Active Suspension - Rear Shocks Replacement - Bleeding System (literally!!!!!!)

Neil Hicking

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Jun 13, 2013
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Any help with this appreciated. I understand when you replace the rear shocks the active system needs to be bleeded, which involves using the active height switch by the drivers left leg next to the heated seats switch. I can't find any info on the active suspension height system, not even in the service manuals in this website. Can anyone advise/help please?
Sorry it is an 04 manual diesel amazon 100
Neil
 

BobMurphy

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I am in scotland
Mar 1, 2010
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Kirkliston, Scotland
I can't find any info on the active suspension height system, not even in the service manuals in this website. Can anyone advise/help please?
Sorry it is an 04 manual diesel amazon 100
Neil
I'm looking for info on this as well as I'm trying to understand the system on my 2001 'VX'. The 'Expert' appears to be 'uHu' in Norway, hopefully he'll pop in.

Why are you replacing the struts ??

My understanding is that the struts are just that - they contain the AHC fluid which is pumped in to make them longer or let out to let the car settle.

Fluid, from the pump assembly under the bonnet, passes through an 'Actuator' mounted on the chassis alongside each strut. The rate at which fluid is allowed to pass in and out of the strut is controlled by this Actuator - which gives the necessary damping.

Fluid can't be compressed, so on the other end of each 'Actuator' is a sphere (or Globe) which contains a diaphragm with compressed gas on the inside. As the suspension moves, the fluid from the strut is pushed through the Actuator and into the Globe, compressing the gas. This gives the suspension travel.

The height of the suspension is controlled by the AHC ECU which gets its readings from the three 'Height Sensors' (one at each side at the front and a single one above the rear axle).

So. Height is set by the switch in the car which causes the pump to pressurise the system (going up) or release fluid back into the reservoir (going down). All managed by the ECU which is watching the Height Sensors.

Ride characteristics (Comfort, Sport) alters the Compression Damping at each Actuator. I'm not sure whether Rebound Damping is affected - probably.

Suspension Travel is determined by the gas in the Globes . . . Which is where we get problems.

The Globes can lose their gas with age. When this happens everything else continues to work but instead of pressurising the gas, the globes fill with fluid. You have the same Ride Height as before but there will be a lot less fluid in the reservoir under the bonnet and the suspension will be rock hard.

This may, of course, only affect one corner - or any combination of the four :icon-wink:.

I don't know the procedure for replacing any one item in this assembly, but I expect it to be messy. Looking at the underside of mine (which has had 13 years of Northern road salt) I can't imagine anything coming apart cleanly.

So back to my first question - why are you wanting to replace something ??

(If 'uHu' can come along and correct my understanding I'll be very grateful :whistle:).

Bob.
 

uHu

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I am in norway
Mar 7, 2010
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Oslo, Norway
Fantastic Bob. Good description.

Bleeding is easy. Just put the suspension at any other level than Lo, put a small hose on a bleeder and into a bottle, crack open the bleeder and let the car sink down. Close before/when it bottoms out. Start car, close doors, let it raise again, check fluid level / fill. Stop engine. Repeat until clean fluid, and on other side.

I think there's a thread in here on bleeding, but in any case, there are many on mud. E.g. this: http://forum.ih8mud.com/threads/ahc-fluid-change-how-to-need-input.438560/#post6127557

And yes: Why change the shocks? Are they leaking?
 
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frank rabbets

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Mar 1, 2010
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Stourbridge
Just a tip if you need to take the rear struts off. Some of the nuts can just be got at via the wheel arches. There is a slot which you can just slide a spanner through.
 
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Neil Hicking

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Jun 13, 2013
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Very many thanks to Frank, Bob and uHu - the info provided above is priceless. OK in answer to the question why replace the shocks? I have banging when i go down potholes and I sort of assumed this was the shocks not doing their job, as we had already replaced all the bushes on the rear suspension arms (and there are lots of them!) It seems the problem is one or more of the globes from what you have said. As a result of your info, I have also now found this link:
http://activesuspensionsystems.com/lelx470susy.html
which agrees with your advice - the globes failing is the most likely reason for the height adjustment not working properly and the spongy hard bangy ride. Lexus 470 is the same as the 100LC in all but the name and badge...........
So Guys where do I get new globes from? I guess scrappers yard ones are not the solution as these could well be nearly shot just like mine. Yes I understand they are extremely expensive new, but I need to solve the banging and the ride that is like a decomposing beached whale. Globes frequently fail after 6-8 years and 80-100K miles so I read somewhere else on the web.
Once again any info most welcome.
Neil
 

uHu

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I am in norway
Mar 7, 2010
2,071
424
83
Oslo, Norway
Have you tried riding said whale? (I do like the comparison tho').
Globes should last a bit longer, if you keep the Neutral Pressure within specs. But yes, somwhere after 100 k miles.

Scrappers could be good. Depends on why the car was scrapped. I got some 2nd hand, and I've used them for more than 100 k km now. Otherwise, I've heard only good about Pleiades, also on this side of the North Sea.
 

Neil Hicking

New Member
Jun 13, 2013
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I think I am on top of this now?! Please see the link to ebay where i bought x4 replacements from. Most importantly this includes comprehensive installation instructions.
http://www.ebay.co.uk/itm/121539677...X:IT&_trksid=p3984.m1561.l2649#ht_1943wt_1266

Their website is at

www.wtvuk.com which has a pdf version of the instructions within.

Having said that I now need to do the job!

Regarding decompossing beached whales and my LC's ride..................... bone hard in places, but otherwise very horribly spongy.........

Neil
 

Dark Dude

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Feb 28, 2011
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Second vote of confidence for the boys at Pleiades. They replaced all four spheres on my wagon which at the time was being used as a ambulance to ferry our Sharon back and forth to the Royal Free. After the spheres were replaced/renewed, Shaz didn't throw up ONCE on her way to hospital, the ride was silky smooth, even when we had to ride over the numerous sleeping policemen lying in wait in Crouch End and Highgate. I'm looking to replace and renew both the struts and springs in the very near future and hopefully the dude at Pleiades will be able to help......
 

nathanrobo

Well-Known Member
Apr 6, 2010
655
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48
Kettering - UK
Second vote of confidence for the boys at Pleiades. They replaced all four spheres on my wagon which at the time was being used as a ambulance to ferry our Sharon back and forth to the Royal Free. After the spheres were replaced/renewed, Shaz didn't throw up ONCE on her way to hospital, the ride was silky smooth, even when we had to ride over the numerous sleeping policemen lying in wait in Crouch End and Highgate. I'm looking to replace and renew both the struts and springs in the very near future and hopefully the dude at Pleiades will be able to help......
Martin at Pleiades is definitely the top choice for spheres... I've known him since the 1990's when I had a big Citroens (I originally asked him to look at LC spheres). The best thing about Martin is his rigour. He uses an endoscope to check the condition of the sphere and gives a decent warranty (can't remember how long but for example he always used to offer a year or two more than new Citroen spheres). The other great thing is that if you are doing it yourself, he'll provide advice / instructions. What more could you ask for :)
 
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