XM rear height corrector
Moderator: RichardW
XM rear height corrector
Does anyone happen to know how much travel there should be on the rear height-corrector valve. On advice I cleaned up and lubed the selector rod to height corrector assembly as everything had seized and the back of the car was not raising. The small plastic pushrod is intact but even after cleaning around where the rod enters the valve there seems to be less than 5mm of travel. Is this normal?
You'll be glad to know that after cleaning and lubing rear height corrector links and rods, the car now raises and lowers like it was meant to. Playing with the height control when stationery is the nearest thing to owning a 'low rider' without resorting to a boot full of batteries and aircraft hydraulics!
What do you mean Paul ???
The HC is checked by selecting various heights - or by loading the suspension - i.e. the common "bumper test" where you press down either end of car with the weight of your body on the bumper.
The car should gentle sink - then after some 15-30 sec's regain height. Opposite - if you jump off - the height should bounce up - then after some 15-30sec's slowly sink back again.
Of course flat wheel spheres will deny the suspension to sink on load.
The HC is checked by selecting various heights - or by loading the suspension - i.e. the common "bumper test" where you press down either end of car with the weight of your body on the bumper.
The car should gentle sink - then after some 15-30 sec's regain height. Opposite - if you jump off - the height should bounce up - then after some 15-30sec's slowly sink back again.
Of course flat wheel spheres will deny the suspension to sink on load.
Hi Anders,
What I mean't was how to service the height links and rods; eg exactly where they are on the car etc. My XM seems too low on the road and when it lurches about on narrow country roads the mudflaps hit the ground. Everything has been replaced on the car within the last 5kmiles, but it doesn't seem like it was done very well.
What I mean't was how to service the height links and rods; eg exactly where they are on the car etc. My XM seems too low on the road and when it lurches about on narrow country roads the mudflaps hit the ground. Everything has been replaced on the car within the last 5kmiles, but it doesn't seem like it was done very well.
Right Paul -
You're facing the standard problem : loads of bills paid to solve problems - and still problems remains - now it's time to DIY [:)]
The HC unit itself is easily recognised once you're under the car.
It's approx half the lenght and same size of a good old cylindric ignition coil. Has rubber end caps both ends - and 4 rigid pipes + 1 small rubber hose connected.
It's controlled by the antiroll bar - position of which is transferred by steel rod linkages to the HC for height regulation.
It's the linkage clamp position on the antiroll bar you alter - to set the drive height. The clamp is made up by 2 halfshells - linked one end and bolted other end.
You simply loosen the bolt to just barely move the clamp on the antiroll-bar (by tapping it) - if you get it loose fit - it turns too easy - and you can not control the height setting - as the setting is very sensitive.
The correct ride heigt in normal height is found pr rule of thumb :
simply record the height in lowest & highest settings - then set the normal height exactly halfway between these 2 extremes.
Doing it this way - it's of no significance where you actually measure the height - as long as you use the same point for each measurement [;)]
Adjusting takes a couple of trial & errors before you get it right. Remember to jerk the suspension after each setting - to release any minor bindings.
You need either a service pit - or to lift the rear wheels on blocks - to gain safe workspace under the car. Remember the car needs to have weight on wheels for this adjustment !
When under car adjusting the clamp - the clampshell joint pointing rearwards of car - must be adjusted/turned/tapped upwards to raise the height on rear suspension. Be sure only adjusting a couple of mm each time - as this will cause approx 10times the change in height.
You're facing the standard problem : loads of bills paid to solve problems - and still problems remains - now it's time to DIY [:)]
The HC unit itself is easily recognised once you're under the car.
It's approx half the lenght and same size of a good old cylindric ignition coil. Has rubber end caps both ends - and 4 rigid pipes + 1 small rubber hose connected.
It's controlled by the antiroll bar - position of which is transferred by steel rod linkages to the HC for height regulation.
It's the linkage clamp position on the antiroll bar you alter - to set the drive height. The clamp is made up by 2 halfshells - linked one end and bolted other end.
