Throwout Bearing Failure?

[JustCallMeNick]

Wetmyson,

 

if you were closer to me, I'd do that job for you at 20% of that cost. damn stealerships are crazy!

I'd learn how to do it myself if I had a garage! I do have tools and attempt new jobs (though I'm not always up for it).

[covertrussian]

I've replaced mine with a WRX clutch kit several years ago, it's a lot better than the DMFW.

Better how? Longevity? Pedal feel? Lighter to press in pedal?

 

Dual Mass Flywheels are a pipe dream by engineers since they "smoother & quieter", unfortunately in the real world they tend to fail a lot due to their complexity.

 

Lets start with the design differences of the internals, we actually have SACHS flywheels too so this image is perfect:

http://legacygt.com/forums/attachment.php?attachmentid=260237&stc=1&d=1515079860

 

As you can see from above, DMFW has two separate plates, the part that bolts to the engine, and the face that bolts to the pressure plate. These two plates need to rotate at the same speed to effectively deliver power to the transmission. Thus DMFW flywheels have a series of springs and gears. Since the flywheel does all the moving, a solid unsprung clutch disc can be utilized.

 

 

While Single Mass Fywheel is usually a solid two piece (bolted together) hunk of metal with no moving parts. Since engine delivers power in pulses, that could be jarring to the transmission, SMFW usually utilize a sprung disks, which has a little bit of movement built in to absorb those vibrations. Sprung disks can fail too, but usually your due for a new disk by that point anyway.

http://legacygt.com/forums/attachment.php?attachmentid=260238&stc=1&d=1515080409

 

 

With facts out of the way, we can now talk about real world results...

 

• Dual mass flywheels are built to the car's specific torque output (the springs have to be stiff enough). Rarely do you see a turbo Subaru with stock power levels .
  
• Dual mass flywheels tend to fail a lot in even stock cars, just look up "dual mass flywheel failure" on google.
  
• Dual mass flywheels cannot be resurfaced, and cost $1k in parts due to complexity. Single mass flywheels are about $300 new.
  
• Dual mass flywheels are heavier, this can be a good thing if you tow or mountain drive, bad if you like quick acceleration.
  
• Less of a fact, more of an opinion: Even Subaru admitted that DMFW's suck and switched to SMFW in 2007+ Legacies . Subaru is not alone, in 2000's Nissan played with DMFW and switched back, in 2010ish Ford played with them in Mustangs and switched away too. I think VW is the only one that's too dumb to switch away from DMFW's.
  

 

Also DMFW Torx Bolts SUCK, they are a PITA to get out and usually end up stripping at the head:

http://legacygt.com/forums/attachment.php?attachmentid=260249&stc=1&d=1515081435

 

See my build post on how I did the conversion: http://legacygt.com/forums/showpost.php?p=5545536&postcount=799

 

 

What happens if it totally fails? I’m having this TOB work done and it’s espensive as it is. They tried to sell me clutch too which I don’t need. Ugh. It’s looking like $1300+ for TOB, fork, repair sleeve, I think that’s all they said. $110 an hour they say.

 

If your paying someone $1300 to drop the transmission, you better be putting a brand new clutch in there. This is a turbo car with probably 100k miles, your gonna need a clutch any month now.

 

Dual mass flywheel will be about $1k, plus $300ish for clutch/pressure plate. Or you can do 2007+ LGT/WRX conversion, $300 for SMF and $300 for clutch. +$1300 install all over again in a year or so.

 

You do the math.

[JustCallMeNick]

I got my car back today and I'm pleasantly surprised. The clutch hasn't felt this good as long as I've owned the car. The pedal is no longer heavy. Now you barely have to apply any pressure at all! It's like butter. It also turns out the clutch was a lot more worn than I had thought. I downshifted into 4th on the highway tonight and could feel the difference. Guess the old clutch was starting to slip a little in higher gears and I didn't even realize it.

 

The shop did the clutch, TOB, sleeve kit, replaced seized flywheel bolts, clutch fork, and leaky rear main seal.

 

Thank you all for your contributions!

 

stuff

It's a 2009 with ~144,500. They showed me the old worn clutch and I recognize the sprung hub design in the picture. I appreciate you including that technical explanation with visuals!

