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Installing a TKO into a 1966 era Impala

Please see the page that details the ‘66-’67 GM A-body.  The details on that page are applicable.

Installing a TKO into a 1966-67 GM A-Body

You’ll need to shorten the first driveshaft and install the Ford slip yoke just like all of the other GM conversions.

This 66 Impala began life as a 427, 4 speed bench seat car.

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Owned by  Bernie Coffey

Even though this car already had a hole in the floor from the factory shifter, this only aided in viewing where we actually had to cut to install the TREMEC TKO 5sp. The cut was approx. 8 1/2 inches.

Owned by  Bernie Coffey Owned by  Bernie Coffey

After the floor was cut, the TREMEC was secured to the bellhousing.

Owned by  Bernie Coffey

The engine and transmission were raised enough to trial fit the original crossmember. The crossmember had to be moved back approximately   1 1/4 inches. The stock frame bracket for the 66 is welded to the frame. These welds could be ground off and the bracket repositioned and welded but we decided to adjust the crossmember instead.

Owned by  Bernie Coffey

This meant drilling an additional hole in the frame bracket and notching the crossmember enough for it to fit with about 3/4 inch hanging outside the frame bracket. The crossmember and the bracket are very strong in this area. The fit after the repositioning does not compromise their integrity.  By adjusting the crossmember and not the frame brackets it would be easier to reinstall the Muncie if required at a later date. Since the crossmember sits inside the frame bracket for both installations there would be no problems returning this to original.

Owned by  Bernie Coffey

Now that the crossmember was in place it was time to install the transmission mount.

After the installation of the original Muncie transmission mount the TREMEC butted against the transmission tunnel and the floor had to be adjusted. The tunnel was cut in three areas but not at the top near the firewall.

Owned by  Bernie Coffey
Owned by  Bernie Coffey

With the three cuts in place the tunnel was pried up about 3/4 inch to get the floor off the top of the transmission. A curved brace was made up to support the tunnel at its new height just ahead of the shifter. This restored any rigidity lost when the floor was cut. The cut and raised transmission tunnel was then covered with sheet metal and riveted down.

Owned by  Bernie Coffey Owned by  Bernie Coffey

In order to get full advantage of this conversion it was decided a new clutch was required.  The flywheel was resurfaced by Competition Automotive in Richmond Hill, Ontario and a Hays 11 inch diaphragm with street/strip disc was installed.

The stock 66 driveshaft was shortened about 3 inches and installed.

The new speedo gear was installed and the speedo cable relocated to the driver's side.

A stock Hurst shifter lever with a 2 inch spacer was used and the fit in the rear shifter position is perfect in a big car.  There is plenty of room from the dash and the bench seat in any gear.

Owned by  Bernie Coffey Owned by  Bernie Coffey

The TREMEC was filled with Dexron III (Mercon) and run for about 15 minutes, constantly shifting through the gears. The shifting is very smooth.  The 3.27 first gear feels alive and launches this 4000 + pound car with amazing ease and the .68 overdrive on the highway (2500 rpm @ 70-75mph) seems effortless especially with a 427 with over 400 horsepower.  (this car has a 3.55 rearend with a 27" tire)

 Thanks to Mike Pell of JAM Performance Transmissions in Camby, Indiana for all the help in selecting the TREMEC and answering the multitude of questions a conversion like this generates.


Mike Pell  JAM Performance Transmissions at http://www.5speedtransmissions.com

Doug Lipps
Competition Automotive  http://www.CompetitionAutomotive.com
45 Maple Ave
Richmond Hill, Ontario
L4C 6P3

This write was provided by Bernie Coffey (owner), so special thanks to him for taking the effort and sendind us the pics and write-up!!

Canadian Classics Magazine has agreed to publish this article! Watch for it at http://www.canadianclassicsmag.com/ 

Here’s a couple of additional pics, just in case you didn’t get enough above.  :-)

Owned by  Bernie Coffey Owned by  Bernie Coffey

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This website is a comprehensive collection of information regarding the installation of TREMEC transmissions into various vehicles. Material contained in here may be reproduced for PERSONAL USE ONLY. No material may be redistributed in electronic or printed form without the written permission of Brad Wedan (owner). Owner believes to the best of his knowledge this information to be correct, however no warranty is made as to its accuracy. Owner also disclaims any liability for financial loss, property damage or injury in connection with use of this information. Not affiliated with, endorsed or compensated by TTC, or any sanctioning body mentioned within. Any trademarked names are property of their respective trademark holder and are used for identification purposes only. Portions of this website may be copyrighted by other individuals or organizations.

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