DIY - Swap clutch slave cylinder and hydraulic line for improved feel and control

[Ultramaroon]

Originally Posted by rburrow87

Yep, still enjoying it after driving a bunch more today! No problems with feathering, or hill starts, even with the grab point higher than it should probably be.

It's much easier to drive and it's hard to understand exactly why. It just seems more linear and predictable now, as if this is the slave cylinder size everything was designed around. It seems strange that a larger slave, which you'd think would simply increase the pedal travel required, could throw it off so much. Must be some odd geometry somewhere. You could sort-of get used to the original one to an extent, but one drive in a different car (NA Miata in my case), and it was just painful going back.

This has pretty much saved the car. Now I can concentrate on important stuff like an OFT and E85 or something

You're echoing my experience exactly. For a manual transmission, precise clutch control is critical. I'll take a sloppy gear selector over a sloppy clutch any day. Subaru doesn't get that and it's a damn shame.

Too much mechanical advantage makes it difficult to modulate engagement with precision. Have to swing the whole leg instead of just rotating the ankle. That's really all there is to it.

[jcw99]

What if I want to avoid the pedal adjustment and the spring removal and just do the slave cylinder? Should this work out pretty well? Right now I'm driving with my seat way back and this seems to be the only seating position that allows me to work the clutch smoothly most of the time, but, it's still iffy. Also, my arms are stretched way out and on a trip the right one starts aching.

[Ultramaroon]

Originally Posted by jcw99

What if I want to avoid the pedal adjustment and the spring removal and just do the slave cylinder? Should this work out pretty well? Right now I'm driving with my seat way back and this seems to be the only seating position that allows me to work the clutch smoothly most of the time, but, it's still iffy. Also, my arms are stretched way out and on a trip the right one starts aching.

The pedal adjustment is required because the slave swap increases travel at the pressure plate. I warn about this in the OP. It is a precursor to avoid potential damage.

Spring removal is optional. I actually have mixed feelings about it. If you leave it installed don't freak out when you bleed the clutch. Each time the pressure is relieved the pedal will stick to the floor. That's just the assist spring doing its job.

[jcw99]

Thanks so much! I read your complete thread back when you first posted but forgot some of it and have been reading all the comments since then. I'm kind of a late bloomer. When I do it I'll get back to you. Thanks again.

[Ultramaroon]

Better to bloom late than to die on the vine. Anytime, man! Don't worry about asking redundant questions. I'm not that guy.

[rburrow87]

Originally Posted by Ultramaroon

The pedal adjustment is required because the slave swap increases travel at the pressure plate. I warn about this in the OP. It is a precursor to avoid potential damage.

Spring removal is optional. I actually have mixed feelings about it. If you leave it installed don't freak out when you bleed the clutch. Each time the pressure is relieved the pedal will stick to the floor. That's just the assist spring doing its job.

The pedal is pretty heavy without the spring, I wouldn't blame someone for wanting to put it back or go to an MTEC spring. I'm happy with mine without a spring, but I haven't tried one so who knows.

When I went to bleed mine, I was getting nowhere and wasting fluid for a while. Finally just pulled the bleeder off the slave, pushed the pushrod in, covered the bleeder hole with my thumb, then let go of the pushrod to get it to suck down some fluid. Did that a couple times then put the bleeder back in and it finally bled normally.

Also when I bought the slave, I wanted to just get new crush washers. My local AutoZone had Dorman HELP 66250 in stock which is an assortment pack which had the correct size in it. Nobody seemed to stock individual sizes here.

[ck-GT86]

So i have a new clutch and flywheel, the car dies if i dont give it gas before releasing the clutch while its fully depressed. Im guessing this is because the clutch is grabbing way faster. Going to raise the height of the pedal, i want to say its a bit underneath when compared against the brake pedal. @Ultramaroon whatcha think?

[Ultramaroon]

Originally Posted by ck-GT86

So i have a new clutch and flywheel, the car dies if i dont give it gas before releasing the clutch while its fully depressed. Im guessing this is because the clutch is grabbing way faster. Going to raise the height of the pedal, i want to say its a bit underneath when compared against the brake pedal. @Ultramaroon whatcha think?

How long have you run it since reassembly? I'm going to say it's the ECU relearning the fuel trims.

If you can get it into gear, it's ok. Try going from neutral to first and back to neutral. raise the pedal a smidge. try it again. repeat until you feel resistance to engagement. There's your touch point.

[ck-GT86]

Originally Posted by Ultramaroon

How long have you run it since reassembly? I'm going to say it's the ECU relearning the fuel trims.

If you can get it into gear, it's ok. Try going from neutral to first and back to neutral. raise the pedal a smidge. try it again. repeat until you feel resistance to engagement. There's your touch point.

Happens only when i run my headlights, or HVAC. The power draw is dipping the idle. Been about 240 miles now with the clutch

. ck

[Ultramaroon]

Originally Posted by ck-GT86

Happens only when i run my headlights, or HVAC. The power draw is dipping the idle. Been about 240 miles now with the clutch

. ck

Hmmm... I'll still say not clutch but raising it certainly won't hurt.

I'm not an expert with this ECU but maybe it hasn't spent enough time idling. Maybe let it idle from a cold start all the way to normal operating temp?

Let's make an emergency call out to @steve99. Any opinions, sir?

[ck-GT86]

Originally Posted by Ultramaroon

Hmmm... I'll still say not clutch but raising it certainly won't hurt.

I'm not an expert with this ECU but maybe it hasn't spent enough time idling. Maybe let it idle from a cold start all the way to normal operating temp?

Let's make an emergency call out to @steve99. Any opinions, sir?

Raised the clutch pedal so its a bit above the brake, car doesnt immediately die with the HVAC and headlights on. Thanks!

. ck

[Ultramaroon]

Originally Posted by ck-GT86

Raised the clutch pedal so its a bit above the brake, car doesnt immediately die with the HVAC and headlights on. Thanks!

. ck

Great! For the record, stock parts?

[steve99]

Originally Posted by ck-GT86

So i have a new clutch and flywheel, the car dies if i dont give it gas before releasing the clutch while its fully depressed. Im guessing this is because the clutch is grabbing way faster. Going to raise the height of the pedal, i want to say its a bit underneath when compared against the brake pedal. @Ultramaroon whatcha think?

Originally Posted by Ultramaroon

Hmmm... I'll still say not clutch but raising it certainly won't hurt.

I'm not an expert with this ECU but maybe it hasn't spent enough time idling. Maybe let it idle from a cold start all the way to normal operating temp?

Let's make an emergency call out to @steve99. Any opinions, sir?

If your new clutch and flywheel assembly is significantly lighter than the original unit it can cause issues with idling as the ecu software detects abnormal changes in idle speeds and trys to compensate.

lighter clutch flywheels can also cause difficulty in initiial takeoff as less stored energy in lighter components so you have to use more rpm to takeoff, also if clutch has more "bite".

you could try adjusting the pi/di tables to run full DI up to 0.3 engine loads and bump your idle to 750 if not already done.

running full DI at idle seems to allow ecu to compensate quicker

also try removing the weird negitive intake cam advance settings in the intake avcs tables at low rpm/load they seems to be for emmissions only

see tune tweaks thread

[ck-GT86]

Originally Posted by Ultramaroon

Great! For the record, stock parts?

Far far far from stock parts.

. ck