Technical lowdown on shock absorbers,what to look for and what to buy

Having introduced the fairly unknown Kayaba (KYB) range to the mini market in 1997 I am still amazed how gullible people are when buying cheap dampers. I have tried every type popular type available in the last 35 years, Armstrong including their adjustables, Girling, lockheed, Koni, Spax., Avo, Bilstein,Monroe,Boge,Gabriel and GMax The best to date were probably the very expensive special design Koni adjustables that we had built for the Monte Carlo rally.

I also used the spare set on my 8 port car. You get what you pay for? For a non adjustable, Bilsteins rate highly although like the Koni specials are expensive, but you get what you pay for. The essence of a quality damper is to upgrade performance by using more sophisticated higher quality component build in the valving, piston, rod and seals etc along with a performance upgrade to improve the cars road holding. Cheap upgrades simply make the damper stiffer to make it feel like an improvement. Often this is not long lasting since poor grade oil tends to degrade very quickly when the damper is stiffer because it gets hotter. You can make a cheap damper with quality oil/components in relatively low volumes but Kayaba manage it because they make millions of them as they are the largest manufacturer of dampers on this planet.
Companies who claim 25% up-rated do not help, as you might ask, what are they a 25% upgrade on ?, They don’t tell you that, especially if they only make one damper and have nothing to compare it with.. Many of these sort of claims are speculative and usually unproven.
On high pressure gas filled mono tube dampers the piston mounted valve will have a dual duty, dealing with both bump and rebound control, it therefore has to be very well developed, and made of quality componentry. In this case, the nitrogen is introduced under high pressure-typically 25-30 bar-to the base of the damper . A floating piston is used to separate the oil and gas. When assembled, the air gap is completely removed by this design, vastly improving damper response virtually eliminating aeration and foaming. Nitrogen is slightly compressible. Combining the effects this has with superior valve design, it is feasible to produce a “self adjusting” damper that can out perform many cheap adjustable types. Essentially the self adjustment comes about from the gas being compressed ,the more the damper is loaded(by either weight in the car or by cornering forces),consequently increasing the damping performance. The easy test for checking if a gas damper is pressurised ,is that when unbolted it will open up to its full length its full travel automatically
The monotube design also means the damper body is slimmer than the more conventional twintube.
This helps alleviate tyre rubbing problems where wider or deeply inserted wheels are used.

Although it sounds that a montube damper is at a slight disadvantage to the twin tube as far as the valve performance goes a quality design and manufacture mono can easily eclipse a cheap twin tube :adjustable type. The quality of the piston rod which should be micro smooth and usually hard chromed for long life reliability of the oils seals. Multi lip seals and self sealing packing keeps oil in, contamination out, even under repeated hard use. Finally there is a need to minimise foaming which keeps the shock absorber fade free. All these things can only be done by large and leading manufacturers who have test facilities and resources to use performance quality parts as standard in mass production of all their range.
After reading all this you are probably thinking? ”why has nobody brought out a quality twin tube gas shock at sensible money with all the attributes it has to offer” Mini spares have found one.