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Clutch Questions- adjustment?

39K views 21 replies 6 participants last post by  ramm21 
#1 ·
Hey all, have a couple of questions about the clutch. Mine is a 11 WRX hatch, 43K miles, stage 2 power, everything else stock. When I redline in any gear (sometimes it takes more than one time/gear), the next time I press the clutch in it feels very rough, not smooth at all. That feeling goes away after a little bit, but I'm just wondering why that is, what the fix for something like that would be.
My other question is this- the clutch doesn't engage as sharp as it used to, the RPM's dip for a split second right after I release the clutch pedal, and it feels like for a brief moment the power isn't all there. It's worse in the lower gears, and the problem isn't there when I ride the clutch, kind of like a mini-launch. When I asked some non-subie peeps at work they said it might just need a clutch adjustment. How hard is adjusting the clutch, can it be done at home with the car on ramps? What can you adjust with a clutch anyways?
How long do the clutches usually last in our cars? I know it depends on driving style, in my case I would say spirited, but I've never tracked the car.
 
#2 ·
As far as adjusting, idunno.

As for how long the clutch will last. Well that has a ton of factors. I've never blown one and have been driving a stick for 17 years. I drive pretty spirited myself.

Sorry I'm not a ton of help. I just saw your post hanging and didn't want you to think nobody was looking.
Sometimes it takes a day or two until the right person reads it.
 
#5 ·
Ramm,

What your describing sounds like a shot clutch, or possibly a glazed/warped flywheel. If the friction material on the clutch is damaged it may only be biting on part of the flywheel which can make it seem rough during low gear shifts. As for the lack of power the same issue would mean less power moving from your flywheel to the actual wheels.

As for clutch adjustment, its pretty simple, on Subarus it been hydraulic for as long as I can remember, Its super easy to adjust hydraulic clutches. Check the reservoir to make sure the fluid isnt gross (its usually dot 4 oil, so look for dark or pale fluid and any other signs of bad brake fluid) and then just pull the clutch pedal out towards you ( i use my left big toe, just get under the clutch pedal and pull it out), then push the clutch pedal all the way in and pull it out towards you again. Repeat that process until you can feel a change in the pedal feel. if it still isn't right you can adjust the actual pedal position by moving the locking nuts on the clutch pedals master cylinder rod.

I would give the adjustment a try first but if that doesn't yield the results your looking for 43k miles is within expected operating life, especially if you ride the clutch a bit.

I did run into an odd issue with my old mitsubishi where the clutch pedal was adjusted a bit too far out by the previous owner and it was putting a tiny bit of pressure on the clutch, effectively riding the clutch for me. that clutch only ran for 30k miles before it gave up. I didn't notice until I swapped out for a performance clutch/flywheel combo. the performance clutch was strill strong until the day i sold it with 118k miles so everyone's results will vary.
 
#6 · (Edited)
Thanks Jason,
Ill try the adjustment myself and see if anything changes. I'm hoping the clutch will last a little longer, maybe until fall. I don't mind driving the car as it is now, but if the issue is with the clutch or flywheel or both (and I'm thinking about swapping both out at the same time), will it put any more strain on the engine or the tranny or something like that if I keep driving on it? I mean if I'm going to replace flywheel/clutch, might as well ride it out unless it will mess up more stuff.

gunk007- yes, the car is on its second life. I figure she has 7 more! haha. The clutch, flywheel, and tranny are all original, those weren't messed with. The clutch felt rough even before the mishap, but I can't really say if it got worse afterwards. I didn't drive the car for about 3 months, so its a little hard to say if it got better/worse.
 
#7 · (Edited)
So I'm not sure I understood after trying the adjustment. If I understood correctly, I am to sit in the drivers seat and pull the pedal out towards me, then press it in and repeat until the pedal feel changes. Well, I couldn't pull the pedal out anymore than it already is. There is a metal bracket with a couple of nuts on it, which also has some sort of button/pin on the end. The pedal is pushing the button in, and releases it when you depress the clutch to the floor. Thats the pin that makes the cool clicking sound when I shift. What is the pins function? Is the nut attached to that metal bracket what I have to adjust? Or is the adjustment done under the hood?

The pin I'm talking about is right below the yellow puck on clutch pedal. The nut I'm referring to is just below the pin, and the bracket right below that. Pic was taken with the clutch pedal depressed
 

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#8 ·
The adjustment will only work if the clutch cylinder is sitting somewhere in its throw If it is already as far out as it can go then it will be more complicated than a simple pull adjustment. You can look for the clutch cylinder under the hood, it should be towards the passenger side of and lower than your master cylinder, check the fluid levels and for discoloration. It still sounds like a clutch issue but its never a bad idea to check your fluids.

The pin you are looking at is what tells the ECU to that you pressed the clutch. It triggers events like opening the wastegate and actuating the BPV, it also disengages cruise control and the like.

As for driving with a bad clutch there are 2 points of view the posotive POV says that every clutch on the road IS "worn" and the more we drive then the more worn they get. the negative POV says that you are already outside the limits of your clutch material/flywheel and eventually you will lose connection between the clutch material and flywheel all together, that will yeild your car unable to accelerate at all and you will have to hope you can get it somewhere safe to have it towed. Worst case scenario the clutch material could fail entirely and it could cause damage to your flywheel and if you are not in neutral when it happens lock you into a gear making your car a rolling road hazard.

Please take it by your tuner and have them take a look, the 5 minutes is well worth the piece of mind knowing that things are safe to drive on till fall.
 
