Finally done my rear arm bearings, now rear won't rise

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Jabo
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Finally done my rear arm bearings, now rear won't rise

Post by Jabo »

*Finally* got round to doing my driver side rear arm bearing. No more clunking, yay!
Didn't think I disturbed any of the hydractive electrics but the rear height is now constantly changing, even with the engine off.
I can't make the rear rise fully with the buttons but I can with the Lexia.
I've tried depressurising twice but made no difference to the unhappy height.

My method involved undoing the anti roll bar at both ends and pulling the arm right out so that it was sitting on my knees.

Any suggestions?

Edit: The Mrs was lying, the Lexia command doesn't make it rise.
Last edited by Jabo on 25 May 2012, 00:41, edited 2 times in total.
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Jabo
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

By constantly changing I mean it will pump to where it wants to be then drop. Pump again then drop etc. Some times it will pump and stay there for a few seconds then drop again.
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Jabo
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

And one time the buttons let me rise it fully and it stayed there. One time.
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Jabo
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

I think I've actually put the pushrod back into the sphere the wrong way. I put the cone end into the unit and have the other end pushing on the arm.
This would cause a leak in pressure causing my symptoms, wouldn't it?
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Re: Finally done my rear arm bearings, now rear height unhap

Post by RichardW »

The push rod may not be helping, but this has been reported before. What seems to happen is that there is wear in the height sensor, but this is masked by the friction in the worn radius arm bearing. Remove the friction, and the height sensor sends odd messages to the suspension ECU. Change out the rod for the correct way, but if it is stil doing it, then you will need to fit a new height sensor - not that dear or difficult to fit IIRC.
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Jabo
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

Spent ages giving that push rod a good pull there with mole grips and couldn't budge it.
Was thinking of 2 ways to try now - either remove the unit, is it just the 2 torx bolts holding it in place? or can I remove the sphere and knock the push rod out?
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dnsey
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Re: Finally done my rear arm bearings, now rear height unhap

Post by dnsey »

Did you remove the 'dogbone' from the height sensor? If so, check that you've replaced it so that the sensor arm moves within the correct quadrant, and in the right sense (compare with the front sensor). It's easy to fit it incorrectly, which causes oscillation such as you describe.
On the other hand, if the problem turns out to be 'wear' on the sensor, you have two options other than replacement:
Try drilling a small hole in the body of the sensor and injecting switch cleaner, then exercising the sensor thoroughly. If successful, refill the hole with melted plastic to avoid contamination. This worked for me as a permanent fix.
Otherwise, add a resistor of, say, 5% of the sensor's overall resistance to one end of the bridge, then reset the height with a Lexia, so that the sensor is operating over a different portion of its track.
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

dnsey wrote:Otherwise, add a resistor of, say, 5% of the sensor's overall resistance to one end of the bridge, then reset the height with a Lexia, so that the sensor is operating over a different portion of its track.
That's a great idea, I'll need to try that if changing the orientation of the pushrod makes no difference.

I didn't touch the height sensor at all when changing the bearings. I only undone the ARB at either end and pulled the arm out.

Need more method suggestions on removing that damn pushrod!
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Re: Finally done my rear arm bearings, now rear height unhap

Post by Jabo »

Got the pushrod sorted. Didn't fix the problem. Must be the height corrector.
This bloody job should've only taken 3 hours, it's taken 3 days and it's still not done!

The rear end is stuck in low.

Looking at the parameters in the Lexia the front height sensor seems to be working fine, it go up in its "steps" range incrementally whereas the rear stays at something like 70 steps then if I try to raise the height it shoots to something like 238 steps (which is definitely out of the range it should be in) with no increments in between. Sounds like a duff sensor to me. What do you guys think?
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Jabo
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Re: Finally done my rear arm bearings, now rear won't rise

Post by Jabo »

You can see from the attached Lexia log the readings that the front and rear sensors were giving.
Front is working as it should, rear is reading too high when it's at 180 steps (which I think is fully raised) and too low when it's at 74 steps (which I think is fully lowered)

New sensor time.
Attachments
suspensiontrace.zip
(6.01 KiB) Downloaded 78 times
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dnsey
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Re: Finally done my rear arm bearings, now rear won't rise

Post by dnsey »

Try cleaning it first as I suggested - you might be pleasantly surprised!
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Re: Finally done my rear arm bearings, now rear won't rise

Post by RichardW »

service.citroen says:

00005273J4 SENSOR 36.17 GBP

Worth a punt at cleaning it first!
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Jabo
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Re: Finally done my rear arm bearings, now rear won't rise

Post by Jabo »

I left it attached and gave it a good spray with WD40, including the plug and plug socket. Any other recommended method?
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Re: Finally done my rear arm bearings, now rear won't rise

Post by dnsey »

See my post above - it's the internal track that needs cleaning.
Jabo
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Re: Finally done my rear arm bearings, now rear won't rise

Post by Jabo »

Went to EDINBURGH and got a new corrector. 140 mile round trip, the only place in the entire central belt that had one in stock.
Suspension all sorted!
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