Afternoon D.R. -
You are on the right track on this problem and I appreciate that someone understands what I have been bitching about for the last maybe 6 years..
I don't think BMW technicians ever figured out the spline wear problem. Somewhere in the management of all this warranty and service problem, there has been a high level assumption made that no one at lower levels really thought about and defended the problem and its source to management. And this is why the design approach was radically revised As an example, the number of posted theories and red herrings that have come up on this issue over the last 15 years suggest that it is not a simple deal. One that seems to be missed by many is the barrel shaped wear pattern that is said is due to flywheel run out. Easy and obvious to check, but the disk spider design already has appropriate compliance in that direction. It takes a specially made fixture to do a radial alignment check. No one seems to be doing this, and I have only sent my free rig to a couple of other riders. Of course i think the barrel shaft shape is due to differential hardness in the mating parts and the need for wear to be conjugal. Even other obvious competent high level mechanics disagreed with me (not you though - THX). FWIW I've only seen this failure on a couple of R1100 bikes, and never on any R1150s etc. My experience is very limited but from work I had access to a couple of gear/spline gurus (one now dead, and one from Russia!). They immediately confirmed radial misalignment.
I too been suspicious of the housing accuracy. This too is impossible to check as a loose part and it may simply be different details in the original machining setup as the raw casting distorts differently depending on how much Fritz torques the hold-down fixture. Day shift-nite shift problems? Who knows but BMW never got to the bottom of it.
Maybe there is more than one problem source? And maybe once the crankshaft rear main bearing is worn that future failures are inevitable.
I agree the clutch push rod should not be used for preliminary alignment of the engine and transmission. Thas should be done with 8 mm guide studs. It should only be slipped in and used to release the clutch during final pull up. Again i am reaching for straws here.
Yes, definitely lots of speculation on the spline wear issue with some holding credibility & some really reaching for the stars.
Working for a major auto company I just can't believe that BMW didn't try to find the root on this as soon as warranty claims started piling up. My firm belief is that BMW qualified all the parts involved & set up spot quality checks on those parts as well going over the assembly process & fixturing pretty quickly.
I'm not saying that BMW didn't have a run of out-of-spec parts but no way do I believe that they didn't get a handle on that area pretty darn quick.
One thing that I keep thinking about is maybe the problem wasn't happening at original parts machining, or parts handling, or even at original build assembly. (that part of the failure chain would very easy for BMW to isolate & correct quickly)
An old dealer tec friend of mine had a theory that sort of holds water (at least in my mind)-- He claims he vaguely remembers uncrating the BMW 1150 era bikes & that they were shipped with no front wheel installed (this I know for a fact). His remembering is there were wood chalks or cribbing under the chassis in the rear of engine transmission area with the bike strapped down pretty tight.
These bikes were mainly shipped by ship so a dropped shipping crate with a motorcycle inside would hit the deck, or ground, or ??? pretty darn hard. His though is that due to the chalking or cribbing under the bike that a dropped crate could bend the front trans housing enough to cause a misalignment problem. (as I'm sure you know it doesn't take much input shaft misalignment to cause the basic spline joint to work as a gear-set instead of a spline coupling). He "thinks" that BMW changed the shipping crate strap down & under-bike support area on the later BMW 1150 bikes.
I do know that I saw a BMW tec/porter/whatever drop a motorcycle crate with a 1200RT inside about 4' when he was unloading it off a delivery truck with a small fork lift.
My friend was a pretty sharp tec but unfortunately he says uncrating bikes was not something he regularly did, or did often.
It's a credible theory anyhow as well as possibly explaining why it might have taken BMW a l-o-o-o-n-g time to identify.
I have heard (no confirmation though) that European 1150 bikes had a lot less spline failures. If this is true then most were probably not shipped by ship or stacked 10 crates high so it could fit the above theory I suppose.
Just another random theory tossed in the ring, eh?