13 replies to this topic

[toro]

My mate recently had a power steering rack & Astra electric pump installed in his LX the steering works great but won't self centre.

Any one have a similar problem or can guide me at what to look at next.

 

Cheers 

Toro

[UCgazman]

Where did he get the rack?

[toro]

Where did he get the rack?

 

A hydraulic engineering company in New Zealand it is some sort of modified subaru rack

[claysummers]

Dial in a heap of caster. You can do that with power steering without making it too heavy. That is the key to self centring.


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[Bigfella237]

Sounds similar to Lenny's conversion kits (maybe it even was one of his that found its way across the ditch)?

 

Steering racks themselves don't have any kind of "self centering" device built in, so can we assume you mean it doesn't self-centre while you're driving?

 

The first thing I'd check is whether something is binding, like the steering column itself (has it had the lower bearing mod)? Or the uni joints (not too sharp an operating angle)? Or rubbing on extractors?

 

If you jack up the front end, can you turn from lock to lock easily without the power steering pump running, is it smooth through the whole range of motion or does it feel like it's binding sometimes more than others?

 

Other than that, the next thing I'd do is stick it on a wheel aligner and check (mainly) the caster. Also what size rims is it running on the front (IE. has it got a massive Scrub Radius)?

[toro]

It has 14 inch GTS wheels on it, When you turn the steering wheel it won't turn back you have to turn it back yourself otherwise it's fine no binding of any sort

[76lxhatch]

Those popped up a while ago, not the same setup that Axistr offers. They look like the typical drag racer/straight-line setup, not really intended for handling as the rack hangs way out in front of the cross member, Ackermann in particular wouldn't be great.

 

Regardless the self-centering issue is probably just the rack itself, not uncommon to have a problem in the valve body. No doubt the rack was second-hand so it probably just needs an overhaul/repair.

[axistr]

From memory PG hydraulics was the company doing the conversion kits in NZ, but only built ten kits. I believe they did recondition them and made a new rotary valve to get them to fit into a Torana. I do similar. They copied my kit but as 76lxhatch has mentioned they didn't get the mounting bracket right. They mounted the rack to far forward from the k-frame and unfortunately suffers from a less than impressive steering geometry. I did email them quite a few years ago with my concerns but got a rude response. Just for the records I sent four of my kits to NZ in the past twelve months.

 

I would start by checking for positive caster as Clay has mentioned. I have found a minimum of 1 deg of positive caster is needed and more is desirable. If you have negative caster or heaps of toe in than this would be a problem. If you have HQ stub axles than you need more caster to offset the difference in king pin inclination. HQ 7 deg, LX 9 deg.  KPI also helps to return the steering back to centre, even with zero caster the steering should return back to centre by KPI alone. If you put it on the wheel alignment machine just double check the KPI to ensure you don't have bent stubs. Also when on the alignment machine check the rear diff alignment (thrust angle) so the rear isn't fighting with the front going down the road. Check for any tightness or binding in the steering system (this is a more likely problem). The last thing that comes to mind is incorrect rack shaft adjustment. On the drivers side front of the rack you will notice a large nut and plug with a 14mm raised bolt casted into it. Back off the large locking nut and  turn the plug no more than a quarter of a turn anticlockwise. I would mark the plug position first before turning as a reference point. If the adjustment doesn't change the feel then return it back to the original spot. Make sure you retighten the lock nut.

[toro]

Thanks for all the info everyone, this community is a wealth of information.

[Heath]

If I had power steering in my car, I would be running like 5 degrees +ve castor. That's like... the only point of having power steering almost.

 

I would checking for +ve castor first because it's desirable anyway. If that doesn't fix it, I'd be seeing if something is mechanically binding. Any car without self-centering steering is devoid of all driving pleasure.

[axistr]

If I had power steering in my car, I would be running like 5 degrees +ve castor. That's like... the only point of having power steering almost.

 

I would checking for +ve castor first because it's desirable anyway. If that doesn't fix it, I'd be seeing if something is mechanically binding. Any car without self-centering steering is devoid of all driving pleasure.

 

Ha Ha yes correct Heath, but there are a few more advantages with having power steering other than quicker return to centre that some car owners on here may not know. The more positive caster you add the more camber gain you get cornering. The tighter the corner and steering angle the quicker and more camber gain towards the inside of the corner. (more negative camber on the outer front and adds towards or positive camber to the inside front cornering tyre) which equals more grip.

 

Secondly and of course can depend on suspension setup but will increase traction to the outside rear tyre on corners. If you have an LSD or locker diff than this will also help rotate the car through corners. If you have a spool diff than heaps of positive caster is a big plus. Most modern rear wheel drive cars have between 9 & 16 degrees of caster. Its a pity the Torana front end design didn't allow for heaps of caster adjustment.

 

And lastly high positive caster reduces front dive under braking, As we all know the more positive caster the heavier the steering. Positive caster put more feel in the steering, and more weight to the suspension ball joints which gives more car stability especially at high speeds. 

 

Just as a reference and a classic example,

 

I set my Go Karts up with 19 deg of positive caster, . We do endurance races that last eight hours or more with two drivers. After the first hour I wish they had power steering.

 

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[claysummers]

I don't know about Toranas, but with early Holdens you can tilt the crossmember to attain additional caster. It's just a matter of shortening the front mounting bolt crush tubes, ensuring that the front outrigger top has clearence to the bottom of the radiator support.

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[76lxhatch]

Easiest way with the Torana is offset lower arm bushings, it doesn't take much and helps with centering the wheel in the arch (move top ball joint back, bottom one forward). I have around +6.5 degrees without significant modifications to the cross member or control arms.

[Heath]

^ Yep, I would be doing exactly what you've shown in your thread with the offset bushes if I had power steering. Magnificent work, and not awfully hard.