1991 348 shifting issue

The change to redline should smooth it out a lot. It'll still be a little hard to second cold, but quickly be fine. You may find that the change will show a new leak from the case, tho. No biggie.

 

348's shift easier when your rpms are higher going into gear (as opposed to when you first push in the clutch pedal).

If you short shift into gear at low rpms (e.g. less than 4000), then your 348 is going to clunk. Especially cold.

Red Line has a variety of gear oils. Some have very similar names, but do wildly different things.

75W90 is different than 75W90NS.

75W90NS will improve your cold shifting in your 348 compared to the OEM Shell or AGIP gear oil.

Red Line has a gear oil for damaged transmissions, and Red Line has another gear oil called Superlight Shockproof 75W90 that works amazingly well in 348's (though tends to accumulate condensation so you'll want to change out your gear oil at least every year if you use that fluid).

Of course, when you change your gear oil you will want to examine the drainage for metal debris. Your problem could be due to gear or bearing damage (though more likely is just due to bad old gear oil and perhaps some built up condensation in your tranny), so the metal will help tell the tale.

Bad shifts can also come from a forward shift seal that's gone bad, shift cables that need realinment, or even your shift gate in your cockpit that might need better placement.

 

......

http://www.ferrarichat.com/forum/showthread.php?t=101885&page=7