need help, standard trans grinding in my vert

[big_tuna]

I've got a 93 convertible. I bought it already 5 speed swapped last year. The trans. grinded bad in every gear up or down shifting. I checked the oil it was good so I decided this spring to pull the trans and swap in a different one.

I changed the trans, clutch/pressure plate, put in an oem nissan throwout bearing, slave cylinder, and master cylinder. The clutch is just an Exedy replacement, and there was an almost brand new light weight flywheel in there already.

I noticed after a couple weeks of driving the trans started grinding just like the old one. If you put the clutch in to down shift there is a terrible grind even before pulling it out of gear. It wont grind at all if you rev it before downshifting at any rpm. If you up shift at 1500rpm it shifts fine. Any higher it will crunch in every gear.

I wanted to autocross the car this year but any kind of quick shifting into second is impossible, it wont go in! The oil is new 80-90, the pedal is properly adjusted, the master cylinder has clean fluid.

I'm just baffled that 2 different transmissions would have the same symptoms. Is it possible the replacement pressure plate may not work well with a lightweight flywheel?

Sorry for the long post! I'd really appreciate some advice because i'm stumped!

[dawagarage]

did you try adjusting the clutch pedal? cuz thats what it sounds like to me... adjust it in our out. try them both and see what works for you. and best of all, its free.

[mechanicalmoron]

What gear oil did you use?

Either a GL5, or a GL4/GL5 hybrid (or, oils that don't fall under either) will corrode your synchros. I used royal purple for two years, then found out about even the hybrids slowly screwing up yellow metals, when I went reading after noticing my transmission takes forever to synchronize now compared to before. Switching to amsoil in the next week or so, hopefully it will be mostly okay.

Try double clutching it: clutch fast and take it out of gear, let the clutch out in neutral, rev match and then, without letting revs move up or down as you do this, clutch and put it in the new gear. This will probably let you at least drive it for the time being, and may tell you what's wrong.

Also, synchronization tends to take longest on first, second longest on second, and so fourth. I BELIEVE this is because lower gears are larger, and take more force to get spinning. Even before my royal purple adventure, second was a bit slow, try shifting slowly and feeling for the synchronization.

I can't really tell from what you're saying, it might be the pedal as hot said. If it grinds when you put the pedal in, it could mean you need to adjust it so the pedal is further from the cylinder, and the rod is longer. It just strikes me as odd that the new transmission fixed it AT FIRST, but then the same thing happened.