Ride Height Varying At Front

Hi

In this relentless quest for a smooth XM suspension before I expire........... If I set the suspension to high then return to normal, the front ride height ends up with about 3 finger widths between the top of the tyre and the wing. But if I set it to low and then to normal it ends up over 4 finger widths between wing and tyre. When I start off at '3' it looks right visually and drives perceptibly smoother than when I start off at '4', but the annoying thing is that it always ends up at '4' after I've driven for 100yds or more and gone over a few bumps. And then it looks too high and feels harsher! The rear ride height stays at pretty much same height, no matter whether I start off in high and select normal, or low and select normal. And the passengers in the back say its smooth in the back Dad!

I've just clambered underneath and checked the mechanical links to the height correctors front and rear and sprayed WD40 to excess, done about 10 up and downs, but it still does the above and its harsh at the front. Its like the front suspension has got a homing instinct for the intermediate height setting at the front. Sometimes I can catch it out when on the move by selecting high or low for a few seconds then it finds its way to the correct height and we get smoothness all round for a minute maybe. But then it goes back to too high at the front.

Does this make sense to anyone? I reckon its mechanical but cant see what to adjust or slacken. All 8 spheres are near new and car has good H5 hydractive ECU.

Any suggestions welcome as I'm running out of ideas again!!!

Hi Mark

Are you sure then that the levers move freely -no matter if u showered them in wd40-? In my experience there no way to knwo if they are free unless you disconnect them from the height corrector or you slack the bolt that attaches the other end of the levers to the antiroll bar.

Anyway, another thing that can stick overthere is a brass bolt-ring kind of thing were one bit of the lever slides. This can get rusty. I've replaced mine with a new one when I was trying to repair my suspension. It costs about £2 from Cit and you should be able to do it yourself if you managed to spray wd40.

This said, that was not the problem for poor height correcting in my XM. The problem was clearly that the height correctors were internally full of sludge. I was getting similar height discrepancies to you, and also slow correction or no correction at all (very reduced sensitivity). After running on Hydraflush for many 1,000s miles all these mischiefs are gone. Now the height is, for example, corrected within 10secs of stepping out of the car, and there's no or minimal "whistleing". Before, I had to wait a good minute to see the car react -if it reacted at all- and there was a loud "hissss" as they corrected, audible even as you walked away from the car.

BTW what year/model/mileage is your car.

cheers
George

This post has been edited by jorgy9 on August 22, 2008 02:04 am

Hi George

Thanks that makes sense, I'm going to slacken the clamp on the anti-roll bar check if the levers move freely and check that brass thingy. I'm guessing as long as its on axle stands the car wont drop if I turn clamp to set height?

The fluid is clean and I've replaced both height correctors with ones from Pleiades in the last 6 months so I know their ok. I did the hydraflush treatment 18 months back for about 5,000 miles. Each step seems to result in a small incremental improvement! But I did notice a step change in responsiveness when I fitted the HC's (rear one first, front one about a month later). But within a couple of weeks it wasn't as responsive, which makes me wonder whether the hydractive blocks are causing a restriction. Anyway its not so bad now, certainly much better than before the hydraflush and new HC's. Just need to get the front height to stay right.

Car is 96 XM2.5, 177,000 miles.

Cheers

Hi Mark

Yes worth rechecking linkage, perhaps it just comes from there. Let us know if u resolve it.

That said: it is possible that as you say the problem is not with the height correctors but with other obstructions in the system. Problem is...you can never know unless you open up each and every component and see! It might be other sludge bits that remained in the system and travel till they get stuck at a narrow point. The 5,000mls you did on hydraflush sound sufficient (I had done 1,500+6,000) but you never know what is "sufficient", at the end it depends on the way the car was treated before it comes to your ownership.

Besides, note that "1 finger" of difference is probably (marginally) within the range of regulation of the height correctors. Just empirically speaking (I've never measured it), they need at least about 1cm of wheel movement to be activated -I guess you have seen this yourself over the hinge that activates them: it has a designed slack, otherwise car would try to correct height after every single bump on the road-.

So perhaps the not-so-soft probelm of your front is not directly related to this "1 finger" difference. I guess by now you've set the heights correctly, but: is the front ride height correct or maybe a tad higher?

cheers& good luck
G

I would concur with that. The hatchback which I recently put on the road after standing for about three months would not raise at the back unless I set it at full height and then to low. It continued like this for quite a few miles and several soakings of the linkage with oil, after about three weeks on the road it eventually settled down and now rises to the correct height immediatly. Incidentally, the suspension had been fine when I parked it up, but it had been parked on grass and was somewhat rusty underneath.

Peter.N.

just being a bit thick here....

but won't slackenning the bolt alter the ride-height setting when things move?
Also, watch the car as it will drop if this is the case!

ciao
Dave

Yes it will, you have to be careful to take a note of where it was.

For the record, we don't do height adjustement from this clamp, but from the height corrector's side, having untightened the clamp then working the corrector with e.g. a screw driver till car comes to the required height, then tighten clamp wherever it has settled on the antirol bar (height lever being in "drive" position thoughout).

G