Clutch Delay Valve?

[Dave-ROR]

Originally Posted by Akari

No offense to anyone in here but a good set of shoes doesn't solve the issue here. The issue is when shifting quickly, especially 1st to 2nd, you have to delay how quickly you get back on the accelerator, otherwise your clutch will not be fully engaged yet even though the pedal is fully released. Yes this is easy to avoid but it's not a behavior that is constructive towards spirited driving or track use.

I said live with, not solve.

I am rarely (ie once per session) in first gear on the track. Just shift slightly slower. I never notice it in the other gears.

[Porsche]

Originally Posted by Dave-ROR

I'm not concerned about this CDV. I wasn't concerned about the one in my S2K either. It's very easy to learn to live with it.

Do we know, absolutely and unequivocally, that the Subaru BRZ does in fact have a clutch delay valve?

I don't drive in such a way that it would be readily apparent; like you, Dave, I don't notice it on my S2000 (parked for the winter).

Has anyone posted or linked to, say, an exploded parts diagram that proves the Subaru has such a valve? Although, if you've disassembled yours and held the valve in your hand, Dave, I'd be inclined to believe you. I'm not denying it exists, I have no idea either way, merely asking for convincing evidence. If proof has been posted, could someone direct me to it, please? Until I see something like that, I'm skeptical.

Thanks.

[trd87t]

Originally Posted by Porsche

Do we know, absolutely and unequivocally, that the Subaru BRZ does in fact have a clutch delay valve?

I don't drive in such a way that it would be readily apparent; like you, Dave, I don't notice it on my S2000 (parked for the winter).

Has anyone posted or linked to, say, an exploded parts diagram that proves the Subaru has such a valve? Although, if you've disassembled yours and held the valve in your hand, Dave, I'd be inclined to believe you. I'm not denying it exists, I have no idea either way, merely asking for convincing evidence. If proof has been posted, could someone direct me to it, please? Until I see something like that, I'm skeptical.

Thanks.

x2

I do notice it myself but I learned quickly to drive around it. I have noticed that it not as noticeable since i took delivery of her. Never had that "feeling" with my other manual cars (supras, wife's miata and z24).

If there is no valve to speak of, then could it be the fact that our clutch does not directly drive the master cylinder? Could even be that there is a banjo setup on the slave cylinder (but I very highly doubt this is a cause). These two things I have never seen/experienced on a car before so I'm only speculating here.

my .02 fwiw

[Dave-ROR]

Originally Posted by Porsche

Do we know, absolutely and unequivocally, that the Subaru BRZ does in fact have a clutch delay valve?

I don't drive in such a way that it would be readily apparent; like you, Dave, I don't notice it on my S2000 (parked for the winter).

Has anyone posted or linked to, say, an exploded parts diagram that proves the Subaru has such a valve? Although, if you've disassembled yours and held the valve in your hand, Dave, I'd be inclined to believe you. I'm not denying it exists, I have no idea either way, merely asking for convincing evidence. If proof has been posted, could someone direct me to it, please? Until I see something like that, I'm skeptical.

Thanks.

Hmm good call. I notice that 1-2 and 2-1 shifts suck ass but that could be trans design more than anything else. It feels like a CDV because the symptom is similar to the clutch not being fully disengaged. I haven't tried to locate a CDV which is reportedly in the BMC. Subaru and many others are using these days so it just made sense but I certainly never confirmed it.

[BRZfan]

We need an informed and competent automotive drivetrain engineer in this thread.

[SirBrass]

Lowering the grab point of the clutch helps, and a smooth let out of the clutch (not a dump) works.

That, and a good heel-toe blip while clutching out, makes for some good spirited shifts.

If there's a CDV there, then I'm not yet good enough or fast enough to notice it yet.


@chrisl, do you go for Puma motorsport shoes, or just Puma shoes in general?

[trd87t]

When it warms up in the next day or two, i'm going to check out the engine bay and look for things that are similar to a link that was reference earlier in this thread.

http://www.iwsti.com/forums/how-inst...post-pics.html


From what I remember I don't remember seeing a type of "container" or "proportioning valve" on the clutch system but again, I don't exactly remember and rather go check again.

