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Old 11-17-2020, 08:41 PM
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eschaider eschaider is offline
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Join Date: Feb 2006
Location: Gilroy, CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4.6
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The shifting technique in the YouTube video is a technique that Dennis Oltoff and many others, Tremec included, have coached TKO owners about for about as long as most of us can remember. Make no mistake about the fact the technique will provide some relief from the gear change hanging in the 2-3 gate but only to a point.

The 2-3 shift gate hang up problem is a multi faceted problem and the shifting technique modification only partially addresses one facet of the problem. The spring bias that returns the shifter to the neutral gate when moving the shift arm forward to third gear can help, but only to a point.

When the speed of the shift exceeds the spring loaded shifter's ability to find the neutral gate because the spring pressure was too low to accomplish the job at the speed the shift was executed at, you still have a missed shift. In fairness you really need to be capable of impressive gear change performances to bump up against this limitation — but it is there and people have discovered it because of how quickly they can change gears.

So if that's the case, then for mere mortals (like most of us) this should fix our problem. But it doesn't and it hasn't. The reason for the doesn't and hasn't unhappy ending involves the other two facets of the gear changing mechanism / event — the diminutive 1960 style brass synchronizers and the timing interlocks on the and shift rails.

The interlocks are designed to prevent you from engaging two forward gears, simultaneously. When you shift very fast, the spring loaded interlocks need to make a go / no go decision in a fraction of a second. The decision is centered around whether two forward gears are about to be engaged simultaneously. If this occurs the transmission will lock up and so will the rear tires. Microseconds later the car spins out of control and likely crashes.

This, as luck would have it, turns out to be a pretty big deal — not just for the driver but also for Tremec. So they err on the conservative side and you have interlocks that can impede a 2 - 3 speed shift. Liberty's modified interlock design on the replacement shift rails which they sell corrects this problem.

The last piece of this sordid puzzle is the synchro's themselves. The size of the gears in a TKO are substantially larger and heavier than 1960's four speeds. When you use 1960's style synchronizers to speed up the TKO sized gears they fall short of the mark.

To the driver, the sensation he will recognize is the feeling of hitting a wall in the 2-3 shift gate and not being able to engage third gear. The reason (assuming your speed shift got this far) is the synchronizer's inability to speed up the gears internal to the TKO to allow, what Tremec calls, the synchronizer collar to engage third gear. When the speed differential is too great the completition of the shift is preempted to protect transmission internals.

The spectrum of drivers and their speed shifting skills runs the gamut from slow to stunningly fast. If you are at the slow end of the scale all this talk is going to sound like just so much sour grapes because you have first hand knowledge that belies it all. On the other hand if you have speed shifting skills that fall into the good to great window you will know exactly what all this banter is about.

If you have never had this problem, God Bless and be happy. If you have had the problem, at least now you understand the why and you should now know how to mitigate although not eliminate it. To eliminate the problem you will need to replace the TKO with a TKX (hopefully it actually fixes the problem) or a T-56 which absolutely fixes the problem but presents cost and potential fitment issues with some Cobra replica's.

In the 1960's Chrysler could not find a 4 speed transmission that would stand up to the torque of their drag race versions of the Hemi engine. In the end they ended up licensing / OEMing a Ford light truck transmission to get the required reliability they wanted for the drag cars. Chrysler called it the A-833.

The transmission was strong but the synchros were incapable of reliably changing gears above 6000 / 6500 rpm. Chrysler came up with a non synchronized version of the transmission for racing only that later would become known as a crash box. Below is an in car video of Ken Montgomery and his rare, for 1965, four speed A-833 crashbox version of the transmission. The more you approximate the way Ken can shift, the more problems you will have with the TKO. BTW Ken passed on a few years ago but his car and his shifting are impressive, even today.

Here is the video (below), a little eye and ear candy for the racer in you.

Click here => Ken Montgomery


Ed
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Last edited by eschaider; 11-18-2020 at 01:14 AM.. Reason: Spelling & Grammar
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