E53 Tyres, 'Scare Story or True Story?'

[Steamyrotter]

[quote="Davrosbimmer"]
did I see you say it made no difference on the pre-face lift?
[/quote]

What i said / eluded to was...

the Pre facelift (ie non XDrive) E53 Transfer box (Centre Diff) is less susceptible to this failure mode due to the design of the internals (1 planetary gear set and a chain!)  there are no clutches or controlling mechanisms within that can be stressed by the differential loading.
This is not to say then Can't fail, as anything mechanical can cause issues.

The XDrive versions appear to be more temperamental due to the controlling mechanisms in place within. (Not had one of them apart (yet) so cannot comment)


The BIG issue and stands for ALL X5's (amongst many others i expect) are the front and rear differentials.
These are a right pain and i believe are specified to be just sufficient for what the vehicle needs and no more....
Therefore any unexpected loadings could, can and most likely will botch something up for you in a most hideously expensive fashion!

They are rare and as far as i can tell, spare parts are not held by anyone!!! (or at least anyone who was willing to divulge that to me when i was looking to refurb mine)

[X5Sport]

These diffs should be up to it.  I think part of the problem at present is no one has explained what the failure mechanism root cause is.  Without knowing which components are overstressing and either breaking, or causing breakages it is hard to work out.  It also seems to be wear differences of 5mm or more between axles.  Something is winding up and then failing.

Because BMW take all the broken units (from Dealers) back to Germany and keep quiet and there are very few in the scrap market at present, this is just making it harder to puzzle out.  As Steamy says, it is the xDrive models that seem to suffer and that has to be down to the way the torque is shifted and then what other condition has to be present in addition to the tyre treads to tip a strain to a shattered crown wheel.  Is it corners, bumps, wear in the suspension, torque, temperature, lubrication, soft alloys, too much backlash, bearing adjustment, end float etc.etc.

There are also problems with the splines being turned off propshafts too.  To me that points at either incorrect materials choice or incorrect hardening chosen for the loads being imparted.

I'll bet BMW know what is wrong but are just keeping it to themselves in case they get sued for it.

[henrym3]

I do understand the reasons and explanations you both are are giving. At work we are suffering equipment failure on heavy armour where things are now on their third refurb and metal is cracking in the most unusual areas, splines and engine mountings are bending  Is this why they say the likes of the E30 was over engineered because it didn't suffer as much. I know its considerably lighter but they can take some abuse and survive.

[X5Sport]

May be this is all part of the reason why so many car manufacturers still only offer 3 year, 60,000 mile warranties?  Build them light, build them quick but don't build them to last!  IMHO a luxury brand should offer market leading warranties.  Even the likes of Vauxhell offer 100,000 mile ones (OK it's only to the original owner, but.....).

[Turks]

[quote="Turks"]
Really glad I read this little tip about letting the air out. I have a decent set of Tyres on the rear which has more than 5mm tread but the inside 2" is absolutely gone! I changed my wheels (stuck the winter set on) last week, with the intention of getting it all bushes etc. checked at the dealer. Had a quick look myself though when I changed the wheels and everything looked rock solid... which left me questioning why the uneven wear... had the car 8 years and not had this issue before.


Turks.
[/quote]

So I have had my rear bushes changed at the Dealer, they were completely shot but you couldn't tell without the Air Suspension deflated. The car is driving so nicely now, it is like night and day... guess the gradual decline of the handling and feel wasn't noticable. Had the KDS Wheel alignment done also.

Had a bit of other work done too - kept getting a Tyre Warning flash up on the dash... this turned out to be a front level sensor.

Winter Tyres are on now, so will see how they wear, and i'll get myself some new summers around April time.


Turks.

[RChaloner]

You're right in what you say about variations in tyre tread depth of a couple of mm, but what people are describing about differentials (could be side to side or front rear, which is the more complex and expensive I think) is roughly this;

If one tyre is bigger than another side-to-side (for say a rear diff) or one pair of tyres is bigger than another (for a centre diff / transfer case) then what happens is nothing more complex than the planetary gears spinning more of the time (for a standard mechanical diff like a rear) or friction plates (clutches) having to slip slightly but more continuously in the case of a centre diff of a torque splitting / electrically managed type.


If it's old-school planetary gears spinning more in the diff, with appropriate lubrication and cooling you would just expect a slightly higher rate of wear and eventual failure, but I've never had a problem with standard mech. diffs with 250,000+ miles on BMWs and Audis.

If it's limited slip diffs (like on the rear) or centre diffs that manage torque split, you can imagine there's some sort of mechanism, a 'clutch' or friction plate, that manage how much torque goes to one side or the other (or front to rear if centre diff / transfer box), and where these normally only have to 'slip' for turning or wheelspin a tiny percentage of their life, this more complex type of torque control might be more sensitive to wearing out if it's constantly slipping to cope with different diameter tyre sets?

So what I understand is that it's all about wear & tear, but the more complex the assembly is, the more impact the wear may have, perhaps leading to an earlier overheat and potential failure.

You would of course think / hope / pray that manufactures and all their millions of test miles (we're told) would factor this type of real-world usage in, if they wish to build a brand image of reliability and value.


I had a 1990s Audi V8, auto box, jammed throttle at high speed and desperately trying to slow on the brakes for no more than 2 or 3 secs while 'getting it safe' and switching off... resulted in fried gearbox input clutch, complete loss of drive. That's a clutch bathed in oil too, so you might think it was in a more stable heat-sink, but not so it seems!