P/S Pump swap - line thread depth

[Laird Scooby]

Originally Posted by 940volvoman

Fair point,Dave.
Aren't all manufacturers moving across to electric pumps?

My steering was the best yet on my recent holiday.Refurbished rack,replacement universal joint from a 960/V90 and a new set of boots.The tracking was also done with the rack.

By all accounts,the Americans seem to have worked out how to make their pas systems a lot easier for the driver than our systems.I wonder how they do that...

Errrr, yeah.......but no but yeah but................

They're going to electric motors on the actual column rather than an electrically powered hydraulic pump Shawn. From what i can work out, they're high torque stepper motors running through a reduction drive to the column, mechanically parallel to it. Because it's a stepper motor, it's going to be under microprocessor control and therefore capable of keeping up with however fast you can humanly turn the wheel so it's just down to the torque which it can alter electronically to give variable assistance.

The Americans tend to use higher pressure in their hydraulic systems than Volvo do, my other two beasties (Rover 827 Sterling and Jag S Type) were built for the USA market (the irony with the Rover is ARCoNA pulled the plug as the Mk2 was launched! ) and so have very light steering, certainly at parking speeds. Both also have variable assistance depending on speed so they firm up to almost no assistance at motorway speeds.

Granted the Volvo tends to be fairly firm at motorway speeds but isn't much lighter for parking, in fact it's quite a workout by comparison. I suppose it could be argued that Volvo built it to cope with icy roads where the steering feel could often be misconstrued as the wheels not gripping or even the other way round - you think the wheels are gripping but they're just turning in the direction they're aimed without altering the direction of the car.

You'd probably also find your steering a bit lighter if you'd renewed your strut top bearings at the same time as the other work, they also have a bearing (no pun intended!) on how heavy the steering feels.

[J liddy]

Originally Posted by J liddy

I had same problem it was air in system it cured its self but took weeks . I changed the pump but made no difference air in the system system is a bugger to get rid of

This time everything OK but I've got it back from MOT few times in the past with a vibration on steering .years ago that was

[Laird Scooby]

Originally Posted by J liddy

This time everything OK but I've got it back from MOT few times in the past with a vibration on steering .years ago that was

I've had that too Jim, hence my question - i've come to the conclusion it's when they're inspection the front suspension joints and steering rack and turn the direction of the wheel using the roadwheels rather than the steering wheel - forcing the PAS to oeprate almost backwards and introducing air where it shouldn't be.
On'y seems to be a problem on the Volvo though.

[SwannyUK]

Originally Posted by lynns hubby

It looks like the design is to seal on the end of the pipe with an "O" ring or something like that. Was there any thing like this that came out of the old pump. Has the new pump got the seal in the port where the pipe fits.

There's no I rings, this is the old pump;



This is the new pump;



Nothing on the hard line.

I'm assuming it's the end of the hard line fitting butting up against the flange you can see within the pump which is supposed to seal it.

[SwannyUK]

Well I followed the advice and managed to get it seated properly to stop and leaks. Thanks for all the advice guys.

Unfortunately it still judders when turning corners, so I'm going to have to work out a way to more effectively bleed the system!

On the plus side - the pulley lines up now.

[360beast]

Jack up the front end and keep turning it lock to lock slowly but progressively getting faster, see if that does the trick.

[lynns hubby]

Thats good news well done.
As said on the last post Jack it up and with the engine running, progressively turn steering lock to lock.

[Rversteeg]

By all accounts,the Americans seem to have worked out how to make their pas systems a lot easier for the driver than our systems.I wonder how they do that...

The level of assistance is not determined by the maximum hydraulic pressure, but by the control system in the steering rack itself. When you turn the steering wheel against the left or right lock, you can feel a spring load being built up in the last degree or so. This is actually a spring in the pressure controlling system. The more resistance the steering wheel gets from the wheels, the further this spring will be compressed, the higher the hydraulic pressure will be and as a result the higher the steering assistance will be. At full lock the spring is fully compressed and hydraulic pressure will be maximum, hence the slipping of the belt when not tight enough. Take a softer spring and the power assistance will be higher. Without a spring it will always be maximum, but you would feel some play in the steering. Replace the spring by a very stiff one and the assistance will be almost zero. It is from the degree of torsional deflection that the control system determines the hydraulic pressure. It is probably less simple than just replacing a spring, but this is in theory how the PAS works.

It is not a matter of increasing the hydraulic pressure. During normal driving the pressure is (almost) zero. During steering the pressure will only be a s high as needed for steering, determined by the caracteristics of the spring.

Rob