Kybs Shock Absorber Issues

[Gibla]

All 3 of my 'fleet' have had a suspension refresh over the last couple of years, and every time used Kybs all around.

These shock absorbers match my needs and expectations.

However, recently I had an issue on a car I had recently shod in nearly new Yokohama AD08R on all 4 wheels in FL guise.

it drove like a pig:- many attempts later after 2 sessions of alignment, wheel balancing, repeatedly re-checking tyre pressures < very marginal improvements with each of these.

I was just about to sell the wheels n tyres + forget the sorry episode, when it was discovered that the rear shocks (under 12 months old) were not rebounding whatsoever (even though fluid was still in the shock after stripping)

Anyways to cut a long story short, these rear shocks were replaced this morning + the car is now definitely as it should be.....yet another chastening learning experience 

Moral of the tale ? Kybs are brilliant but manufacturing errors can and do happen with any product

[McMr2]

So strange. I'm looking after a family car at the moment and it has had the rear shocks replaced. They were the correct units but have a complete lack of rebound - there's a noticeable 'thunk' when you come off a speed bump or similar, like the spring is extending with no damping.

[Dev]

KYB manufactures for OEM so their quality is second to none but the KYB replacements are not the same as the OEM and maybe they are made to a lesser quality control standard. It's possible the nitrogen bladder deflated and it was a quality control issue that was contained to a bad batch or supply chain issue were source parts from a different manufacture.
 Very strange regardless.