Fsd spring mystery - help!

I will do, Mike. I just haven't had a chance today.

I did go back to my mechanics' today and have arranged to go there Saturday morning and take the rear springs off, and offer them up against the SE items - a visual reference should show whether they would normally create a lower ride height. No?

The garage maintains there is no way the shocks can be fitted wrong. They just go on. As do the springs. (and as you no doubt know).

They also said that when they test drove the car they thought the ride was 'bouncy' and rather uncontrolled, which is exactly what I think but hadn't the heart to admit to myself. In fact they said it rode like a Vauxhall on tired shocks! Ouch! I don't think it's quite that bad...

I have a nasty feeling I might be in trouble here...

Depending on Saturday's findings I might send off my Sport springs and have them compressed 20mm. I fear the Weitec -30s might be too much.

One thing I would appreciate an educated view on: with a normal shock absorber, if you take the springs off the car would just collapse to the ground as I understand it, the shock absorber only creating damping and control in the rising plane. In other words, only the springs are effecting ride height. But, maybe that's not quite how FSDs work, because we know the FSDs do RAISE the front when fitted with standard springs. Can you bear to enlighten me?

Thank you, Mike. I'll get the pics posted tomorrow.
 
Just a thought are the rear shocks actually the right ones? If they are for a different model they could be too long and have the wrong pressure? Not sure how to check though.
 
KneesUp said:
...One thing I would appreciate an educated view on: with a normal shock absorber, if you take the springs off the car would just collapse to the ground as I understand it, the shock absorber only creating damping and control in the rising plane. In other words, only the springs are effecting ride height. But, maybe that's not quite how FSDs work, because we know the FSDs do RAISE the front when fitted with standard springs. Can you bear to enlighten me?...
Click to expand...


this is how I understand it, you can take a typical damper and hand compress it, there is no rebound force. But also to my knowledge, the rear FSD are tunned conventional dampers, not the dual valve one like the front FSDs.
 
humps said:
this is how I understand it, you can take a typical damper and hand compress it, there is no rebound force. But also to my knowledge, the rear FSD are tunned conventional dampers, not the dual valve one like the front FSDs.
Click to expand...

Well, damping forces of all automotive shocks mainly are controlled by velocity. The faster the damper piston moves the higher the damping forces of the compression valve and of the rebound valve become.

The FSD shocks offered for the A2 - both fronts and rears - feature that unique additional valve that is triggered by motion frequency. This A2 specific Koni set #2100-4041 is identical to the one for Polo 9N, Seat Ibiza/Cordoba 6L and Skoda Fabia 6Y.

At both axles a twin-tube design is utilised for our FSDs. The main difference between "our" front and rear FSDs is the gas pressurisation of the fronts (<5 bars = low pressure) versus non-pressurised rear dampers.

The application of a gas cushion element reduces (eliminates) the development of air bubbles in the damper oil which would change viscosity and thus damping characteristics. Also the response characteristics of pressurised shocks are improved potentially.

The Bilstein B6 or B8 shocks for instance are mono-tube high pressure shocks (up to 25 bars of nitrogen per shock). These shocks can raise a car by 10 to 15 mm. But normally a car will settle down to its regular height level after a couple of months...

With respect to KneesUp's problem at the rear I hope it's only a spring issue. He should swap to his standard rear springs for testing. Changing springs at the rear is easy.
 
Humps and Schnelletrecker in particular, as ever, thank you for all your time and consideration.

This weekend I will experiment with swopping springs around and check the Koni part numbers.

I bought my FSDs off EBay and paid near-list for them. The private seller had apparently bought the wrong versions for his car. They appeared unused and came in a box sporting the right part numbers on the box. I mention this, not so much suspiciously, but because I therefore have no come-back to Koni as I have no original receipt.

Anyway... we'll see what the weekend brings.

Many thanks to everyone again.

Richard
 
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