Rear Axle Strip Down - Part 4

The last major part of tearing down the rear axle / subframe was to remove the lower wishbones and fulcrum shafts from the wishbone tie.  This part of the rear subframe can be seen at the top of the photo below.  The 'pendulum' (the rectangular looking bracket at the left) was removed from the front of wishbone assembly by Simply Performance when they removed the diff for refurbishing.

Lower wishbone assembly (top)

As has become usual with stripping down the rear, this was not as straightforward an operation as I had hoped.

Firstly the lower wishbones have been designed so that they pivot on the fulcrum shafts only at each side, the middle section of the shaft is partially exposed to the elements and of course gets extremely corroded.  The engineer in me fails to understand why anyone would think this was a good design!!  The previous design of the XJ40 suspension appeared to have recognised this problem by having a spacer tube over the central section of the fulcrum shaft which at least (if properly greased) would give some protection to the shaft.  For some reason the later design made no such consideration. So the long and short of it was that the fulcrum shafts were well and truly rusted into the lower wishbones.

When I had helped fellow AK Cobra builder Richard with his body and chassis delivery, he had advised me that AK no longer need the wishbones as exchange items and that he had resorted to cutting the wishbones off the fulcrum shafts.  So I didn't bother trying any other method myself, I simply reached straight for my trusty angle grinder!

The first part of the operation to cut away part of the front of the wishbones was  relatively easy - some straight passes with the grinder and some assistance from a cold chisel and I managed to free up the front part of the fulcrum shaft.

Front sections of both wishbones cut away

Corrosion of fulcrum within pivot section
as well as exposed central section

Cutting the rear section of the wishbones was not quite so easy.  I was worried about damaging the wishbone tie (which needs to be reused) with the grinder so couldn't cut along the line of the fulcrum shaft.  Instead I tried to cut through the front section at an angle. 

Unfortunately this part of the wishbone is quite thick and of course is a solid casting and took a lot of grinding to cut through.  I was never imbued with a great amount of patience and on the first wishbone I managed to nick the fulcrum shaft with the angle grinder (actually it wasn't a nick, it was a bloody great gouge....).

Deciding that this shaft was now effectively scrap (and having checked that I could actually source a replacement one) I simply cut the end of the fulcrum bolt to free the wishbone from the tie.  I then managed to hammer the shaft out of the wishbone.

One scrap fulcrum shaft...

The other side was slightly more successful.  I managed to cut the front of the wishbone at a slightly better angle which meant that I was able to hammer the wishbone off the shaft without resorting to butchering the fulcrum shaft (although I will probably buy replacements for both sides having knackered one side).

Ironically I could have done this much more easily.  When Simply Performance removed the diff from the subframe, they also removed the two bushes in the wishbone tie that the diff mounting bolts pass through.

Wishbone tie with diff mounting bushes removed

These bushes are not available as a replacement part.  In fact bizarrely neither the inner or outer bushes on the wishbone tie are available as a replacement part (several fruitless internet searches eventually confirmed this - although the bushes for the pendulum which mounts the front of the diff are all available!) and neither is the wishbone tie itself.

Ben at Simply Performance was happy to provide a replacement wishbone tie free of charge (as part of their guarantee that all parts can be refurbished) - he also sent me a set of spacer tubes (from the old style XJ40 rear suspension) as I had noticed in the AK build manual that these are required.

Replacement Wishbone Tie (middle) with
all bushes present and correct!!  XJ40 fulcrum
shaft spacer tubes supplied by Simply Performance

So for fellow builders out there - when you do manage to separate the rear wishbone tie DO NOT ATTEMPT TO REMOVE THE BUSHES!!  

So of course I needn't have been so careful in cutting off the rear part of the wishbones to try and protect the wishbone tie, as mine turned out to be scrap in any case.....

Oh well - all the main parts have now been stripped down.  Now to clean, derust and refurbish all parts that are going to be reused.

An exploded rear end!!