tranny grind
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From: western New York
If it's a very faint sound you'll be OK. A heavy or unusual "grinding" or heavy rattle is a problem. All the manual shift 350Zs do this, it just depends on how bad the noise is. If the noise goes away under pressure I'd say it's fine.
Under normal circumstances it's just a little vibration making the the clutch fork and throwout bearing wobble a bit.
Under normal circumstances it's just a little vibration making the the clutch fork and throwout bearing wobble a bit.
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Joined: Dec 2006
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From: Edina, Minnesota
What is a good rule to follow when this problem needs a repair vs. just keep driving?
--Spike
--Spike
If it's a very faint sound you'll be OK. A heavy or unusual "grinding" or heavy rattle is a problem. All the manual shift 350Zs do this, it just depends on how bad the noise is. If the noise goes away under pressure I'd say it's fine.
Under normal circumstances it's just a little vibration making the the clutch fork and throwout bearing wobble a bit.
Under normal circumstances it's just a little vibration making the the clutch fork and throwout bearing wobble a bit.
New Member
Joined: Feb 2013
Posts: 548
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From: Midwest
With your foot off the pedal the clutch is engaged, the TOB is disengaged. In neutral, the transmissions input shaft will spin. In this condition, if one hears the frequently mentioned "cement mixer" sound, it's frequently the bearings on the input shaft.
With the pedal depressed, the TOB is engaged, the clutch is not. If a grinding/rattling noise is heard, the TOB is the first probable source, the tranny's input shaft is no longer spinning and should be quiet.
A worn/damaged dual mass flywheel running out of balance is a frequent cause of this particular type of damage, as is expected wear from high mileage, or, drivetrain shock from too many hard launches. DM Flywheels can become defective in a disappointingly few miles, resulting in unintended stress to crankshaft mains and transmission input bearings.
The shifter in your car is solidly mounted and not isolated by long linkages that will damp transmission vibrations. You should be able to feel gears and bearings in operation. Vibrations that actually move the shifter are a strong indicator of an imbalance in the drivetrain.
OP, suggest you change transmission lube and inspect for metal particles. Non-magnetic filings are evidence of ordinary synchronizer wear and not a great cause for concern. Bright particles that respond to a magnet relate to gear or bearing wear, this is not so easily disregarded.
Noise heard when standing a few feet away from your Z may be common to the platform but it did not leave the factory that way, it is evidence of either wear or damage. Other than the notoriously problematic early models the transmission in your car is tough and even when worn or with minor damage can operate reliably for tens of thousands of miles.
IMHO the DMF is a POS, replacing it is a good place to start in ensuring your Z continues to be dependable. For extended reliability, a mid-weight (+ - 20lbs) forged steel single mass flywheel might be considered.
With the pedal depressed, the TOB is engaged, the clutch is not. If a grinding/rattling noise is heard, the TOB is the first probable source, the tranny's input shaft is no longer spinning and should be quiet.
A worn/damaged dual mass flywheel running out of balance is a frequent cause of this particular type of damage, as is expected wear from high mileage, or, drivetrain shock from too many hard launches. DM Flywheels can become defective in a disappointingly few miles, resulting in unintended stress to crankshaft mains and transmission input bearings.
The shifter in your car is solidly mounted and not isolated by long linkages that will damp transmission vibrations. You should be able to feel gears and bearings in operation. Vibrations that actually move the shifter are a strong indicator of an imbalance in the drivetrain.
OP, suggest you change transmission lube and inspect for metal particles. Non-magnetic filings are evidence of ordinary synchronizer wear and not a great cause for concern. Bright particles that respond to a magnet relate to gear or bearing wear, this is not so easily disregarded.
Noise heard when standing a few feet away from your Z may be common to the platform but it did not leave the factory that way, it is evidence of either wear or damage. Other than the notoriously problematic early models the transmission in your car is tough and even when worn or with minor damage can operate reliably for tens of thousands of miles.
IMHO the DMF is a POS, replacing it is a good place to start in ensuring your Z continues to be dependable. For extended reliability, a mid-weight (+ - 20lbs) forged steel single mass flywheel might be considered.
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Joined: Jan 2010
Posts: 611
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From: western New York
That's true, but even a good throwout bearing will make noise once the bearing and linkage have been broken in....It's just how this fork and pivot ball design works. Go ahead and replace everything, it'll still make some noise after a good break in.
I'm still waiting for the op to give us a better idea of how bad, or not, this noise is.
I'm still waiting for the op to give us a better idea of how bad, or not, this noise is.
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From: Midwest
Regards, myfirstzcar: OP states the noise is heard when the clutch is engaged and stops when the pedal is down.
