Which Acuity parts needed to just remove lateral slop on shifter?

[Spart]

Even dct trans from paddle pull to gear change typically runs 100-300ms.

Don't conflate delay between a commanded shift and an executed shift with the actual shift time (that is, drop in torque output.)

It doesn't matter if the car waits 100ms to shift for you if it's executing that shift in the tens of milliseconds. I've seen it claimed that some DSG can do 8ms shifts.

Anyway, here's a random 2-3 shift in the GT350. Shift lasts about 8 frames, 30fps video, 8/30 = 0.266.

My 3-4 shifts are generally snappier, but you get the idea.

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[Victorofhavoc]

Don't conflate delay between a commanded shift and an executed shift with the actual shift time (that is, drop in torque output.)

It doesn't matter if the car waits 100ms to shift for you if it's executing that shift in the tens of milliseconds. I've seen it claimed that some DSG can do 8ms shifts.

Anyway, here's a random 2-3 shift in the GT350. Shift lasts about 8 frames, 30fps video, 8/30 = 0.266.

My 3-4 shifts are generally snappier, but you get the idea.

In the video I assume you're using image stabilization because of the mirage effect? That can effect frame sequence and timing. You'd have to look at the raw file to check the frame time stamp from initiation to end to get the full timing accurately. It might be 260ms (in which case, holy crap batman you're the fastest shifter I've ever seen in a mustang with a tremec box) or it might be a lot higher than the video indicates and closer to the rest of us. Image stabilized video often gets frame drop and overwrite to keep the image smooth in post processing/export. Regardless, you shift very quickly. I would bet as fast as those synchros are capable of (because you haven't mentioned grinding gears or surging torque on shifts).

My point from the beginning was that 30 ms on clutch re-engagement will not be perceptible to most people, even most pro drivers. The 200-300ms of turbo engine (single scroll not twin) input lag will be far more noticeable. Even on a drive by wire NA engine the pedal to TB actuation on tuned and race ecu will drop to 30-50ms, which is typically defined as "largely imperceptible". Factory dbw systems can be much higher than that due to applied software smoothing.

Let's remove the clutch in from the equation, because that's easily adjusted for by your anticipation of the road ahead (ie, you should know when you're about to shift before you shift).

The clutch out portion of the action will involve the delay valve and damper for sure. If they're adding 60ms altogether, the driver would have to perceive that slowed down clutch slip as or after their foot comes up. In your argument, you're defining total time of the shift, not the driver's perception of that shift. I'm not arguing shift time is unimpacted by fluid flow, that's fact. I'm arguing the driver's perception of 30ms during that phase is largely imperceptible given everything else going on.

In your example and an expected sub 300ms shift pace, if you're deleting 30ms of actuation in a turbo car, you'd have to be back on throttle before your shift begins.

On that note, it does bring up another question for me, and that's "does reducing clutch re-engagement time make the gear change slower overall in a turbo car because it engages at a rate where the throttle and turbo lag can't quite keep up?"

... I couldn't help it, this had me curious so I asked chatgpt (not always to be trusted so context is key) and the answer is:

"Yes — in a turbo manual car without anti-lag or flat-foot shifting, reducing clutch re-engagement time too much can make the gear change slower overall. That’s because the turbo and throttle response can’t supply torque fast enough, so the drivetrain “catches” an engine that hasn’t recovered, leading to bog or lag. A smoother, slightly longer re-engagement often results in quicker net acceleration."

 

[Spart]

You must not have read my post, because I made it pretty clear that you're removing nearly 100 ms of various kinds of delay from the system by deleting both components. 315 ms down to 218 ms.

And you're just hypothesizing. I'm telling you my actual experience with it (which you lack) - it makes a very noticeable difference.

I am not the most talented stick shift driver out there. The GT350-spec TR3160 (a far cry from the average TR3160) is far better than you give it credit for and it actually likes being shifted at the limit like this as much as or even better than "around town" driving. There's a trans-mounted MGW shifter in that car, but it's otherwise stock. The trans is designed to work on track and it does that very well. Whoever told you it was notoriously clunky... gotta be honest, never heard that a single time from the GT350 community. That person probably should just keep their day job.

 

[Victorofhavoc]

You must not have read my post, because I made it pretty clear that you're removing nearly 100 ms of various kinds of delay from the system by deleting both components. 315 ms down to 218 ms.

And you're just hypothesizing. I'm telling you my actual experience with it (which you lack) - it makes a very noticeable difference.

I am not the most talented stick shift driver out there. The GT350-spec TR3160 (a far cry from the average TR3160) is far better than you give it credit for and it actually likes being shifted at the limit like this as much as or even better than "around town" driving. There's a trans-mounted MGW shifter in that car, but it's otherwise stock. The trans is designed to work on track and it does that very well. Whoever told you it was notoriously clunky... gotta be honest, never heard that a single time from the GT350 community. That person probably should just keep their day job.

Your assumptions around my experience are inaccurate, but that's okay... We don't really know each other so we can make all sorts of assumptions.

