I'm planning on replacing my steering rack w/ a rebuilt unit; car is a 1978 XJ-S.
Bernard Embden mentions below in his website that Conventry West recommends the new Post-HE version and supposedly has better internals.
I spoke w/ a gentleman (Brett) this morning at Coventry; he personally was not aware of the Pros/Cons either way.
Jaguar XJ-S Steering Rack Upgrade

Externally the only difference according to what I'm ready is that the tie rods are thinner at 14mm VS 16mm and thus be sure to get corresponding tie rod ends.
It also seems to be that 14mm tie rod ball-joint ends are more readily available.

Thoughts if the Post-HE version w/ the 14mm tie rods is better than the older version w/ 16mm tie rods?

Thoughts?

 

The earlier rack tie rods were imperial, not metric. The late ones are metric and as you say gave a slightly smaller diameter. It does not matter which sort you use, but the later ones with the metric threads are easier to find rack/steering arm balljoints for. So I would go for the later metric rack.

 

The later racks have less turns lock to lock and a thicker torsion bar. Jaguar changed the pinion to speed up the steering.A newer rack is a bolt in replacement for the old one. Both these changes improve road feel and steering response. A worthwhile upgrade.

 

What you really want is the face-lift Aluminum XJS rack made by ZF. I've taken many out straight out of cars headed for scrap, installed them as is and they work and dont leak straight away. I believe these can be found in 1992 and later cars but I'm not entirely sure when Jag switched over. They are easy to identify as they are aluminum and look quite different but are a direct bolt in. Some slight tweaking of the fluid lines is necessary in some cases.

 

I have done this and it gives more road feel and slightly less assistance. The PS hoses are not the same threads into the rack as on the earlier Adwest racks though, so new hoses are needed. These are available from the usual specialist like David Manners etc.

 

Can someone elaborate on what is needed to upgrade my 89 xjs rack to the ZF rack ?

 

+1 for the ZF rack.

 

1. buy one - second hand only available
2. buy the pipes - new available
3. fit it using new bushes.