Rattling noise when clutch is engaged.

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
chris52
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Rattling noise when clutch is engaged.

Postby chris52 » Sat Aug 21, 2010 9:35 pm

I have a rattling noise when the clutch is engaged. The noise goes away if I press the clutch pedal down a little bit. I've noticed this while sitting at a light in neutral but I think it may also happen with the car in gear(it's hard to hear over the exhaust.) Any idea what might be causing this?

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fa22raptorf22
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Re: Rattling noise when clutch is engaged.

Postby fa22raptorf22 » Sat Aug 21, 2010 10:32 pm

throwout bearing :?

Fix? Nothing really without taking the tranny housing off the engine block.

Possibly fix? Drive it hard, give it some good full throttle runs and nice hard/quick 1-2 shifts.

I am not held responsible for anything that may or may not break during this test run... lol... end post.

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Re: Rattling noise when clutch is engaged.

Postby Rope-Pusher » Sat Aug 21, 2010 10:49 pm

Clutch Release Bearing / Throw-out Bearing might be worn.

or

The bearing might not be being sufficiently preloaded against the fingers of the diaphragm spring of the clutch cover assy. there should be enough pressure that the bearing is in constant contact with the spring fingers and pressed tightly enough NOT to slip - the face of the bearing and the spring fingers should rotate at the same speed.

If the bearing has a lot of drag due to corrosion, contamination, viscous grease or grease seal friction, it could slip relative to the fingers.

It's not a trivial job to replace this bearing - you have to separate the trans from the engine - so if the noise isn't too bad, you might want to consider living with it (or sell your car to a deaf guy - yeah, that's the ticket, a deaf guy!).
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fa22raptorf22
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Re: Rattling noise when clutch is engaged.

Postby fa22raptorf22 » Sat Aug 21, 2010 10:53 pm

^^ Yup..good infos there.

I actually have a little bit of that rattle sound myself. And I know just what its from. Its from the woman who drove the car before me, constantly holding the car in 1st at red lights....stretching out those poor pressure plate fingers...

Every girl who ive seen drive a manual, does that same exact thing....its so so bad.

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Re: Rattling noise when clutch is engaged.

Postby Rope-Pusher » Sat Aug 21, 2010 11:10 pm

I don't know that it's so bad. Loading a spring for a longer time isn't much different than loading it for a shorter time. Would you think it better for your suspension if you tried to get the car airborne as often as possible, so the weight of the vehicle wouldn't always be resting on the springs? Oh sure, getting air is always fun, but at the end of the day, I don't think your car would ride measurably higher.
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Re: Rattling noise when clutch is engaged.

Postby theholycow » Sun Aug 22, 2010 7:42 am

Rope-Pusher wrote:The bearing might not be being sufficiently preloaded against the fingers of the diaphragm spring of the clutch cover assy. there should be enough pressure that the bearing is in constant contact with the spring fingers and pressed tightly enough NOT to slip - the face of the bearing and the spring fingers should rotate at the same speed.
Well, that answers a question I had regarding that preload in my project's slave...I worried that it would wear out the release bearing. So when people talk about wearing the release bearing by holding the clutch pedal down, the issue isn't that it's spinning, but rather how heavily loaded it is.

It's not a trivial job to replace this bearing - you have to separate the trans from the engine - so if the noise isn't too bad, you might want to consider living with it (or sell your car to a deaf guy - yeah, that's the ticket, a deaf guy!).
That is always my first question when I have a new symptom that doesn't prevent me from driving...what happens if I ignore it?
- Wheel bearings ignored too long will wear tires and could break off the wheel (modern hub bearing style units).
- CV joints ignored too long will leave you broken down on the side of the road, unable to send power to your wheels.
- Worn clutch friction disc ignored too long will score your flywheel, requiring you to buy a new one instead of resurfacing the old one.
- Imbalanced tire, misalignment, or failed shock absorbers will result in bad tire wear and possibly ill handling.
- Underinflated tire will eventually explode or delaminate.
- Overinflated tire won't have a catastrophic failure.
- Apparently a worn release bearing won't have a catastrophic failure.
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Re: Rattling noise when clutch is engaged.