I'm a certified instructor who has spent 12+ yrs driving in performance scenarios in a variety of street vehicles and racecars. Cdv deletes and full slave removals have been as common as tire changes ime. They certainly have their benefits. I've had passengers and drivers that are current and former pro drivers, including recent NASCAR and IMSA drivers. They're on another level compared to the rest of us, so I take their opinions to heart. When they tell me they're fighting the trans, I believe them. Could they be wrong? Sure.

I want to stress that I don't have individual numbers on only CDV deleted and only CMC damper deleted. Just did not have the time or interest in bleeding my clutch system three times instead of once. I'm just interpreting the data based on differences that make sense based on how each device works.

Ignoring the initial delay (which I attribute to the damper and not the CDV) the amount of time it takes from the time the clutch fork starts properly moving at full speed to reach full engagement with the CDV was 99ms. After the delete, that component of the engagement time dropped to 62ms.

So while the CDV+damper delete dropped the delay to full-speed clutch fork movement nearly in half, it dropped the rate of engagement once motion begins by 37%.

Your statement was that both cdv and damper delete removed 37ms in total (99-62=37) that you measured with a 1000fps camera, is that correct?


Honestly I don't know what the argument is anymore... My statement was that dampers don't typically cause perceptible impact to shift time, they more reduce the flutter of the clutch spinning at the pedal than anything else. Cdv is what's intended to reduce clutch actuation time. Removing either or both or neither are all valid options based on your own personal goals.

 

[Spart]

Your assumptions around my experience are inaccurate, but that's okay... We don't really know each other so we can make all sorts of assumptions.

Have you or have you not driven a DE5/FL5 with both the CDV and CMC damper removed? That's the only experience I care about.

Your statement was that both cdv and damper delete removed 37ms in total (99-62=37) that you measured with a 1000fps camera, is that correct?

Negative. The total is 31 ms from the initial delay (attributed to the CMC damper) and then once the clutch fork starts moving, it takes 37 ms more time to fully engage. 31 ms + 37 ms = 68 ms.

But again that's one way. The reason I split them up is because the effect the delay valve has on the rate of engagement should in theory only be in play when you're releasing the pedal. But the delay caused by the damper will have an effect in both directions of pedal movement.

For example:

You push the clutch pedal in, and you increase the pressure at the master. The damper "sees" this increase in pressure and has to equalize before fluid flows to the slave. Once it equalizes, the slave starts moving.

The other direction, you release the pedal and decrease the pressure at the master. The damper "sees" this and has to equalize once again before the pressure can drop at the slave. Once it equalizes, the slave starts moving.

That's two delays caused by the damper in one shift.

So really, the total effect is (31*2)+37=99 ms.

It's a BIG difference, and I believe the damper is responsible for over half of it.

Honestly I don't know what the argument is anymore... My statement was that dampers don't typically cause perceptible impact to shift time, they more reduce the flutter of the clutch spinning at the pedal than anything else. Cdv is what's intended to reduce clutch actuation time. Removing either or both or neither are all valid options based on your own personal goals.

Your statement is that "dampers don't typically cause perceptible impact" and yet here I am with hard numbers and experience that says otherwise... and you want to just fall back on "typically."

You haven't tried this, you don't have any first-hand knowledge what it does.

You continue to shit on it for no reason.

You ignore or misrepresent the data I've provided.

You claim that despite my experience with it, it must be in my head ("imperceptible").

Welcome to the ignore list! See ya later! This is just not worth my time.

 

[Tw1stedlog1k]

@ashmostro I've been meaning to ask, and I probably missed it somewhere, what does the "L" stand for when you mention the ITL?

 

[ashmostro]

It means I'm dumb and should have been typing ITS the whole time. I have no idea where the 'L' crept into my ridiculous brain. Lmao!

 

[ashmostro]

i mean, wtf is a "Type L" anyway? lmaooo

 

[Victorofhavoc]

i mean, wtf is a "Type L" anyway? lmaooo

"type large"

No joke, backseat of these cars is massive for the class. Head room be damned because we all end up slouching in bench seats, lol. I can fit a doona (with base) behind me and still adjust my seat to my comfort level at 6' tall. I couldn't do that in my gti WITHOUT the doona base. Not in the M3 either. An explorer was also a very tight fit.

That plus the trunk that can easily fit 3 bodies definitely makes this a type L

 

[ashmostro]

Hahaha let's change the name to type LS and then do engine swaps to make it even more legit

 

[ABPDE5]

Hahaha let's change the name to type LS and then do engine swaps to make it even more legit

We can use all that rear seat space to house the new drivetrain. Rear-mid-engine, front-wheel-drive V8. No torque steer if your front wheels have no grip

 

[ashmostro]

Could just add the LS to the trunk for a lightweight AWD car. Right? Right?

 

[Tw1stedlog1k]

I just dropped off a full set of wheels with 275/30 tires mounted at the shop for refinish. Still had room to spare.

Type BB - Big Back

 

[ashmostro]

Hmmm. Don't give me any ideas dangit!

 

[Tw1stedlog1k]

For you track folk, I've seen the car can fit a set of tires, a jack, tools, and a cooler. As I'm sure you've probably figured out already.

Get to the track fully loaded, spend a full day on the track, and drive back home with full Honda reliability.

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