Omega Owners Forum

Omega Help Area => Omega General Help => Topic started by: amba on 11 March 2011, 21:05:13

Title: Self Levelling rear shocks
Post by: amba on 11 March 2011, 21:05:13
As this has been a popular posting over the last few weeks I just needed a bit of technical/operation details on the above.

Do s/l shock absorbers function identically to standard shocks except air gets pumped into the shock if the bodywork needs correction to level.?

What would be the effect of s/l shocks being fitted without the compressed air pump working ?

Does the air charge give any additional suspension benefit/make ride softer or firmer ?
Title: Re: Self Levelling rear shocks
Post by: Andy H on 11 March 2011, 21:34:43
I am going to fit new self levelling dampers to my saloon tomorrow because the old ones are wet with oil and I have odd knocking noises from the rear end.

My impression is that there is a normal oil filled damper inside with an air filled condom on the outside. When the steel springs are not sufficient the air compressor pumps air into the condom which then acts as an air spring.

An air pipe links them together which means that they don't offer any roll resistance :(

I have been driving mine 'enthusiastically'  ::) over the last few days and it does feel a bit like driving a bouncy castle..

Hopefully new dampers will reduce the bouncy castle feel :y I will report back if I feel any improvement.
Title: Re: Self Levelling rear shocks
Post by: feeutfo on 11 March 2011, 21:43:19
I have always been tempted to pull the fuse and see what the damping is like with no air in the bladders. But I am unsure if the bladder will get damaged as the inside surfaces rub up and down over bumps.  :-/

Title: Re: Self Levelling rear shocks
Post by: Andy H on 11 March 2011, 21:44:26
I think the air pressure maintains the shape of the condom. Without any air pressure there might be a risk of a crease forming and damaging the rubber :-/

The air pressure increases the load carrying capacity. If you start off with soft Elite springs you can add weight to the rear of the car and the air compressor will add air to stiffen the springs and maintain the ride height. The ride quality remains feeling quite 'soft' though because the increased spring stiffness ('spring rate') is balanced by the increased weight.
Title: Re: Self Levelling rear shocks
Post by: des.allen on 11 March 2011, 21:51:23
I have a problem with mine as it just keeps pumping up and up and.....
So until i get around to sorting it i pull the plug and just keep topping it up every couple of days :)
Title: Re: Self Levelling rear shocks
Post by: amba on 11 March 2011, 22:49:44
Interesting theories.

Mine was the spring carried the weight of the cars body and being that s/l springs were softer the car would have a more floaty feel...bouncey castle effect.

The shock absorber as its name suggests allows the bumps and humps in the road to be smoothed out and had no influenece or effect from the air.When car is started ,pump under drivers side front wing cuts in and assuming the car needs to be levelled due to more weight being in the rear end of the car be it passengers or load in boot,air is pumped in to the rubber bladder and the shock is extended to push the back of the car level with the front.Therefore in theory when the shock is extended this must inturn extend the spring length and still allow the cars weight to rest on the spring,but as the shock has now been extended the effect of shock absorption must be decreased as it is now also holding the extra cars weight.

So if the fuse is removed or the air is escaping then the shock is always at its shortest length and this must also be the case with the spring.Now as we know the s/l springs are slightly softer than standard non s/l spring therefore the  entire ride of the car is too low and has little or any shock absorption  and cushioning.

Does this theory sound about right ?

Main reason I question this is I fitted new s/l springs and shocks about 2 weeks ago.Since then I have had a constant battle trying to get the air valve to seal on the o/s nipple on the s/ l shock.Despite numerous attempts with extra rubber "0" rings and botched pipe joins I cannot get a permenant air tight seal.Up to now I have been driving a car with brand new shocks and springs and air leaking from 1 shock.The ride has not been what I had expected or hoped for with the new parts and  I wanted to be sure that I could expect an improvement with an "air tight" fitting.I was unsure if the extra benefit of the levelling was just  for towing.
Title: Re: Self Levelling rear shocks
Post by: Andy H on 12 March 2011, 21:48:33
Fitted! Both dampers had a build up of rust and dirt under the rubber on the outside of the steel tube. The nearside damper had rusted right through.

For Amba's benefit here are some pictures of the air connector and seal.

(http://homepages.nildram.co.uk/~aholter/P1000430.JPG)

(http://homepages.nildram.co.uk/~aholter/P1000431.JPG)

(http://homepages.nildram.co.uk/~aholter/P1000432.JPG)

The seal is rather like a couple of 'o' rings on the outside of the plastic pipe. The cap pushes the seal into the bore in the connector on the damper. The plastic pipe goes through the seal and the end on the pipe stops it from pulling out of the seal.

HTH