This problem has been bugging me for a while. Although, I have no idea exactly what it is. I have a stock 91 firebird formula 305 TPI with a T5 on it. When I am idling, and I push the clutch in and put it in second and slowly let the clutch out without giving any gas, the car will start to move,as the clutch pedal is released further, the transmission will pop out of second gear. Also, when I am driving under normal conditions, and I shift into second gear from first or third, I have to forcefully hold the shifter down until the clutch is all of the way out or it will pop out on occasion. What needs to be done to fix this?
Thanks

 

synchronizer maybe?

 

Don't the synchronizers make it so that you can shift the transmission into gear at a different RPM than it should? My transmission is already in second gear with the clutch in, but it pops out as a load is put on it.

 

i wish somebody would come in on this, im no mechanic but i would think that is the problem. ive always been told that when a tranny pops outa gear that its the synchro for that gear. it very well may not be the synchro. could be in the shifter/selector mechanism. those are two things i can think of and would look into if it were me.

 

The "synchronizer assembly" is the entire group of stuff that's responsible for shifting. It includes the "synchronizer" itself, which is a sort of sleeve, that has teeth on its inside (they look more like splines actually) that mate with the teeth on the gears. The teeth that are on the sliding part are made with a taper that tends to pull the slider onto the gear. When they wear, they often don't wear straight, but rather develop taper in the opposite direction; then, they try to push the slider off the gear.

The thing most people call the "synchro" is actually named "blocking ring". All it does, is prevent the shifter from sliding the slider over the gear, until the clutch surface on the ring (which mates with a surface on the gear) has equalized the speed of the gear to the speed of the mainshaft, so that the slider will slide onto the gear without grinding.

 

Thanks for the description. It clears up a lot of the mystery around the weird things my transmission does.