Xantia steering - gets v stiff at high revs HELP!!

angus405 · Post by **angus405** » 09 Sep 2005, 17:22

I have a 95 xantia, 1.9 TD i've had it for a while now, and have had very little problems with it, until now!
The steering tends to almost lock sometimes when trying to turn a corner, more so with higher revs meaning i need to either drop the clutch or give it a good yank to stop me going into the hedge!
When the weather is warm, or when the car has been used a lot that day the problem goes away so i am assuming that when the hydraulic oil has thinned slightly through being heated there is not a problem.
I have changed the oil and cleaned all filters. I don't want to change the pump or rack if it is not going to solve the problem.
Is this a common fault, any ideas what could be causing it?
any help or advice please
cheers

Clogzz · Post by **Clogzz** » 09 Sep 2005, 18:21

Wouldn't it be a loose belt slipping ?

Post by **Peter.N.** » 09 Sep 2005, 20:05

Yes, quite likely. Check your hydraulic belt tension, it sounds as though you are loosing hydraulic pressure, as the steering demands more fluid than anything else, thats where a slipping belt will show up first.

mezuk04 · Post by **mezuk04** » 09 Sep 2005, 22:02

Ive noticed on my newly acquired Xantia that when i do full lock (only notice when backing out the drive and then moving forward) that the wheels dont automatically start moving back straight once moving off unlike the ZX.....had to back the ZX in the drive this afternoon, good the steering is so heavy in comparison its amazing

Rostami · Post by **Rostami** » 09 Sep 2005, 23:11

Could be the accumulator!

Mandrake · Post by **Mandrake** » 10 Sep 2005, 04:39

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by mezuk04

Ive noticed on my newly acquired Xantia that when i do full lock (only notice when backing out the drive and then moving forward) that the wheels dont automatically start moving back straight once moving off unlike the ZX.....had to back the ZX in the drive this afternoon, good the steering is so heavy in comparison its amazing
<hr height="1" noshade id="quote"></blockquote id="quote">
Both my Xantia and my Dad's one behave this way too - after full lock, driving forwards doesn't self centre the steering much if at all, until it is manually turned towards straight ahead a bit, then it starts self centering.
I put it down to bad geometry and wheel tracking due to the McPherson strut design on the Xantia... [}:)] It's clear from the amount of scrubbing the tyres do on gravel when doing a full lock turn that the full lock wheel tracking is a compromise...
Regards,
Simon

jeremy · Post by **jeremy** » 10 Sep 2005, 04:56

The accumulator is not in the steering circuit - this is true for both single and twin outlet pumps.
Jeremy

Clogzz · Post by **Clogzz** » 10 Sep 2005, 17:05

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mandrake

after full lock, driving forwards doesn't self centre the steering much if at all
<hr height="1" noshade id="quote"></blockquote id="quote">Same finding, and wondering if all front wheel drives aren't like that.

Mandrake · Post by **Mandrake** » 10 Sep 2005, 18:01

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Clogzz

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Mandrake

after full lock, driving forwards doesn't self centre the steering much if at all
<hr height="1" noshade id="quote"></blockquote id="quote">Same finding, and wondering if all front wheel drives aren't like that.
<hr height="1" noshade id="quote"></blockquote id="quote">
No, it's nothing to do with being front wheel drive, its determined by the suspension geometry, things like the kingpin inclination, caster angle, scrub radius, and so on.
In fact the Xantia is the first car (front wheel drive or otherwise) I've ever driven that doesn't self centre from full lock. My GS certainly did, and thats front wheel drive with manual steering. (But then again it had proper geometry design...)
Not sure exactly what they got wrong to muck up the self centering, but its certainly not the norm for front wheel drive cars... heck even my little manual steering Daihatsu Charade with McPherson struts has plenty of self centering action from full lock... [}:)]
One possibility is that due to the offset of the top pivot point being inboard a bit, when the wheel is on full lock it forces the strut mounting block to bend sideways, and this puts the strut under a lot of sideways thrust (see my recent thread about the strut design and side thrust) and this extra side thrust may cause enough increase in friction of the strut movement to overcome the natural self centring torque from the wheels...thus the steering "sticks" at this angle because the power steering has no inherant self centering like DIRAVI.
Regards,
Simon

Clogzz · Post by **Clogzz** » 10 Sep 2005, 19:17

Thank you for the expert opinion, Simon.
I now remember the Charade being heavy in the steering, but always centering properly.
The 1992 Hyundai was throwing the steering further out as you were steering and applying the torque at the same time.
I noticed just recently that my Xantia's front suspension was rising and dropping at full lock when parking, a sign I thought of great stresses in the struts.
After all, the high caster angle does cause you to 'lift' the car at full lock.

