DIY - Easy clutch grab adjustment (~10 mins)

[8987846]

Originally Posted by s0sl0w

Did this today, HUGE improvement in the clutch.

I did modify the technique discussed however, Subaru didn't intend for you to spin the metal rod to adjust the clutch.

I took off the safety clip, squeezed the plastic safety clip on the pin and took out the pin then pulled the rod down and spun the long "u" shaped bit down, took two tries to get it at a point I liked but it was much easier that trying to spin the rod. Also the gear indicator and cruise worked without adjustment.

Video please...........................

[JonnyRocket]

Originally Posted by 8987846

Can you upload a video showing us how to do it? I want to follow what you did but I have no idea what are you talking about without visualizing. e.g what's the pin? what's the bolt and U thing....

He's talking about the clevis and pin seen at roughly ~50sec into my video. By pulling the cotter pin out of the clevis pin, you can then remove the clevis pin and spin the clevis (that's the u-shaped thing) rather than trying to spin the rod itself.

See here:

[s0sl0w]

Originally Posted by 8987846

Video please...........................

Oh jesus man.. It's COLD outside!!

I'll see what I can do.

[JonnyRocket]

Originally Posted by s0sl0w

Oh jesus man.. It's COLD outside!!

I'll see what I can do.

I explained it to him.

[1Cor10:23]

Originally Posted by Ozzman

You can verify freeplay at the top of the stroke is correct, by a simple function check.

Open the hood and look at the clutch master cylinder reservoir while pulling the clutch throwout lever towards the clutch slave cylinder. If you can not get any travel out of the throw out lever and the fluid level doesn't rise in the reservoir, then the clutch pedal is adjusted too tight. And you have to back off the clutch pedal/cruise control switch a bit. If you drive around in this condition for very long the clutch will start slipping even with your foot off of the clutch pedal and the you will wear out the clutch in short order.

If you can depress the throwout lever toward the slave cylinder a significant amount and the fluid level rises in the reservoir while pulling/depressing the throwout lever than the freeplay adjustment is good to go.

There is a bleed/transfer port between the reservoir and the master cylinder, this port is only open when piston in the master cylinder is topped out aka clutch pedal released. This port must be open in this position to allow for expansion of fluid when the clutch is not being depressed. Once enough pedal travel has been utilized to push the piston passed this port the hydraulic clutch circuit becomes pressurized.


To check that you have enough pedal travel to fully disengage the clutch there is another function check you can do. With the vehicle fully warmed up, this also means warms trans fluid. With the vehicle stopped and your foot on the brake, Depress the clutch and immediately shift to first gear, you should hear a clunk/thunk.

Put it back in neutral and then depress the clutch again, wait 3 seconds and then shift into first gear, there should be no clunk/thunk. No clunk/thunk after 3 seconds means you should be good to go. (the clunk/thunk is the sound of the input shaft stopping rotation to mate with the output shaft) If there is still a thunk/clunk when shifting into 1st after depressing the clutch for 3 seconds then the clutch is not fully disengaging and you have your pedal adjusted too low. You will kill your syncros in short order if you drive around in this condition for long.

Repeat these function checks again after driving a while after having made any adjustments just to make sure everything is adjusted within safe functional tolerances. Check again a week later just to be sure.

Would the thunk/clunk occur when you release the clutch or when you move the shifter to 1st?

Just did the mod, have the clutch pedal resting about 1-2mm below level with the brake. Want to make sure I'm fully disengaged with pedal fully pushed to wall.

Thanks!

[Ozzman]

Originally Posted by 1Cor10:23

Would the thunk/clunk occur when you release the clutch or when you move the shifter to 1st?

Just did the mod, have the clutch pedal resting about 1-2mm below level with the brake. Want to make sure I'm fully disengaged with pedal fully pushed to wall.

Thanks!

The clunk should occur when moving the shifter into first, this is separate from any noise heard when releasing the clutch. I found that the transmission doesn't clunk when the vehicle is cold though, I figure cold fluid adds enough drag to slow down the input shaft fast enough on its own that input shaft doesn't have enough inertia left to clunk even when moving the shifter immediately into first.

[Suberman]

Originally Posted by 1Cor10:23

Would the thunk/clunk occur when you release the clutch or when you move the shifter to 1st?

Just did the mod, have the clutch pedal resting about 1-2mm below level with the brake. Want to make sure I'm fully disengaged with pedal fully pushed to wall.

Thanks!

When you move the shifter to first, keep the clutch pushed in.

He's saying you select first twice in succession with the clutch pedal on the floor. The first time you may or may not get the clunk as the synchronizers stop the gears from spinning (cold oil may stop the spinning) technically this is called "stirring", the gears continue to spin at engine speed for a period after you push the clutch, even when the car is stationary. How long depends on a number of factors. Selecting any gear while stationary should stop the gears from moving. You then select neutral and then select any gear, first works well as does reverse. There will be another clunk only if the clutch plate is dragging. If your clutch is properly adjusted the second time you select a gear it should go in easily with no clunk.

[1Cor10:23]

Originally Posted by Suberman

When you move the shifter to first, keep the clutch pushed in.

