Throw-out bearing

[mike the snake]

Your throwout bearing will make noise only when you push the clutch pedal in. That's it.

If your getting noises at idle, in neutral, foot OFF the pedal, it is usually the clutch. Either the pressure plate or the clutch disc springs can make noise.
Sometimes with a rough idle the transmission gears can make noise when idling, clutch OFF the pedal.


The only other thing it can be (pedal not pushed) is the input shaft bearing, or trans main bearings, and that's usually on old transmissions.

If the sound goes away when you push the clutch pedal, it is your clutch.

If the sound happens when you push the pedal, it is your throwout bearing,.

[Poodles]

Originally Posted by protpibe

I just recently upgraded to an Exedy stage 1 and it's even worse now. It will make the rattle noise when warmed up and the AC is engaged (lower idle).

I'm thinking it may have something to do with the light weight flywheel? The noise seems to have started when I originally put a light weight crank pully on, and now it's gotten worse since lightening the flywheel. I'm going to put the stock pulley on tomorrow to see if it has an effect.

It's annoying as hell.

Gear clash. Annoying as hell, but ultimately harmless. Usual fix in other car circles is to bump the idle up a bit.

[Brzerker]

Didn't want to create a new thread on this, so I'm reviving it.

I've recently encountered what might be the bearing issue too. Rattling sound when cold start and it goes away when i depress the clutch. Squeaky sound coming from the clutch fork area, however, it comes and goes, hard to replicate.

I've been to the dealer and they tried greasing up the clutch fork, it became better but the rattling is still there. I'm in the process of making a warranty claim through them, having my fingers cross it goes through.

Question is, how much longer can I drive the car without worrying too much? Since I'll have to wait awhile for the dealer to get back and forth with me... Should I tone down my driving now as well?

[jdcorbitt3]

I have a rattle with foot off clutch and AC on. I have had that same rattle in RX7s 8s and Miatas. I have gone over 200,000 miles with the rattle and no issues. I think it is the damper springs. As they loosen up with a few miles, it begins to rattle. I had one replaced on an RX7 only for it to come back. I don't worry about it anymore. That is just one of the things that comes with this type of setup. I suspect it has something to do with low torque engines.

John

[Ganthrithor]

In the last few weeks, my car has developed a new noise.

• On a cold start, there is a squealing sound from the engine bay... sounds a little like a quieter version of a fluid-starved power steering pump with the car on the lock stops.
• The noise seems to minimize at idle (~500-700rpm), but as soon as I bump the RPM to ~1000 or above, the noise returns and seems RPM-sensitive (the sound changes with RPM).
• The squealing sound persists regardless of clutch position (although the sound sometimes fluctuates a bit as the pedal is being moved in or out).
• I poked my head around the engine bay trying to figure out where the noise was coming from but couldn't locate its origin. My mechanic at a local shop put the car on a lift and said he though it was coming from the clutch and said it sounded like a throwout bearing.
• The noise lessens as the car warms up.

I've got a call in to the nearest dealer (an hour away, unfortunately)... hopefully I can bring the car in soon. I've also noticed that the clutch fork squeaks when the clutch pedal is moved. Hopefully Subaru will warranty it, I guess... maybe it's a good time to do a lightweight flywheel?

[Packofcrows]

Originally Posted by Ganthrithor

In the last few weeks, my car has developed a new noise.

• On a cold start, there is a squealing sound from the engine bay... sounds a little like a quieter version of a fluid-starved power steering pump with the car on the lock stops.
• The noise seems to minimize at idle (~500-700rpm), but as soon as I bump the RPM to ~1000 or above, the noise returns and seems RPM-sensitive (the sound changes with RPM).
• The squealing sound persists regardless of clutch position (although the sound sometimes fluctuates a bit as the pedal is being moved in or out).
• I poked my head around the engine bay trying to figure out where the noise was coming from but couldn't locate its origin. My mechanic at a local shop put the car on a lift and said he though it was coming from the clutch and said it sounded like a throwout bearing.
• The noise lessens as the car warms up.

I've got a call in to the nearest dealer (an hour away, unfortunately)... hopefully I can bring the car in soon. I've also noticed that the clutch fork squeaks when the clutch pedal is moved. Hopefully Subaru will warranty it, I guess... maybe it's a good time to do a lightweight flywheel?

Does sound like tob. Mine is opposite and only present when warm. I worried it could cause flywheel/clutch wear. If clutch pedal also makes sound it might be in need of lubrication. So, test it out first. Get under pedal and tighten up under there.

[thambu19]

What do you folks think of this:

http://www.ft86club.com/forums/showp...&postcount=102

[humfrz]

Originally Posted by thambu19

What do you folks think of this:

http://www.ft86club.com/forums/showp...&postcount=102

I'm thinking that most of the time most of us, should just leave the factory clutch adjustment alone!

Clutch wear will be compensated for by the clutch system.

