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IRS and 15" Wheels
Before Courtnie left she made it clear that neither pin drive wheels or 15" rims are compatible with the new IRS.
Can you guys explain specifically why this is so? I'm not challenging but want some edumacating on the subject.
And are there any reasonable workarounds?
Thanks so much!
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Steve >> aka: GoDadGo
The IRS set up uses the Ford Mustang IRS Rear Knuckles from the 2015-thru-2017 model years and likely beyond.
The size of the brakes and size of the knuckle is was designed for 17-thru-20" wheels and only the base V6 wears the 17's.
Those parts simply don't fit inside a 15" wheel; however, Gordon Levy of Levy Racing may have a solution.
Hope this help and try reaching out to Mr. Levy because he is an expert on these cars.
You can see the parts at the site shown below:
https://www.americanmuscle.com/frpp-...-kit-1516.html
Last edited by GoDadGo; 07-30-2017 at 07:46 PM.
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Senior Member
As mentioned, the new Mustang brakes and Factory Five available Wilwood upgrades only fit 17-inch and up wheels. So a 15-inch wheel solution isn't available from Factory Five. But Gordon has developed Wilwood brakes that will fit, and I've seen at least one build completed with them. But pin drive won't be so simple. With the required pin drive adapters, the suspension track needs to be narrowed. That means shorter control arms, axles, etc. Plus whatever affect it might have on suspension geometry, chassis clearance, etc. Factory Five has not chosen to support this option. I suspect due to the low sales volume combined with the brake/wheel limitations. Due to the revised suspension and higher unsprung weight (plus rules issues in some cases) pin drive typically isn't desirable for competition either.
Last edited by edwardb; 07-30-2017 at 08:07 PM.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
Build 2: Mk4 Roadster #7750. Sold 04/10/2017.
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Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020.
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Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020.
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Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023.
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Originally Posted by
edwardb
As mentioned, the new Mustang brakes and Factory Five available Wilwood upgrades only fit 17-inch and up wheels. So a 15-inch wheel solution isn't available from Factory Five. But Gordon has developed Wilwood brakes that will fit, and I've seen at least one build completed with them. But pin drive won't be so simple. With the required pin drive adapters, the suspension track needs to be narrowed. That means shorter control arms, axles, etc. Plus whatever affect it might have on suspension geometry, chassis clearance, etc. Factory Five has not chosen to support this option. I suspect due to the low sales volume combined with the brake/wheel limitations. Due to the revised suspension and higher unsprung weight (plus rules issues in some cases) pin drive typically isn't desirable for competition either.
Thanks for the input.
Could not wheel backspace make up for the thickness of the adapter? Or am I missing something?
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Originally Posted by
GoDadGo
The IRS set up uses the Ford Mustang IRS Rear Knuckles from the 2015-thru-2017 model years and likely beyond.
The size of the brakes and size of the knuckle is was designed for 17-thru-20" wheels and only the base V6 wears the 17's.
Those parts simply don't fit inside a 15" wheel; however, Gordon Levy of Levy Racing may have a solution.
Hope this help and try reaching out to Mr. Levy because he is an expert on these cars.
You can see the parts at the site shown below:
https://www.americanmuscle.com/frpp-...-kit-1516.html
Thanks for the info, muchas gracias. I'll drop Mr. Levy a note.
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Senior Member
Originally Posted by
CobraboyDR
Could not wheel backspace make up for the thickness of the adapter? Or am I missing something?
I'm at the end of my knowledge on this subject. I don't know. I only know that historically for the FF pin drive option the suspension parts are different and FF chose to not offer them for the newer IRS setup. I understand the desire for authenticity, but IMO the 5-lug halibrand style wheels with the covers looks pretty OK and everything is pretty straightforward. These are 18's on the FF Anniversary Roadster prototype. Looks similar on the other wheel sizes.
Build 1: Mk3 Roadster #5125. Sold 11/08/2014.
Build 2: Mk4 Roadster #7750. Sold 04/10/2017.
Build Thread
Build 3: Mk4 Roadster 20th Anniversary #8674. Sold 09/07/2020.
Build Thread and
Video.
Build 4: Gen 3 Type 65 Coupe #59. Gen 3 Coyote. Legal 03/04/2020.
Build Thread and
Video
Build 5: 35 Hot Rod Truck #138. LS3 and 4L65E auto. Rcvd 01/05/2021. Legal 04/20/2023.
Build Thread. Sold 11/9/2023.
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