Originally posted by theisgroup
mark,
this may help. As your tire gets smaller, to maintain the same ride height. the droop screw will need to be backed out to maintain the same amount of chassis up travel. It is true that the droop setting is basically how much the arm will travel below the plane of the chassis, but we are talking about how much up travel the chassis will have will definatly change. And to maintain the same up travel is critical in maintaining the amount to weight transfer there is in the car. So as the tires get smaller the arm will have more of an angle to maintain ride height. And that angle reduces up travel.
So basically, Droop will not change with ride height, but chassis up travel will. But I think droop is not the critical setting we should be looking at. Chassis up travel is. As this does change with ride height and must be check every run. And this does affect performance of the car, because weight transfer is affected
I think we are explaining droop in different ways and maybe this is where the confusion is coming from.
I'm explaining it in terms of how much the arms are able to drop down from the "in-the-springs" position and you are explaining how much up-travel the chassis has - but these are the exact same things just our reference points are different. If I take the chassis as the reference, then the droop screws dictate how much I can lift the chassis in an upward direction until the droop screws hit the chassis.
But again the limiting factor in the amount of up-travel of the chassis or the down-travel of the arms is the same: the droop screws.
Let me explain what I mean from your pictures - as I still think we are describing the same thing with different words.
Top pic - lets say the tyre diameter is 62mm the ride height is 6mm and the droop (i.e. the distance between the bottom of the droop screw and the top of the chassis is 6mm).
Lets say the picture shows the car "in-the-springs". We can now lift the chassis up 6mm before the droop screw hits the top of the chassis. Or, we could say that the arms will travel 6mm in a downwards direction before hitting the top of the chassis.
Ok, lets move onto the second picture.
Now the tyres have worn down to 60mm and we have reset our ride height to 6mm (it would have been 5mm without resetting the ride height because of the tyre wear).
Due to resetting the ride height, the arms are now angled more in a downwards direction when "in-the-springs" (as shown in the diagram). This now means that the distance between the not yet adjusted droop screw and the top of the chassis has reduced to 5mm - which you can see visually in the diagram.
In order to get back to our 6mm "droop" setting, the droop screw has to be backed out 1mm.