Dinnu wrote:

... I would personally only fit Ashcroft shafts to my 90, as all other aftermarket could be too rigid. I also have a concern about the clamping force of the LOF shaft due to the smaller bolt, however there are many satisfied users of the LOF shaft, so probably is fine too, and I am just over thinking.

Dinnu wrote:

...It seems to me that the design engineers at JLR understood the difficulties to get a proper alignment, given typical manufacturing tolerances, but their original design was flawed that it lacked any way of lubricating, and missed an important detail that dry splines will fret.

Here, unusually, I find myself unable to agree! I can see nothing which suggests that the LR engineers even bothered to think about this issue, they simply designed the easiest (and cheapest) possible method of mating two existing gearboxes. They may have given some thought to lubrication (there is a seal of sorts on the joint which is pointless otherwise), and certainly failed to stipulate that the joint should be lubricated on assembly. The engineering of this aspect of the installation of the 2.4 Duratorq engine is mirrored in the other aspects, such as the barely-adequate fuel system (no rear pump, frail VCV, and stupidly-located fuel cooler), and indeed the nose-up attitude of the engine which gave rise to driveline problems. The only thing they got right was to opt for a sprung clutch driven plate, even though they managed to come up with one made by Toblerone.

Nothing, not a single aspect, of the conversion to the Ford engine, suggests competent engineering to me, It only just manages adequate engineering. It suggests to me that the process of replacing engineers with stylists was well underway, and I have speculated that the job was left to the work experience team.

Ironically once the enthusiastic owner, aided by very competent aftermarket component suppliers, has reworked the vehicle at considerable expense and corrected the inherent defects, I think that the 2.4 Defender is undoubtedly the best classic Land-Rover of recent times.

Dinnu wrote:

It seems to me that the design engineers at JLR understood the difficulties to get a proper alignment, given typical manufacturing tolerances

I elaborate... why would an 'engineer' design another point of failure, and what to me seems a rather expensive solution? I can only assume that they needed to fulfill the MT82 mainshaft bolt torque requirement of 180Nm, as that holds the gearbox together (preload), so they needed to have access to the bolt while still having some 'flexibility'. A design like the IRB concept is easier and surely cheaper to manufacture! Or perhaps they had tunnel vision and they only could see splines?

The additional splines probably gave that additional misalignment compensation- perhaps on paper was a good design - but possibly FoMoCo, the manufacturer of the adaptor housing did not bother to keep to the specified tolerances, and possibly one of the explanations to the wide range of life time out of the original adaptor shaft.

As with everything, there will be (I hope) a normal distribution. Some adaptor housings just happened to be on the nominal dimensions. Those went to the lucky ones Mine probably is one that should had been rejected, as probably falls on either of the extreme ends of the distribution with a Cpk < 1, .... but instead went to the assembly.

But the above is just speculation. 1988 90 Hard Top, 19J Diesel Turbo, Shire Blue - Restoration ongoing
2012 90 CSW, 2.2TDCI, Santorini Black