You simply loosen the bolt to just barely move the clamp on the antiroll-bar (by tapping it) - if you get it loose fit - it turns too easy - and you can not control the height setting - as the setting is very sensitive.
The correct ride heigt in normal height is found pr rule of thumb :
simply record the height in lowest & highest settings - then set the normal height exactly halfway between these 2 extremes.
Doing it this way - it's of no significance where you actually measure the height - as long as you use the same point for each measurement [;)]
Adjusting takes a couple of trial & errors before you get it right. Remember to jerk the suspension after each setting - to release any minor bindings.
You need either a service pit - or to lift the rear wheels on blocks - to gain safe workspace under the car. Remember the car needs to have weight on wheels for this adjustment !
When under car adjusting the clamp - the clampshell joint pointing rearwards of car - must be adjusted/turned/tapped upwards to raise the height on rear suspension. Be sure only adjusting a couple of mm each time - as this will cause approx 10times the change in height.
Hi Anders,
Many thanks for your lucid description of that procedure I will do that soon and report back.
The car tends to roll/dive front left and right which is bad compared to my v6sei (which although fully serviced has had no big money spent on it). I noticed when going through the receipts that all the spheres were replaced on the front together with the bumper/ bumper absorbers, radiator and subframe due presumably to an accident which must have also caused the heads to blow later (only just a bit later and I think that must have persuaded the person to sell it). That was about 8,000 miles ago (although 2 years since the car wasn't been driven much since) is it likely that it would need new spheres or could adjusting the height cure this tendency? I must say that compared to my previous v6 it jumps up like a youmg puppy when I start the engine!
Another question:
Is antigel just another word for anti-freeze or should these cars have this special antigel in them. I have been adding Halford's antifreeze in since I got it in Nov since the previous owner said it was loosing some water and there was a bag in the boot of about 5 2 litre lemonade bottles full of water. When I looked at the coolant it seemed very clear so I decided rather than have a disaster I would add some neat run it and then add some more until it was full.
Many thanks for your lucid description of that procedure I will do that soon and report back.
The car tends to roll/dive front left and right which is bad compared to my v6sei (which although fully serviced has had no big money spent on it). I noticed when going through the receipts that all the spheres were replaced on the front together with the bumper/ bumper absorbers, radiator and subframe due presumably to an accident which must have also caused the heads to blow later (only just a bit later and I think that must have persuaded the person to sell it). That was about 8,000 miles ago (although 2 years since the car wasn't been driven much since) is it likely that it would need new spheres or could adjusting the height cure this tendency? I must say that compared to my previous v6 it jumps up like a youmg puppy when I start the engine!
Another question:
Is antigel just another word for anti-freeze or should these cars have this special antigel in them. I have been adding Halford's antifreeze in since I got it in Nov since the previous owner said it was loosing some water and there was a bag in the boot of about 5 2 litre lemonade bottles full of water. When I looked at the coolant it seemed very clear so I decided rather than have a disaster I would add some neat run it and then add some more until it was full.
antigel = antifreeze.
If you assume as pr the bills that the new spheres has approx 8kmiles in service - then I can't see they need replacement again. They should last something like 60kmiles. Worn down spheres means they loose their gas precharge pressure - which during hydraulics function on car is replaced by LHM fluid to compensate for correct height. Then the car feels very stiff in the suspension - like riding on hard rubber - and in turn prevents roll tendencies.
There is a chance that the front spheres are wrong type - or modified for a softer ride. This is indeed quite bothersome to track down - i.e. it's a lot cheaper, faster & easier simply to replace them with known correct type for your specific XM model/year.
That is if no other severe problems are present :
1) the front antirollbar could be the culpritt.
This could be damaged as well from the incident - and if so - it would allow for extreme roll on front if the bar itself has split.
I've never seen a split anti-rollbar though - they are heavy springsteel. But I'd certainly inspect for any odd/weird looking things down there with such roll/dive as you describe.
The anti-rollbar connects each side´s wheel by the droplinks (connecting rods with balljoints). I've seen a droplink totally given up the ghost in one balljoint one side on an old car - a neglected car killed by rust.
