do diffs do this???

[ex4x4]

Hi folks - been around lurking for years - and only do I feel the need to ask a question to all those in the know.
My vehicle is a X5 E53 3.0d ( 2006) but the question is related to rear diffs on the whole.
Im getting a weird vibration / throbbing /juddering at any speed although the faster - the more severe.
checked and replaced usual suspects - guibos / shaft support bearings, and inspected all CV / UJ.
I came across this today when poking about at the rear.
youtube videos of concern.
https://www.youtube.com/watch?v=ubtp-dpqtNM
https://www.youtube.com/watch?v=ZQDis9KS5N0





Videos taken with both rear wheels off the ground - handbrake off and in N.
The two output shafts from rear diff ( left and right) have a lot of radial play in them where they meet the diff output stub shafts.
I removed the shaft from the diff to isolate and the flange of output stub shafts still wobbles - 1-2mm radially. I popped the stub shaft out to inspect the splines on both the shaft and the internal drive of Diff and found no discernable wear or damage. I could see what seems to be cylindrical roller bearing ?? inside the output port, but could not feel any play.
The CV joint of shaft feels firm with little or no play.
I had always imagined the out flanges of the diff would be solid but having never had one aprt before - im not sure.

[StuBeeDoo]

It's a long time since since I had a diff apart, but I would say the amount of play shown in those videos is excessive. There's always a small amount of "lash" between the input and output shafts, but there shouldn't be any discernible up/down or side-side movement within individual bearings.

[ex4x4]

So pulled the diff out this morning and stripped down to find root cause.
Guess Im now searchinf the breakers for a very rare 3.91 ration diff.

[StuBeeDoo]

Yep, that'll do it! That diff is toast. Mind, it must have taken some abuse to go like that.

I don't know about rare. There are several on everyone's favourite auction site, but they aren't cheap.

[ex4x4]

Ive rang a dozen or so "bmw" breakers - and they are like hens teeth. Only option is to get a front and rear lower/higher ratio and swap both.
Thinking along the lines of getting a 3.73 or 4.1 diff and swapping my ring gear over??? to keep the same ratio?? probs not that easy!

[Alan Gunn]

Some on the bay but £400 upwards.

[X5Sport]

Caused by tyres? Just asking in case this is a car equipped with non ‘*’ marked rubber, though I thought that was less of a problem on the E53 than say the E83?

[ex4x4]

Currently no - but I ve only had her for a year and travelled 6k miles in it with same mid quality tyres. In hindsight probably been busted for quite some time as car always had a bit judder above 60 which dissappeared as car warmed up, which then eventually became permanent - hence investigation.

[StuBeeDoo]

I'm no expert, but I wouldn't have thought that damage is tyre-related. It's the sort of thing that happens to drag racers.

[Greydog]

My rear diff on the 4.6 went at 72k full BMW history and correct size Michelin tyres. At that time BMW quoted over £900 just to supply the diff plus labour which back then meant a £2k+ bill from BMW and they keep the parts so no evidence?
The BMW Specialist I use managed to get a rebuild kit from the US. Parts, shipping and rebuild came to less than the cost of a new diff from BMW. I have to say my diff was not a complete bag of bits I don't know if the one pictured could be saved I would be concerned about hairline cracks in the casing with that much damage.

[X5Sport]

It’s the BMW keeping the evidence but that has always concerned me. By doing that they may be able to keep a stock if refurbished parts but they also keep any evidence of design flaws ‘in house’ and can be very choosy about what information then gets into the public - or regulatory - domain and then they become liable for.

If a repair kit is available then you could try a fluorescent dye to check for fractures in the casings?

[StuBeeDoo]

Does the planet gear carrier come in the repair kit, though?

[Greydog]

From memory the kit was pretty comprehensive I will see if I can dig out the invoice if I still have it which was itemized. My diff was making uncomfortable noises the bearing and seals were gone on the drivers side and the bearing was on it's way on the other side. The one pictured looks as though its exploded ??
Apparently with different rules in the US rebuild kits for many "sealed" units are available. Probably why the US get recalls and repair under warranty on all sorts of makes and marques that apparently never happen in Europe?

[ex4x4]

The one pictured looks as though its exploded ??
Believe it or not the car was driving before i took it apart. - it had a judder - almost misfire like above 40mph - esp under load - but free wheeling in neutral - even at 70 - smooth as butter.

[Leslie]

Surprised that was still driving ,Did the bearings fail ? Not sure why diffs are expensive given the modest value of these cars now .Cheaper to buy another car to get the diff out of it.
I watched a guy I know who just got an e53 nail it from a standing start on a dry road with the rear wheels spinning up this week and this is what I imagine will happen quite soon !