Why would a TOB make noise when it's not engaged? 1: Loose linkage causing a rattling sound. 2: A ticking sound caused by incorrect installation. This is related to side pressure contact with another rotating mechanism. If the TOB is engaged when the pedal is out, then the TOB is seriously out of adjustment. Clutch slippage is likely and self destruction of the TOB (in short order) is to be anticipated.
An easy explanation from "CarPedia":
"The Release or "throw-out" bearing, is only engaged when your foot is on the clutch pedal, this means that the bearing is pressing down on the levered springs of the pressure plate and holding them there while rotating at the speed of the engine. When this bearing goes bad you could hear a squealing or screeching noise whenever the clutch pedal is depressed. This bearing is not engaged when your foot is off the clutch pedal."
I just replaced the OEM concentric bearing in my '08 Z with ZSpeed's heavy duty unit. When it's cold I hear a slight whirring sound when the TOB is engaged (pedal down) so I'll have to agree that noise might be heard from a relatively new unit. However, unless there is a gross misalignment of the TOB, no sound should be heard from it when it is not engaged.
This question has been raised thousands of times, particularly on BMW and VW forums. This one is typical:
http://forums.bimmerforums.com/forum...ow-out-bearing
If you take the time to do some research on your own, you should be able to determine which noise is which, and why.
"Search" is your friend. Bye now.
Why would a TOB make noise when it's not engaged? 1: Loose linkage causing a rattling sound. 2: A ticking sound caused by incorrect installation. This is related to side pressure contact with another rotating mechanism. If the TOB is engaged when the pedal is out, then the TOB is seriously out of adjustment. Clutch slippage is likely and self destruction of the TOB (in short order) is to be anticipated.
An easy explanation from "CarPedia":
"The Release or "throw-out" bearing, is only engaged when your foot is on the clutch pedal, this means that the bearing is pressing down on the levered springs of the pressure plate and holding them there while rotating at the speed of the engine. When this bearing goes bad you could hear a squealing or screeching noise whenever the clutch pedal is depressed. This bearing is not engaged when your foot is off the clutch pedal."
I just replaced the OEM concentric bearing in my '08 Z with ZSpeed's heavy duty unit. When it's cold I hear a slight whirring sound when the TOB is engaged (pedal down) so I'll have to agree that noise might be heard from a relatively new unit. However, unless there is a gross misalignment of the TOB, no sound should be heard from it when it is not engaged.
This question has been raised thousands of times, particularly on BMW and VW forums. This one is typical:
http://forums.bimmerforums.com/forum...ow-out-bearing
If you take the time to do some research on your own, you should be able to determine which noise is which, and why.
"Search" is your friend. Bye now.
Last edited by timeltel; Mar 5, 2014 at 04:25 PM.
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Joined: Jan 2010
Posts: 611
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From: western New York
^Quit being a dork^ All manual shift 350Zs with a stock clutch make the "TOB" sound, it's perfectly normal. I agree that a bad TOB will make noise under pressure, but a slight noise when it's unloaded is perfectly normal.
How bad is this sound on the OP's car? I'd like to know.
How bad is this sound on the OP's car? I'd like to know.
Last edited by myfirstzcar; Mar 6, 2014 at 01:35 AM.
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Joined: Jan 2010
Posts: 611
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From: western New York
Mine makes a slight noise, but it's not a rattle or grinding sound, it's just a slight whirring noise that goes away when I press the pedal.....sounds exactly the same at 54,000 as it did at 27,000.
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Joined: Dec 2006
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From: Edina, Minnesota
I’m confused or just not understanding this. Isn’t the throw-out bearing engaged when you depress the clutch pedal? Your problem description is just the opposite (you state the noise goes away when you press the pedal). You said:
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Joined: Jan 2010
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From: western New York
With my foot off the pedal, it makes a slight whirring/chattering kind of sound. Many other vehicles do this too.
The OP is describing exactly what I'm describing, but it appears as if the OP is gone, so who knows how bad (or not) his really is.
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From: Midwest
OK MFZC, let's see if we can get through this without name calling? There are three bearings contained in the Z's clutch operation. Each has it's own characteristic sound.
The pilot bearing is fixed to the flywheel. When the clutch is disengaged (pedal down) and the tranny is in gear the input shaft is stationary while the flywheel/pilot spins. Noise heard as a grinding as the pilot bearing spins on the input shaft indicates the pilot bearing MAY be suspect.
With the tranny in neutral and the clutch engaged, the input shaft is linked to the flywheel and spins relative to engine RPM, the pilot bearing serves to align the input shaft to the flywheel, it does not slip. At this point the input shaft bearings are in operation. If they are in good condition (it sounds like yours are) then a whirring may be heard, as they wear or suffer damage a rattle or tick is the result.
