Rpms not dropping fast enough when speed shifting

[Higgs Boson]

I've never once felt this in the car. And I'd be willing to bet it isn't real.

Exactly. Once again, driver error. If you don't let completely off the gas before you start the clutch pedal pressing.....rpms will hang or rise. Normally this is a good thing in a speed shift, which is why some stay wot through the shift.

Sponsored

 

[Blake5]

If you're trying to smoothly match your RPMs during a "fast shift" then it isn't fast.

This is all I was wondering the entire time. If it was rev hang or if that's what this car is like during hard shifts, because I've driven a 850whp gt500 with SMOOTH hard shifting

 

[Higgs Boson]

Because I know if I said it originally I'd have people like you saying its driver error when I know it's not. I know how to shift slow even with the 2nd stage rev hang for the next gear, but I'm talking about when I shift fast

I know you think it's not driver error but that doesn't mean it's not. Post a question, be open to learning not just waiting for the answer that reinforces what you want to hear.

 

[Higgs Boson]

This is all I was wondering the entire time. If it was rev hang or if that's what this car is like during hard shifts, because I've driven a 850whp gt500 with SMOOTH hard shifting

That was said multiple times to you in this thread.

 

[Blake5]

That was said multiple times to you in this thread.

No it hasn't. Everybody thought I was talking about the rev hang for the next gear when I wasn't even remotely talking about that. I now realize the hard jerkiness is a normal part of a hard shift. I thought it wasn't good for the transmission therefore I tried to make it smooth

 

[Higgs Boson]

No it hasn't. Everybody thought I was talking about the rev hang for the next gear when I wasn't even remotely talking about that. I now realize the hard jerkiness is a normal part of a hard shift. I thought it wasn't good for the transmission therefore I tried to make it smooth

I never told you it was rev hang, I told you multiple times it was:

1. Not a speed shift
2. Driver error

Both of which turned out to be correct.

You can apologize by pm if you want, it will mean just as much to me.

 

[Horse]

I agree it is 100% a discrepancy in what speed shifting really is. When you are shifting fast, the idea is to have the clutch in for as short a time as possible. There is no rev hang because a fast pedal release engages the next gear and the motor drags the rpms down. If you are waiting at all for the car to do something then you are waiting far too long.

The rpms drop slow during normal "gas off" events because the throttle blade does not shut all the way or quickly like a cable actuated throttle. This makes no difference in a speed shift....I don't even let off the gas anyways.

Otherwise it's a normal shift and you have to slip the clutch at least a tiny bit to smoothly couple the clutch and pressure plate.

Understood.

But, no-lift (power)shifting is not smooth BY DEFINITION, b/c rpms don't match. I know many of you don't care/feel it, but it does not mean the non-smoothness does not exist.

Yes, the factory tune plus slow reaction of throttle blade are to blame for the rev-hang (plus heavy flywheel). But this also indicates that with a right tune, lighter flywheel, and right throttle blade set-up, the rev hang can be eliminated and the rpm will drop fast just enough for the fastest driver. (I know this kind of car would be hard to drive for ordinary drivers. But in theory, such cars have it value. In fact, race cars behave like this, as far as I know.)

 

[Horse]

No it hasn't. Everybody thought I was talking about the rev hang for the next gear when I wasn't even remotely talking about that. I now realize the hard jerkiness is a normal part of a hard shift. I thought it wasn't good for the transmission therefore I tried to make it smooth

Yes, if you don't want to do anything to the car and still want to shift fast, you have to accept non-smoothness as an integral part of shifting. After a while, it won't feel that bad any more, and the jerky impact pushes you back into your seat.

 

[Higgs Boson]

Understood.

But, no-lift (power)shifting is not smooth BY DEFINITION, b/c rpms don't match. I know many of you don't care/feel it, but it does not mean the non-smoothness does not exist.

Yes, the factory tune plus slow reaction of throttle blade are to blame for the rev-hang (plus heavy flywheel). But this also indicates that with a right tune, lighter flywheel, and right throttle blade set-up, the rev hang can be eliminated and the rpm will drop fast just enough for the fastest driver. (I know this kind of car would be hard to drive for ordinary drivers. But in theory, such cars have it value. In fact, race cars behave like this, as far as I know.)