[apexi]

I didn't want to say anything before because I wasn't sure if the job had already been done yet, but I'm glad to hear they replaced the clutch while they were in there too. If you're paying a shop to do all that work (accessing the TOB to replace it), I think it's the only way to go.

[covertrussian]

Glad to hear you got it replaced and it's better now. Do you know what brand clutch setup and throw out bearing that they used?

 

Also I missed that your car was on 09, so you already have a SMFW, so the conversion stuff doens't apply since your already converted stock .

[JustCallMeNick]

A few other things I'm not sure I mentioned:

1) I've been tentatively planning to upgrade to a VF52 in the next couple of years.

2) I mistakenly thought the clutch was in better condition than it was.

3) I was concerned of the possibility that it already had a non-OEM clutch, one that seemed to be holding my little Stage 2 + TMIC + EBCS power levels, and that the shop would replace it with a clutch that wouldn't hold the power or something.

4) If I install an aftermarket clutch with the VF52 in a couple years, chances are I'd be able to plan out doing it with a friend. This was an unexpected occurrence and I'm a one car man right now with no garage.

5) When I first talked to the front desk guy, he said "you need a new clutch" and so I asked if it was bad or worn because it felt fine. He told me, "no," but it just made sense while they were in there. I had the impression the clutch had tens of thousands of miles left and I got anxious that they were selling me a clutch I didn't need and then in 2 years I was going to install a new one anyway with a friend.

 

Anyway, I took the auto to the auto shop and they repaired it. case solved. Sometimes I overcomplicate things.

[JustCallMeNick]

Glad to hear you got it replaced and it's better now. Do you know what brand clutch setup and throw out bearing that they used?

 

Also I missed that your car was on 09, so you already have a SMFW, so the conversion stuff doens't apply since your already converted stock .

Not sure

[covertrussian]

Stock clutch can handle a decent amount of power, it just wont handle it for 140k miles. Heck I went from VF46 to 16G and it actually stopped my clutch from slipping for another year. Bigger turbo didn't onset boost as quickly and as low of RPM, this reduced the low end torque (because laggy turbo) but I was fine with that.

 

I think you should just run it, do the VF52, if it starts slipping then worry about it again.

[JustCallMeNick]

Stock clutch can handle a decent amount of power, it just wont handle it for 140k miles. Heck I went from VF46 to 16G and it actually stopped my clutch from slipping for another year. Bigger turbo didn't onset boost as quickly and as low of RPM, this reduced the low end torque (because laggy turbo) but I was fine with that.

 

I think you should just run it, do the VF52, if it starts slipping then worry about it again.

Yeah I think it worked out pretty well actually. I think this new clutch will hold the power for more than long enough and I'll need time to gather some more car part money anyway.

 

It's funny - the car felt so fast on the way home tonight. On the highway I shifted into fourth and it just WENT. I'm unsure if this is due to the clutch, the cold air, or driving a 2018 Ford Focus and N/A Outback 4EAT while the Legacy was in the shop.

[covertrussian]

Sadly I think it's the latter .

 

Keep it easy on the new clutch for at least few hundred miles. You don't want to glaze it over, you want it to kind of bed itself in (especially if it original flywheel was used and not resurfaced).

[JustCallMeNick]

Sadly I think it's the latter .

 

Keep it easy on the new clutch for at least few hundred miles. You don't want to glaze it over, you want it to kind of bed itself in (especially if it original flywheel was used and not resurfaced).

Thank you for the reminder! I forgot to mention that they did resurface the flywheel also.

 

I was mostly pretty ginger with the new clutch last night but it was more out of cautiousness while I acclimate to the new pedal feel than it was actually understanding why. So thank you.

 

I also appreciate you all not trolling me too hard for not knowing some of these things.

[FJuan]

Trolling?? Who does that?

 

 

 

 

 

 

 

 

 

 

[covertrussian]

Thank you for the reminder! I forgot to mention that they did resurface the flywheel also.

 

I was mostly pretty ginger with the new clutch last night but it was more out of cautiousness while I acclimate to the new pedal feel than it was actually understanding why. So thank you.

 

Alright so I have a love hate relationship with resurfaced WRX/LGT SMFW flywheels...