In the Z's hydraulic clutch system the master cylinder is ported. There is a small vent which is exposed when the pedal is released. This ensures a constant supply of fluid to the slave cylinder and also allows pressure to equalize. The effect is usually referred to as a "self adjusting clutch". With the pedal up the fluid which actuates the TOB is returned to the master cylinder until back pressure (return force from the now engaged pressure plate) is neutral. Some slight contact between the TOB and pressure plate may exist but the TOB is no longer under load. If noise increases as the pedal is depressed, a faulty TOB is likely. There is typically a 10mm or so of pedal travel before the piston in the master cylinder covers that port and the system can be pressurized. You should be able to feel this at the pedal.
When adjusting the push rod between the pedal and master cylinder the clevis should be just barely under load or a clicking will be heard as the linkage is compressed. If the push rod is overly extended the vent in the master cylinder will remain covered. If fluid can not return then either the slave cylinder will not recharge, or, if through heat expansion too much hydraulic pressure exists in the system the TOB cannot fully retract, the pressure plate will not provide full clamping and the clutch may slip. A TOB under load at all times will fail in short time.
Leaving you with this link, OP hope this helps:
http://www.rx7club.com/3rd-generatio...aring-1045877/
Done.
The pilot bearing is fixed to the flywheel. When the clutch is disengaged (pedal down) and the tranny is in gear the input shaft is stationary while the flywheel/pilot spins. Noise heard as a grinding as the pilot bearing spins on the input shaft indicates the pilot bearing MAY be suspect.
With the tranny in neutral and the clutch engaged, the input shaft is linked to the flywheel and spins relative to engine RPM, the pilot bearing serves to align the input shaft to the flywheel, it does not slip. At this point the input shaft bearings are in operation. If they are in good condition (it sounds like yours are) then a whirring may be heard, as they wear or suffer damage a rattle or tick is the result.
In the Z's hydraulic clutch system the master cylinder is ported. There is a small vent which is exposed when the pedal is released. This ensures a constant supply of fluid to the slave cylinder and also allows pressure to equalize. The effect is usually referred to as a "self adjusting clutch". With the pedal up the fluid which actuates the TOB is returned to the master cylinder until back pressure (return force from the now engaged pressure plate) is neutral. Some slight contact between the TOB and pressure plate may exist but the TOB is no longer under load. If noise increases as the pedal is depressed, a faulty TOB is likely. There is typically a 10mm or so of pedal travel before the piston in the master cylinder covers that port and the system can be pressurized. You should be able to feel this at the pedal.
When adjusting the push rod between the pedal and master cylinder the clevis should be just barely under load or a clicking will be heard as the linkage is compressed. If the push rod is overly extended the vent in the master cylinder will remain covered. If fluid can not return then either the slave cylinder will not recharge, or, if through heat expansion too much hydraulic pressure exists in the system the TOB cannot fully retract, the pressure plate will not provide full clamping and the clutch may slip. A TOB under load at all times will fail in short time.
Leaving you with this link, OP hope this helps:
http://www.rx7club.com/3rd-generatio...aring-1045877/
Done.
Thread Starter
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Joined: Feb 2014
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From: San Clemente Ca
Sorry I been out of service guys but the sound is pretty loud and distinctive the tranny has 180k on it so you guys think input shaft bearing since the clutch pedal it let out when it makes the sound right
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Joined: Jan 2010
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From: western New York
Timeltel, I said quit being a dork, I didn't say you were a dork.
Anyway, everything you said is correct, and to be sure it's the TOB here's an easy test. Idle the car in first gear with the clutch fully engaged. Now start pushing the pedal slightly, but not enough to stop the car from driving in first. Did the sound change at all? You may also be able to feel the bad TOB with your left foot as well.
Either way, a transmission drop is needed to assess the situation, it's rare to have a bad input bearing but still possible...since it is in an oil bath as opposed to the one time greased TOB.
Anyway, everything you said is correct, and to be sure it's the TOB here's an easy test. Idle the car in first gear with the clutch fully engaged. Now start pushing the pedal slightly, but not enough to stop the car from driving in first. Did the sound change at all? You may also be able to feel the bad TOB with your left foot as well.
Either way, a transmission drop is needed to assess the situation, it's rare to have a bad input bearing but still possible...since it is in an oil bath as opposed to the one time greased TOB.
Thread Starter
Registered User
Joined: Feb 2014
Posts: 50
Likes: 0
From: San Clemente Ca
OK MFZC, let's see if we can get through this without name calling? There are three bearings contained in the Z's clutch operation. Each has it's own characteristic sound.
The pilot bearing is fixed to the flywheel. When the clutch is disengaged (pedal down) and the tranny is in gear the input shaft is stationary while the flywheel/pilot spins. Noise heard as a grinding as the pilot bearing spins on the input shaft indicates the pilot bearing MAY be suspect.
