Gas vs oil

Post by **Peetee** » Thu Mar 08, 2007 6:55 am

It is my undestanding that a lot of modern cars now have gas dampers where oil was more commonly used. Both of these options are available for telescopic kits for the Minor. My understanding is that gas is a superior action but everyones preferences for suspension feels is different - what is better for one person is worse for another. How does gas compare to oil? having been in a large number of avarage modern cars what strikes me is their ability to provide superior roadholding with comfort. the sort of grip and handling a 80's GTi would give but with none of the hashness of stiff suspension. Is this the difference of gas dampers perhaps?

Post by **chickenjohn** » Thu Mar 08, 2007 7:22 am

Just try changing your worn out springs and dampers for new items. A friend in the club was considering upgrading, but couldn't believe how much better the car felt after replacing the worn out springs and dampers with new STANDARD items.

The car now feels well damped and comfortable as you desire and the handling has returned, really dramatic- no need to modify unless you intend to go racing.

For an everyday car, stick to standard set up. When healthy, standard Minors handle and ride really well.

Post by **gairlochrosie** » Thu Mar 08, 2007 3:10 pm

chickenjohn wrote:Just try changing your worn out springs and dampers for new items. A friend in the club was considering upgrading, but couldn't believe how much better the car felt after replacing the worn out springs and dampers with new STANDARD items.

The car now feels well damped and comfortable as you desire and the handling has returned, really dramatic- no need to modify unless you intend to go racing.

For an everyday car, stick to standard set up. When healthy, standard Minors handle and ride really well.

I agree 100% with this, I too replace for new....anyway, some may call me boring when I say: I'm a believer in keeping all my cars standard...the way they were when first registered. But I prefer to keep them that way...so that when I hand over my collection...my childrens children will have a better idea of what we ran around in...in the past. I dont see any point in knocking a piece of our history out of all recognition....after all, if we all modified ....then we would be in danger of loosing it forever.

Post by **d_harris** » Thu Mar 08, 2007 4:26 pm

which is why you keep a standard car and muck about with another one!

Post by **gairlochrosie** » Thu Mar 08, 2007 4:34 pm

Dan_Harris wrote:which is why you keep a standard car and muck about with another one!

Hi Dan

Post by **dunketh** » Thu Mar 08, 2007 4:58 pm

In the simplest possible answer gas must provide better damping than oil.

Before gas became standard many 'sportier' cars, such as the Ford XR range used gas whereas the standard variants (eg Fiesta Popular, Escort L etc..) only used oil.

Post by **Peetee** » Fri Mar 09, 2007 6:57 am

Just try changing your worn out springs and dampers for new items

I appreciate your comments and agree it would be a straightforward solution for the rear of the car but (I think I'm right in saying) 'new' torsion bars are not available so it's not an instant fix. There is also the often raised issue that refurbished standard dampers don't last too long.

I was specifically trying to think around the problem of uprating the damping while reducing to a minimum the almost inevitable additional forces applied to the structure of the car. I know from experience that oil based uprated dampers can be really punishing to a vehicle. I was wondering if gas can provide the happy medium.

Post by **jonathon** » Fri Mar 09, 2007 9:15 am

Peetee, gas dampers are essentially the same as oil only ones. Both rely on the compression of the oil within the two tubes of the damper. Gas dampers differ in the way that the gas is seperated from the oil by a floating piston,and instead of the damper having a foot valve the gas one uses a piston with a non return valve and restrictors. The gas which is contained below the oil floating piston only acts as a pre-load on the oil. a higher pre-load pressure can be achieved, which offers smoother and more instant action of the damping effect.

Post by **JimK** » Fri Mar 09, 2007 9:59 am

Peetee, I've got this on the Noleen shock on my Proflex (the one with the piggyback gas chamber).

The damping is still oil, but the gas does what Jonathan says i.e. it smooths out the pressure changes in the damping oil. The larger the gas chamber the smoother the pressure change, which is why Noleen put the extra gas chamber outside the line of the shock where there is space.

For those who have no idea what I'm talking about, my bike's rear shock is the one on the left (you can see the gas reservoir I'm talking about):

Post by **Innovator** » Fri Mar 09, 2007 5:54 pm

Quite often gas dampers are another name for mono tube, whereas oil are dual tube. Mono tubes have a larger piston diameter so pass more oil through the valves per mm of damper movement.

I am sure I heard that Gas Spax are oli with a bag of gas in there.

John

Post by **IslipMinor** » Fri Mar 09, 2007 6:16 pm

acts as a pre-load on the oil

Not sure which came first? The gas pre-load is also there to inhibit oil foaming during the normal damper operation. This was a real problem with any 'oil' hydraulic damper, but is slightly less in a telescopic design.

Was the improved response the planned benefit or was foam suppression, and then the spin-off benefit was the other? Either way they work well!