Getting a new clutch?

djxpress · Mar 4, 2018

The original clutch that comes on the 2017 STI is pretty difficult to use. I've been driving stick shifts for years and have driven many different cars that were manual. The clutch on the 17 STI is by far the hardest to get used to and the engagement point always seems to shift a bit mainly in 1st gear from a stop, sometimes changing into 2nd gear when picking up speed from a slow roll. It almost feels like the catch point could be anywhere in the first 25% of clutch pedal travel, but once it catches, you kind of have to ease the clutch pedal out, otherwise the car jerks/shudders pretty hard. It's sort of a finesse game with the OEM clutch, would you agree?

I almost feel like I'm burning the clutch a little bit when I'm letting the pedal come up from the floor, mostly going from a stop to 1st gear. I know that the Hill Assist has something to do with it, as it seems so much easier to start from a stop when the Hill Assist is off.

I was wondering if changing out the clutch to an aftermarket clutch would make the clutch pedal less difficult to push down, and the engagement point more precise with less of a need to finesse the clutch pedal (slowly bring it off the floor once it finally catches)?

mheyman · Mar 4, 2018

djxpress said:
I was wondering if changing out the clutch to an aftermarket clutch would make the clutch pedal less difficult to push down, and the engagement point more precise with less of a need to finesse the clutch pedal (slowly bring it off the floor once it finally catches)?

No, they are universally as stiff and most are stiffer, More importantly other things are the cause of your complaint. As you noted Hill Assist has been blamed, clutch release valve is another, and bucking can be significantly reduced with a single piece drive shaft of which CF shaft are very popular.

Jay11STI · Mar 4, 2018

When i first got my sti many years ago I COULDN'T STAND HILL ASSIST! It made it impossible to drive the car in my opinion, it felt like an insult for people who have been driving manual for years. I was so bad at it that i couldnt even get out of the dealership lot the day of delivery LoL. The first thing i did when i got home was turn that sh*t off. After that my opinion of how the car drove completely changed.

I would recommend turning hill assist off first and then driving the car for bit before you go about replacing any parts.

nightdown fox · Mar 4, 2018

Curious, how much do you press the accelerator to get moving? Are you a “slowly let up the clutch then gas” sort of person, or do you rev first to about 1200 rpm before letting off the clutch?

RX7RIP · Mar 4, 2018

I have the same issue in my '18. I have had a s10, prelude, RX-7 FD, evo, brz, s4, and non of them made me second guess my manual driving skills more than this STI. I feel like a horrible pilot if anyone is in the car and I have to creep at a speed between 1st and 2nd gear and the car just doesn't like you when you let off the gas pedal. Even had someone say "man your car does not like rolling through a parking lot at 5mph in first or second does it?"

I have smelt my clutch several times when I had hill assist on, I'm hoping I was actually smelling a mix of clutch and brakes, but much less after I turned it off. I even had it off thinking I just needed to learn this clutches bite point as there was no friction point at all, after I felt I had the clutch learned I turned it back on and within 5 minutes had that burnt smell again. Now, I have found that I just can't baby this car off the line. What I mean is that the stock throttle mapping seems to be really....bad. If you look at the acceleration gauge it goes from about 2% - 12% basically instantaneously (estimated %'s) just like how at about 75% of actual pressing the pedal reads 100% on the gauge. Anyway, what I mean by not babying it is I just let the car ahead of me get rolling first then I quickly get the clutch about 75% up and I see the rpms begin to wiggle and I give it enough gas to get to around that 12% point and the car rolls out smooth as can be. For second gear I don't shift till around 4.5-5.5k and the rev drop doesn't seem to be as bad so 2nd gear isn't as jumpy if you even out the acceleration when the rev drop....hope that makes sense.

Either way this clutch still has me 2nd guessing myself all the time. Wish they would have not done...whatever they did that made it so temperamental.

nightdown fox · Mar 4, 2018

It seems that, especially since this car has all four wheels moving at all times through 3 different differentials that are receiving different variants of torque, the STI responds better to people who give the car a bit of gas before letting out the clutch instead of releasing the clutch under 1000 rpm.

If I’m on an incline or any surface where the car moves when I let off the brake, then I can let the clutch out with no gas, no problem. Every other time, I give a quick stab to around 1200 rpm while letting the clutch out, and it’s smooth as butter everytime, with the hill assist on.

I was recently in a quiet neighborhood at night with a headache trying to crawl through, and I had a lot of jerkiness trying to start from stop signs at as low of an RPM as possible. My wife even noticed it. But when I went back to my gas and release method, I went back to my usual smoothness.

