Have 10,400 miles on my '04 6MT, been driving the car very conservatively most of the time, "babying" it and rarely speed shifting, except when necessary (pulling out in heavy traffic, needing to make a quick start to get ahead of others at the light and change lanes, etc.). I have NEVER raced the car, as the tire and brake wear will attest (and clutch wear, once they get in there to see).

Saw many comments about how others have had 6MT's replaced (some as many as 3 times !!), but I was hoping that my build date of 12/2003 would have the latest revision (read upgrade/improvement) of the the 6MT, and I'd be OK. I understand this tranny has been redesigned/revised 6 times now ??

But alas, about a week ago, during hard acceleration I got a synchro "crunch" when I shifted from 1st to 2nd quickly. Now, EVERY time I shift from 1st to 2nd quickly, at 4,500 RPM's or more, I get the crunch. Beginning this morning, it has started crunching on the 5th to 6th shift EVERY time I shift it quickly, even at 2,500 - 3,000 RPM. If I pause a split second, then go into 6th, it's OK, but a straight shift (like in any other car) results in the crunch, every time. I don't think I should have to "double clutch" or hesitate when shifting ANY car, much less a car of this "higher" caliber.

Seems that Nissan would be able to design a decent transmission. Also, isn't this the transmission that's in the "Z" ? So, even after 3 years of production, they haven't been able to get this tranny fixed right? Are the "Z"'s having these same problems ? Why the hell didn't they just buy Getrag units, or some other proven manufacturer's product, and just be done with it?

My '96 Honda Accord 5MT has 165,000 miles and shifts like butter (original clutch); my son's '88 Acura Integra 5MT has 270,000 miles and shifts like butter (2nd clutch); my '86 Mazda B2000 5MT has 224,000 miles and shifts like butter (2nd clutch). What gives, Nissan ??

Comments/feedback appreciated ???

Sport Sedan Fan - 2004 6MT Sedan
Sport/Navigation/Premium/Aero; "Invisiguard" Bra, Madico Onyx Tint
Obsidian Black/Graphite & "Titanium"
SHE'S SILVER & BLACK - GO RAIDERS!

 

Infiniti (Nissan) is very good at replacing. They've done mine three times. I would recommend that you take it in right away and get the new tranny put in. As I said I have had three new trannys and this one is awesome. Very strong

Base 6MT Silver sedan
Stillen Exhaust
Stillen CAI
Eibach Pro Kit
Eibach Sway Bars
Kaaz LSD

 

Thanks for the encouraging words, 6speedG35sedan.

I'm leaving on vacation next week, and don't think I can clear time for a replacement for about 3 weeks - I'll keep babying it, then take 'er in after I get back.

How long did they keep the car when replacing the tranny?

Sport Sedan Fan - 2004 6MT Sedan
Sport/Navigation/Premium/Aero; "Invisiguard" Bra, Madico Onyx Tint
Obsidian Black/Graphite & "Titanium"
SHE'S SILVER & BLACK - GO RAIDERS!

 

They do the tranny swap really fast. They had my car for only a day and a half. I got a newer revision tranny swapped in for my old one and this one is much tighter.

2003.5 6MT Sedan. Caribbean Blue / Graphite

 

Did they ever say what the tranny problem was?

2004.5 G35 Sedan 6MT Garnet Fire/Graphite Leather
Premium / Bose / Sport / Aero / Sunroof / Tint / K&N

 

6speedG35sedan:

Can you quickly run down the symptoms for me... those leading to the replacement. Thanks!

I have been complaining of diffficult shifts from 1-2 and sometimes from 2-3. Plus I notice more of a whining sound in 1st and 2nd. I have been asking them to check since January and it has slowly become worse. They keep telling me that things are "normal"



2003.5 Sedan 6MT, Brilliant Silver

 

Mine is also dying. 04 Sedan 6mt, Sept 03 manufacture date.

It has been grinding for about 10k of miles going into 2nd at high rpms. Now if I am over 4k rpms, and try to skip 5th and go to 6th, i am locked out of 6th. If I force it, it will grind. So yea, mine goes in Monday for tranny issues.

Guess what the dealer says? Never seen any 6mt problems yet.

2004 Infiniti G35S, 6MT, Premium, Sport, DP
Mods: JDM Clears, 20% tint, Z-tube, Stilen CAI
Track: 14.32 at 98.79 mph 2.2032 60ft
Dyno 07-07-04 - 234.2 hp & 233.8 tq
http://www.g35world.com

 

I think that most of the problems people are having with their transmissions is related to user error, not major design flaws. The job of the synchronizer is to synchronize the two cogs. If you shift faster than the synchro can sync, you are going to have problems and crunch gears. Not only does shifting too quickly damage the gears, it severely overloads the synchros – causing premature wear. If you are getting a crunch when shifting, you are shifting too @#$% fast.

