2015 IRS Drive Shaft to Drive Shaft Adapter - Bolts bottomed out.

[RRussellTx]

This is mainly an FYI in case any one else has the same issue.

Background, I had noticed a slight drive shaft slap from the beginning but I just figured it was transmission tolerances. It was particularly noticeable the other day when I was taking a short trip in the car so I turned around and parked the car until I could look at it. I also wanted to check the torque recommendations based on the latest update that was sent out by FFR.

When I took off the transmission tunnel cover, I noticed that the torque marks were broken but that the bolts had not turned at all. I reached in and tried to turn the driveshaft by hand and I was able to turn it slightly without the driveshaft adapter turning. I tried to tighten the bolts but it became obvious that the bolts were bottomed out in the adapter.

I contacted FFR tech support and they confirmed that it should be an M10X25 bolt and suggested that I use a washer to keep the bolt from bottoming out. Washers were not included with my kit. I’m not sure if they are delivered with new kits.

Interestingly, none of the threads were damaged and everything should go back together fine with a washer.

The length of the bolts vs the thickness of materials is soooo close to the same length (see images below) it may be hard to notice at first so I thought I would post the information just in case others have the same situation.

[edwardb]

Good post and good reminder. I've had communication with several builders about this issue. One of the variables appears to be differences in the driveshaft U-joint. At least two different versions have been supplied with FF kit driveshafts, with different flange thicknesses. Resulting in the supplied bolts being too long in some cases. May not be exactly what's happening with yours. But something to watch out for as well.

Personally, I'd recommend grinding a little off the end of yours vs. using a washer.

[David Williamson]

There were or are 2 styles of drive shafts, one with a steel flange like you have and another with aluminum. The aluminum is thicker and longer bolts were sent out for it. Suspect you have the longer bolts for the aluminum flange drive shaft.
I ended up with 4 different drive shafts until they got the correct IRS and length one to me and I have had both styles. They also sent out a revised instruction with new bolt torque values by email.
David W