Yes that's pretty much what I was saying.

The slow reaction of the throttle blades is due to the stock tune, so I also agree with the second part of your post.

Cars have been like this for quite a while now, especially since they went to torque based logic instead of airflow based.

A lighter rotating assembly, whether a crank pulley or flywheel or pistons, rods, or crankshaft will all spin up faster and once the turn is made to decel, spin down faster. This is why stock flywheels are heavy. Quieter and easy for the regular Joe to modulate. Light flywheels often require retuning just to catch idle without stalling.

 

[Horse]

Everybody thought I was talking about the rev hang for the next gear when I wasn't even remotely talking about that. I now realize the hard jerkiness is a normal part of a hard shift. I thought it wasn't good for the transmission therefore I tried to make it smooth

In your case it's not driver error. If anything, it was only that you were asking for something (both fast and smooth) that the stock S550 can not deliver (due to rev-hang).

 

[Higgs Boson]

In your case it's not driver error. If anything, it was only that you were asking for something (both fast and smooth) that the stock S550 can not deliver (due to rev-hang).

What car in the last 15 years can do a "fast and smooth" shift without some pedal or clutch modulation? OP already stated that the issue he experienced is not due to rev hang. Again, if you are doing a "smooth" shift, there is no way it is also "fast."

 

[Blake5]

What car in the last 15 years can do a "fast and smooth" shift without some pedal or clutch modulation? OP already stated that the issue he experienced is not due to rev hang. Again, if you are doing a "smooth" shift, there is no way it is also "fast."

I still believe it is rev hang from 1st to 2nd as this morning I tried again and the same problem reoccurred. Even with stress to my pedal timing the rpms just don't drop like they should from 1st to 2nd

 

[Horse]

What car in the last 15 years can do a "fast and smooth" shift without some pedal or clutch modulation? OP already stated that the issue he experienced is not due to rev hang. Again, if you are doing a "smooth" shift, there is no way it is also "fast."

Let us both read OP's original post and see what he was asking.

(And, let's don't splitting hairs over what `speed shift' means. Instead, let's try to answer the OP's question/concern. Simply telling the OP to do power shifting may not be what he needs, even though you and many others have been power shifting with success.)

The OP clearly stated that he wanted to match the rpm for 1-2 shift. But the engine rpm does drop fast enough (rather, it hangs there for too long). Yes, one can take it slow and wait for the rpm to drop. But the OP also wants to shift fast (while matching the rpm). So the OP asked why/how, etc.

Yes, you can tell the OP that what he tries to accomplish is not possible in stock S550 due to factory dialed-in rev hang. You can also suggest the OP to power shift and forget smoothness.

But I would not call it driver error.

 

[Horse]

Speed shifting is let off the gas pushing the clutch down and shifting as fast as you can shift. Power shifting is when you matt the floor with you loud peddle and shift with the clutch and never let off the gas peddle. Snatch a gear and at the same time side step your clutch. And release it via letting your foot slide off the clutch peddle.

Why do you need the rpms to drop while shifting? I want my rpms to be up there so I can keep the engine in the power band.:cheers:

This is also how I interpret speed shifting and power shifting.

Why I need rpms to drop when upshifting? Because I want the rpm to match (for smoothness). Don't get me wrong, I do understand why you guys like to power shift. But please also try to understand those of us who pursue smoothness over power :cheers:

 

[Blake5]

Speed shifting is let off the gas pushing the clutch down and shifting as fast as you can shift. Power shifting is when you matt the floor with you loud peddle and shift with the clutch and never let off the gas peddle. Snatch a gear and at the same time side step your clutch. And release it via letting your foot slide off the clutch peddle.

Why do you need the rpms to drop while shifting? I want my rpms to be up there so I can keep the engine in the power band.:cheers:

For a smooth shift without having to slip the clutch.. Basically just a fast shift without the jerk in the car. I get when hard/racing shifting it'll jerk, but I'm talking about a smooth fast shift when not racing so its comfortable.

Sponsored