Hi, I'm new to the forum. I just bought a 1983 280ZX last week and it runs beautifully.

However, I do have a small issue. Whenever I shift into the 3rd gear, I get this nasty vibration feedback before it sits in the third gear. The 4th does the same thing, although it is milder.

The first, second, and fifth does it fine. Reverse does it sometimes, only milder than the 4th.

How would I go about to solve the issues?

Any feedback would be much appreciated.

The synchronizers in the transmissions are brass or bronze and they tend to wear out. They are also susceptible to damage from using the wrong gear oil. (GL-5 has too much sulfur for "yellow metals".)

You could try draining and re-filling your transmission with Redline MT-90. If some one has put the wrong lube in the transmission the Redline will help significantly, but if the syncros are truly worn out you are probably looking at a rebuild or swap from a parts car.

By the way, the 83 transmission is considered by many to be the most desirable. Just something to keep in mind.

By your description, my guess would be the bearings-3rd and 4th are on the same shaft. I just rebuilt an '82 tranny (I had never run it) and the countershaft bearing was fried. You can buy a rebuild kit for around $120.00 that has the baulk rings, syncros and seals. Maybe a little intimidating at first but you just have to study the diagrams a few times.

The tranny works great and is very smooth.