GT4 helper spring info
Discussion
PorscheGT4 said:
OK, so I read many things about helper springs and as normal on forums you get 4 answers depending on the forum.
so here is the GT4 rear shock.
does the helper spring fully compress when the car is on the ground ?
No. It is there to absorb fast oscillations, as in the 964 RSR when these were introduced by Porsche.so here is the GT4 rear shock.
does the helper spring fully compress when the car is on the ground ?
That one does. Its blocked under static load.
In this set up its there to allow the car to sit at the right ride height with appropriate travel in both directions which would otherwise not be possible using the main spring rate.
In short, with just the main spring fitted the car wouldnt settle low enough on the shock and there would be very little negative travel.
This is important as without it there would be risk of the wheel losing contact with the road if the surface were to drop away.
Under cornering for example having this prevents the car feeling like its suddenly toppling over on the loaded side if the unloaded wheel was to have the road drop away from it for any reason.
If you cast your mind back, we had a brief conversation about stacking springs in this way and the benefits. I run a much more advanced version of this on my Cup (as do a few GT racing teams now) which moves the game on way beyond the set up shown in the picture. Unfortunately it requires careful calculation so its not really suitable for mass produced cars or off the shelf setups. It requires each car to have bespoke rates/lengths etc that only work for it.
The difference between this and just sticking two springs together is that in this latter case, the springs do not block and instead just operate together as a regular single spring but with a new rate. This rate is given by (Rate 1 * Rate 2)/(Rate 1 + rate 2) and is less than the softer of the two springs used.
In this set up its there to allow the car to sit at the right ride height with appropriate travel in both directions which would otherwise not be possible using the main spring rate.
In short, with just the main spring fitted the car wouldnt settle low enough on the shock and there would be very little negative travel.
This is important as without it there would be risk of the wheel losing contact with the road if the surface were to drop away.
Under cornering for example having this prevents the car feeling like its suddenly toppling over on the loaded side if the unloaded wheel was to have the road drop away from it for any reason.
If you cast your mind back, we had a brief conversation about stacking springs in this way and the benefits. I run a much more advanced version of this on my Cup (as do a few GT racing teams now) which moves the game on way beyond the set up shown in the picture. Unfortunately it requires careful calculation so its not really suitable for mass produced cars or off the shelf setups. It requires each car to have bespoke rates/lengths etc that only work for it.
The difference between this and just sticking two springs together is that in this latter case, the springs do not block and instead just operate together as a regular single spring but with a new rate. This rate is given by (Rate 1 * Rate 2)/(Rate 1 + rate 2) and is less than the softer of the two springs used.
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