Shift Assist (rev hang) and quick/short shifters...

[cxwrench]

I've got a question about short shifters. The goal is to reduce the time required to shift gears. Shorten the throw and change the ratio of shift lever movement to the gear changing stuff in the transmission and you get quicker shifts.

But...

For as long as this car has been around people have complained about 'rev hang'. They've complained how it makes it impossible to upshift quickly w/o getting some clutch slip. Some of these same people have short shifters. How come?

 

[METZGER]

The fly wheel is too heavy in the fiesta ST I heard.. mine is slow at reving down too..

I've got a question about short shifters. The goal is to reduce the time required to shift gears. Shorten the throw and change the ratio of shift lever movement to the gear changing stuff in the transmission and you get quicker shifts.

But...

For as long as this car has been around people have complained about 'rev hang'. They've complained how it makes it impossible to upshift quickly w/o getting some clutch slip. Some of these same people have short shifters. How come?

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[cxwrench]

The fly wheel is too heavy in the fiesta ST I heard.. mine is slow at reving down too..

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We know why it happens and the flywheel isn't part of the problem...it's in the ECU for emissions reasons. My question...again...why are guys installing quick-shifters when you can't shift quickly?

 

[METZGER]

Yeah well I guess because it makes it a shorter throw therefore making less effort to shift just not exactly faster to shift.

There is rev matching added in there too so that holds it at a certain amount of rpm's while your foot is on the clutch.

We know why it happens and the flywheel isn't part of the problem...it's in the ECU for emissions reasons. My question...again...why are guys installing quick-shifters when you can't shift quickly?

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[cxwrench]

Yeah well I guess because it makes it a shorter throw therefore making less effort to shift just not exactly faster to shift.

There is rev matching added in there too so that holds it at a certain amount of rpm's while your foot is on the clutch.

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No, there is no 'rev-matching' on our cars. Not at all. Rev-matching is an entirely different thing...for down shifting only. The entire reason for short shifters is to make quicker shifts.

 

[Ford ST]

People still bang through the gears regardless of rev hang just saying.

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[cxwrench]

People still bang through the gears regardless of rev hang just saying.

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Absolutely, as do I. Is it noticeably worse w/ a quick shifter?

 

[Ford ST]

Absolutely, as do I. Is it noticeably worse w/ a quick shifter?

To be honest it's only noticeable when I shift slowly. like if I'm trying to make a smooth shift. If I shift the hell out of it I don't notice it nearly as much. I don't feel modifying the shifter in anyway changes how it feels.

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[alexrex20]

Rev hang is to assist slow shifters on the upshifts. It is a sort of rev matching, though not for downshifts. Has nothing to do with emissions. Lots of us have it disabled anyway.

 

[cxwrench]

Rev hang is to assist slow shifters on the upshifts. It is a sort of rev matching, though not for downshifts. Has nothing to do with emissions. Lots of us have it disabled anyway.

There are a bunch of articles on the net about it being for emissions, but then again it's proper name is 'shift assist' right? Can you truly get rid of it in a tune?

ETA: This is one thing I found during a quick search.
"The cause of rev hang can be put down to the war on emissions. Recently, manufacturers have been intentionally implementing rev hang within ECU programming to save themselves from a potential emissions scandal. When the throttle is released and the clutch is dipped, an ECU with rev hang is programmed to leave the throttle slightly more open than usual.

This strategy is used because it was found that suddenly closing the throttle produced a sudden spike in gas pressure within the crankcase which emphasised the rate of oil vaporisation, thus adding to emissions from the engine. Also, when the throttle is suddenly shut, the fuel mixture suddenly becomes lean which creates NOx (oxides of Nitrogen) which also contributes to emissions."

 

[METZGER]

Look at MarkCup on YouTube.. he has rev matching and heel toe videos when he had his red FiST.. he mentions that the car holds the revs in between gears.. has all the guages on the screen so you can see it all happening too.

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[cxwrench]

Look at MarkCup on YouTube.. he has rev matching and heel toe videos when he had his red FiST.. he mentions that the car holds the revs in between gears.. has all the guages on the screen so you can see it all happening too.

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Let me repeat...the ST does NOT have rev-matching. When you down-shift in the ST there is NO feature that automatically blips the throttle to rev-match. Does not happen. Rev hang/shift assist is an accidental immitation of the real thing.

ETA: Rev-matching is not a thing when upshifting no matter what he says. That's what has been referred to as 'shift assist' and it's the rev hang. If the ST didn't have that it would actually be easier to upshift quickly. Rev-matching is ONLY for downshifting. You blip the throttle to bring the rpm up to what you need to be in the next LOWER gear. In Markcup's video he brings the rpm up by about 1000 for each downshift. THAT is rev-matching.

 

[M-Sport fan]

Absolutely, as do I. Is it noticeably worse w/ a quick shifter?

I don't notice it at all with a Mountune 30% reduction 'plate', but maybe I just got used to it?

MANY who have short shift mods also have the rev hang disabled through an aftermarket tune.

 

[cxwrench]

I don't notice it at all with a Mountune 30% reduction 'plate', but maybe I just got used to it?

MANY who have short shift mods also have the rev hang disabled through an aftermarket tune.

I think you're dead on w/ this. I'm guessing if you buy an aftermarket tune you can specify how you'd like it? I have only Cobb OTS Stage 1 at this point.

 

[alexrex20]

The shift assist is technically rev matching for you, if you think about it. It allows the rpm to drop no lower than the perfect rpm for the next higher gear, given your speed. So in effect, it is matching revs for the next gear. But I agree, rev matching traditionally refers to throttle blipping on downshifts.

Shift assist can be disabled via ForScan (free software, just need a OBDII-USB cable) or with any AP tune. I have mine disabled. I absolutely HATE it because it doesn't let you skip gears smoothly/quickly.

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[METZGER]

It doesn't blip the throttle it just stops the revs dropping at a point.. mine does it too. I never said that it blips the throttle...

Let me repeat...the ST does NOT have rev-matching. When you down-shift in the ST there is NO feature that automatically blips the throttle to rev-match. Does not happen. Rev hang/shift assist is an accidental immitation of the real thing.

ETA: Rev-matching is not a thing when upshifting no matter what he says. That's what has been referred to as 'shift assist' and it's the rev hang. If the ST didn't have that it would actually be easier to upshift quickly. Rev-matching is ONLY for downshifting. You blip the throttle to bring the rpm up to what you need to be in the next LOWER gear. In Markcup's video he brings the rpm up by about 1000 for each downshift. THAT is rev-matching.

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[alexrex20]

Btw, I have an FSWerks short shift adapter plate set at 25%. I don't know if it makes my shifts any quicker, but it certainly feels nicer lol.

When I'm flat foot shifting and slamming gears, I don't think the short shift kit makes a difference.

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[cxwrench]

It doesn't blip the throttle it just stops the revs dropping at a point.. mine does it too. I never said that it blips the throttle...

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Maybe you should re-read my posts a few times...I don't think you're understanding what I'm posting. Try again.

 

[Ford ST]

Why would anyone want to answer somebody that's as rude as you. Disable the damn feature problem solved and quit bitching at people.

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[cxwrench]

Btw, I have an FSWerks short shift adapter plate set at 25%. I don't know if it makes my shifts any quicker, but it certainly feels nicer lol.

When I'm flat foot shifting and slamming gears, I don't think the short shift kit makes a difference.

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You just did the plate? No bushings or anything else? It feels good stock, I wouldn't mind at all if it felt a little more solid.