Postby Rope-Pusher » Sun Aug 22, 2010 10:02 am

theholycow wrote:
Rope-Pusher wrote:The bearing might not be being sufficiently preloaded against the fingers of the diaphragm spring of the clutch cover assy. there should be enough pressure that the bearing is in constant contact with the spring fingers and pressed tightly enough NOT to slip - the face of the bearing and the spring fingers should rotate at the same speed.
Well, that answers a question I had regarding that preload in my project's slave...I worried that it would wear out the release bearing. So when people talk about wearing the release bearing by holding the clutch pedal down, the issue isn't that it's spinning, but rather how heavily loaded it is.

It didn't used to be the case - back in the daze of z-bar clutch release linkage, they designed in a gap between the bearing face and the spring fingers and there was an adjustment feature for getting the gap just right. Were they afraid of wearing out the bearing - maybe, but I'm sure there was at least one important factor dictating this gap - NVH. The rod linkage was very direct and would transfer all the vibrations from the trans, engine, etc. to the interior of the vehicle where something connected would resonate and driver's (AND their wives!) would feel / hear it and say "Is something wrong - why does it do that?".

Why don't current designs feature a gap? Cable and hydraulic clutch release systems can attenuate vibrations, so it isn't necessary to maintain a gap for NVH amelioration. Also, in smaller vehicles, the amount of space (Yeah, I know, "The Final Frontier, Yadda, Yadda, Yadda") in the pedal area is reduced and clutch pedal pad travel is reduced. In order to reduce engagement zone sensitivity and to achieve a reasonable pedal effort ratio, clutch release systems were designed w/o a gap between the release bearing and the spring fingers, so the amount of pedal travel formerly devoted to traversing this "dead zone" could now be applied to useful release bearing travel. Also, I'm sure that somewhere along the way, someone discovered that a bearing designed to accommodate the peak clutch release loads could operate under a small preload literally "all day long". Bearing will last nearly forever if they are designed to handle the peak loads and duty cycle, are adequately lubed and contaminants are kept out.
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Re: Rattling noise when clutch is engaged.

Postby Ron008 » Thu Nov 18, 2010 12:32 pm

I just noticed the same rattling noise when the clutch is engaged in neutral. The car is fully stopped. My car only has 1000 miles on it... The noise is not really that loud (I can barely hear it inside the car with the windows up. Could it the throw out bearing be worn with such low miles on the car? Should it be fixed or should I just deal with it?

I think I hear the noise before a few days ago but it went away after 10 minutes of driving. But the rattling occured with the car in gear and accelerating in this instance.

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Re: Rattling noise when clutch is engaged.

Postby AHTOXA » Thu Nov 18, 2010 1:43 pm

Ron,

My 08 rabbit had that noise for 45000 miles since new. Only happened when the car was cold after sitting at least overnight and only when ambient tema were below 50 or so.

I suspected it was the throwout bearing. Dealer changed it but the noise never left.

Also, it never caused any immediate issues, never got worse or better. Very consistent in behavior and very odd. I lived with it.

Give it some time, like 5k miles or so and if it still bothers you then or gets worse, take it to the dealer.
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Re: Rattling noise when clutch is engaged.

Postby Rope-Pusher » Thu Nov 18, 2010 4:51 pm

Could it be the clutch damper or the trans gears and shafts rattling (Neutral Rattle)? FWD 6-speeds are often more sensitive to this because they have two intermediate shafts. Some FWD 5-speeds also have two intermediate shafts. Dual-mass flywheel helps to tune it out, but they aren't cheap, so it isn't a given that a vehicle manufacturer would turn to using one, especially in a price-conscious segment of the market.
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