Quote:
Originally Posted by Phloozy
fe1rx Amazing thread and I am slowly trying to wrap my head around it piece by piece. I did have a question about the ride height. It looks like you used 328mm for the front and rear. Based on this is it fair to assume the wheel arches to hub center are the same front to rear when at 0 rake?
I am trying to dial in my ride heights and i wanted to start a 0 rake for the track and go from there. Would all i need to do is make sure my hub center to wheel arch is the same front to rear?
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Thanks.
To answer your question, we need a clear idea understanding of what datum feature rake is measured from. The simplest approach is simply to define zero rake as equal wheel-arch ride height front and back, which makes the answer to your question "yes" by definition.
The way I actually look at it is to treat the 4 jack pad attachment points as points on the rake reference plane. My aero underbody does use the jack pad attachment points as attachment features and my underbody centre section is parallel to that plane, so that definition seems logical for aerodynamic purposes.
Using this reference plane, when the wheel arch ride heights are the same front and back, the jack pad reference plane is positively raked by 0.6° or 27 mm when measured between axles. You would have to lower the rear by 27 mm to achieve zero rake using the jack pads to define the datum plane.
At the moment I am running 0.4° rake relative to the wheel arches, which is 1° relative to the jack pad (aero) datum.
This is probably way too much information ...
The most useful rake definition is probably the one that is most easily measurable. I suggest that you stick with the wheel arch datums, but realize that that does give your underbody a bit of rake. Also, lowering your rear to get zero aero rake would put you hard on your rear bump stops.