Morning,
Just awoke from a night dreaming of whether it is possible to slightly reduce the level of power steering sensitivity on a SIII XJ6.

Is there any reason that a slight reduction in pump regulated fluid output pressure could not be utilized to reduce the effective boost level of steering assist?

I believe these pumps were used on a whole range of different cars, so there must be an output pressure regulating valve that can be swapped or reset to a lower output pressure. Or am I just dreaming? Ian

 

Not dreaming.

GM, Ford, Toyota, and others all used that Saginaw pump.

Some pump outlet valves are o/ring seal, others are a flare seal, so would pay to check your pipe first.

Memory, HAHA, is the Ford circa 1978ish is a lower pressure valve. We used to sell them under different preseures at work, but that was 25+ years ago, and I dont remember 100%.

Any rebuild hydraulic people will know what is what.

The later, 1992ish V12 XJS had a less sensitive steer, and the rack and pump are the same, just a different valve.

 

I know it can be done but am not familiar with the specifics.

If nobody chimes in with an answer try Googling "Saginaw power steering pump modifications" or something like that.

Cheers
DD

 

Thanks guys - at least I'm on the right track. Just trying to get a bit more feedback/feeling into the steering. I like to feel the road a bit, as opposed to the "floating above the ground" that I currently get. Time to do some research - another winter project - I'll be an expert by springtime!

 

Yes.


I recall reading of alterations in an off road magazine. Can't cite it, but Doug's suggestion just might hit it. It involves spring tension and orifice sizing.


And, Andrew Weinberg's site, Jaguar-Specialties touches on the issue.


And, somewhere in cyberspace on hydraulics, just might be a valve to introduce into the hoses to adjust the PSI delivered to the rack.


The later LT1 PS pump on my car works just about right as to steering input. But, it is a completely different pump. Adaptation ???


Carl

 

In addition to investigating reducing the amount of assist also check you alignment settings.

Lack of positive caster can give a sort of loosey-goosey feeling to the steering.... as can worn steering rack bushings.

I always ask the alignment guy to come as close as he can to maximum allowable positive caster and negative camber.

Cheers
DD

 

Yup. I've noted an extreme "slant" on Mercedes and Bimmer wheels when at full lock. Indicative of lots of caster.


Oddly, my IHC Scout II had negative caster, a lot it. Odd looking wheels when at full lock. Steered just fine !!! And it seemed to enable a very tight turning radius. Why, beats me....
Carl

 

I don't remember the exact Castor specs for the sedan but the XJ-S was about 1 or 2 degrees MORE positive and the steering effort was increased.

You can set the Castor to 4.5 degrees? like the XJ-S instead of the 3 degrees? for the sedan.

bob

 

There are two (maybe three) specs for the Series III sedans: 12 cylinder, early 6 cylinder, late 6 cylinder. It might be that the V12 and late 6 cylinder were the same or very close.

The 'late' 6 cylinder specification coincides with the change in upper control arms...circa 1983. The control arms were changed to the same ones used on the V12s and the XJS. Slightly different geometry.

Cheers
DD

 

Reducing overall power steering pressure is not the way to go. It will do something but very little for low pressure situations like changing lanes slowly or just general driving. Reducing the pressure will cause high momentary effort during emergency maneuvers like a situation where you have to avoid hitting a person or another car.

The torsen bar in the rack affects feel and is not easy for a hobbyist to get to.

It would be ideal to find a rack from a late XJS. The later the better as I don't know exactly when they increased steering effort. I use 1995 XJS rack on all my projects. They boarder on stiff in parting lot situation but on the road they are perfect. I always retain the stock pump and pressure.

It would be good to check your alignment but this is not where the difference lies. The xj6 xj12 xjs and db7 all have nearly identical alignment settings yet all drive and feel very different.

 

I think the XJS "sportpack" steering rack is what you're thinking of....which I believe was standard issue on USA market V12 cars 1989-later.

Some research required as to the spacers that limited maximum wheel travel used on these racks, though. I can't remember if they're removable...or what. But you probably wouldn't want the spacers on a sedan

Cheers
DD

 

Lot of different elements make up the overall feel of any given car.

Tweaking the alignment settings CAN provide a noticeable difference in steering feel. If, for example, the caster is set at minimum spec and then changed to maximum spec, the driver should expect to feel a difference in the way the steering feels/behaves.

Cheers
DD

 

Absolutely. I run an non standard amount of caster on the red coupe... It's becasue I like the wheel to snap back like a 90's BMW. As a performance enthusiast I accept the tire wear implications as I'm not putting 15k a year on the tires and will likely replace them becasue of new technology or age before they wear unevenly.

With a bit more caster you get a bit more feel but some many alignment shops wont do non standard specs becasue of liability. I had to learn to do my own alignment with a string box and a camber gauge. Then I adjust caster until I get the the feel I like.

 

Well I have the opposite problem. The steering wheel on my xj6 III is not sensitive as I would like ti to be, then suddenly after rotating it half way it starts to get much more sensitive. it is not linear in the behavior like perhaps it should be. I can't say for sure though because this is the only xj6 III I had in my life, so I cannot say what is the normal steering behavior.

 

Not normal.

Check your steering rack bushings, pronto !

Cheers
DD

 

thanks

 

You can also do this if you feel "handy": lol

EPAS Performance Application Specific Electric Power Steering Conversion Kits | JEGS

Real cheap using a Saturn Vue EPS and an $55 eBay controller:

$100 Power Steering? Yes you can. Use Column Electric Power Assist System (EPAS) ! - Ford Muscle Forums : Ford Muscle Cars Tech Forum

https://www.ebay.com/itm/Saturn-Vue-...dZfvBH&vxp=mtr

 

Take the pump to a machine shop and have them produce a larger pulley?