Hello everyone!
So I'm new to the forum however I have a 2008 350Z I bought brand new. At 1500 I installed a GTM Twin turbo kit with a bunch of other upgrades. I've ran my car at 9.5#boost with no issues until recently. It seems to me the synchos are gone in 3rd and 5th (I think). Normal driving the car shifts fine, sometimes grinds 3rd gear. But if I take off and want to run fast the tranny will only grind into 3rd gear under moderate to heavy load. Currently the car only has 31K. If it starts to grind I just typically keep the clutch in and let the RPMs drop, most of the time it goes in but I have had to fight it. I'm an experienced mechanic and work on my own cars however I've never worked on transmissions. I understand them and know how they work but I've always stayed away but currently I left my job to go back to school and money is a little tight so I'm heavily considering replacing the synchros myself. Here is my problem, I cannot find a synchro for my car, the closest I found was a 3rd gear synchro for an 03. Does anybody know where I can find transmission parts for my car? Also if anyone has any other information that would think they can help it would be much appreciated, because I can't find ANYTHING hardly on these transmissions. Thank you all and look forward to partaking in the forums.

 

I believe owners experiencing transmission problems replace the entire transmission with a rebuilt unit.

I'm surprised you are experiencing transmission problems with a 2008 that has only 31k miles.

 

Yeah, I'm not sure why it is going bad. Maybe poor shifting. I beat the car up drag racing and running it on the track. Idk, my boost controller just stopped working. Waste gates and blow off valves are not working so I have a lot of **** pulled apart tonight, trying to hope it's not the valve manifold. Yay boost

 

I know you only have 31k, but is the clutch stock? Since you have to pull the tranny anyways, I'd check your clutch first. Sounds like the pressure plate is getting weak. Nissan clutches have 2 primary failures. Obviously, the disc wears out. But also, the pressure plate fingers get weak and deform if they get hot. This causes the plate to not fully retract when you depress the clutch. The first symptoms of this problem are 3rd and 5th grinding. It's possible you wore the disc or got the plate hot due to the extra power you're making.

All that just to say that if you DO have a high performance clutch, you probably tore up the 3rd and 5th synchros. Unless you have long bearing pullers (15" long), you're not going to be able to rebuild the tranny.

 

If both wastegates aren't working, it's the solenoid or a vacuum leak.

 

Thanks, cobra! I do have a spec super twin disc clutch in the car. A bit over kill but it's a fantastic clutch. I already tested for a vacuum leak and didn't find anything tonight so you're saying solenoid went out then? and sorry that's what I meant by valve manifold. Then what about the blow off valves not releasing? I know they aren't releasing because dust formed on the piston itself and I they stopped fluttering. I was thinking maybe a minor boost leak or something and also don't hear any turbo surging. And no, the throttle body plates are good. Btw thanks for you help!

 

If the wastegates and bov's aren't working, there's definitely a vacuum issue somewhere. That's the only thing they have in common.

 

I have the Z on jack stands so i can get under it. used smoke machine and found nothing wrong. Tried using propane to find a leak or something, my boost controller is reading properly at -9.8 psi at idle. waste gates are free moving (they are not fun to try and reach). I know I need a vacuum gage but im done running around town for the day. but the other thing i was skeptic about was the soleniod but im thinking about building a little rig with a bicycle pump and trying to pressurize the sensing line slowly and see if the solenoid is shifting. The problem is the car runs fantastic with NO issues except BOV's and waste gates dont work lol.