Not meaning this patronisingly, but have you ever heard of lucas oil stabiliser? It's like super sticky but not thick sludgey way if that makes sense. Or in more technical terms it has one mother Effer of a surface tension leading to natural thick film forming characteristics, but a reasonably viscosity, off hand I don't know what its centistrokes or 3/6/9 rheological characteristics are, but at a guess I'd say it's viscosity & rheology is in the same range as 90/140w gear oil. And were I putting together a diff like yours, ie: with dressed teeth on it, I'd run neat lucas oil stabiliser as the "oil".
 
Not meaning this patronisingly, but have you ever heard of lucas oil stabiliser? It's like super sticky but not thick sludgey way if that makes sense. Or in more technical terms it has one mother Effer of a surface tension leading to natural thick film forming characteristics, but a reasonably viscosity, off hand I don't know what its centistrokes or 3/6/9 rheological characteristics are, but at a guess I'd say it's viscosity & rheology is in the same range as 90/140w gear oil. And were I putting together a diff like yours, ie: with dressed teeth on it, I'd run neat lucas oil stabiliser as the "oil".

I'm aware of Lucas oil stabiliser. ;)

I am thinking of using EP 140, maybe adding some molybdenum to the oil, to make is more slippery.
 
I'm something of a Lucas Oil Stabiliser evangelist :cool: Seeing as you are starting with 140 as your choice of oil, and it's the heaviest automotive oil, I'm going to bounce a couple of alternative off you for you to consider, you also get 220 / 320 / 460 weights of gear oil... which are typically not used in automotive applications, but are extra pressure and widely available.
 
I'm something of a Lucas Oil Stabiliser evangelist :cool: Seeing as you are starting with 140 as your choice of oil, and it's the heaviest automotive oil, I'm going to bounce a couple of alternative off you for you to consider, you also get 220 / 320 / 460 weights of gear oil... which are typically not used in automotive applications, but are extra pressure and widely available.

I'm looking at all grades of oil, including industrial oil grades, which I can locally, from farm equipment suppliers.
 
I’d be choosing oil for max bearing lube, all gear oils will lubricate meshing teeth

The bearings will be new, the gears are decidedly second hand, so gear protection will be top of my list.

However I can't use oil that's too thick, as this design of diff has very poor lubrication path to the pinion outer bearing (my thoughts as to the reason they fail), so the oil can't be too thick, or it might not get to the bearing that needs it.
 
The bearings will be new, the gears are decidedly second hand, so gear protection will be top of my list.

However I can't use oil that's too thick, as this design of diff has very poor lubrication path to the pinion outer bearing (my thoughts as to the reason they fail), so the oil can't be too thick, or it might not get to the bearing that needs it.

My point exactly
 
our quality department stuck a large sign up in their department saying " do it right - do it once" - i printed off a tiny "revision 16" label and stuck it in the corner - no one ever noticed lol
 
I think John is a bit too "by the book" to cobble the diff back together knowing that since the mating faces on the teeth were damaged and dressed down, ergo their hardening would have been compromised, meaning the diff, if simply refurbed with bearings and refilled with oil, could theoretically be a ticking timebomb.

Yesterday I put an offer on a 54k miles diff from a 2013 Evoque, which is the same as that in my 2009MY FL2.

The offer of £250 was accepted, against a selling price of £300, so I've saved £50. I'll put this £50 saving towards a new front bearing for this new diff, then get it back together and in the car.

I figured it best to simply replace the diff, replacing the fragile bearing before I put it in.

I've decided to go this route, as it'll save money and my down the line.
The reasoning being, it'll cost £150 for decent bearings, seals, spacer and new nut. Coupled to this will be around, £50 for the Haldex service consumables.
This means it's going to cost over £200 to "bodge" repair the current diff. So say the bodged diff lasts 12 months, before I'd be buying another to replace it. At this point I'd need to find a suitable diff (for whatever it costs), replace the fragile bearing for £50, and spend another £50 on Haldex consumables, again, as the Haldex needs draining to remove it from the diff.

The option I've gone for, will initially be more expensive, but will save me money and time later on.
Here's why. The diff is £250, add to this the £50 bearing kit (for the single fragile bearing) plus £50 for the Haldex consumables, plus diff oil, so it'll cost around £360 done and forgotten. Also I'm going to add a drain plug while the diff is apart, as this makes sense to me.

Long term, this is the way that makes most sense, even though it'll cost me an extra £150 now. And besides, Nodge don't bodge!! ;)
 
Have you any bearing factors near you ? Get a heavier duty bearing from them in the same dimensions?
 
This totally makes sense, glad to hear it.
That's the way I figured it. It seems silly to spend £200 on a less than perfect repair, when I can have a low mileage replacement for £360 fitted.
Have you any bearing factors near you ? Get a heavier duty bearing from them in the same dimensions?

I'm going with an OE bearing kit, which will give it a 50k mile life, or more with regular oil changes, and slightly less bearing preload.
 
Today I had this
20210119_183724.jpg

delivered.
It's off a 2013 54k miles RR Evoque, which is the same shape and ratio as the FL2 diff.

I decided to give is a quick assessment, to see if I either fit it as supplied, or rebuild it first.

It didn't take long to determine what to do. An attempt to turn the pinion by hand proves impossible, as it's so tight. This is I believe the issue with these diffs failing so soon. There's no way that the pinion bearings should be so tight, it's impossible with hand pressure.

So the answer to the question is, I'll be replacing the bearings in the pinion, before I fit this diff to my FL2.
 
Fitting a bearing so tight that it can't be turned by hand is crazy. I remember watching a trailer wheel overtake me because it had been overtightened by an ape with a rattle gun so I'm not surprised the FL2 diff causes issues.
 
Fitting a bearing so tight that it can't be turned by hand is crazy.

Obviously I don't know if this replacement diff is an original Ford built unit, or a later dealer repair, but the pinion is way way to tight. The only way I can turn it by hand, is to wear thick working gloves and turn the input splines and pinion gear with a hand on each. Once it's rotating, it gets a but easier to turn, but it can be felt to "cog" round, as the rollers actually feel to be going through valleys created by the over tight rollers.

Ridiculously tight, and if this is how they left the factory, its no wonder the bearings fail so soon.

I've ordered an OE rebuild kit, so hopefully will be able to get this done and back in the vehicle weekend after next.
 
Just out of curiosity, why are you switching from Timken bearings to OE?

Because Timken don't have the size of the later and larger bearing in their stock list. Or at least I couldn't find it. It seems only SKF make the later bearing, which is SKF32206J2, which has a dimension of 62mm OD, 30mm ID and a width of 21.25mm.
 
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