Weird sound and vibration when deaccelerating - Page 2 - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Def · 08-29-2008, 12:35 PM

I've explained this problem so many times before... It's a harmonic vibration in the diff caused by the compression strokes of the engine when decellerating. It is loudest in 4th because it is a 1:1 ratio.

The solution is to get a clutch disk with the proper stiffness springs like a stock disk. If your clutch has springs, but you get this decelleration vibration, then the springs are the wrong stiffness. This means the springs are now damping vibrations that aren't there, and failing to damp the natural frequency of the driveline.

Pho Man · 08-29-2008, 10:41 PM

Quote:

Originally Posted by Def

I've explained this problem so many times before... It's a harmonic vibration in the diff caused by the compression strokes of the engine when decellerating. It is loudest in 4th because it is a 1:1 ratio.

The solution is to get a clutch disk with the proper stiffness springs like a stock disk. If your clutch has springs, but you get this decelleration vibration, then the springs are the wrong stiffness. This means the springs are now damping vibrations that aren't there, and failing to damp the natural frequency of the driveline.

Well the way your saying it, it only happens on decelleration. Mine is also upon acelleration too. If it's coming from the diff wouldn't the sound be coming from the rear of the car and not the transmission? (IDK just asking)

I had a spec stage 3 clutch with a shaved flywheel in my 95 with SR and didn't have this problem. This problem on my 90 has been there even through break in period of the exedy.

flip3d · 08-29-2008, 11:28 PM

I have this prob too. Never really thought much of it though.

Spec Stg 3, Spec billet flywheel, DSS steel 1 piece.

sdblackgloves · 10-16-2008, 11:05 PM

interesting that I find this thread. I just installed a new 4 puck clutch with chromoly lighten flywheel. New pilot bearing and new TO bearing. I never had any noise before the install since I had a stock clutch kit. Now it does the same thing most poster here have.

No noise on acceleration but as soon as you decelerate around 3k rpms theres a humming vibrating noise heard behind the shifter and vibration is felt in the clutch pedal if you lightly step on it. Loudest on 3rd and 4th gear.

Im gonna have to check with the company I bought this Clutch kit from and check the specs.. If it is a bad clutch disc with the wrong spring Im gonna get it fixed for sure. Either my pressure plate is loose (i hope not I put blue loctite on the bolt and torqued it to 30lbs not sure if thats the correct torque spec) or my Clutch disc has the wrong spring specs.. maybe to hard?

sdblackgloves · 10-16-2008, 11:08 PM

heres the spec for my clutch.

OUR OWN DESIGNED CLUTCH IS MADE WITH THE DRIFTER IN MIND! WE USE A HEAVY DUTY PRESSURE PLATE WITH OUR OWN UPGRADED DIAPHRAM TO INCREASE TORQUE SPECS. OUR CLUTCH KIT CAN HOLD UP TO 300 FT. LBS. OF TORQUE! WE USE A 4 PUCK CERAMIC SPRUNG DISK TO ENSURE AN IMPRESSIVE AMOUNT OF BITE WHEN YOU CLUTCH KICK TO INITIATE A DRIFT. ALTHOUGH OUR CLUTCH WORKS GREAT ON THE TRACK, YOU CAN ENJOY AN EASY PEDAL FEEL WHILE DRIVING ON THE STREETS!

HEAVY DUTY PRESSURE PLATE WITH UPGRADED DIAPHRAM
-HOLDS UP TO 300 FT. LBS. OF TORQUE
-PEDAL FEEL GREAT FOR DAILY DRIVING, ONLY 20% OVER STOCK FEEL

*4 PUCK CERAMIC SPRUNG DISK*
-WE USED A 4 PUCK DISK FOR IT'S AGGRESSIVE CHARACTERISTICS NEEDED FOR DRIFTING
-SPRUNG DISKS ARE MUCH SAFER FOR YOUR TRANSMISSION AND EASIER TO USE ON THE STREETS
-CERAMIC DISKS ARE FAR MORE SUPERIOR THAN AN ORGANIC DISK
-WE USE A SPECIAL PLATE COVER OVER THE SPRINGS TO ENSURE THE SPRINGS WILL NOT COME OUT DURING DRIFTING AND AGGRESSIVE DRIVING (AS WE'VE SEEN IN THE PAST)

Def · 10-17-2008, 01:03 PM

Quote:

Originally Posted by sdblackgloves

interesting that I find this thread. I just installed a new 4 puck clutch with chromoly lighten flywheel. New pilot bearing and new TO bearing. I never had any noise before the install since I had a stock clutch kit. Now it does the same thing most poster here have.

