Shifting fine is a description I would never associate with a TKO. The transmission while strong, uses larger gears to get the torque capacity up to the 600 ft/lb threshold. When Tremec did this they did not do a corresponding upgrade to the synchronizers.
TKO's use a synchro that is basically an old top loader synchro from the 1960 generation top loaders. Those synchros worked fine in the 60's with the top loader gear sets but not so much today with the much larger and heavier gear sets in use for TKO transmissions.
In terms of shifting ease pecking order, the 60's transmissions sorted out lfrom best to worst like this:
- BW T-10
- GM Muncie
- Ford Top Loader
- Chrysler A-833
The strength pecking order exactly mapped against the shifting ease with the easiest to shift being the lightest duty box and the hardest to shift being the most durable box.
The A-833 Chrysler box was in fact a repurposed Ford light truck transmission with larger gears than the other Detroit four speeds of the day — which gave it the strength to handle launching a 3400 lb car with a Race Hemi in front of the transmission.
However, like the TKO's today the strength and corresponding size / weight of the gears meant the A-833 had "shifting issues" above 6000 / 6500 rpm. I don't recall anymore whether the first crash box was a Performance Parts modification or whether Ted Spehar and the Mowtown Missle gang first did the modification. Either way the transmission's high rpm shifting problems disappeared.
Joe Liberty improved upon the original Chrysler crash box design with his design which was marketed under the Pro-Shift name. This is what the difference between a Pro-Shifted gear and a normal synchronized gear looks like;
The lack of a synchronizer was made up for by the increased spacing between the engagement dogs on the gear and the corresponding receiver grooves on the shifting slider. This modification allowed for substantially reduced time between shifts no matter the skills of the driver. Skills not withstanding better drivers still had quicker shift times gear to gear.
Liberty productized the modification and made it available for any transmission. Today the original Liberty design has evolved and we now refer to as face plating. Without Pro Shifting or face plating a TKO they simply will not produce race quality gear changes. That doesn't mean that people with lesser gear change performance thresholds may not find the synchronized version of the transmission attractive.
Tremec was aware of the shifting issues with the TKO box but was unwilling to invest money in the "old" transmission. The T-56 was the new frontier and got all the new good stuff. The TKO not so much. When the T-56 Magnum came out the dual and triple cone synchronizers had been well sorted out and the newer stronger Magnum gear sets brought the T-56 up to a 700 ft/lb service rating with synchronized shifting qualities that were like putting a hot knife through butter.
After the shifting improvements, the dual overdrive in fifth and sixth provide a very nice highway solution. Even with a 3.73 ring an pinion the dual overdrive will give you essentially a 70 mph highway cruising speed at only 2000 rpm with 295 x 55 rears. If you drop the ring and pinion to 3.27 for a more useful first gear the 2000 rpm cruise speed jumps up to 77mph.
Be careful about going too tall with the ring and pinion, if you have an engine with a lumpy idle and poor low rpm performance. 2000 rpm sounds high but if your engine is just getting out of its lumpy performance range, your car will be bucking and misbehaving at highway speeds,
Aside from the improved shift quality, the T-56 gear choices seem to provide a gear for virtually every road condition you can find — which makes driving the car all the more enjoyable.
Ed