unknown trans grind

[c72c]

I got a 96 s14, sr20de 5spd. ONLY after start up i get a rattle-ish grinding from the mission. it will only do it in 1 or R. I'll put it in gear and about 1/4 off the clutch it'll start, it'll grind anywhere between 1-10mph then goes away, unless i stay constant under 10. when i first start it's somewhat obnoxious but as i increase speed it smooths then stops. It does this warm and cold, but after couple hours cruisin, stop, and startup again, it seems a bit worse. There was also one time i put it on stands, put it in first and let it go, it did the same grinding but the whole time in 1st till i shifted. then i stopped, put it back in first still runnin, no grind??? i'm stumped, as is everyone else i've asked.I bought it in march and it was grindin when i bought it, had it drained and filled about 2 months later, got a new clutch and release bearing last week. I'd like to have a possible suspect before droppin it to fix(can't afford down time).-ALSO, there's times i'll push half throttle in low gears and when it would normally break loose, it feels like somethins slippin a bit. feels just like when a clutch is goin, but it did it today and like i said, new clutch. I didn't notice this till last month.

[ravera]

Given that usually 1st gear is the closest gear to the midplate on the transmission, I'm going to guess that the PO liked powershifting and just beating the crap out of that transmission. When you put excess side thrust on the gears of the transmission. When you start it up, even in Neutural, all the gears are constantly meshed. You probably knew this. That's why you hear the grinding sitting still at startup. It's not actually grinding it's the sound of helical gears that are not in the correct lash for whatever they're meshing with. When you have high load on 1st gear, like at low speeds in 1st, you'll get a loud grinding because the effect is magnified, essentially, it's not completely meshing as it was designed. When you shift, the synchro and selector rings move off the teeth on 1st, also pulling it closer to second and the drive collar due to friction on the teeth, this not only moves it away from the midplate but also takes the load off it since you're now in 2nd. If you're looking for a place to start, I'd try re-shimming the transmission and replacing the baulk rings while you're at it. When you have it apart you could check for chipped teeth and improper wear patterns on the gear teeth.

If you clutch was slipping you'd notice as the rpm would stay constant and speed would increase, similar to an automatic.