No noise on acceleration but as soon as you decelerate around 3k rpms theres a humming vibrating noise heard behind the shifter and vibration is felt in the clutch pedal if you lightly step on it. Loudest on 3rd and 4th gear.

Im gonna have to check with the company I bought this Clutch kit from and check the specs.. If it is a bad clutch disc with the wrong spring Im gonna get it fixed for sure. Either my pressure plate is loose (i hope not I put blue loctite on the bolt and torqued it to 30lbs not sure if thats the correct torque spec) or my Clutch disc has the wrong spring specs.. maybe to hard?

That's harmonic vibration, the springs in your clutch disk are either too soft or too stiff.

sdblackgloves · 10-17-2008, 06:16 PM

okay thanks for clearing that up.

krislin · 03-23-2009, 02:34 PM

yet another bringing up an old post. Same issues, ACT 6-puck unsprung. Slightly different question: is it bad for the driveline? AKA, should I avoid compression braking in fourth gear because of this vibration? Or does the driveline really not give a shit about it?

Thanks!

superbraut · 04-17-2009, 02:48 AM

delete .

mxexux · 04-17-2009, 05:22 AM

I kinda just skimmed through the previous posts but I have to say, why does everybody keep blaming the driveshaft? I didn't see any body say that swaping it solved the problem. If the driveshaft was imbalanced you would feel the vibration all the time at higher speeds in all gears since the speed of it is only directly proportional to the speed of the wheels. Stop wasting money on new drive shafts when you don't really need it.

Since this is only happening on decel we could probably narrow it to differential or old busings flexing the opposite way of accel.

warauto · 01-20-2010, 07:00 AM

Just did my clutch swap and the same thing is happening...the 4th gear accel and decel humming noise....I hate it

fiberwire · 06-20-2017, 11:49 AM

I feel really bad for bringing this topic up but has any of you found out what the problem was?

I have the EXACT same problem. The thing is, even though I had a new 6puck clutch installed recently, I don't recall having such issue soon after I got the car back.

It feels like its coming from the back of the car, maybe differential area. Unless its totally misleading.

04-17-2009, 02:48 AM	#39
superbraut Leaky Injector Join Date: Dec 2008 Location: - Posts: 99 Trader Rating: (6) Feedback Score: 6 reviews	delete . delete . Last edited by superbraut; 06-18-2020 at 09:16 PM.. Reason: delete .

08-29-2008, 12:35 PM	#31
Def Post Whore! Join Date: Apr 2004 Location: Houston, TX Posts: 2,701 Trader Rating: (16) Feedback Score: 16 reviews	I've explained this problem so many times before... It's a harmonic vibration in the diff caused by the compression strokes of the engine when decellerating. It is loudest in 4th because it is a 1:1 ratio. The solution is to get a clutch disk with the proper stiffness springs like a stock disk. If your clutch has springs, but you get this decelleration vibration, then the springs are the wrong stiffness. This means the springs are now damping vibrations that aren't there, and failing to damp the natural frequency of the driveline.

08-29-2008, 11:28 PM	#33
flip3d Zilvia FREAK! Join Date: Feb 2008 Location: Ft Lauderdale, FL Age: 36 Posts: 1,473 Trader Rating: (1) Feedback Score: 1 reviews	I have this prob too. Never really thought much of it though. Spec Stg 3, Spec billet flywheel, DSS steel 1 piece.

10-16-2008, 11:05 PM	#34
sdblackgloves Zilvia Member Join Date: Mar 2006 Location: San Diego Posts: 239 Trader Rating: (2) Feedback Score: 2 reviews	interesting that I find this thread. I just installed a new 4 puck clutch with chromoly lighten flywheel. New pilot bearing and new TO bearing. I never had any noise before the install since I had a stock clutch kit. Now it does the same thing most poster here have. No noise on acceleration but as soon as you decelerate around 3k rpms theres a humming vibrating noise heard behind the shifter and vibration is felt in the clutch pedal if you lightly step on it. Loudest on 3rd and 4th gear. Im gonna have to check with the company I bought this Clutch kit from and check the specs.. If it is a bad clutch disc with the wrong spring Im gonna get it fixed for sure. Either my pressure plate is loose (i hope not I put blue loctite on the bolt and torqued it to 30lbs not sure if thats the correct torque spec) or my Clutch disc has the wrong spring specs.. maybe to hard?

