I have a gsr tranny I bought 2nd hand and ever since I've had it in the car it pops out of 1st after being driven for a short amount of time, about 10 or 15min. Everything else about the trans is perfect and when its cold it stays in 1st no problem. When it's popping out of 1st it dosnt even feel (from the shifter) the same when I put it in 1st, almost like it dosnt fully engage. Even trying to baby it from a stop it does this. I'm having it looked at Saturday but would love any input or suggestions.

 

What fluid are you running and how often do you change it? Nobody will be able to tell you very much without having the transmission split apart in front of them.

 

I recently had my mechanic use synchro tech in it.

I actually went and found a person in the cincy area who I was going to have work on the tranny look at it and he suggested that it may be a problem with my shift linkage/shifter/shift bushings. Everything except the linkage is only a year old (skunk2 ss, energy bushings, new oem bitch pin) but there is still a lot of play in my shifter. I might try hasport shift linkage or a k tuned shifter (the model with adjustable throw) to see if they help the issue.