Welcome back to Sipa's garage.
This time I'm going to show how to refurbish this kind of BMW LSD rear diff.
This our unit is bit faulty because the LSD unit doesn't work properly anymore.
it's slipping quite badly and while driving it feels almost like open rear diff.
I can't now rotate these by hand but when this was mounted I could make this slip by rotating the tires.
So it was very close being open diff.
These have originally 25% LSD unit which is good for most of the use cases when the unit is in good condition.
And I mean in good condition. When these wear too much you will start having problems.
So I'm now going to show how to refurbish this.
You can find this kind of LSD units from the old vintage BMW's.
So for example e39 and e46 are too new and those have different style rear diffs.
But these typ188, smaller typ 168 and larger typ 210 rear diffs can be found from the older cars.
This particular one is typ188 diff from e34.
Not sure from which exact model, but it's typ188 at least.
Of course you could put these LSD units to newer diffs but you will need lathe to do that.
So these instructions are only for the old diffs.
And what wears out in these LSD units are the friction disks inside the unit.
So here I have new set of disks that need to be swapped in the LSD unit.
These were bit over 100 € in eBay so these probably aren't OEM parts.
But still these should be fine.
So lets see how to get these in the diff and get it working properly.
The first thing we need to do is to drain the old oil out of diff using the drain plug.
Oh wait. This doesn't have drain plug.
I will need to do this the dirty way.
Which means that I need to open the back cover to drain the fluid.
...all over the floor.
So lets just do it.
Yack
And the gear oil smells disgusting.
Then we need to get this LSD unit out of the casing.
And to do that I will first need to remove these output shafts.
Like that.
Then I need to pry out the bearing covers.
okay and now we have the LSD unit with gear ring out of the casing.
now we can go the other table and open the LSD unit itself.
Oh!
Come look at this.
These are in really bad shape.
Quite much wear.
yeah. Never seen that bad friction disk.
Nice..
Fuck these are slippery.
As you saw the friction disk were in really bad shape.
But to fix that just put in new disks and assemble in same order.
And really make sure that the parts go in in same order as they came out or the LSD unit wont work properly.
But otherwise this is really simple job to assemble everything.
And lastly tighten up the bolts before putting it back to the diff.
These seemed to be normal m8 bolts so I did tighten these to 23 Nm
I didn't find real spec for these but 23Nm should be enough for m8 bolts.
These weren't very tight when I opened the thing.
(not related to this topic)
And then we can put the unit back in the diff casing.
In reversed order.
Just be sure to put in the bearing covers, shims and everything same places and orientation as they were originally.
For example if you put the bearing covers in upside down, the oil will want to go out of the case and bearings are not properly lubricated.
But when you remember to put everything back in same way they came out, there isn't risk to ruin anything while doing this.
And it's stuck.
(not related to this topic)
And you probably know how to tighten the bolts and put in new seal for the cover.
So lets stop here.
You probably already got the idea how to fix the slipping LSD unit.
And  of course after assembling the diff you need to put in new oil.
And you can't put in just any diff oil you can get.
But you need to put in this kind of 75w-140 LSD oil.
You don't need to have this exact Castrol oil. You can use what ever brand you prefer.
The OEM oil for theses is mobil  vs500 but at least in here it hard to get that oil.
But this Castrol and any other 75w-140 Limited Slip oil will be ok.
Just fill the diff using this until it pours out and you can go hooning again.
