After the engine and transmission install, the next step is to ensure the car is level and align the driveshaft in accordance to the IRS differential. One nice thing about the IRS is that the pumpkin doesn’t move or shift like a live axle.
Three spacers were needed to raise the tail shaft of the Tremec TKX into alignment. I got those from Mike Forte who has a Transmission Spacer Kit. This helps to align the tail shaft to the IRS rear-end.
Another item that is regularly used it a driveshaft safety loop. I got one from Metco Motorsports in a group buy on the forums. Driveshaft Safety Loop, Factory Five Mk III & Mk IV Roadster This is a stout piece that installs under the transmission, but around the driveshaft in the case of a failure with the driveshaft or U-joints. The placement of the driveshaft is near the interior hips of driver and passenger. For $150, it’s cheap insurance as compared to a hip replacement.
Of course with customizations, comes complexity. The transmission mount has the default depth for the bolts, and the driveshaft loop also adds thickness, and adding the spacers makes it even deeper. Mike provides longer bolts, but it doesn’t account for the Metco loop thickness as well.
After 6 trips to Lowes, Home Depot and Ace Hardware, we finally found some Grade 8 7/16-14 1″ bolt that we needed to mount the Metco frame to the transmission. The 1.25″ bolts provided by Metco were too long (bottomed out) and the .75 bolts from FFR were too short and didn’t bite. We also put red Loctite on the bolts from the driveshaft to the yoke adapter.
It’s hard to take ‘after’ pictures of this setup when on your back under the car, but here’s a good photo borrowed from the forums:
