Track Width

[Bob Wright]

Im interested in the front rear track width ratios that are being used. I know that a narrower rear means that getting around cones is easier but there seems to be other problems. A lot of open wheel race cars rely on the front set of wheels to do about 60% of the roll resistance. Ive found it difficult to get info from other teams, but the few I have talked to, including us at Monash found our car working well at 40-45% front elastic roll resistance. At the race the cars that seemed to be handling well were sometimes even visibly lifting an inside rear- teams like RIT, Wollongong, WA, etc. This is very different from formula ford/ 3000/ 3 or any of that. I have seen some f3 cars that completely couple there front suspension to get the % front up as high as possible. This leads me to believe that FSAE cars on tight tracks handle best when set up like go karts in this respect. Now when this is the case, wouldnt it make sense to have an even wider rear track or at least equal? With a rear track 100- 150 odd mm narrower than the front and a cg height of 275mm it is nearly geometrically impossible to get in the good working range. We tracked our car out 50mm at the rear and found it worked beatifully, without compromising wheel rates. The best bit is that even small increase in rear track gives the inside front wheel a noticable increase in reaction force, BUT you can only use it properly if your camber change is not to severe at the front(again a bit different to usual fsae setup)- its worth sacrificing a bit of outside wheel +ve camber to let the more efficient inside wheel work harder. When it is doing this there is also no longer a need for such extreme ackerman geometries. Anyway, if anyone has done much on this, can you let me know, because I think it answeres a lot understeer problems.

Bob Wright
Monash University
Australia

[Bob Wright]

Im interested in the front rear track width ratios that are being used. I know that a narrower rear means that getting around cones is easier but there seems to be other problems. A lot of open wheel race cars rely on the front set of wheels to do about 60% of the roll resistance. Ive found it difficult to get info from other teams, but the few I have talked to, including us at Monash found our car working well at 40-45% front elastic roll resistance. At the race the cars that seemed to be handling well were sometimes even visibly lifting an inside rear- teams like RIT, Wollongong, WA, etc. This is very different from formula ford/ 3000/ 3 or any of that. I have seen some f3 cars that completely couple there front suspension to get the % front up as high as possible. This leads me to believe that FSAE cars on tight tracks handle best when set up like go karts in this respect. Now when this is the case, wouldnt it make sense to have an even wider rear track or at least equal? With a rear track 100- 150 odd mm narrower than the front and a cg height of 275mm it is nearly geometrically impossible to get in the good working range. We tracked our car out 50mm at the rear and found it worked beatifully, without compromising wheel rates. The best bit is that even small increase in rear track gives the inside front wheel a noticable increase in reaction force, BUT you can only use it properly if your camber change is not to severe at the front(again a bit different to usual fsae setup)- its worth sacrificing a bit of outside wheel +ve camber to let the more efficient inside wheel work harder. When it is doing this there is also no longer a need for such extreme ackerman geometries. Anyway, if anyone has done much on this, can you let me know, because I think it answeres a lot understeer problems.

Bob Wright
Monash University
Australia