Originally Posted by Ubersuber
My 2 c.
The shifter on these cars is, in effect, already a short shifter. I can't imagine the effort the actual short shift kit might add to changing gears on these cars but it must feel pretty slick on a track when everything is nicely warmed up.
This means you feel just about everything that is going on during the shift, unlike regular cars which have shift leverage possibly up to twice as much as our stock shifters. You just don't feel the shift in a regular car and so you tend to shift with higher forces which only feel "light" because of the extra leverage from that long spindly shift lever. Our cars have short levers.
The first two gears are triple cone synchronized so there will be a difference in the feel when you shift into first or second. You think the 1/2 shift is hard, try shifting into 1 in a cold box at anything above idle speed. You just need to recognize that the shift lever effort in these cars is much higher than on a more normal car, and this affects the cold shift disproportionately more.
3,4,5 and 6 are just regular double cone synchronizers which feel different when shifting.
The 1/2 gear cluster is the largest and heaviest gearset and the box is constant mesh, which means ALL the gears in the box are turning at high speed when in first and second. That second gear synchronizer has to slow down the whole gearset in order for the dogs to engage. The dogs are the "gears" you feel when changing gear, the gears themselves are always fully meshed (except for reverse of course). That clash is not the gear teeth (fortunately) but the much larger and squared off teeth in the dogs which actually engage the selected gearset.
These gearboxes use baulk ring synchronizers invented by Porsche. There is no slippage when the dogs engage because the synchronizers can't allow the dogs to engage until the baulks match the notches in the baulk rings. That buzz or clashing you feel comes from the baulks and the dog teeth and they are designed to take that sort of punishment.
The synchronizers are likely bronze faced (not brass, that is too brittle) and they need to both absorb and hold gear box oil and also press though the lubricating film in order to work but not wear too rapidly. The less time the synchronizers spend slipping the better.
So, in our cold boxes you need to shift slowly and quickly at the same time. This sounds impossible but if you understand what is going on (and you can feel everything through the shift lever in these cars, one of the many delights of driving one) it isn't so tricky.
I learned to drive on cars with old worn out synchronizers because those were cheaper to buy, after a series of incompetent previous drivers had prematurely worn the gear box. I was taught to shift firmly but deliberately in three quickly executed but definitely separate steps (this is the "eggshell" technique described elsewhere in this thread, it isn't really as gentle as described but the concept is the same). When the car is in first and you wish to change gear you select neutral as you lift off, then you pause ever so briefly, shorter pause if the gearbox is warmed up and longer if it is still cold, then you firmly select second gear.
If you do this I guarantee your baulky 1/2 shift will proceed butter smooth even in a very cold box. I routinely drive my BRZ in minus 30C weather with no shifting issues if I use this old clapped out gearbox technique. In truth, if you treat your synchronizers with more respect the box will never wear out and you will never clash a shift again.
You will note that the pause on the upshift is equivalent to the double clutch throttle blip on the downshift, also required if the synchros are worn and recommended even if they are new (though DO NOT double clutch unless you do it correctly as you will wear the synchronizers more if you overspeed the blip).
It is all in the timing on a cold upshift. You will find the exact length of pause (and we are talking multiples of nano seconds here, not one mississippi two mississippi!) that allows the gearcluster to slow down more closely to the second gear speed.
Finally, well built gearboxes need quite lengthy break in periods before they work fully as designed. This is not gentle break in but miles accumulated. Many manual gearboxes aren't fully run in until you have driven 5,000 to 10,000 miles of multiple shifting. How many owners still have trouble with this shift after 10,000 miles? It takes time for the synchronizer faces to wear smoothly and fit exactly into their mating surfaces and for the bronze to absorb the correct amount of lubricant into the pores of the metal for the synchros to work flawlessly. How many of you noticed how notchy the brand new gearbox felt compared to now after a year of ownership?
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