[Porsche]

Originally Posted by Dave-ROR

It feels like a CDV because the symptom is similar to the clutch not being fully disengaged.

DISengaged?

You meant not fully "ENgaged," right? A feeling as though the clutch isn't "biting" as crisply as it should? So, it might be difficult to abruptly break away the rear tires, for instance?

Otherwise, I'm confused ... which is a frequent state for me in my old age.

[Porsche]

Originally Posted by trd87t

When it warms up in the next day or two, i'm going to check out the engine bay...

I don't recall seeing anything topside. If the BRZ employs a clutch delay valve it might be located down around the bellhousing/clutch assembly. IIRC that's where the CDV is found on my S2000, and isn't that where the CDV is located on the STi?

I recall the S2000 needed one, not to protect the clutch, but because the differential was prone to breaking, so Honda employed a clutch delay valve to soften the driveline shock resulting from abrupt clutch engagement as drivers sought to deliberately break the rear tires loose.

It is 1.1* F here right now. Oi!

It'll be months before we experience warmth again.

[Porsche]

Originally Posted by SirBrass

If there's a CDV there, then I'm not yet good enough or fast enough to notice it yet.

My thought is that a well-timed, well-executed, smooth shift would MASK the presence of a clutch delay valve.

That's why I have not noticed any such valve ... 'cuz I'm so GOOD, don't ya know.

(I'm sorry; I'm weak and couldn't resist...)

[Porsche]

Originally Posted by FRSKEV

Glad Im reading this because I thought I was going crazy not being able to figure out how to shift smooth 1-2.

You're not going crazy.

Oddly, this BRZ is one of THE most difficult cars to shift smoothly that we've ever driven.

You have a low post count, so I'm guessing you're new to this car. Smoothness will come in time, as it did for me. But, I'm still hard-pressed to define exactly what the issues are here.

I'm thinking the "awkwardness" of shifting, especially the 1-2 shift, is attributable to an odd clutch take-up and an awkward drive-by-wire throttle pickup. The throttle (as I recall) is sort of nothing-nothing-BAM more than I wanted sort of thing producing jerky shifts, rather than the smooth, SEAMLESS shifts that I strive for. I try to shift so that as a passenger you cannot tell that I've shifted, smoother than any automatic transmission. Quickly, too, but not faster than it "likes."

Now that I can shift seamlessly (after some time), all I can say is that I just "squeeeeze" the throttle and properly coordinate the clutch engagement such that my shifts are smooooth. I wish I could be more specific for you, but my body just "does it," now, and I cannot say exactly how. Kind of like walking on a tightrope; I don't fall off anymore, but I can't exactly describe WHY except to say that I kept practicing until I got it.

I realize this hasn't been much help, apart from reassuring you that you're not crazy. Keep working at it, and it will come in time.

Just do not slip your clutch too much; you'll wear it out prematurely.

[BRZfan]

We need an informed and competent automotive drivetrain engineer in this thread.

[Dave-ROR]

Originally Posted by Porsche

DISengaged?

You meant not fully "ENgaged," right? A feeling as though the clutch isn't "biting" as crisply as it should? So, it might be difficult to abruptly break away the rear tires, for instance?

Otherwise, I'm confused ... which is a frequent state for me in my old age.

Depends on the shift. Sometimes it doesn't feel like it's disengaged (mine has ground gears on slow shifts with the pedal on the floor) and sometimes it feels like there's a delay in engagement. I only notice it in 2-1 and 1-2 shifts though so maybe it's just trans design.

[IronSean]

Originally Posted by Porsche

... an awkward drive-by-wire throttle pickup. The throttle (as I recall) is sort of nothing-nothing-BAM more than I wanted sort of thing...

This is completely true. I wasn't sure if I was just crazy, but every time I test drove a BRZ I would be surprised how far I had to push the pedal to get any throttle at all. It was quite the shock coming from my 06 Camry (which is also Drive-by-wire) where you can ease onto the pedal and start getting controlled throttle.