He's saying you select first twice in succession with the clutch pedal on the floor. The first time you may or may not get the clunk as the synchronizers stop the gears from spinning (cold oil may stop the spinning) technically this is called "stirring", the gears continue to spin at engine speed for a period after you push the clutch, even when the car is stationary. How long depends on a number of factors. Selecting any gear while stationary should stop the gears from moving. You then select neutral and then select any gear, first works well as does reverse. There will be another clunk only if the clutch plate is dragging. If your clutch is properly adjusted the second time you select a gear it should go in easily with no clunk.

Thanks! (and @Ozzman as well) very informative.

[Ozzman]

Originally Posted by 1Cor10:23

Thanks! (and @Ozzman as well) very informative.

The basic theory is that the input shaft should take at the absolute most, 3 seconds to slow down after stepping on the clutch.

On my old car you could test pilot bearing friction clutch drag etc, by depressing the clutch, waiting 3 seconds and throwing it into reverse, if it ground then something was wrong, either the clutch was dragging or the pilot bearing was buggered.

On the BRZ/FRS it seems that reverse is synchronized as I have never heard it grind even being impatient with reverse. So throwing it into first/second, whatever and listening for the clunk serves the same purpose.

[1Cor10:23]

Sorry to bring this up again but it seems like there was 2 slightly different variations of this test mentioned above, both yielding slightly different results for me

@Suberman - holding clutch-in and quickly shifting to first (clunk if done quickly after clutch-in), still holding clutch down -> neutral -> re-select first (no clunk; barely any resistance)

@Ozzman - clutch-in and quick shift first (clunk) -> shift neutral, release clutch -> clutch-in for 3 seconds, shift first (slight clunk, much less than quickly shifting into first without holding clutch first 3 seconds, however; not as smooth as holding down clutch and re-selecting first (as per @Suberman suggestion)

Difference is that 2nd method prescribes releasing the clutch before clutching-in for 3 seconds pre-shift to first.

Bottom-line I guess is that I've got the clutch set at most perhaps 2mm below the brake (it's really hard to tell down there, even with a ruler) - any danger here? When trying to get the car rolling from stop, I've got about 1" on the pedal before feeling it - just worried that it's dragging and it's minimal to the point that I can't feel it.

thoughts?

Greatly appreciate all the mechanically-inclined members of the community chiming in!

[Suberman]

Originally Posted by 1Cor10:23

Sorry to bring this up again but it seems like there was 2 slightly different variations of this test mentioned above, both yielding slightly different results for me

@Suberman - holding clutch-in and quickly shifting to first (clunk if done quickly after clutch-in), still holding clutch down -> neutral -> re-select first (no clunk; barely any resistance)

@Ozzman - clutch-in and quick shift first (clunk) -> shift neutral, release clutch -> clutch-in for 3 seconds, shift first (slight clunk, much less than quickly shifting into first without holding clutch first 3 seconds, however; not as smooth as holding down clutch and re-selecting first (as per @Suberman suggestion)

Difference is that 2nd method prescribes releasing the clutch before clutching-in for 3 seconds pre-shift to first.

Bottom-line I guess is that I've got the clutch set at most perhaps 2mm below the brake (it's really hard to tell down there, even with a ruler) - any danger here? When trying to get the car rolling from stop, I've got about 1" on the pedal before feeling it - just worried that it's dragging and it's minimal to the point that I can't feel it.

thoughts?

Greatly appreciate all the mechanically-inclined members of the community chiming in!

Because reverse is also synchronized the simplest test for a dragging clutch plate doesn't work on the BRZ.

Either method works but the method I describe should be foolproof. By selecting a gear while stationary the gears must stop spinning. Selecting neutral while still holding the clutch pedal down will start the gears moving again only if the clutch plate is dragging.

Waiting with the clutch pedal depressed is less precise as you don't know how long it takes for the gears to stop spinning.

Either method will work if correctly applied.

Basically, if the gears don't crunch when you shift, especially into first or reverse when stationary, then your clutch is disengaging enough.

The really important aspect is adequate free play at the top of the clutch pedal stroke. As long as you have the correct pedal free play then your clutch fully engages and will not slip.

That is the critical thing to be sure about.

[1Cor10:23]

Originally Posted by Suberman

The really important aspect is adequate free play at the top of the clutch pedal stroke. As long as you have the correct pedal free play then your clutch fully engages and will not slip.

That is the critical thing to be sure about.

And my understanding is that moving the pedal via rod/12mm nut does not affect free play and that the only thing that can affect the free play from doing this mod is the sensor that is held by the 14mm nut pushing down on the clutch?

Thanks

[Suberman]

Originally Posted by 1Cor10:23

And my understanding is that moving the pedal via rod/12mm nut does not affect free play and that the only thing that can affect the free play from doing this mod is the sensor that is held by the 14mm nut pushing down on the clutch?

Thanks

That's my understanding. You are lowering the pedal AND lowering the engagement point at the same time which preserves the free play.

This is also why the practical limit on this mod is clutch drag when the pedal is fully depressed. If you have no clutch drag when the pedal is on the floor and you still have the specified free play at the top of the pedal travel then the pedal adjustment is perfect.

[Siege]

Thank you for this great DIY! It made a great difference in overall drivability.

To add to the discussion above, a great test to ensure the clutch is disengaging fully is to find a perfectly flat parking lot and place the gearbox in 1st with the clutch in. Rev the engine slowly up to 6K RPM. If the clutch isn't disengaging fully then the car will start to move.