Quote:
Originally Posted by beta
Seeing as the 1->2 shift can be made faster with better engine mounts, this would point that the issue is either:
a. The twisting of the engine in relation to the gearbox is changing the geometry of engine -> gearbox causing the linkages to not match up properly.
b. A combination a. and a mechanical issue with the gearbox.
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Have you ever taken a gearbox apart from an engine?
A gearbox has an cast aluminium housing which is bolted to the block with 10 bolts or so. Any twisting in that construction would cause the gearboxhousing to crack, the clutch to break, the block to crack, the bolts to break or the crank to break (or any combination of those
). I think I can pretty shurely say that it is 100% impossible for the engine ->gearboxconnection to have any flex.
Also there are no linkage
s to the gearbox: it is 1 linkage. That is connected to the shift lever. When the engine-gearbox assembly moves for say 10mm, the shifting in eg. 2 shifts accordingly. The shift mechanism itself is suspended in a rubber bushing (shifting arm bearing), so it flexes all the time. Even when you shift gears when stationairy.
When you shift in another gear you always use the tactile feedback from where the shifter was in the previous gear.
Whatever the reason for grinding 1->2 is (and I'm pretty shure I know what the reason is), it's absolutely impossible that it's from twisting of the engine in relation to the gearbox. And 3->2 denial is driver error; not using the feedback from the stick and just yanking it in a place where the gear simply isn't located.
If you want to know why 1-2 is grinding, you first have to know why and when a gearbox grinds its gears, and that is not an issue with gearbox suspension or flexing of the engine-gearbox assembly, cause that last one is plain impossible unless you're in a serious crash. It's a synchro problem.
I'm not saying that stiffer gearbox mounts (or engine mounts) have no advantages, because a stiffer suspension reduces the pendulum effect from the assembly which makes the whole car for a more stable platform (the same reason why eg. a fluel truck has bulkheads in its cargotank; without that it would tip over in the next corner.). But you won't reduce grinding gears, and if you can't find the gears: learn how to shift.