Auto Transmission 7AT Rattle at low Rpm's

370Zfeeler · 01-23-2013, 09:16 PM

A week ago, my car started having this weird sound coming from the bottom, it would make this rattling noise at around 1.2-1.5k RPM (every time i would stop and go, and when the trans shifts) from 1.5k rpm's up it would go away, at the beginning, thought my FI exhaust may had become loose from one of the hangers, so today I took it to the exhaust shop and noticed everything was ok with the exhaust, checked all bolts, all hangers, everything.

As we studied the sound, found out it was coming from inside the transmission, right where it meets with the engine, its a rattle between 1.2-1.5k RPM's, after that it would go away, you can replicate it by bumping the revs in the low range and also if you hit the brakes and gas at the same time you can replicate the sound continuously. Seems exactly like what the MT guys refer to as clutch chatter.

Transmission shifts perfectly find, everything works as it's supposed to, manual and auto mode, except for the rattling which is very annoying while cruising because the engine speed is around 1.3-1.5RPM's, every time you'd stop and go and when it shifts in the low rpm's. Have any ideas??

DEpointfive0 · 01-23-2013, 09:17 PM

Flex plate?

Trips · 01-23-2013, 09:25 PM

I would get it looked at before in some cases the flex-plate is at fault like member depointfive0/Andrew has pointed out.

Z eliminator · 01-24-2013, 10:28 AM

flex plate is cracked.

370Zfeeler · 01-24-2013, 12:28 PM

My car is out of warranty, so I want to go ahead an order the part before taking off the transmission, i was looking on courtesypartsnissan, but still not sure.

Which if these two is the one I need?

#1 -PLATE ASSY-DRIVE & GEAR (PLATE ASSY-DRIVE & GEAR - 370Z (Z34) 2009+ :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com)
#2 -PLATE-CRANKSHAFT TO CONVERTER (PLATE-CRANKSHAFT TO CONVERTER - 370Z (Z34) 2009+ 3 7L V6 7-Spd A/T |WITH :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com)

Megan370z · 01-24-2013, 12:37 PM

you will also need the 7AT sleeve 12330 if its needed

I know the 6MT guys has to change their bushing but im not sure with the metal sleeve for the 7AT

You shouldnt need #2 but only #1 from that picture you put on.

Z eliminator · 01-24-2013, 02:25 PM

all you need is the flex plate,, 5 year powertrain warenty ?

370Zfeeler · 01-25-2013, 09:28 AM

Thanks for the help guys!! Just ordered the Flex Plate Part #1

DEpointfive0 · 01-25-2013, 12:45 PM

Heyo! Got the answer right on the first guess!

Why can't my flex plate break?!?!?! I want the dealershít to replace parts for free!!!

OP, when you get it out, can you snap some pics?

370Zfeeler · 02-11-2013, 04:41 PM

Here are the pics of the broken plate, my mechanic was even surprised I could've gotten there driving

Megan370z · 02-11-2013, 05:06 PM

holy %#@ !!!!!
and I thought my first flex-wheel was bad !

Its gonna be expensive for the 7AT owner once the car is out of warranty !
they seem to break way way too easily.

W.O.W. 370Z · 02-11-2013, 05:07 PM

Who did the work?

BeemaaZ · 02-11-2013, 07:39 PM

sometimes I could hear rattling noise at 1st gear (low rpm)... could it be the same (flex plate) issue? I have an MT

DEpointfive0 · 02-11-2013, 08:10 PM

Quote:

Originally Posted by BeemaaZ

sometimes I could hear rattling noise at 1st gear (low rpm)... could it be the same (flex plate) issue? I have an MT

You don't have a flex plate

A flex plate is the AT's "flywheel"

BeemaaZ · 02-11-2013, 08:49 PM

Quote:

Originally Posted by DEpointfive0

You don't have a flex plate

A flex plate is the AT's "flywheel"

Thanks!

01-23-2013, 09:16 PM	#1 (permalink)
370Zfeeler Base Member Join Date: May 2011 Location: Miami Posts: 89 Drives: Sport Cars Rep Power: 14	Auto Transmission 7AT Rattle at low Rpm's A week ago, my car started having this weird sound coming from the bottom, it would make this rattling noise at around 1.2-1.5k RPM (every time i would stop and go, and when the trans shifts) from 1.5k rpm's up it would go away, at the beginning, thought my FI exhaust may had become loose from one of the hangers, so today I took it to the exhaust shop and noticed everything was ok with the exhaust, checked all bolts, all hangers, everything. As we studied the sound, found out it was coming from inside the transmission, right where it meets with the engine, its a rattle between 1.2-1.5k RPM's, after that it would go away, you can replicate it by bumping the revs in the low range and also if you hit the brakes and gas at the same time you can replicate the sound continuously. Seems exactly like what the MT guys refer to as clutch chatter. Transmission shifts perfectly find, everything works as it's supposed to, manual and auto mode, except for the rattling which is very annoying while cruising because the engine speed is around 1.3-1.5RPM's, every time you'd stop and go and when it shifts in the low rpm's. Have any ideas?? R@n1n3913 likes this. Last edited by 370Zfeeler; 01-23-2013 at 09:22 PM.

