MORE ON 2005 MUSTANG REAR SUSPENSION
MORE ON 2005 MUSTANG REAR SUSPENSION
(OP)
Though few tears will be shed, the 2005 Mustang will probably be the last RWD beam axle car with significant production numbers. But, since many of the owners will be taking them to the dragstrip, I find the possibility of offsetting the upper link fascinating. Retired and with nothing better to do, I've written a little BASIC program to iterate the upper link position and angle, for a given offset, to provide equal rear tire loading and no squat or rise during acceleration. But, I need some dimensional information if it's to be of any value. Anyone out there, who pulls a paycheck from Ford, who can help me out?





RE: MORE ON 2005 MUSTANG REAR SUSPENSION
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
Rear:
Track: 62"
LCA: 18.5"
3rd Link length: 8.25" and 7-8" above axle CL centered on axle
LCA bracket on axle: 4.75" below axle CL
Spring base: 37.5"
Since the car was up on the rack, the suspension was in full drop position so I could not measure the angle of any links.
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
In case anybody's wondering why I mentioned using an iterative procedure, rather than solving directly, it's simply because of my limited patience, coupled with a high propensity for error. I did solve directly for the case when the unsprung mass is not considered and my work is available in the student workbook which accompanies the Millikens' "Race Car Vehicle Dynamics." But, when a finite unsprung mass is considered and the no squat/no rise line, consequently, does not pass through the rear tire patch, the algebraic manipulation becomes overwhelming! I did put together an EXCEL program which tackles it in steps and this BASIC program is kind of a check. I'd certainly like to see a direct solution, but, due to its very limited applicability, I doubt if anyone will go to the trouble.
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
CG height can be got from the NHTSA website I think (the rollover page), either directly from a table, or indirectly from the SSF (Track/(2*CGZ)), of 1.53. CG height typically changes very little between kerb loading and design (2 PAS)
Cheers
Greg Locock
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
Assuming an all up weight of 3250 (yeah, that's light) with 250 in the axle assembly, the lower link horizontal, the CG height 24, and a 4.11 axle, the offset comes out to 14.6. This is quite reasonable and much less than I feared. With a 3.08 ratio, it's still only 19.5 inches. The IC is a little closer than I would have liked, being only 38.75 ahead of the axle with any ring and pinion.
Still, everything's within reason and it looks like I could help some kid with his drag Mustang...if I'm ever asked.
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
When I mentioned the use of the 05 geometry or similar, it was not received well by the group in which I presented the idea (another forum).
Any help you or others could provide would be greatly appreciated!
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
My thought if it was not clear, was to fabricate and test your design.
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
(The thrust loss due to acceleration of the the rear axle assembly is ignored, but this introduces a relatively small error.)
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
RE: MORE ON 2005 MUSTANG REAR SUSPENSION
the tangent of the link angle(s), as measured at the rear mounting point(s), positive up from the horizontal:
h/l-KR(1+m/M)/yG
where (h/l) is the ratio of CG height to wheelbase, "m" is the mass of the rear axle assembly, "M" is the remaining mass of the car, "y" is the offset of the single link, "R" is the tire effective radius, and "G" is the axle ratio.
"K" has a value of unity for the symmetrical links and a value of:
(mR + Mdo)/(mR+Mds)
for the "odd" link. "do" is the vertical height, at axle centerline, of the single link, and "ds" is the same for the symmetrical links.
(Note that the odd link can be either above or below the symmetrical links. For a tubbed dragstrip car, the lower position is more easily implemented.)
Hope that's clear and I haven't made any typos. Wish you could have found the book. I'm surprised it was discontinued.
RE: MORE ON 2005 MUSTANG REAR SUSPENSION