#11 ·
Hey, Paul's back from his hyadis.

Yea the engage point is typically in there a little bit.
I always catch myself riding with the pedal in an inch or so.
I've never seen bad effects come of it.
 
#12 ·
Took the car to a professional over the weekend. His feedback- clutch feels okay, maybe showing signs of wear. He checked my transmission fluid, and he said it was a little low and the color wasn't the best. He topped me off at the shop, but after some researching I decided to switch tranny fluid to the andrewtech cocktail. Picked up the Redline Lightweight, have the Motul on order. From what I hear the shift feel should improve..

I did a little more research on clutch adjustments. From what I understand, the clutch and teh flywheel are ~whatever~ far apart when both are new. As the car is driven and clutch is worn, the distance between clutch and flywheel increases. The adjustment part is moving the clutch a little closer to the flywheel to make up for teh wear. That being said, most people don't even know about any adjustments, or say it doesn't work that way..
 
#14 ·
I did something today that helped shifting tremendously-reset the ecu. It's much smoother when shifting lower gears. Plus, when i used to get off the gas, the car would jerk just a little. Now the transition is almost unnoticeable. It's almost like there's a new better map that just got loaded. I've been running a stage 2 Cobb setup for over 30k miles now. Has anybody had this experience with resetting the ecu?
My motul will be here in a couple days..
 
#16 ·
Does anybody know what exactly the ecu "learns"? Is there any way to turn that feature off? From what the dealership told me when I bought the car it has something to do with cruise control, but I could def do without it since I never use it anyways
 
#17 ·
ECU Learning is how the car adjusts to its particular environment, Without that learning people would experience a much higher knock rate and in many cases without ECU learning even a small ammount of overboost would cause distructive AFR. ECU learning is something that people typically want to train for better output, not shut down or remove. The correlation between cruise control and ECU learning is that the dealership reccomend not using cruise control during the first few hundred miles so the ECU can learn what parameters it needs across the map rather than just at 3,000 rpm. If you feel like the ECU is learning "bad habits" and making your vehicle slower then there could be all kinds of problems behind the scenes that you should keep and eye out for. Now is a great time to talk to your tuner and pull some logs.

To answer your question the ECU reads hundreds of parameters per second and adjusts things like Air fuel ratio and boost to do 3 things, First and foremost to protect the engine, the ECU will respond to things like excessive temps, odd readings on sensors, changes in driver input and can do things like retarding timing limiting your total power to protect from knock after-burning and pre-det. Second it adjusts to external changes like poor quality of fuel and a dirty air filter to make sure things continue running smoothly and safely. Finally so long as the ECU feels safe it will slowly (over 50-200 miles)advance timing, in effect increasing power output up to a predetermined maximum.

IMHO you dont want to "turn off" ECU learning. it learns to make your car safer and more reliable and if you feel like the ECU reset made things better I would pull a few logs ASAP and get a view of whats going on inside the ECU, It wouldn't limit your power output just for the hell of it, those changes come with a reason and a few logs should help you and your tuner figure out why your ECU is making those kinds of learned changes. It could be as simple as a bad fuels, a shot O2 sensor or a boost leak. That said the log will lead the way to a solution.

I hope that helps
 
#18 ·
So if I'm understanding it right, the map you flash onto the ecu is not set, but flexible, and is fine-tuned by the learning feature. If I just reset my ecu, that means I shouldn't use the cruise control for a bit. Should I not get on it hard for the next 100-200 miles as well? Seems like the first 200 miles or so would be like a mini-break in for the ecu after a reset?
Also, what kind of effect would weather have on learning? Im in Cali, so the temps range from 30's in the winter to 105 in the summer.
The roughness until reset isn't new. I remember thinking how much smoother the car ran when I flashed to stage 1. Then the same feeling after I put the DP on and flashed to stage 2. Thats how I came up with the idea to reset ecu to make shifting better...
 
#20 ·
I blame my issue on a boost leak for a long period of time. After my stage 2 I missed a clamp on the IC. Also I babied it like crazy. It has been 600 miles after reflash and the car seems to idle, take off and go better through the RPMs. I have been getting on it a lot more and the response seems way better than before. I am also getting a slightly better MPG as well.
 
#21 ·
Did you find the leak by logging a pull? I haven't had a chance to get out of town to do that. However, I did change my tranny fluid to the andrewtech cocktail yesterday. Shifting is a little smoother, but the biggest change is rolling at 5 mph and not lurching forward. I like!

I also came upon some interesting info on another forum. Basically our if you try to shift 1-2 really fast, it puts a lot of load on the back diff and it bangs on the crossmember. Lately I've been taking my time with the 1-2 shift and it's really helped. I'm also shifting at a little higher rpms in first to make up for that acceleration difference. After all this, I don't think my clutch has an issue, and I've learned a lot.
 
#22 ·
I know this has been a while, but I've done something completely different to improve shifting feel a little. I came across a couple threads discussing benefits of cleaning you MAF sensor. I had the car for about 50k miles, and had no idea this was something you should clean fairly often. I had recently reset my car, and I was wondering why exactly the car would drive so smooth for a while afterwards. It made sense that it would drive smooth at the beginning, but with a dirty sensor the ECU would throw a bunch of corrections into the map pretty quick, making it run more sluggish. I did not have time to log a pull before/after, so my feel is the only thing I have to go on. If you haven't cleaned your MAF lately, I would do it sooner than later, and it only took 15 mins.
 
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