A similar damage to a droplink may occur after an incident.
It's quite easy to check : lift the front - wheels off ground - then start engine and set the height controller to lowest height - stop engine when suspension has dropped. Now the front wheels will hang freely without supension pressure. If you lift on one wheel - the other side's wheel must follow - by the anti-rollbar & droplinks.
If this does not happen you have a severe problem.
Try rattle each wheel up/down (I know - it's heavy [;)]). If any severe knocking is heard from the suspension components - you have worn balljoints in droplinks - or worn bushings in lower control arm or anti-rollbar.
2) With weight on wheels again & normal height :
Have a look on the top of the front struts each side in the engine bay - does it seems like they are striking the underside of bonnet when closed ?
Place a long even-edged ruler transversely over the engine bay - resting on both front wings - exactly over the strut tops.
Check that you have a clearance under the ruler to each strut top equal both sides of approx 5mm.
If this is not true - the strut mountings are on their way out - at some point they will release the strut which then shoots up thru the bonnet !
It's either the strut rubber vulcanising, the rubber itself or the bodysheetings that may be detoriated/damaged.
If you assume as pr the bills that the new spheres has approx 8kmiles in service - then I can't see they need replacement again. They should last something like 60kmiles. Worn down spheres means they loose their gas precharge pressure - which during hydraulics function on car is replaced by LHM fluid to compensate for correct height. Then the car feels very stiff in the suspension - like riding on hard rubber - and in turn prevents roll tendencies.
There is a chance that the front spheres are wrong type - or modified for a softer ride. This is indeed quite bothersome to track down - i.e. it's a lot cheaper, faster & easier simply to replace them with known correct type for your specific XM model/year.
That is if no other severe problems are present :
1) the front antirollbar could be the culpritt.
This could be damaged as well from the incident - and if so - it would allow for extreme roll on front if the bar itself has split.
I've never seen a split anti-rollbar though - they are heavy springsteel. But I'd certainly inspect for any odd/weird looking things down there with such roll/dive as you describe.
The anti-rollbar connects each side´s wheel by the droplinks (connecting rods with balljoints). I've seen a droplink totally given up the ghost in one balljoint one side on an old car - a neglected car killed by rust.
A similar damage to a droplink may occur after an incident.
It's quite easy to check : lift the front - wheels off ground - then start engine and set the height controller to lowest height - stop engine when suspension has dropped. Now the front wheels will hang freely without supension pressure. If you lift on one wheel - the other side's wheel must follow - by the anti-rollbar & droplinks.
If this does not happen you have a severe problem.
Try rattle each wheel up/down (I know - it's heavy [;)]). If any severe knocking is heard from the suspension components - you have worn balljoints in droplinks - or worn bushings in lower control arm or anti-rollbar.
2) With weight on wheels again & normal height :
Have a look on the top of the front struts each side in the engine bay - does it seems like they are striking the underside of bonnet when closed ?
Place a long even-edged ruler transversely over the engine bay - resting on both front wings - exactly over the strut tops.
Check that you have a clearance under the ruler to each strut top equal both sides of approx 5mm.
If this is not true - the strut mountings are on their way out - at some point they will release the strut which then shoots up thru the bonnet !
It's either the strut rubber vulcanising, the rubber itself or the bodysheetings that may be detoriated/damaged.
Thanks again Anders,
I will check the anti rollbar and I think this or perhaps the droplinks may be causing the problem, because according to the bills the car definitely had a frontal and since this involved changing the front subframe it must have been fairly severe. As far as the struts and corrosion are concerned this car has been cosseted and pampered all it's life in a warm and dry garage and sadly is only just now being put to work.
I will check the anti rollbar and I think this or perhaps the droplinks may be causing the problem, because according to the bills the car definitely had a frontal and since this involved changing the front subframe it must have been fairly severe. As far as the struts and corrosion are concerned this car has been cosseted and pampered all it's life in a warm and dry garage and sadly is only just now being put to work.