has been too.

Now, onto the gearbox... Gulp, wish me luck!!!

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  1. Wayne, did you use the same diff housing from the gearbox casing you chose? this is important as when they are produced they are line bored to ensure all tolerances are correct, swopping diff housings can cause problems if you where not aware of this my friend

    1. Oh dear, I don't think I did. Let's hope the 'can' doesn't become a 'will'! Thanks for the tip Gav. It's small nuggets of knowledge like this that are so useful.