2015 IRS Driveshaft Adapter

[edwardb]

There have been several discussions on the forum regarding the driveshaft attachment on the new 2015 Mustang IRS center section. The new design used on the Mustang has a CV style connection between the driveshaft and the center section. An adapter is provided with the new Factory Five IRS setup to allow a standard Spicer U-joint to bolt to the new IRS center section and eliminate the CV style joint. Like this one: http://www.factoryfiveparts.com/manu...shaft-adapter/. The adapter bolts into the center section pinion flange with six 10mm bolts, which seems robust enough. However the U-joint bolts to the adapter with only four 10mm bolts. The former Ford 8.8 pinion flange used four 12mm bolts.

Is there engineering data that shows the reduction in bolt size is adequate for this application? I am aware there was considerable testing of the new IRS, including track time. Also aware of at least one challenge car that ran with the new IRS. But I'm not sure how many actual customer builds have run significant miles with the new IRS. Especially in a higher HP installation with sticky tires, how is this going to hold up? Interested in actual data or an engineering type answer. Not just "None have broken."

BTW, I have one the 20th Anniversary Roadsters nearly completed with the new IRS. I'm satisfied with my street type cruising this connection will be fine. But this is a subject that seems to be getting some interest so thought I would ask. For myself and others.

[Jim1855]

Paul,

I would think that FFR could provide some form of engineering / CAD analysis of the adapter's strength. This should be a fairly simple using their SolidWorks design software. To do this properly the dimensions, material, heat treatment and assembly hardware would need be known. They might be reluctant to share this outside of their control.

From the photos it looks like there was a decision to use 4 - 10mm bolts for the input rather than 12mm and then potentially compromise the available material between the threaded holes and the c'bored holes.

BTW I still look at the photos I took of your MKIV last winter. And I'm still plotting and planning for my own FFR, just now a Gen3 Coupe. I have an engine block, so that's a start.

Jim

[edwardb]

Hey Jim. You might be right. The layout of the adapter may limit the thread size. I wasn't expecting anything proprietary to be shared. But would be nice to have some assurance of the design since this is the premium setup and there has been some questions about it.

The Gen 3 Coupe is very interesting. I have my eye on it too and look forward to seeing it in person next year.