Citroen XM Forum

On the harsh ride at low speeds: I came to the conclusion that a well maintained hydroactive car does feel a little harsh over bad surfaces and single wheel bumps, but it only feels that way in comparison to the way it soaks up everything else. In absolute terms, I don't think they are worse than anything else.

My Alpina handled choppy surfaces better, as does my SM. The XM handles them better than my old Merceedes 210 with brand new shocks and spheres, so some things are right, but it is the contrast that is so poor. I'd definitely say my 2.1 Series 1.5 handles choppy roads much better than the Series 2 V6, and that was with the latter's tyres being quite underinflated as I found out.

On that basic subject, I took a long-time Mercedes owner to our team Christmas lunch today in my V6 Xantia.

He was bowled over and for the entire journey he kept saying what a lovely smooth and comfy car it was. Not this is a Xantia d it has nothing on an XM in those departments so what on earth is a Merc like. Must be awful as against the XM I don't consider the Xantia that good...

It does depend largely on the tyres, there is a tremendous variation, I have Nexen on both cars now and the difference in ride and noise had to be tried to be believed.

Peter

Peter's bang on with this. John has written in similar vein a while ago. The first line of "absorption" is the tyre, and the more pliant they are, the less thump gets through to the wheel and then everything else.

Appropriate Michelins seem always to have been pretty good in this respect (one-time Pilot, then Primacy, and now [because of profile availability] Energy). Any 'rigid' tyre is going to give a nobbly ride. The Michelins can be annoying too if at all over-inflated.

With my suspension now sorted (new spheres and regassing), the ride on tarmac is exemplary, with the exception of lateral ruts and grooves, or suddenly coming off a speed hump (when things go firm, because of the sudden rise of the front wheels). Keep this last thing below 10km/h, and all is sweetness - so all seems to be working as per the book.

Have noticed (Jorgy has written on this) that ride is harder when conditions and car are cold. Presumably this is in part down to the LHM being more viscous at lower temperatures, and therefore encountering more damping. Interesting to note that Citroen recommend a different version of LHM for Scandinavia. Have also seen (? FCF) suggestions that "weekend cars" and some others might be run on Hydraurincage (Hydroflush) full-time, but perhaps this is for clean-up reasons, rather than viscosity. I understand its lubricating properties (for pistons, etc) are less good, though, and it's not something I'd rush to.

This is one thing I have noticed more with the weather getting colder recently, the ride, initially, is harsher until everything has warmed up and it gets more supple.

I suspect the ride becoming more brittle due to the cold weather is more to do with the rubber suspension components becoming harder.

Not sure that a 10degC drop in temperature is enough to make rubber (presumably bushes?) behave much differently, but it is enough to affect the way road ridges are dealt with. In any case, on a cold day, the fluid may warm up on a decent-length journey, but suspension bushes (unless they're in the engine bay) won't - and it's the back end that tends to be crashy.

White Exec wrote: with the exception of lateral ruts and grooves, or suddenly coming off a speed hump (when things go firm, because of the sudden rise of the front wheels). Keep this last thing below 10km/h, and

I read this with surprise but didn't say anything till I double-checked with my 1993 21TD. It's going through large humps at 20 miles per hour without switching to hard -the car crowling on its own idle in 3rd gear. The 2000 V6 I was driving till a month ago was the same -one needed to go pretty fast to make it go hard, fast as in doing it on purpose -and again there's no special drama from the hardened rear, as the speed is quite high. 10 kilometers per hour (6 mph) for switching to hard due to the front antiroll bar sensor, surely indicates something is not right. 10km/h is what, like idling on 2nd gear? No way it should enter hard at that speed. Of course I don't know what kind of hump you're thinking of, they come in various lenghts and heights... I'm talking of ones that you'd naturally pass at about 20mph, and more if you were...excited.

I remember reading on french fora of XMs that were behaving strangely on humps, i.e. rear hitting remarkably bad, or even jumping... is yours anything like that?

I wonder how other examples behave??

In the Xantia V6, I had a lot of test runs on the rather harsh speed bumps in the Cambridge science park and found that at exactly 19MPH they disappeared, any slower and the front suspension would start to follow the bump, and any faster and the hydroactive would switch to hard mode before the rear wheels hit the bump. I took some colleagues down there one day and they thought i was mad attempting the bumps at more than 5MPH.

I did the road once in the XM and it had similar behaviour at 19MPH.