this happens not all the time, but really only when i "throw" it in secnod.
it grinds and then catches, a loud and honestly distrubing noise....
Syncro rings are worn out. You could just slow the shift down a little bit, too. The more you grind it, the more worn out it will get and the worse it will become.
My original trans was getting pretty bad for 1 and 2. Picked up a reconditioned one and 3rd grinds a lot, but at least 1-2 works great. Never really need to slam it into 3rd though, so it works out.
Also, changing the gear oil may help a little..or a lot. If it is really old and yucky, it will make a bigger improvement. That's what I did about 10,000 miles before getting another trans and it made a huge difference.
im not sure whats the best fluid, but i would use whatever vw recomends, go to germanautoparts.com and see what fluid they have listed for the car. site is very reliable (for me at least), never had any problems. i recently got a bunch of power steering fluid and brake fluid to do a flush, and it was a lot cheaper than going through the stealership.
The unofficial list of good oils are:
GM synthetic fluid (I forget the name of it, but I've heard most chain stores have it)
Basically, you just need one that is GL-4 certified/approved. Some bottles say it right on there, but others may need some skimming of the documentation.
2000 vr6, my 2nd gear has been grinding every up shift and inconsistent downshifts. I recently changed gear oil (Lucas 80-90). 2nd still grinds but all the other gears are MUCH smoother. They were all getting a little rough. So it looks like I will just be continuing to avoid 2nd gear to save the syncro.
Well something else you can do to help the syncros out is to get a lot closer with rev-matching, like you would do when you float the gears. If you're hitting it as an upshift, you'll eventually figure out the timing of when you drop your foot off the gas and the revs fall down, you end up with a short window to get 2nd to be pretty close to rev-matched.
Can also just slow down your shifting process, too. Regardless, it does sound like the syncro for 2nd is pretty worn-out.
For real. Not allot of people check out the bushings on the cables where it enters the shift box. Not included in rebuild kit and allot overlook it. Same for the 3 on top of trans holding the front cable bracket.
If the symptom lessens as the trans warms, it's likely a bushing/alignment issue. If it sucks from cold to warm, probably internals as mentioned.