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I had my T56 magnum repaired, it was grinding really bad going into 5th. They replaced 5th gear, 5th counter gear and 5/6 synchro and sent it back to me.
I got the car put back together and did a 20 mile test drive. The first time I put it into 5th gear, there was a loud shrill whine that would change with throttle position. The noise went away after a couple of minutes. The next time I shifted from 4th to 5th, I got on the throttle around 3000 RPM, and at 3500 RPM it made a terrible sound and the engine was free revving. I put it into 6th and drove it home, pulled the transmission.
What would cause this gear to totally destroy itself after only a few minutes? The car only makes 300-400 ft/lbs of torque at 3500RPM. I'm not naming the shop right now, as they haven't received the transmission yet so I don't know how they are going to handle this.
It's in a 3rd gen firebird with a procharged LS. Street and track day car. I had run the transmission for about 2 years prior until the synchros started grinding. I think that was caused from my clutch coming out of adjustment so the shop swapped out the 5th gear hardware.
can you cycle the forks by hand and spin it to see if theres any binding ?
having all the teeth on that gear removed the same is quite curious
during my short stint thinking AR-5s are a worthwhile endeavor i blew quite a few teeth off gears and it was always just a section of 5-10 teeth and the rest of the teeth were pretty ok.
05-03-2023, 01:46 PM
T56 magnum rebuild lasted 10 miles 
