Transmission grinds when I shift fast

[H251umdinger]

I have a 03 350z with a 6sp and the trans grinds when I shift fast especially in 3 and 5. Is this a sync problem or too thick trans oil problem or what, Whatsup?

[BusyBadger]

3rd gear grinds are fairly common in higher mileage '03 & '04 models, hard/fast shifting will certainly make it more noticeable. Grinds in 5th are less common because it's not a gear you're moving through a lot - but it still happens. Like you, I'd say it's the synchros.

If you're not looking to have your transmission rebuilt you can try different transmission oils. I've heard people have success with Redline Shockproof (aka Smurf Jizz), AMS 2000 75W-90 and Royal Purple 75W-90 Max Gear Oil. Do some research on your own and figure out which one you want to use.

Keep in mind though that chemicals will never really fix mechanical problems.

EDIT: AMS Severe Gear 75W-90 has replaced the Series 2000 75-90 that I linked to earlier.

[bryan d.]

I own a 03 and definately the 3rd gear is the one to grind the most. I rarely grind in 5th but it does happen. If I take my time, which I usually do, then it dosen't happen. But like it was said above the transmission fluid from either one would help. I havn't put any in my Z but I will in the near future just to see if a change occurs. I've heard that the redline fluids need to be mixed and I don't really like that idea.

[PalmerWMD]

I have had grinding in 3rd on 2 seperate Z33's's both times replaced under warranty with an 05 part number MT.

Fred..