Outer Limits 4x4 Board

Right then, here are my questions... These are not questions that require answers like ' i recommend ranchos, ome etc' or 'stay away from x brand because they're crap'. These questions are about finding out the theoretical pros and cons of certain types [not brands] of suspension options as well as their characteristics.

1. Pros & Cons of gas filled shocks vs. Foam cell shocks vs. oil shocks? [which are harder/softer/ more likely to fade/, which are shorter/longer etc]

2. Monotubes vs. Twin tubes [which are harder/softer/ more likely to fade/, which are shorter/longer etc]

3. Does shock Bore size matter when most have the same size piston rod? What are the advantages/disadvantages of large vs. small bores.

4. Linear vs. Non linear springs - which are typically more appropriate for 4x4ing, expedition adventures, competitions

5. Medium vs HD springs - which are better for 4x4ing, expedition, competitions etc

6. What combinations of springs and shocks [again stay away from brands] tend to work best for recreational 4x4ing, a loaded expedition vehicle and competition vehicles.

I think that's enough questions to open a can of worms

I look forward to reading your replies/opinions.

OK - gotta get this bit outta the way. Search, noob!

Right, now that's done, lets move on...

1. I'm not sure.

2. Twin tubes offer better mechanical protection to the working tube, but have poorer heat dissipation. Fade is generally caused by overheating, so you could argue twin tubes are more likely to fade than monotube - all else being equal. Hard/soft, short/long - it all comes down to the individual shock.

3. Larger bores size means more volume of oil for a given stroke and larger surface area for heat dissipation, so probably less likely to fade. I presume larger piston area means they can do fancier tricks with valving too, but I don't know if that happens. The largest bore you can fit may be limited by your suspension design - you may not have room for larger.

4. Many people have had progressive springs sag quite early, so prefer linear springs. A progressive spring will supply more droop travel than a linear spring, which helps with articulation - if nothing else limits your articulation first. The most obvious benefit of progressive springs is the ability to have a softer spring when unladen, and a stiffer spring when loaded for trips. Because the progressive is softer when unloaded it will compress more than a linear spring would when loaded - so the difference in ride height between loaded and unloaded will be greater. If you will ONLY ever drive your car loaded, linears are probably a better option. If it's a "one car does all" situation, I'd go progressives every time. (I did, and they're still fine...)

5. The spring rate you require depends on the weight they need to carry, and what you want to do with it. Softer will normally give better articulation, along with more body roll. Harder carries weight better but will lift the body sooner when crawling over big rocks/wombat holes. Essentially, it's horses for courses, so a suspension design will always be a compromise. Decide what's important to you, and tailor your suspension accordingly.

6. Shock absorbers need to be selected to suit the springs and suspension travel. Adjustable shocks allow you to fine-tune the damping on the car, and even adjust it for different road conditions - soft for slow off-road work, stiffer for highway driving.

Let the arguments begin!

Scott

Im only going to talk about the 1st Qs. NJ SWB pretty much said everything that I would have said. So.
1 . Gas shocks are great for comp' , but they tend to loose pressure over time. Therefore, your shocks are no longer matched.(because each loose pressure at differant rates.
All shocks have gas of some type. Its needed to allow the oil to expand as it gets hot. The standard "Oil shocks" just have air at normal pressure. "Gas shocks" use a gas that is unlikly to cause rust, and is pressurised above normal. The higher the pressure the less chance of the oil boiling.
Foam cells are ment to replace the gas, but can compress like a gas.
The trouble with gasses is it can mix with the oil and make it "airrated" which makes it less dense/thiner.
The foam wont mix with the oil, but may not return to full size after time, thereby restritcking the shock from opening to full length.
Some mono tube gas shocks, have a floating piston between the oil and the gas. These are the ants pants of shocks (except for remote canister shocks) but they are longer than twin tube shocks, but have less stroke.
Insert diagram here. Sorry to tied, maybe next time.

for q1:

http://www.outerlimits4x4.com/PHP_Modul ... l+gas+fade
http://www.outerlimits4x4.com/PHP_Modul ... l+gas+fade

I think NJ has answered the rest adequately, but searching with apropriate search terms would have found you the answers instantly!

cheers

Brian