7AT Owner , look at this !

[Megan370z]

Let me explain my story a little bit...

I bought the Z in December 2009 .. around November/December 2010 the car started to pull timing for no reason , I was doing dyno test with different custom mod and we couldnt figure out why the ECU was pulling timing at every pull


I tried to find the problem for over 6 months then I just let the car go like it was.
The power at 7000 was about 20whp less .

then in October 2011 , I was at the drag to look at the time I was able to get, I did quite a few pull , I was doing burnout by removing the brake fuse.
then I went home.

The next morning I saw some oil under the car
It was the tranny that was leaking.

Once at the dealership they discover the flex flywheel was badly cracked !!!
ok well they replaced it at the same time because the tranny had more problem than just a leaky oil seal.

Once I got the car back I did some pull with datalog (Uprev)
the Ign timing was perfect and where it should be !!

then I went on the dyno and gained the 20-25whp back !


this was the first story

next

after about 15 000kms I blew the VVEL . I made a post about it ,, its all good
but today was the day that I removed the engine/tranny and I discovered something !

That flywheel was badly cracked again !!!!
I blew the engine at a Time attack and I was wondering why the engine didnt pull the same as eailer this year...

I only did 3 Time Attack ,, I never had any problem in the first 2 ,, but the 3rd , the power was not there completly


The engine is only N/A .. never put any nitrous/Turbo/SC



if you think your car make less power and have that 7AT ...
take a look at the flywheel it might be the cause incase the ECU is pulling Ign Timing

EDIT ; some year error

[bdavis89]

Where is the flywheel? Can I see it without having to take anything off?

[Trips]

Originally Posted by Megan370z

Let me explain my story a little bit...

I bought the Z in December 2009 .. around November/December 2010 the car started to pull timing for no reason , I was doing dyno test with different custom mod and we couldnt figure out why the ECU was pulling timing at every pull


I tried to find the problem for over 6 months then I just let the car go like it was.
The power at 7000 was about 20whp less .

then in October 2011 , I was at the drag to look at the time I was able to get, I did quite a few pull , I was doing burnout by removing the brake fuse.
then I went home.

The next morning I saw some oil under the car
It was the tranny that was leaking.

Once at the dealership they discover the flex flywheel was badly cracked !!!
ok well they replaced it at the same time because the tranny had more problem than just a leaky oil seal.

Once I got the car back I did some pull with datalog (Uprev)
the Ign timing was perfect and where it should be !!

then I went on the dyno and gained the 20-25whp back !


this was the first story

next

after about 15 000kms I blew the VVEL . I made a post about it ,, its all good
but today was the day that I removed the engine/tranny and I discovered something !

That flywheel was badly cracked again !!!!
I blew the engine at a Time attack and I was wondering why the engine didnt pull the same as eailer this year...

I only did 3 Time Attack ,, I never had any problem in the first 2 ,, but the 3rd , the power was not there completly


The engine is only N/A .. never put any nitrous/Turbo/SC



if you think your car make less power and have that 7AT ...
take a look at the flywheel it might be the cause incase the ECU is pulling Ign Timing

EDIT ; some year error

Good to Know! & Sorry you had to go thru that But again it's like you were driving like normal.

I'll keep that in mind to inspect if the trans gets dropped.

Originally Posted by bdavis89

Where is the flywheel? Can I see it without having to take anything off?

You're kidding right?


The transmission needs to be removed along with the torque converter to get a view of the flex-plate for cracks.

[Megan370z]

Originally Posted by Triple's

Good to Know! & Sorry you had to go thru that But again it's like you were driving like normal.

I'll keep that in mind to inspect if the trans gets dropped.






You're kidding right?


The transmission needs to be removed along with the torque converter to get a view of the flex-plate for cracks.

actualy its possible to look at the flywheel without having to drop the tranny..

there is a small cover plate in the middle at the bottom of the tranny , to have access to it you must remove the small alluminum plate that is right under it which is bolted by 4 allen screw if I remember correctly ( i removed that plate 2 year ago) but the one in bottom of the tranny is holded down by only a small 10mm bolt

once this is removed you can see the flywheel . the dealership has a tool to go there to block the flywheel from moving when removing the crank pulley bolt.


both of my flywheel had the same type of crack

[Trips]

Thats Good to know.

I just figured the view would've been pretty restrictive from the cover plate so thats why I said what i said and I stand corrected.

Thanks for clarifying thats its possible

[CrunchyCajun]

It looks like the 7A is a weak link. This trans is in most Infinitis. Nissan is going to have a serious credibility issue with a fragile transmission bolted to high output engines.

Leave it to Renault to build a $9,200 transmission that is sealed, can't be serviced and can only be replaced. They blow their noses in our general direction!

Nissan replaced my 7A last week. Paperwork said locked up torque converter, but the car was driveable. I wonder if it was a cracked flywheel.

Warranty is out in 7k, maybe time to sell.

[Z eliminator]

my flex wheel was also cracked because it came loose. That the only way it can crack if the torque converter bolts come loose.
i have taken my car atleast 120 passes down the drag strip, shift at 8000 rpm and have not issues with, I also have 4.08 geaers and full bolts on with 305 35 18 drag radials and have line lock on the car.
no isues, it shift like a terror .
GTM has all the parts to rebuild it.

[DEpointfive0]

How can you tell if it's pulling timing without going on a dyno? I think my car is really quick, no issues there, but I beat on it all the time, and I would LOVE a new transmission/transmission parts, LOL

[Megan370z]

Originally Posted by DEpointfive0

How can you tell if it's pulling timing without going on a dyno? I think my car is really quick, no issues there, but I beat on it all the time, and I would LOVE a new transmission/transmission parts, LOL

well you can know its pulling timing when it take longer to accelerate up to 7500rpm

but the best way is either the dyno or datalogging

Originally Posted by Z eliminator

my flex wheel was also cracked because it came loose. That the only way it can crack if the torque converter bolts come loose.
i have taken my car atleast 120 passes down the drag strip, shift at 8000 rpm and have not issues with, I also have 4.08 geaers and full bolts on with 305 35 18 drag radials and have line lock on the car.
no isues, it shift like a terror .
GTM has all the parts to rebuild it.

trust me , those flywheel bolts were not loose as I checked them before I removed the tranny/flywheel
good for you if your Z is running strong

[370zproject]

was this the noise?

[Megan370z]

Originally Posted by 370zproject

was this the noise?

no ...

my problem was really not really audible but the knock sensor were annoyed by it.

[370zproject]

hmmm ok

[jrb55gh]

The 7AT flex plate cracked twice. I notice in some of your other posts that your car sounds like it shifts very quickly. Did you adjust anything on the transmission to make it shift faster/harder than stock?

[DEpointfive0]

Originally Posted by jrb55gh

The 7AT flex plate cracked twice. I notice in some of your other posts that your car sounds like it shifts very quickly. Did you adjust anything on the transmission to make it shift faster/harder than stock?

You can up the line pressure with UpRev, only downside is that downshifts take a hair longer

[falconfixer]

Originally Posted by DEpointfive0

You can up the line pressure with UpRev, only downside is that downshifts take a hair longer

There's no downshifting in drag racing.