These cars have a lot more going on from a stop compared to 2 wheel drive cars, or even other AWD cars that aren’t “all wheels all the time” cars.

nec9 · Mar 5, 2018

The clutch/tranny is finnicky. Always has been on these cars. My grandpa, who was a semi truck driver, cement truck driver, dump truck driver, and in general only drove manual transmissions (and complicated ones at that) from 1960-present, even had trouble when first driving my car. He also killed it a couple times! And he also made a comment about how weird the transmission is. So I think that says something. Basically don't be too hard on yourselves for driving these cars. They are their own beast.

mheyman · Mar 5, 2018

I've written this to many times:

mheyman said:
2.5l WRXs 05-015? were similar to their sister STIs. WRX is no longer a useful category alone so not sure what cars you are referring to.

STIs have always had issues nearer to 2800rpm. Search stumble.
Many or most or the family has had rev hang.

Bucking: it is easy is cause an STI to buck at start, but not so difficult to avoid it. Feather the throttle, not the clutch! Start the clutch release at near 1500rpm after you've let off the throttle. Get back on it as soon as you feel it start to grab. Feather as needed.

CFDS: pretty much everyone who has very had one felt it help with bucking. I think bucking may become more of an issue as our cars age and there is more play in the driveline.

mheyman said:
Kind of did above. Will find a better description, but while looking I remembered this

Yes rule that out too.

Feather pedal at start, on gas to 1800 or so tailor to your car. Stock 1500 is probably good
Vvrrhh . . . off gas . . . Vvrrhh . . . . off gas . beginning release - just beginning to roll . . . on gas . . . Vvrrhhh o o m m . .

sound is
Vvrrhh . . Vvrrhh . . . Vvrrhhh o o m m . .

After you can do this reliably without bucking, practice at lower rpms. you may get to the point you don't need to.

Added: This is a method that works. It's not mandatory, it's just works because by keeping your foot moving you are not trying to depend on any particular position being the correct position, and you are not trying to achieve a perfect position with your foot. Instead your always moving and correcting and using the timing of what you are doing.

HeatSource · Mar 5, 2018

I hopped in my friends brand new '18 with 40 miles on it and drove it like butter. My new clutch rated for ~500 is a different story, but have yet to have an "issue" with it. I think you are doing something wrong.

jpetro1010 · Mar 6, 2018

Man, I'm glad I'm not the only one, lol! I only buy manual cars...besides a C63 Black Series...but I made an exception for that one.

Anyways, the engagement with the STi is...just...different, lol. I never get the 'bucking' but I'll get either WAY too much gas before engagement or far too little gas before engagement. I swear it feels like sometimes the clutch engages within the first 10% and sometimes it's within the first 50%. I was starting to wonder if there was a clutch delay valve (I believe that's the name) similar to what S2000's have?

Either way, I have a manual Audi that I use and I really never get the same issues. Anyways, I was just about to search for a delay valve to see if that could be it.

nightdown fox · Mar 6, 2018

mheyman said:
I've written this to many times:

Added: This is a method that works. It's not mandatory, it's just works because by keeping your foot moving you are not trying to depend on any particular position being the correct position, and you are not trying to achieve a perfect position with your foot. Instead your always moving and correcting and using the timing of what you are doing.

I agree 200% with this post. Feathering the throttle is what I’ve done in all my cars, and I continued it in my old WRX and this STI... and it’s always been smooth for me. Thanks for posting this, mheyman... it’s the best way of explaining what I’ve been doing. I’m always blipping/feathering the throttle instead of making clutch adjustments.

I think even for manual pros, there’s still individual style in how we drive... and certain styles appear to have difficulty with this clutch engagement. I don’t think it’s right or wrong, just different styles. I taught myself to drive stick about 15 years ago, so I didn’t have professional guidance on if what I was doing was “right”. But I’ve always feathered the throttle over paying too much attention to engagement, and I haven’t had a car yet (all manuals for the past 15 years) that the method hasn’t worked. Could potentially put more wear on the clutch over time if done wrong... but it works.

jpetro1010 said:
I was starting to wonder if there was a clutch delay valve (I believe that's the name) similar to what S2000's have?

I believe there is one on these cars.

awenthol · Mar 6, 2018

nightdown fox said:
I believe there is one on these cars.