I would suggest for those that don't like the disengagement point, just adjust your leg or your expectation.




humfrz

[xxBrun0xx]

Originally Posted by humfrz

I'm thinking that most of the time most of us, should just leave the factory clutch adjustment alone!

Clutch wear will be compensated for by the clutch system.

I would suggest for those that don't like the disengagement point, just adjust your leg or your expectation.




humfrz

Have had my clutch lowered and return spring out since car had 800 miles. I now have 36k and have had zero issues with clutch or throw out bearing noise. Less pressure = less wear makes sense. Leaving factory clutch alone because reasons doesn't.

[thambu19]

Originally Posted by xxBrun0xx

Have had my clutch lowered and return spring out since car had 800 miles. I now have 36k and have had zero issues with clutch or throw out bearing noise. Less pressure = less wear makes sense. Leaving factory clutch alone because reasons doesn't.

With so many people complaining about TOB failures occurring much earlier than clutch wear out and many complaining about rattle at idle I am starting to wonder if our TOBs really are fully clearing the clutch fingers when clutch isn't used.

If the TOB is not returning to its withdrawn position or of there is some contact whatsoever then the TOB is being spun all the time. This means the TOB is used all the time and maybe why so many premature failures and rattle at idle.

When I adjusted my clutch I made sure the master cylinder plunger is fully back sitting at its base and made sure the clutch switch position is not preventing the master plunger from fully retracting. If it was preventing the plunger from fully retracting it could be pushing the slave cylinder plunger ever so slightly that the TOB might be rubbing against the clutch spring but not exerting pressure. If this rubbing continues the TOB can fail.

Those with failed TOBs can you make sure the main plunger at the footwell is all the way back when you release the clutch and that the switch is not preventing it from retracting fully?

[humfrz]

Originally Posted by thambu19

With so many people complaining about TOB failures occurring much earlier than clutch wear out and many complaining about rattle at idle I am starting to wonder if our TOBs really are fully clearing the clutch fingers when clutch isn't used.

If the TOB is not returning to its withdrawn position or of there is some contact whatsoever then the TOB is being spun all the time. This means the TOB is used all the time and maybe why so many premature failures and rattle at idle..........

Some hydraulic clutch systems use a constant-engagement type of throw out bearing.

I believe that this might be the case with the FR-S.


humfrz

[thambu19]

Originally Posted by humfrz

Some hydraulic clutch systems use a constant-engagement type of throw out bearing.

I believe that this might be the case with the FR-S.


humfrz

I think so too because I tried looking for a return spring pulling the fork back to withdrawn position and I see none. I have seen other designs from other companies use a return spring.

Perhaps the grease they use on these TOBs are also not meant for colder temps. Just speculating since people mention that the whining noise they hear goes away after warm up. When I read about noise of a bearing in cold temps it always leads me to lack of lubrication in cold. If that is the case then Subraru should not slap the repair bill on the customer saying its a normal wear and tear. This would be a design flaw.

[Tcoat]

OK, I have done a pile of research on this and developed a theory. I don't think the throw out bearing itself is the issue but is actually a symptom. The root cause is actually bent or off center release forks. If the fork is not perfectly aligned or is even slightly twisted it can put lateral pressure on the bearing which of course is going to produce premature wear and failure. It would not have to be that far out to cause an issue and could sneak past a visual inspection pretty easily.


Subaru uses a stamped part for this fork (above) and I know that historically (at the one plant I work at) stamped parts such as this have a very spotty quality record since it is very easy to miss small imperfections or errors in specs.

Through the course of my research I found many different cases of failure of these forks on Subaru products right up to them actually breaking (in fact somebody on here broke one and although I am not positive @ichitaka05 's name comes to mind). Now obviously a cracked or broken fork is the extreme and very easy to spot but an even slightly bent or twisted fork could put some extreme pressure on the bearing and cause it to heat up when it is spinning.


Added to the evidence is the fact that many of the guys that have had issues initially just had the forks lubed when they went in. Although the lube seemed to help for a while eventually the bearing failed anyway. This would lead me to believe that the act of lubing at least temporarily centered the fork and took the sideways/angled pressure off the bearing.

Well, there you have it guys that is my theory. I guess the point of my post is to look beyond the direct result and try to find the root cause. If you have bearing issues it may be worth while changing out the fork as well since a bad batch of forks could easily explain why so many have issue but loads of others don't.

P.S. Or I could be talking out of my ass on the subject and am totally wrong.

[Ultramaroon]

Originally Posted by Tcoat

P.S. Or I could be talking out of my ass on the subject and am totally wrong.

I'd have to sketch up a free body diagram to effectively illustrate my point but by design, the fork cannot place any radial or torsional load on the TOB, even if it's warped. It's a see-saw that pivots on a spherical joint on one end and the middle so it conforms to whatever orientation the TOB wants.

I got excited for a second and had to think about it.