 

Most other SMFW flywheels out there have the pressure plate mounting and clutch disk surface be the same plane, so resurfacing is easy, just remove the guide pins and adjust the equipment to one set height and resurface the whole flywheel in one go.

 

WRX/LGT flywheels are stepped, which means they have the pressure plate mounting surface be on a different plane then the clutch disk surface. The process to resurface these is more complicated. First they have to grind away the clutch disk surface, they have to figure out how much material was removed to remove all the uneven spots/hot spots. Then they have to readjust the equipment to resurface the pressure plate mating surface and remove the same amount of material as they removed from the clutch disk surface.

 

As you can imagine, technician competency and equipment accuracy becomes much more important with stepped flywheels. There are plenty of threads on other WRX forums where the flywheel was not resurfaced correctly, causing clutch slippage under power or clutch disengagement issues.

 

For this reason I decided not to bother resurfacing my "30k mile, never launched it" WRX flywheel. Sadly it still had hot spots, so guy that drove it probably learned stick on it . I have an exedy stage 1 and it's been holding fine to my daily 265whp/wtq uncorrected (though I am hitting closer to 300whp/wtq on cold days uncorrected, which is the limit of my clutch).

 

You can see the stepped surface in the left pic.

http://legacygt.com/forums/attachment.php?attachmentid=260260&stc=1&d=1515081485

 

 

I also appreciate you all not trolling me too hard for not knowing some of these things.

 

We only troll people that can't do a lick of searching themselves, you seemed competent enough and had an interesting enough of a problem

[JustCallMeNick]

Alright so I have a love hate relationship with resurfaced WRX/LGT SMFW flywheels...

 

Most other SMFW flywheels out there have the pressure plate mounting and clutch disk surface be the same plane, so resurfacing is easy, just remove the guide pins and adjust the equipment to one set height and resurface the whole flywheel in one go.

 

WRX/LGT flywheels are stepped, which means they have the pressure plate mounting surface be on a different plane then the clutch disk surface. The process to resurface these is more complicated. First they have to grind away the clutch disk surface, they have to figure out how much material was removed to remove all the uneven spots/hot spots. Then they have to readjust the equipment to resurface the pressure plate mating surface and remove the same amount of material as they removed from the clutch disk surface.

 

As you can imagine, technician competency and equipment accuracy becomes much more important with stepped flywheels. There are plenty of threads on other WRX forums where the flywheel was not resurfaced correctly, causing clutch slippage under power or clutch disengagement issues.

 

For this reason I decided not to bother resurfacing my "30k mile, never launched it" WRX flywheel. Sadly it still had hot spots, so guy that drove it probably learned stick on it . I have an exedy stage 1 and it's been holding fine to my daily 250whp/wtq (though I am hitting closer to 300whp/wtq on cold days, which is the limit of my clutch).

 

You can see the stepped surface in the left pic.

http://legacygt.com/forums/attachment.php?attachmentid=260260&stc=1&d=1515081485

 

 

 

 

We only troll people that can't do a lick of searching themselves, you seemed competent enough and had an interesting enough of a problem

Wait back the truck up... Your car gains 50 wheel horsepower and 50 wheel torque when it's "cold?"

[covertrussian]

Wait back the truck up... Your car gains 50 wheel horsepower and 50 wheel torque when it's "cold?"

 

Woop sorry about that I was thinking 250whp which is SAE corrected, while the closer to 300whp would be uncorrected (aka what the car is seeing at that moment). If taking both uncorrected it's more like 265whp (at 58f, 29.79in/Hg) vs 288whp (42f, 30.15in/Hq).

 

So with lower temps and higher Barometric pressure difference it's 23whp gain. Higher barometric pressure = similar to running extra boost.

 

These cars will also lose a lot of power when it's warmer due to top mount intercoolers that are heat soaked in the engine bay.

[JustCallMeNick]

23 still sounds like a lot to me but now that I'm thinking about it, it does feel drastically different. Yup I'll buy that.

[covertrussian]

Right, it surprised me at first, really threw me back into the seat. Colder temps = denser air, plus our intercoolers work much better too, making air more denser. Turbo cars just shine a lot more when it's colder.

[JustCallMeNick]

That’s really interesting. I hadn’t heard of correction factors or the SAE J607 correction factor (I had to look up SAE Corrected).