SUSPENSION CHARACTERISTICS

ACTIVE8 · Post by **ACTIVE8** » 20 Jan 2005, 17:29

Do Xantia's, or indeed any other L.H.M Citroens actually have anti squat, and anti dive because of the design.

Robin · Post by **Robin** » 20 Jan 2005, 17:36

The height control valves do that for you. As they sense a drop or rise they try to compensate. Possibly not a full anti dive or squat system but certainly a very good mimic of one.
The hydractive system is more sophisticated I think and my XM is far less prone to dive or squat than the Xant is. Robin

dan.2cv · Post by **dan.2cv** » 20 Jan 2005, 18:01

I remember it was used as a selling point on the BX in the sales brochure. I still have it somewhere (along with brochres from around 100 other cars c1988-90) I collected them as an enthusiastic schoolboy.

alexx · Post by **alexx** » 20 Jan 2005, 18:09

It has nothing to do with hydraulics; height correctors are designed to react with a delay of several seconds.
It's just the mechanical construction of front and rear suspension that does the job, like in any other non-hydraulic car

ACTIVE8 · Post by **ACTIVE8** » 20 Jan 2005, 18:43

I asked the question because, I enjoy the handling on my Xantia Activa, and the car has great handling, and cornering abilities.
So I wondered about the anti dive, and anti squat characteristics. As when either braking hard, or accelerating hard, it does not dive or squat, like a conventionally suspended non hydractive car.

Oystercatcher · Post by **Oystercatcher** » 20 Jan 2005, 21:45

The Hydractive ones do and, by analogy, your Activa will. My mk1 Xantia VSX would take off perfectly level from a standing start (as long as you actually accelerated, not 'continental-drifting' it up to 30mph in half a mile [:)]) but would squat under acceleration after say, a slow 90deg left-hander. You could also feel the front stiffen up under braking.
My current SX on the other hand squats like a good 'un. In these dark nights, you can see the headlamp cut-off climbing up the rear of the car in front [:)]
Alan

paranoid · Post by **paranoid** » 20 Jan 2005, 21:50

Cit specialist says normal xant's aren't antidive, but if you brake over a long distance the front dip will correct after a while if the hydraulics are up to scratch, clean fluid, moving h/c etc, but agreed it wasn't noticable in everyday driving, says it's really noticable after driving older cits but not as bad as same age fords/ vauxhalls etc.

406 V6 · Post by **406 V6** » 21 Jan 2005, 02:01

it has to do with the rear suspension's geometry.
When braking is applyed, the force the makes teh suspension "dive" a bit, thus maintaining the car levelled.
On regular cars, anti-dive is related mostly with the front suspension geometry, but i only know that it only works on a double triangle setup, where the upper one has an inclination towards the reverse of several degrees, i.e., the front support of the triangle is higher than the rear support.

Panjandrum · Post by **Panjandrum** » 21 Jan 2005, 02:03

Yup - to the best of my knowledge, and based on driving one, the Activa will not squat or dive. It has many other eccentric qualities, but on rapid braking or acceleration it clings frantically to the horizontal.

Dave Burns · Post by **Dave Burns** » 21 Jan 2005, 02:16

Xantias have so called anti dive front suspension geometry, if you look you will see the track controll arm front mounting bush is much lower down than the rear one, so the pivotal angle of it is inclined to the rear thus providing a degree of anti dive.
The fact that the rear brakes will drag the back of the car down a fraction is probably just a trait of the trailing arm design, and is not necessarily a design function of it.
Dave

alexx · Post by **alexx** » 21 Jan 2005, 03:46

On previous Citroen vehcles, like CX, GS, BX, front arms were inclined forwards as much as 10 degrees, so anti-dive effect was strong. On my BX, front didn't dive a bit upon heavy braking - the car was completly leveled. Pug 405 had similar front suspension geometry. On newer cars, this angle is reduced. On non hydractive XM, for example, it's 4 degree, on hydractive only 1 degree, because suspension will switch to hard upon heavy braking, preventing excessive diving of the front (front will dive anyway, but slowly).
On my non hydractive Xantia, both ends dive when braking, which is good - roadholding is improved in critical situations. It's similar on cars with conventional suspension.
Patxi, that drawing of the front axle you probably found on autozine is wrong (like some other explanations there, for example anti-roll bar). As Dave said, front suspension arms are slanted forwards to produce anti-dive effect, and you don't need double triangle suspension - lower triangle is enough. If similar setup is used for rear suspension, arms are inclined to opposite direction - backwards, like on my fathers AR156.