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Old 10-03-2006, 11:36 AM   #168
SVT Robzor
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Here's my take on that, slow me down if I stop making sense:

I read a post a while back, maybe it was in this thread even, that somebody talked to his friend who was an engineer for SVT (I'd love to talk with him, if thats really his position..) who responded to knowledge of this "mod" with anger. Apparently, it was "put there for a reason" and removing it would put EXTRA stress on the shift cables and cause failure. This bothers me for some specific reasons.

The cables should cause the input shaft to move around to mesh with a different gear on the output shafts (plural cause we're dealing with the wierdo Getrag). The cables dont attach directly to the input shaft, they mount way too high. They actually mount to a bracket that rotates about some pin, or shaft, OR pulls out, depending on how the 2 shift cables are acting on it. This bracket must be somehow mechanically connected to the input shaft. This bracket has a post on it that feeds thru a hole on the huge brass counterweight that allows it to push the counterweight around; it actually rotates about the same axis as the bracket.

Now lets look at the system simply, both with and without this chunk of brass. You grab the shifter and shift from 1 to 2. This actuates only 1 of the cables, and I'm 90% sure thats the cable that affects rotation of the bracket, not its in/out position. You're moving the shifter, the base of which moves the cable, the cable moves the bracket, the bracket moves both the input shaft and the ~10oz brass weight. F=MA, to do this at a speed of "X" you need to apply force "Y" to the [NET MASS] of this entire assembly, and the reaction of this force is felt as tension by the shift cables.

Now keep up: Remove the weight, the system now moves an amount of mass equal to [NET MASS] - [MASS of Counterweight]. This is, obviously, a lower amount. Therefor you must conclude that to move less [NET MASS] the same distance over the same period of time (this being the speed you're shifting) you will use LESS force, which is felt as a smaller equal and opposite reaction by the cables. This would mean less tension for the cables to deal with, not more. Think of it as punching a speed bag with a force of "X", versus punching a heavybag with the same force. The heavybag would not move as far or as quickly; to move the heavybag the same distance over the same period of time, you'd need to apply more force (much more in this case), which would be felt as a larger equal-and-opposite reaction in your fist, which makes it more likely you'll bust your knuckles (shift cables).

2004 SVT Focus
Custom front-bumper-mount bug guts; precision sprayed brake dust on OEM rims; 15% Pine Tree pollen over the clear coat.
No more SVT autocross, I drive the thing in the avatar.

Last edited by SVT Robzor; 10-03-2006 at 11:45 AM.
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