Quoted: No this is trying to put it in gear while not moving. |
Does this occur after holding the clutch in for a while? How do you get started/stop?
If you hold the clutch in for a while, all the parts inside the transmission come to a stop (if the car is stopped). Then when you try and shift from neutral into ANY gear, sometimes it's impossible. Why? Because the dog clutch can't engage the gear. The teeth don't line up. It's like trying to put a socket over a bolt but you're not allow to rotate either one. Sometimes you luck out and they are already aligned, if not, no amount of pressure will make them fit. In this situation, it has nothing to do with synchros because the synchros only
synchronize the speed of two moving parts (the dog clutch and the gear). If nothing is moving, they don't matter.
Usually if the synchros are going and the car is at a dead stop, you'll hear a grind as you engage the gear (if there is still some rotation of parts within the tranny). That's because the two parts aren't moving at the same speed and the teeth of the dog clutch grind as they engage. Most transmissions don't have synchros on the reverse gear, so it's often quite common to hear a gear grind when engaging reverse if you push in the clutch and quickly try to put it in reverse.
The comment about too thick a gear oil is a good one. If you have too thick an oil, the gears will slow down a lot and the synchros have to try and bring the gear back up to speed. Since the synchros weren't designed to fight this drag, you'll often get a gear grind when shifting into the highest gears. I can't really see it causing your problem.
Give this a try: When you are at a stop, in neutral, with the clutch to the floor, let the clutch out (with the car in neutral), push the clutch back in, then try to put it in first. If it works, then your tranny is fine.
Why does this work? Well, when you have the clutch out (you're not stepping on it), the engine is turning the input shaft to the transmission. Since something is spinning when you push the clutch in a try and shift into a gear, the synchros can match the speed and align the dog clutch so it can engage the gear.
If anyone is curious about how manual trannies work, this webpage gives a great explanation of dog clutches and synchros.
How Manual Transmissions WorkRF