View Full Version : 15" wheels and IRS
jrohrig
02-08-2021, 03:42 PM
I was reading
https://thefactoryfiveforum.com/showthread.php?38700-ERA-amp-Factory-Five-Quality-amp-Authenticity
and realized I don't quite understand why FFR roadsters cant have IRS and 15" wheels. or is it specifically 15" pin drive wheels? My goal with my future build was to get that authentic look with IRS. Is that not possible?
David Hodgkins
02-08-2021, 03:53 PM
From what I understand it is because the 2015+ Mustang pumpkin is so much wider than the older Thunderbird Supercoupe Pumpkin used previously. I'm in your camp: I wouldn't want anything but the IRS/15" Pin Drive/Wilwood brake setup that I have. That deep dish.... yes!
Some folks have shortened the 3-link axle to pin drive width so that is an option...
Did you call FFR to discuss it with Jim Schenk?
https://thefactoryfiveforum.com/attachment.php?attachmentid=92408&d=1535841348
:)
edwardb
02-08-2021, 03:57 PM
15-inch + IRS + 5-lug wheels = yes. IRS + pin drive + any size wheel = no.
Note this is the "new" (since 2015) style IRS. The older one is no longer available. When they switched to the super 8.8 IRS diff from the 2015+ Mustang, the entire thing was re-designed. They decided to offer it in only one version. I don't know the reason(s). Perhaps just not enough volume to support pin drive. Or perhaps some technical reasons. Whatever, it's not an option.
I understand Factory Five has a brake package for the 15-inch wheel / IRS setup now. They didn't used to. Gordon Levy has been selling a package for some time.
jrohrig
02-09-2021, 12:36 PM
you think these would work?
https://www.trigowheels.com/289_5_f_a.html
with the adapter kit https://www.trigowheels.com/AdapterKit.html
looks like they are just adapters that convert 5 lug wheels to pin
CobraboyDR
02-09-2021, 12:43 PM
you think these would work?
https://www.trigowheels.com/289_5_f_a.html
with the adapter kit https://www.trigowheels.com/AdapterKit.html
looks like they are just adapters that convert 5 lug wheels to pinThe issue is the current FFR IRS system is 2.5" too wide per side for the offset and backspace of pin-drive wheels.
There is no current solution, and I'm not the only one to deep-dive for a work-around.
If you want/require pin-drive wheels, the only answer is a shortened live axle.
This is the only reason I'm not building an FFR right now.