5 replies to this topic

[blackbelt1990]

I'm contemplating replacing my shock absorbers. The current ones have been on about 8 years and I think are causing the car's harsh ride. I changed all the donuts last year as they were pretty much flat, it made a big difference but still not great.

I've currently got GMAX Gas ones on, how can I test them off the car? Google doesn't seem to bring up any definite examples, just lots of threads where people disagree!

Finally, what are the handling characteristics of oil vs gas? I see Gas described as "uprated" which I think may be causing my harsh ride. I know the 13 inch wheels don't help but I've never been in a factory MPi that rides as harshly as my car.

Cheers

[nicklouse]

FIRST. they are all oil damped.

 

gas can mean many things and should not be taken to mean much read what the makers say.

 

some will just be filled with an inert gas instead of air. some may have a gas pressure chamber in the shock which might do something.  Or there might just be some Gas stickers on them.

 

neither is better or worse. just different ways of doing the same.

[Ethel]

Ditto,

 

It's squeezing oil through valves that does the damping. You need some something compressibe i.e. gas (it could be just air) because the pushrod takes up more room as it goes in to the cylinder and the displaced oil needs somewhere to go.

 

If they are sealed units (gas filled) they should extend themselves when unloaded. Otherwise I don't think you could do a meaningful test without a rig to generate the same sort of forces and rates they see on the car. I suppose if you have a pair to could compare one with the other by fastening them together and seeing if they behave the same when pushed 'n pulled.

[Cooperman]

The benefit of gas-filled dampers is for competition where the dampers have to work very hard, the inert gas takes the heat increase better, and the dampers are less prone to 'damper fade'.

 

For normal road use there will be no perceivable difference.

 

13" wheels do make for a harsh ride due to the loss of suspension with the low height tyre sidewall. It is surprising how much suspension work is done by the tyre sidewalls on a MIni due to the small suspension travel available.

 

Best option is to switch to the much better 12" or even better 10" wheels and sell the 13" to someone who doesn't mind the limitations of the 13" wheel..

[blackbelt1990]

The benefit of gas-filled dampers is for competition where the dampers have to work very hard, the inert gas takes the heat increase better, and the dampers are less prone to 'damper fade'.
 
For normal road use there will be no perceivable difference.
 
13" wheels do make for a harsh ride due to the loss of suspension with the low height tyre sidewall. It is surprising how much suspension work is done by the tyre sidewalls on a MIni due to the small suspension travel available.
 
Best option is to switch to the much better 12" or even better 10" wheels and sell the 13" to someone who doesn't mind the limitations of the 13" wheel..

I plan to move to 10s when the car gets some work done over the winter. Had 10s on my previous mini and I recall it being a slightly smoother ride.

Like I say, it seems to ride harder than a sportspack car, so I think I will probabaly replace the shocks with some OE ones.

[Spider]

I've currently got GMAX Gas ones on, how can I test them off the car? Google doesn't seem to bring up any definite examples, just lots of threads where people disagree!


Cheers

 

They are difficult for the guy at home to test in a meaningful way. You can do the obvious push and pull (after standing them for a while to allow them to bleed) but it won't really tell you if they are worn and / or what their performance will be once warmed up.

 

Many suspension shops in our parts will test them for free or very modest cost on their shock dyno and they should be able to give you a print out.

 

Normally worn shock don't give a harsh ride, but a wallowing ride, though on a Mini this too is masked somewhat due to the natural damping of the rubber cones.

 

I'd say your harsh ride is likely coming from your tyres, though, I'd also check your subframe mounts.