[cycleguy55]

Here's David Kirkham's post from Facebook:

There had to be another way:

Tremec TKO600 vs. TKX transmission.

Tremec stopped making the TKO600 and now they only sell the TKX transmission. A HUGE problem (disaster) with Cobras is everyone thinks they need the Tremec bellhousing if they are running a Tremec transmission...makes sense...but no bueno. The "Tremec" bellhousing is about 7/8" too tall! (22 mm).

For everything to line up properly in a Cobra, you need to use the Ford Top-Loader bellhousing for BOTH the Top-Loader AND the Tremec.

If you use the "Tremec" bellhousing you will find--too late--your transmission mount won't line up in the right place (neither will your shift handle).

When you use the shorter (original height) bellhousing you HAVE to use a Ford length (shorter) input shaft or you will jam your input shaft into the back of your crankshaft. You can remove the input shaft on the TKO600 by simply unbolting the bearing retainer and the input shaft falls (literally) right out. Tremec makes (made) a shorter "Ford" input shaft kit and it wasn't a big deal to change the input shaft out.

HOWEVER the TKX transmission requires the COMPLETE disassembly of the transmission to remove the input shaft. This is a MAJOR job that no one wants to do.

There had to be another way...

The first thing I noticed was the rear of the crankshaft had a step in it that went deeper into the crankshaft than was needed by the original placement of the pilot bearing. I wondered...could we move the pilot bearing deeper into the crankshaft?

So I busted out the calipers (and Solidworks...and the Mazak Integrex...and the water jet) and started designing.

We figured if we could press the needle bearing from the pilot bearing and make a new, smaller sleeve around the needle bearing we could probably push the bearing about 1/2" further into the crankshaft. If we pressed the needle bearing flush to the new sleeve we could gain another 0.063" or so. If we cut out a new bellhousing backing plate (behind the flywheel) on the water jet that was 1/8" thick (instead of the original 1/16") we could gain another 1/16" (1.5 mm). Finally, if we cut an 1/8" shim and placed it between the TKX and the bellhousing we could get our clutch to release and everything to fit.

After everything was finished, we were able to gain just over 3/4" (about 20 mm) of insertion into the crankshaft--but only had to move the transmission back 3/16" (about 4.5 mm) from its original position.

This was a major work around that proved to be successful with both the 289 and the 427 Cobras.

You may be able to source the necessary pieces from Kirkham.