View Poll Results: Have you mis-shifted?
Yes- I broke something AP1
0
0%
Yes - I broke something AP2
0
0%
Voters: 59. You may not vote on this poll
Have you ever mis-shifted?
10-28-2015, 12:43 PM
#11
Thanks and understood. I'm curious about everything that happens in a case like this.
My admittedly weak math guesstimates an engine speed of about 10,800 rpm would result if 2d gear was engaged at 76mph. I'm interested in the blanket statement that the engine would survive this "one gear down" incident.
(3d gear in an AP2 with OEM tire size is darn near a 100:1 with the tach and speedo. 7800rpm just about equals 78mph. +/- a couple.)
-- Chuck
My admittedly weak math guesstimates an engine speed of about 10,800 rpm would result if 2d gear was engaged at 76mph. I'm interested in the blanket statement that the engine would survive this "one gear down" incident.
(3d gear in an AP2 with OEM tire size is darn near a 100:1 with the tach and speedo. 7800rpm just about equals 78mph. +/- a couple.)
-- Chuck
10-29-2015, 04:00 AM
#12
Join Date: Nov 2007
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The bottom end can survive the momentary ride to 10,800RPM. The valves contacting the pistons is the potential issue at that RPM. A compression and leakdown test should give some insight.
Be kinda smart for car manufacturers to include a clutch disengage solenoid for mechanical over-revs on H pattern manual cars. That's the only type of "rev limiter" that would work in that situation.
Be kinda smart for car manufacturers to include a clutch disengage solenoid for mechanical over-revs on H pattern manual cars. That's the only type of "rev limiter" that would work in that situation.
10-29-2015, 07:52 AM
#13
If you are a manufacturer looking to dummy proof with solonoids, then why not just have a solonoid that blocks off engaging the wrong gear. Prevent the issue, rather than try and correct it once you have an issue.
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
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Nate Tempest (01-07-2021)
10-29-2015, 10:53 AM
#14
If you are a manufacturer looking to dummy proof with solonoids, then why not just have a solonoid that blocks off engaging the wrong gear. Prevent the issue, rather than try and correct it once you have an issue.
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
10-29-2015, 04:07 PM
#15
1-4, it was a long time ago I read about that vette skip shift function, when it first came out. Imperfect memory. Thanks for the correction.
Sent from my SM-G920P using IB AutoGroup
Sent from my SM-G920P using IB AutoGroup
10-29-2015, 07:03 PM
#16
Agree, the mechanical overrev is the dangerous one.
I learned when I started HDPE in my old 911 that a shift is a 2 beat process ( out of one gear then into the next gear, with gentle pressure on the stick). Sounds slower but is just as fast and smoother(and less upsetting to the car) when you learn it.
If you macho shift like a bolt action you get no feedback until its too late.
With a gentle 2 beat shift you'll get resistance and engine sound that gives you the chance to recover.
my 2 cts
I learned when I started HDPE in my old 911 that a shift is a 2 beat process ( out of one gear then into the next gear, with gentle pressure on the stick). Sounds slower but is just as fast and smoother(and less upsetting to the car) when you learn it.
If you macho shift like a bolt action you get no feedback until its too late.
With a gentle 2 beat shift you'll get resistance and engine sound that gives you the chance to recover.
my 2 cts
This car is not a quarter mile dragster. Shift with a deliberate action and you'll be fine
10-30-2015, 06:33 AM
#17
Join Date: Nov 2007
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If you are a manufacturer looking to dummy proof with solonoids, then why not just have a solonoid that blocks off engaging the wrong gear. Prevent the issue, rather than try and correct it once you have an issue.
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
Would seem easier to build that solonoid too. Smaller, lighter, less effort, less travel, etc.
Years back, to meet mpg target, vette's had this solonoid that would engage this ramp shaped wedge that would force a 2-3 shift to instead divert to 2-5 (not making syncros happy). This kept them from having to have a gas guzzler tax. It was easy to disable, just cut a wire.
An early version of what Audi is dealing with now, except it put all the onus on the owner, not on Chevy. But I digress...
Point is, a similar scheme could be employed to make sure one didn't misshift. Prevent the shift from going the wrong way when resulting rpm would exceed some unsafe value. Lockout a downshift when rpm above a set value.
I think that could be done in an unintrusive way that would not take away from the driving experience.
Sent from my SM-G920P using IB AutoGroup
Intuitive or predictive systems are never too great...and are harder to design without being intrusive. Preventative systems are usually better.
You'd turn off adaptive or predictive type traction control because it would get in your way. It would also be a very expensive option if it were to even come close to working well.
You wouldn't turn off a rev limiter that prevents you from blowing up the engine.
Predictive stuff is too conservative. A predictive gear lockout would prevent you from selecting a lower gear at even close to the gear limited speed. When you're at the track braking and downshifting simultaneously, it would likely get in the way. And/or would be expensive.
I figure a solenoid that disengages the driveline after the limiter has actually been reached would be MUCH cheaper/less intrusive and more simple than locking out each individual gear as speed increases on a H pattern car.
10-30-2015, 07:23 AM
#18
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^I suppose that complexity and safety reasons would arise when the solenoid retracts and allows the slave cylinder to release once the speed comes down to an acceptable range. You'd have to do it without shocking the driveline and causing a potential loss of control.
10-30-2015, 08:21 AM
#19
Well, these SMG's, with launch control, etc, seem to have sorted the solonoid activates the clutch issue, so perhaps a clutch disengage solonoid would be effective.
I still think a gear selection lockout could be done seamlessly, and almost invisibly. Yeah, it could also be done badly. But with the right goals in mind...
Sent from my SM-G920P using IB AutoGroup
I still think a gear selection lockout could be done seamlessly, and almost invisibly. Yeah, it could also be done badly. But with the right goals in mind...
Sent from my SM-G920P using IB AutoGroup
11-09-2015, 01:06 PM
#20
They go 1-4 because it doesn't change the shift direction. You pull back from first, you get 2nd - or 4th if the lockout kicks in. A sedate driver headed to the grocery story probably wouldn't even notice the difference. To lock out just 2nd and go 1-3, you would change the driver's shift pattern from "pull back" to "pull back, over, and up". That same driver headed to the grocery story would probably tke the car in for service saying the shifter was broken, lol...