With the tranny in neutral and the clutch engaged, the input shaft is linked to the flywheel and spins relative to engine RPM, the pilot bearing serves to align the input shaft to the flywheel, it does not slip. At this point the input shaft bearings are in operation. If they are in good condition (it sounds like yours are) then a whirring may be heard, as they wear or suffer damage a rattle or tick is the result.
In the Z's hydraulic clutch system the master cylinder is ported. There is a small vent which is exposed when the pedal is released. This ensures a constant supply of fluid to the slave cylinder and also allows pressure to equalize. The effect is usually referred to as a "self adjusting clutch". With the pedal up the fluid which actuates the TOB is returned to the master cylinder until back pressure (return force from the now engaged pressure plate) is neutral. Some slight contact between the TOB and pressure plate may exist but the TOB is no longer under load. If noise increases as the pedal is depressed, a faulty TOB is likely. There is typically a 10mm or so of pedal travel before the piston in the master cylinder covers that port and the system can be pressurized. You should be able to feel this at the pedal.
When adjusting the push rod between the pedal and master cylinder the clevis should be just barely under load or a clicking will be heard as the linkage is compressed. If the push rod is overly extended the vent in the master cylinder will remain covered. If fluid can not return then either the slave cylinder will not recharge, or, if through heat expansion too much hydraulic pressure exists in the system the TOB cannot fully retract, the pressure plate will not provide full clamping and the clutch may slip. A TOB under load at all times will fail in short time.
Leaving you with this link, OP hope this helps:
http://www.rx7club.com/3rd-generatio...aring-1045877/
Done.
The pilot bearing is fixed to the flywheel. When the clutch is disengaged (pedal down) and the tranny is in gear the input shaft is stationary while the flywheel/pilot spins. Noise heard as a grinding as the pilot bearing spins on the input shaft indicates the pilot bearing MAY be suspect.
With the tranny in neutral and the clutch engaged, the input shaft is linked to the flywheel and spins relative to engine RPM, the pilot bearing serves to align the input shaft to the flywheel, it does not slip. At this point the input shaft bearings are in operation. If they are in good condition (it sounds like yours are) then a whirring may be heard, as they wear or suffer damage a rattle or tick is the result.
In the Z's hydraulic clutch system the master cylinder is ported. There is a small vent which is exposed when the pedal is released. This ensures a constant supply of fluid to the slave cylinder and also allows pressure to equalize. The effect is usually referred to as a "self adjusting clutch". With the pedal up the fluid which actuates the TOB is returned to the master cylinder until back pressure (return force from the now engaged pressure plate) is neutral. Some slight contact between the TOB and pressure plate may exist but the TOB is no longer under load. If noise increases as the pedal is depressed, a faulty TOB is likely. There is typically a 10mm or so of pedal travel before the piston in the master cylinder covers that port and the system can be pressurized. You should be able to feel this at the pedal.
When adjusting the push rod between the pedal and master cylinder the clevis should be just barely under load or a clicking will be heard as the linkage is compressed. If the push rod is overly extended the vent in the master cylinder will remain covered. If fluid can not return then either the slave cylinder will not recharge, or, if through heat expansion too much hydraulic pressure exists in the system the TOB cannot fully retract, the pressure plate will not provide full clamping and the clutch may slip. A TOB under load at all times will fail in short time.
Leaving you with this link, OP hope this helps:
http://www.rx7club.com/3rd-generatio...aring-1045877/
Done.
New Member
Joined: Feb 2013
Posts: 548
Likes: 182
From: Midwest
tc0152: Pretty good trip on a high mileage transmission making noise? At minimum, change gear lube, keep fingers crossed. You didn't say what year, Nissan recommends either a 75 w 85 or 75 w 90 gear oil for an '07 - '08. Redline, Amsol or Motul are ester based synthetic, believe you're looking for a GL-4 (check that) rated lube. The 90 wt. will add a little extra cushioning and quieten your transmission somewhat, but may make shifting a little balky, esp. if your synchs are worn. Don't expect miracle cures. For a DD, most owners are happy with the 75 w 85, Redline or OEM Nissan (also syn.) are favorites. If your Z has a lightweight flywheel already in it, it's going to be a little noisy anyway.
https://my350z.com/forum/drivetrain/...ssions-z1.html
IIRC, Fontana Nissan http://www.fontananissan.com (Z friendly, longtime Forum Sponsor) recently mentioned a similar offer. Try an email, ask for Scott. Same guys: https://www.nissanraceshop.com
Good luck!
(MFZC- it's all good.}
https://my350z.com/forum/drivetrain/...ssions-z1.html
IIRC, Fontana Nissan http://www.fontananissan.com (Z friendly, longtime Forum Sponsor) recently mentioned a similar offer. Try an email, ask for Scott. Same guys: https://www.nissanraceshop.com
Good luck!
(MFZC- it's all good.}