Not on GR or later and I do think Renee exactly when they stopped with GD

Sent from my LG-US997 using Tapatalk

SubySal · Mar 6, 2018

I have a 2006 STI. It doesn't have driver modes, hill assist, stability control or any of that, but I've had these issues too. I resolved the wandering clutch engagement by simply removing the clutch delay valve. Here's a pic of it...

The bucking in the lower gears came from the bushing that holds the carrier bearing for the rear driveshaft. It has a 1/4" of space all around it. That basically translates into 1/2" of play. There are two ways to resolve this issue. A one piece driveshaft. I tried that, but it didn't fit. Apparently there's not much clearance on GD's so you have to take a hammer to the body to give it more space. I returned the driveshaft. Instead I used an 80A liquid urethane and filled the void in the bushing. That solved my low speed bucking issues for about $40.

jaswrx · Mar 7, 2018

Subysal-

Is that the same thing as buying the spacers Whiteline makes for the rear diff?

SubySal · Mar 7, 2018

jaswrx said:
Subysal-

Is that the same thing as buying the spacers Whiteline makes for the rear diff?

The carrier bearing bushing is separate from the rear diff. As far as I know nothing better is made to replace it or stiffen it up. Most just go to a one-piece driveshaft and do away with the carrier bearing assembly altogether.

mheyman · Mar 7, 2018

Great post!

SubySal said:
I have a 2006 STI. It doesn't have driver modes, hill assist, stability control or any of that, but I've had these issues too. I resolved the wandering clutch engagement by simply removing the clutch delay valve. Here's a pic of it...

The bucking in the lower gears came from the bushing that holds the carrier bearing for the rear driveshaft. It has a 1/4" of space all around it. That basically translates into 1/2" of play. There are two ways to resolve this issue. A one piece driveshaft. I tried that, but it didn't fit. Apparently there's not much clearance on GD's so you have to take a hammer to the body to give it more space. I returned the driveshaft. Instead I used an 80A liquid urethane and filled the void in the bushing. That solved my low speed bucking issues for about $40.

My only other comment is that your experience with a single piece DS is not normal for any mfgs carbon fiber offering. Single piece AL DSs are half the price of a CFDS but aren't a no mod fit, and yes that mod is normally done with a hammer . . . Your solution is far less than any new DS. I'd try it if I just bought an old STI and wasn't going to mod it to the point where $1K wasn't a big piece of the total expense

Added: Getting rid of the carrier bearing has other minor benefits, It eliminates two u-joints, lower the angle at which the remaining two u-joints operate, and completely eliminate a significant noise path from rotating parts dead in the middle of the car. As for this last benefit, its't surely the reason Subaru didn't fix the joint more firmly itself.

VA STI · Mar 7, 2018

Has anyone confirmed if there is a clutch delay valve in newer 2015+ STIs? If so is it built into the master?

magicmike · Mar 7, 2018

VA STI said:
Has anyone confirmed if there is a clutch delay valve in newer 2015+ STIs? If so is it built into the master?

It's in the clutch line, replacing the OEM one with any of the SS aftermarket ones will take care of it. Due to concerns with the firewall mount for the pitch stop tearing off I picked up the Perrin brace and it came with a SS clutch line, that made a big difference and is something I wish I had done much earlier in owner ship.

blacknblue06STI · Mar 7, 2018

magicmike said:
It's in the clutch line, replacing the OEM one with any of the SS aftermarket ones will take care of it. Due to concerns with the firewall mount for the pitch stop tearing off I picked up the Perrin brace and it came with a SS clutch line, that made a big difference and is something I wish I had done much earlier in owner ship.

So what exactly was the difference in clutch engagement with the SS line vs the oem line? I'm going to upgrade my clutch in the spring, and was simply going to bleed the slave reservoir with my motive.pressure bleeder during the new clutch install

magicmike · Mar 7, 2018

blacknblue06STI said:
So what exactly was the difference in clutch engagement with the SS line vs the oem line? I'm going to upgrade my clutch in the spring, and was simply going to bleed the slave reservoir with my motive.pressure bleeder during the new clutch install

OEM line has a restrictor in it, you ever shift fast and feel the clutch not reacting as fast as the pedal and having hard gear engagement? That's what it fixes.

Getting a new clutch?

djxpress

mheyman

Jay11STI

nightdown fox

RX7RIP

nightdown fox

nec9

mheyman

HeatSource

jpetro1010

nightdown fox

awenthol

SubySal

jaswrx

SubySal

mheyman

VA STI

magicmike

blacknblue06STI

magicmike

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