Xantia Suspension, with 'load' in car

jgra1 · Post by **jgra1** » 15 Dec 2006, 00:40

chaps, if my xantia is carrying lots of weight. would this imply the hydraulic pump/compressor is working harder than usual, and therefore causing a drop in fuel economy?

I should be able to work this out, but I haven't tried

JOhn G

Mandrake · Post by **Mandrake** » 15 Dec 2006, 04:05

Short answer: no.

The hydraulic pump is only doing additional work with a heavier load for the few seconds the car is lifting up to the normal ride height. Once it gets there the pump has nothing extra to do for a heavier load than a lighter one.

Leakage from the cylinders and height correctors (causing gradual height loss) is probably slightly higher with more load in, but the pump is only correcting for losses of height in the order of a couple of seconds every half an hour or so of driving time...eg negligible.

Regards,
Simon

citronut · Post by **citronut** » 15 Dec 2006, 08:57

the pump must be topping up the presure every time the regulator cycles,but i agree it should not have much affect on fuel econamy,you will find the extra weight will cause you to use more fuel,as the engine is working harder to drag the load along
regards malcolm

jeremy · Post by **jeremy** » 15 Dec 2006, 10:12

Most of the time the height correctors will be shut - so the suspension is isolated from the rest of the system. When topping up (necessary due to operation of the height corrector or due to leakage) the accumulator will provide some LHM - but due to the operation of the regulator this will be at normal pressure - which is the only pressure the regulator can operate at.

So - yes slightly more high pressure LHM will be required to lift the car initially (gas in spheres will be a bit more compressed and occupy a smaller volume) and the frequency of topping up might increase (but might decrease as well I suppose as the back end may not rise and fall as much)

A heavy weight in the back may also have the effect of making the steering lighter by reducing the load on the front - so it may not need as much assistance! - which in turn may reduce the hydraulic system's consumption. I think this will depend on the positioning of the load which would have to be right at the back behind the back wheels and I would have thought the self levelling suspension would minimise this.

jgra1 · Post by **jgra1** » 15 Dec 2006, 10:29

thanks all
leaving now, 300 miles with 200 kgs in the back, and it's a v6 ...

john

citronut · Post by **citronut** » 15 Dec 2006, 13:40

the hight corectors will be on the move all the time the car is moving along,as they are linked to the roll bars,also you have the constant movment of the suspention rams,i agree not as much as when the car is rasing up to start with,and the regulator cycling is topping the system up with presure
regards malcolm

Post by **Peter.N.** » 15 Dec 2006, 14:49

I agree with the above, but the extra weight will will affect your fuel consumption!

jeremy · Post by **jeremy** » 15 Dec 2006, 16:18

Yes but with a V6 Xantia you're talking the difference between 20 and 22 MPG if you're lucky. TD BX Estate or ZX 1.9D it would be the difference between 47 and 52!

deian · Post by **deian** » 15 Dec 2006, 23:22

jeremy wrote:A heavy weight in the back may also have the effect of making the steering lighter by reducing the load on the front - so it may not need as much assistance! - which in turn may reduce the hydraulic system's consumption. I think this will depend on the positioning of the load which would have to be right at the back behind the back wheels and I would have thought the self levelling suspension would minimise this.

i don't think the steering would go light as much as other cars would, maybe just slightly as you said, but i don't think this is an issue because of the self levelling suspension, hence the lack of headlight height level adjusters (which like you get in many other basic cars such as mondeos)

also remember the xantia/bx/xm have clever brakes in the back that work in accordance to the weight in the back of the car, the more weight you have, the better the back stops, quite a clever system really, some would suggest loading her up from time to time to excercise the back brakes as they get used maybe at a ratio of 80/20 most of the time.

jgra1 · Post by **jgra1** » 16 Dec 2006, 13:10

well, I got here, smashing drive.. M1 was rubbish above Leicester..
seemed to get about 350 miles on £40.. @86ppl..

not too bad, although was taking it very easy..