How do you guys "mechanically" adjust H3+ height sensors?

[nickyg]

Hello again everyone,

Well, with a bit of perseverance, and no little help from the knowledgeable folk on FCF, I'm working my way thought this years C6 checklist nicely! Got to say, thanks for any help I've taken from the pages of this site. Hope some users have some success reading any threads that I have endeavoured to report back on with updates!

Now, I'm taking a little look again at my front left wheel. Its higher than the others, which I'm going to nail my colours to the mast and say I now think it could possibly be related to my H3+ inability to reach max high. It nearly gets there but never does confirm on screen. Have had this for a good while now, and mentioned here a good while back, so am determined to get it this time! I've taken a more thorough look this evening from outside the car with some citaerobics, and I'm pretty sure the mid to max high stage is accomplished (or at least more pronounced) in every wheel but the front left which, remember, sits higher in normal regardless.

Now, I'm aware I need to be looking at diagbox/lexia height corrections new sensor brackets and/or new sensor in that order for this. Have sprayed liberally with white grese and attempted a height references on lexia but I am going to have to look harder for a sufficiently level surface, as I am not happy with my entries, and I've checked the best spot I could muster with my laser level and its a few mm out.

So, on to the question.. before I go again at the Lexia corrections, I note some talk on some threads of room for some mechanical correction.

This intrigued me, as I always thought of these sensors as Citroen sacrosanct... ie: don't be moving, nudging or touching them or the whole deck of cards will come crashing down! Indeed, I'm pretty certain my higher front left wheel (and possibly related later max high issue) is caused by a rough house drive shaft change out a couple of years ago.

Are we saying that one can get under there and physically move the rod a little and that will simply give it a newly adjusted reference point at whatever height one has the car set at (ideally max high, but will have to be mid high in my case)?

Or would it be best to try the this when set in normal, as the results may possibly be easier to determine. Would this work with the ignition off?

Thanks again, hope you know what the heck I'm talking about!

[Peter.N.]

There is only one height corrector per axle, or at least there is on all the hydractives I have had so if only one wheel is higher its unlikely to be a suspension level fault but something peculiar to that particular wheel.

You can adjust the height by moving the clamp on the anti roll bar but it will change the height on both sides equally. The adjustment is very sensitive so a very small movement can send the car crashing down on top of you so only do it on a ramp or with plenty of clearance under the car.

Peter

[Mandrake]

This might be really obvious, but if one wheel is higher than the others what makes you think its a problem with the car and not just that the car is parked on uneven ground ?

As Peter says there is only one height adjustment per axle so if the front left and front right wheels are at different height its because the ground you're parked on is uneven!

If you think about it its impossible for just one wheel to have the wrong ride height unless the ground is uneven, otherwise the wheel would be off the ground!

If the front right wheel seems at the correct height it could just be a combination of the front ride height being slightly low overall, plus parking on uneven ground. (Normally parking on uneven ground will cause one wheel on a given axle to be too high and the other one too low)

Try parking the car in a few other locations first before you go fiddling with the height adjustments... See if you can find somewhere perfectly flat like an underground car park etc.

[nickyg]

Hello again guys,

Just to bring this aspect of the original question in to sharper focus: it's a C6!

Therefore a height sensor on every wheel, between subframe and the lower trailing arm of the double wishbone arrangement.

The same query regarding the how's and why's still apply, though! If I could get any info as to whether the adjustment on these sensors can only happen at the "dead" side (ARB clamp for C5 H3+, trailing arm mounting bracket for C6 H3+) that would be of great help. I was under the impression from some posts that there may be scope for a little rejigging on the potentiometer "wiper" side, but was unsure if the logic of this was correct ie: all being equal the mounting bracket and ball for the "dead" end of the doggy bone socket/arm and the mounting bracket holding the sensor and "live" ball on the potentiometer should, if unmoved and undamaged, be set in relation to one another in a completely fixed fashion, no?



Regards,

Nicky

[Mandrake]

Individual sensors don't change the laws of physics though, if you have flat ground the only way one wheel could be higher in the wheel arch than the others would be if the wheel was lifting off the ground...

[nickyg]

I'm not sure about that, Simon!

If the information the wheel travel sensor is transmitting is corrupted then that will leave the wheel out of kilter, same as if a C5 was corrupted it would leave the entire axle looking either high or low. My C6 NSF sits high, that is the wheel arch gap is bigger, no matter which way I'm oriented.

As I mentioned, that area had a drive shaft changeout a good while back by a local grease monkey. This is right beside the wheel height sensor. Any disturbance in the geometry requires reprogramming, which I have recently tried but on a, truthfully, unsuitable surface. I will do this again, if I can find somewhere better (I'm out in the sticks and my town is in a valley!) but really I was just intrigued by the notion and logic of the slight leeway for mechanical adjustment in other threads, as a simpler precursor to the height reprogramming in the diagnostic.

Again, thanks for the input!

[Peter.N.]

Out of my depth I'm afraid never seen a C6.

Peter

[nickyg]

It's the same principle as C5 H3+ really, and same sensor type. Just wondering what happens if you were to move the wiper at the sensor end.. Does it offer some kind of mechanical height adjustment, or is it all merely integrated and interpreted into the ECUs as normal road suspension behaviour.

Basically, if I give it a little movement when car is at normal height, will the new normal height of that wheel be adjusted?

[dnsey]

The C5 sensors can be adjusted in much the same way as the old hydraulic height correctors, by rotating the clamp on the ARB. A small movement makes a very large difference, though.
I suspect that the reason this is not recommended on the C6 is precisely that the wheel heights could easily be 'unsynchronised'; there's probably a special jig to set them up.
There should be an adjustment facility via Lexia / Diagbox, though. What happens if you try that?

[nickyg]

Hi, yes, I've done the height resets but, as I say, I really need to find the time to go get a suitable spot perfectly level and ser myself up for an hour. You measure to a given flat spit adjacent to each wheel, deduct it from wheel radius, check your live parameter data, re measure and enter the heights again.

I think I've got my answer, though, you guys can get a mechanical adjustment by jiggling the ARB clamp side of the arrangement.

Unfortunately then, regarding the C6 my previous logic would be correct. The bracket holding the sensor on the sub frame and the opposing bracket on the wishbone/trailing arm holding the other end of the link rod are mounted rigidly in such a way that would preclude any jiggling for mechanical adjustment (barring a shim was added). No jig needed, they both fit one way only.

I guess this means I'll have to nail the diagnostic heights settings this time!

Thanks again for the feedback!