ItDontGo · Post by **ItDontGo** » 10 Sep 2005, 20:50

The non-self-centring issue is normal on any car. Once you get beyond a certain amount of lock the torque produced on the steering axis by the castor of the front wheels changes direction. I have never looked at it in detail mathematically, which would be the way to do it, so I dont know what factors it depends on but it seems to happen to everything beyond a certain amount of lock. It is very noticable on the single seater I am driving this year which certainly isnt front wheel drive and certainly doesn't have MacPherson strut front suspension. In fact when I have made a mistake and had to go from full lock to straight ahead again very quickly it is really very heavy as it wants to turn the wrong way when at the extremes.

wrinklet1 · Post by **wrinklet1** » 10 Sep 2005, 23:43

I had a similar thing happen on my Xantia, It turned out to be the Hydraulic pump that had got tired. Replaced it with a new one. No problem now.
Paul

Mandrake · Post by **Mandrake** » 11 Sep 2005, 04:09

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by Clogzz
I now remember the Charade being heavy in the steering, but always centering properly.
<hr height="1" noshade id="quote"></blockquote id="quote">
Heavy, I'll say. I've still got it as a run around, a 1984 3 cylinder turbo model with oversize tyres [:D] The steering is very light about the straight ahead, but very heavy to (for example) turn into a right angle street, and very strong self centering from full lock.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
The 1992 Hyundai was throwing the steering further out as you were steering and applying the torque at the same time.
I noticed just recently that my Xantia's front suspension was rising and dropping at full lock when parking, a sign I thought of great stresses in the struts.
After all, the high caster angle does cause you to 'lift' the car at full lock.
<hr height="1" noshade id="quote"></blockquote id="quote">
Yes, at full lock the struts are under a lot of side thrust as I mentioned before, and this causes enough extra friction to sometimes cause the height corrector to start overshooting up and down.
You can simulate this by doing the following (can be quite amusing to watch...) park on concrete or other hard surface with good grip, lift the suspension to the full height position, wait until it fully lifts, then drive the car forward a metre - this relieves the side thrust that occurs with the change in wheel track from the large height change.
Now set the height to normal, and leave the engine running. Depending on the condition of your struts, the car will now go into a cycle of see-sawing up and down overshooting the centre mark. [:D]
What is happening is that the position of the wheels on the ground is now such that there is considerable side thrust on the struts near the middle of the suspension travel, increasing the friction, preventing them from moving freely and therefore the height correction movement overshoots the mark, and keeps overcorrecting.
As soon as you drive forward a bit again the side thrust is released and it behaves itself.
Regards,
Simon

Mandrake · Post by **Mandrake** » 11 Sep 2005, 04:23

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by ItDontGo

The non-self-centring issue is normal on any car. Once you get beyond a certain amount of lock the torque produced on the steering axis by the castor of the front wheels changes direction. I have never looked at it in detail mathematically, which would be the way to do it, so I dont know what factors it depends on but it seems to happen to everything beyond a certain amount of lock.
<hr height="1" noshade id="quote"></blockquote id="quote">
No, it doesn't happen to "everything", only cars with certain geometry designs.
Although I'm not 100% sure, I think the main factor is having a kingpin inclination that is large relative to the caster angle.
Kingpin inclination being the top pivot point being offset inwards towards the engine bay relative to the bottom pivot point.
An interesting fact here is that the GS has *ZERO* kingpin inclination angle, (part of its centre point steering design) and therefore doesn't suffer from this problem - both wheels lean into the corner at full lock on a GS.
On any car with significant kingpin inclination, (most cars) the outside wheel usually leans the wrong way on full lock - the inside wheel leans into the corner, while the outside wheel leans out of the corner, which is WRONG.
Castor angle makes both wheels lean into the corner, while kingpin inclination makes the inside wheel lean in and the outside wheel lean out.
In most cars you have both castor angle and kingpin inclination, so the relative proportions of the two control how far you can turn the steering before the outside wheel starts to lean the wrong way. On some cars, often those with McPherson struts which tend to have a large kingpin inclination, the wrong way leaning of the outside wheel can be extreme - I've seen cars where the outside wheel leans 10 or 20 degrees the wrong way, which is a sure sign of bad geometry design.
On a Xantia, the kingping inclination is fairly small compared to typical McPherson struts, meaning that the outside wheel doesn't lean the wrong way until you're nearly at full lock, and then only by a few degrees, but its still enough to give the characteristic tyre scrubbing on full lock turns on gravel.
<blockquote id="quote">quote:<hr height="1" noshade id="quote">
It is very noticable on the single seater I am driving this year which certainly isnt front wheel drive and certainly doesn't have MacPherson strut front suspension. In fact when I have made a mistake and had to go from full lock to straight ahead again very quickly it is really very heavy as it wants to turn the wrong way when at the extremes.
<hr height="1" noshade id="quote"></blockquote id="quote">
Which is a sure sign of poor suspension and steering geometry design - McPherson struts don't have the entire market for bad design to themselves... [:D]
All of the factors to get good steering and geometry design are well documented and known by the designers of cars, why they don't always follow them I'm not sure. Partly due to compromises for weight, size, cost etc, and partly due to laziness perhaps...[:)]
Regards,
Simon

angus405 · Post by **angus405** » 11 Sep 2005, 23:04

Thanks for your help.[:)]
I'll check the belt first off, would it be recommended to change the belt if the tension isn't a problem?
If this doesn't work i'll look into a change in pump, any ideas on the best place to get a pump either new or 2nd hand? and how much it might cost?
Cheers
angus405