01-23-2013, 09:25 PM	#3 (permalink)
Trips Administrator Join Date: May 2009 Location: Disneyland, Ca Posts: 8,730 Drives: 🔰 Rep Power: 10	I would get it looked at before in some cases the flex-plate is at fault like member depointfive0/Andrew has pointed out. DEpointfive0 likes this. __________________

01-24-2013, 10:28 AM	#4 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	flex plate is cracked. __________________ 12.343 @114.14 . 4.5 stroker motor is now being built. Dec 1 2015.

01-24-2013, 12:37 PM	#6 (permalink)
Megan370z A True Z Fanatic Join Date: Oct 2009 Location: Canada Posts: 1,156 Drives: 370z Rep Power: 24	you will also need the 7AT sleeve 12330 if its needed I know the 6MT guys has to change their bushing but im not sure with the metal sleeve for the 7AT You shouldnt need #2 but only #1 from that picture you put on. __________________ Megan Journal Click Me ....................One Man Team Motorsport Click Me

01-24-2013, 02:25 PM	#7 (permalink)
Z eliminator A True Z Fanatic Join Date: Jul 2009 Location: Ontario Canada Posts: 1,659 Drives: 370 Z 7AT Sports Rep Power: 19	all you need is the flex plate,, 5 year powertrain warenty ? __________________ 12.343 @114.14 . 4.5 stroker motor is now being built. Dec 1 2015.

01-23-2013, 09:17 PM	#2 (permalink)
DEpointfive0 Premium Member Bitches Join Date: Jan 2012 Location: SoCal Posts: 14,824 Drives: a lot Rep Power: 17151	Flex plate?

01-24-2013, 12:28 PM	#5 (permalink)
370Zfeeler Base Member Join Date: May 2011 Location: Miami Posts: 89 Drives: Sport Cars Rep Power: 14	My car is out of warranty, so I want to go ahead an order the part before taking off the transmission, i was looking on courtesypartsnissan, but still not sure. Which if these two is the one I need? #1 -PLATE ASSY-DRIVE & GEAR (PLATE ASSY-DRIVE & GEAR - 370Z (Z34) 2009+ :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com) #2 -PLATE-CRANKSHAFT TO CONVERTER (PLATE-CRANKSHAFT TO CONVERTER - 370Z (Z34) 2009+ 3 7L V6 7-Spd A/T \|WITH :: Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com)

01-25-2013, 09:28 AM	#8 (permalink)
370Zfeeler Base Member Join Date: May 2011 Location: Miami Posts: 89 Drives: Sport Cars Rep Power: 14	Thanks for the help guys!! Just ordered the Flex Plate Part #1

01-25-2013, 12:45 PM	#9 (permalink)
DEpointfive0 Premium Member Bitches Join Date: Jan 2012 Location: SoCal Posts: 14,824 Drives: a lot Rep Power: 17151	Heyo! Got the answer right on the first guess! Why can't my flex plate break?!?!?! I want the dealershít to replace parts for free!!! OP, when you get it out, can you snap some pics?

02-11-2013, 04:41 PM	#10 (permalink)
370Zfeeler Base Member Join Date: May 2011 Location: Miami Posts: 89 Drives: Sport Cars Rep Power: 14	Here are the pics of the broken plate, my mechanic was even surprised I could've gotten there driving

02-11-2013, 05:06 PM	#11 (permalink)
Megan370z A True Z Fanatic Join Date: Oct 2009 Location: Canada Posts: 1,156 Drives: 370z Rep Power: 24	holy %#@ !!!!! and I thought my first flex-wheel was bad ! Its gonna be expensive for the 7AT owner once the car is out of warranty ! they seem to break way way too easily. __________________ Megan Journal Click Me ....................One Man Team Motorsport Click Me

02-11-2013, 05:07 PM	#12 (permalink)
W.O.W. 370Z A True Z Fanatic Join Date: Mar 2010 Location: Miami Posts: 1,757 Drives: 2010 Touring Sport Z Rep Power: 19	Who did the work?

02-11-2013, 07:39 PM	#13 (permalink)
BeemaaZ A True Z Fanatic Join Date: Sep 2011 Location: Irvine, CA Posts: 2,594 Drives: 40thAE#472 Rep Power: 508	sometimes I could hear rattling noise at 1st gear (low rpm)... could it be the same (flex plate) issue? I have an MT __________________ SoCal 40th Meet Old & New Mods Steering Lock RECALL**** Own 40th 370Z? Get the build # and the Manuf. date here Last edited by BeemaaZ; 02-11-2013 at 07:46 PM.

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