<blockquote><font class="small">In reply to:</font><hr>

I don't think I should have to "double clutch" or hesitate when shifting ANY car, much less a car of this "higher" caliber.

<hr></blockquote>

What makes you think that your ‘higher’ caliber car is not subject to the laws of mechanical engineering???


2004 Sedan -- 3M Clear Bra - Bought on eBay and DIY -- Rocky Mounts bike racks!

 

I disagree with WWW. I have had my tranny replaced 3 times. If it was my fault because I was shifting to fast, then Infiniti never would have replaced it the 1st time let alone a 2nd or 3rd time. I have owned plenty of manual transmission cars and never had this problem. Your theory is your theory though. I just can't see us Infiniti drivers shifting that much faster than Honda drivers or Toyota drivers and since I have owned the latter two as well and have never had a problem with either then I have to conclude that it is not driver (human) error.

 

LOL, oh please. I have been driving standards for 15 years, this is the first one to give me any type of problem like this. And its not USER error.

2004 Infiniti G35S, 6MT, Premium, Sport, DP
Mods: JDM Clears, 20% tint, Z-tube, Stilen CAI
Track: 14.32 at 98.79 mph 2.2032 60ft
Dyno 07-07-04 - 234.2 hp & 233.8 tq
http://www.g35world.com

 

WWW, I have to disagree with you on user error.

My 6MT shifted great when it was new, but the 5th and 6th synchros slowly died with time, to the point where they would grind no matter how slowly and gently I switched gears. The dealer acknowledged that it's a problem and replaced the tranny. This seems like a common trend on these 6MT's and is likely not user error, especially since it starts happening after a year or 10k miles or whatever.

That being said, I have seen people slam the shifter, ignoring RPM matching when skipping two gears and then complaining about a grind. This _is_ user error and happens right from the beginning.

2003.5 6MT Sedan. Caribbean Blue / Graphite

 

Yeah, WildWildWest, that's it - I'm 46 years old and have owned over 25 manual transmission cars in my life (have 5 right now!), and SUDDENLY, I forgot how to drive a manual transmission.

Your point is well taken - "synchronizers" jobs are to "synchronize", not GRIND, and no manual transmission should allow a human to shift faster than they can synchronize, my friend, as long as you use the clutch. The laws of mechanical engineering apply, as always, and have been aptly dealt with by all the other manufacturers.

This is a shitty transmission - and by the way, I've been having that "lockout" issue as well whenever I skip to 6th from any gear except 5th, unless I "pause" again, to let the grandmotherly synchro catch up.


Funny how there never seems to be a "problem" with the manual trannys in our cars, yet the '05 has a "redesigned" 6 speed that is smoother and easier shifting, per their press releases. Why would you "redesign" a good transmission, especially within the first few years of production ????? OH WAIT, I know this one ....... it's because it's F*cked Up !!!!


Sport Sedan Fan - 2004 6MT Sedan
Sport/Navigation/Premium/Aero; "Invisiguard" Bra, Madico Onyx Tint
Obsidian Black/Graphite & "Titanium"
SHE'S SILVER & BLACK - GO RAIDERS!

 

My car is also build date 12/03 and I haven't had as severe problems as you or G35_TX, but I can tell that the synchros aren't perfect.

I only have 6100 miles and I can shift to any gear without it beaing locked, but the overall feel from the synchros isn't that great. It's become a little worse then when brand new but nothing any dealer would cover as there isn't an evident problem yet.

I wonder if Infiniti will start putting the 6 spd from the 05's in warranty trannies or if they'll just replace it with the same poorly designed synchro'd tranny as before.

Keep us posted.

04 6MT Sedan - Z Tube, K&N Drop-In, 04 Z Suspension

 

BrianV:

As I mentioned in my original post, I tried to "baby" this tranny, after hearing of the problems others had, thinking maybe the "breakin" of the gears and synchros might make a difference, but at 9,500 - 10,000 miles the problems began to show - the "lockout" effect, grinding between 1st & 2nd, then , finally (for me), the grinding from 5th to 6th on EVERY shift, unless I pause between the gears (ridiculous !!).

As you felt with yours, my synchros were always tight and balky - just not a smooth or fluid transmission at all. Love the car, hope they give me the "newly redesigned" 6MT that goes in the '05's. Will keep everyone posted.

Sport Sedan Fan - 2004 6MT Sedan
Sport/Navigation/Premium/Aero; "Invisiguard" Bra, Madico Onyx Tint
Obsidian Black/Graphite & "Titanium"
SHE'S SILVER & BLACK - GO RAIDERS!

 

Yeah definitely keep me posted. I'm not at 9500 miles yet so who knows.

I do double-clutch just about every downshift and I don't skip gears that often. I don't slam the gears but I shift aggressively from time to time.

Hope it works out for you, if it does, I'll lobby hard for a new tranny

04 6MT Sedan - Z Tube, K&N Drop-In, 04 Z Suspension