My 2003 6MT g35 coupe started grinding 3rd gear when above 5k fast shifts...


Shoud I try AcDelco GM synchromesh FM ?

Yes I did alot of reading but I am unsure if it's worth the risk.. I mean even if it fixes the trans for 1-2 years its worth it, not like I'm gone be rebuilding the original trans as getting a cd009 is much cheaper.

I'd check a couple things before going that route because that's a road you might not come back from...

1. Bleed the clutch and verify proper clutch DISENGAGEMENT.

2. Check the maintenance interval on the transmission fluid, if it's near the 30k mark (factory recommended interval) then replace the fluid and see if it helps.

However, those early revision transmissions (zero through 4) had a single synchro on 3rd gear... considering the wear that 3rd gets it's not surprising they went to double synchro for revision 5-8 and eventually a triple synchro for revision 9 ( CD009).

If those things check out then you can try the friction modified gear oil but I don't know how well it's going to work honestly, that stuff is designed mostly for use in transaxles and transfer cases, stuff that uses spider gears, and yes it works good in those applications.

hey thanks for the reply... but how do I "verify proper clutch DISENGAGEMENT." ?

There isn't an actual spec measurement of throw for the CSC piston but you can visually check it under the vehicle usually. Just watch the piston push on the arm for the throwout bearing (withdrawal arm) and see if it looks like it's got the right amount of travel. Bleed the clutch while you're down there, don't use a vacuum bleeder or you ruin the O-rings on the CMS.

http://www.nicoclub.com/service-manu.../Coupe/2003/cl

Thank you,

I'm pretty sure it's a synchro issue as it's just a 3rd gear concern.

I'm gone change the transmission fluid, no idea what I will use yet.. as far as oil. Wish me luck.

Best option would be to buy a new CD00A trans or try to find a used CD009 trans. The 3rd gear grinding was common on the early trans, and why they eventually went with triple cone syncros on the CD009 revision.

As far as what oil to use. Go with OEM Nissan MTF, Redline MT85, or Amsoil Manual Transmission & Transaxle Gear Lube 75W-90. These transmissions call for a GL4 fluid, and the Mobil 1 stuff you can find easily in your local autoparts store is a GL5 fluid and can cause excessive wear, noise, and damage.