10-16-2008, 11:08 PM	#35
sdblackgloves Zilvia Member Join Date: Mar 2006 Location: San Diego Posts: 239 Trader Rating: (2) Feedback Score: 2 reviews	heres the spec for my clutch. OUR OWN DESIGNED CLUTCH IS MADE WITH THE DRIFTER IN MIND! WE USE A HEAVY DUTY PRESSURE PLATE WITH OUR OWN UPGRADED DIAPHRAM TO INCREASE TORQUE SPECS. OUR CLUTCH KIT CAN HOLD UP TO 300 FT. LBS. OF TORQUE! WE USE A 4 PUCK CERAMIC SPRUNG DISK TO ENSURE AN IMPRESSIVE AMOUNT OF BITE WHEN YOU CLUTCH KICK TO INITIATE A DRIFT. ALTHOUGH OUR CLUTCH WORKS GREAT ON THE TRACK, YOU CAN ENJOY AN EASY PEDAL FEEL WHILE DRIVING ON THE STREETS! HEAVY DUTY PRESSURE PLATE WITH UPGRADED DIAPHRAM -HOLDS UP TO 300 FT. LBS. OF TORQUE -PEDAL FEEL GREAT FOR DAILY DRIVING, ONLY 20% OVER STOCK FEEL 4 PUCK CERAMIC SPRUNG DISK -WE USED A 4 PUCK DISK FOR IT'S AGGRESSIVE CHARACTERISTICS NEEDED FOR DRIFTING -SPRUNG DISKS ARE MUCH SAFER FOR YOUR TRANSMISSION AND EASIER TO USE ON THE STREETS -CERAMIC DISKS ARE FAR MORE SUPERIOR THAN AN ORGANIC DISK -WE USE A SPECIAL PLATE COVER OVER THE SPRINGS TO ENSURE THE SPRINGS WILL NOT COME OUT DURING DRIFTING AND AGGRESSIVE DRIVING (AS WE'VE SEEN IN THE PAST)

10-17-2008, 06:16 PM	#37
sdblackgloves Zilvia Member Join Date: Mar 2006 Location: San Diego Posts: 239 Trader Rating: (2) Feedback Score: 2 reviews	okay thanks for clearing that up.

03-23-2009, 02:34 PM	#38
krislin Join Date: May 2005 Location: Florida Posts: 23 Trader Rating: (0) Feedback Score: 0 reviews	yet another bringing up an old post. Same issues, ACT 6-puck unsprung. Slightly different question: is it bad for the driveline? AKA, should I avoid compression braking in fourth gear because of this vibration? Or does the driveline really not give a shit about it? Thanks!

04-17-2009, 05:22 AM	#40
mxexux Zilvia Junkie Join Date: Jun 2008 Location: SoCal 949 Posts: 363 Trader Rating: (9) Feedback Score: 9 reviews	I kinda just skimmed through the previous posts but I have to say, why does everybody keep blaming the driveshaft? I didn't see any body say that swaping it solved the problem. If the driveshaft was imbalanced you would feel the vibration all the time at higher speeds in all gears since the speed of it is only directly proportional to the speed of the wheels. Stop wasting money on new drive shafts when you don't really need it. Since this is only happening on decel we could probably narrow it to differential or old busings flexing the opposite way of accel.

01-20-2010, 07:00 AM	#41
warauto Zilvia Addict Join Date: Oct 2007 Location: GA Posts: 633 Trader Rating: (3) Feedback Score: 3 reviews	Just did my clutch swap and the same thing is happening...the 4th gear accel and decel humming noise....I hate it

06-20-2017, 11:49 AM	#42
fiberwire Join Date: Mar 2017 Location: EU Posts: 9 Trader Rating: (0) Feedback Score: 0 reviews	I feel really bad for bringing this topic up but has any of you found out what the problem was? I have the EXACT same problem. The thing is, even though I had a new 6puck clutch installed recently, I don't recall having such issue soon after I got the car back. It feels like its coming from the back of the car, maybe differential area. Unless its totally misleading.