[xj] Variable Assist Power Steering Modification


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Sorry for the empty post. Big fingers.

I would like to modify the power steering assist to give less assist as
the speed increases. I restored a 73 Citroen SM which, I believe, was the
first production car with this feature. The steering was really fine!!
Of course it also had self centering steering, but that is another story.

Anyway, has anyone ever done this on an XJ6, or other car, or heard of it
being done. I would appreciate any info, or direction to other sites,
etc.

If I can do it, I will, of course, report back.

Many thanks. Jim Gordon__________________________________________________
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SNIP
I would like to modify the power steering assist to give less assist as
the speed increases. I restored a 73 Citroen SM which, I believe, was the
first production car with this feature. The steering was really fine!!
Of course it also had self centering steering, but that is another story.
SNIP

It is possible to run a gear pump directly from the transmission that
progressively equalizes pressure to both sides of the rack as vehicle speed
increases. This would also cause the pressure balance effect of
self-centering steering you mentioned. The best (recent) example I can
think of is on an 86 Honda Prelude. This is the model that came out one
year before the 4 wheel steering.

I would think that a retrofit with existing vehicle parts would be much
cheaper than doing a “one-off” design from scratch. I can foresee many
obsticals trying to pull this one off and still maintaining a reliable and
safe steering system! IMHO

Bob D.===================================================
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a lot of 80s-90s hondas/acuras had variable assist power steering. it was accomplished with a gizmo that plugged into the speedometer gear hole and the speedometer cable plugged into the gizmo. I believe there were 3 hoses going/coming from the unit, going to the pump, reservoir and rack, and they were all low pressure. Basically the unit gradually decreased the power assist as the car went faster by restricting fluid flow to part of the rack. I swapped one of these systems into a honda i used to have, i got it from a parts car i had, and it was a pretty straightforward design, so i would think it could be adapted(not easily though) to a jag rack, I would check out a salvage yard with a bunch of hondas, or other car with variable assist, and see where all the hoses go, it’s not too complicated of a system. good luck to ya…

collin bissett
1986 xj6 vdp===================================================
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You wrote:

I would like to modify the power steering assist to give less assist as
the speed increases. I restored a 73 Citroen SM which, I believe, was the
first production car with this feature.

Nope! The GM variable ratio, high effort power steering box in the WS6
package was available in the '70 1/2 Trans-Ams and Z-28s IIRC…

The steering was really fine!!

Of course it also had self centering steering, but that is another story.

That’d be done with really big positive caster numbers…Mercedes does
that…

GM also used higher positive caster numbers to give that high “on-center”
feel…with a corresponding tendency to edge-wear the tires on the outside.

Jeb===================================================
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Anyway, has anyone ever done this on an XJ6, or other car, or
heard of it
being done. I would appreciate any info, or direction to other sites,
etc.

There has been some discussion on the E-Type list about such a device, but
it’s manually controlled. Apparently taps into the PS lines, and based on
the setting, allows more or less fluid to bypass the rack.

I suppose it would be theoretically possible to take a valve like this,
attach it to a motor, and have the motor shaft position, and thus the PS
boost, controlled by the pulses from the speedo circuit…===================================================
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J&L Autoworks wrote:

You wrote:

I would like to modify the power steering assist to give less assist as
the speed increases. I restored a 73 Citroen SM which, I believe, was the
first production car with this feature.

Nope! The GM variable ratio, high effort power steering box in the WS6
package was available in the '70 1/2 Trans-Ams and Z-28s IIRC…
Jeb

Right, and didn’t the Jag MKIX have it also around the early '60’s ?
Cheers
Richard Griffiths===================================================
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