On my 1989 NA RX-7 GTU I was at a stoplight and I went to neutral and let go of the clutch and the car stalled. I started it up and went to first gear and it keeps stalling. I put it in neutral and it goes in reverse. I had couple people come push the car to parking, pushing the clutch in. I can’t push it into any other gears and first and second gear makes me stall if I let the clutch out. My neutral is reverse. Did I blow the trans and need a new one?

 

Back in May 2014, I was driving my S5 NA with MT to work one morning. I stopped at a stop sign at a not very busy suburban intersection. Shift from 5th to 1st and let off the clutch and the car dies. I restart and try starting off again and the dies again. I immediately realized that my MT was stuck in 5th gear. So, I had it towed to a nearby parking area until that weekend. I thought that one of the shims in the shift lever broke off and partially jammed my shift lever. This happened to me once or twice before. Well, unfortunately it wasn't the shift lever. It must have been either the shift rod or fork, or it may have been something more serious like a clutch hub or synchro. It was my original transmission with nearly 309k miles. I had a spare used transmission with supposedly 190k miles, so I just swapped it out. Threw the old transmission out. Was tempted to tear it apart to find the problem, but I just had surgery and was in no mood.

On these Mazda NA S4 or S5 transmissions, problems with the 5th/reverse shift fork, clutch hub and/or the synchros are somewhat common. I would first suggest checking the shifter bushings. If that's not the problem, than sounds like you will need to have your transmission rebuilt. Only other option is to pickup a good used transmission and swap yours out. These transmissions used to be a dime a dozen on Ebay. Nowadays, they have become scarcer and harder to find.

 

https://www.miata.net/garage/stuckreverse.html