Another 997 GT3 Cup car video from Japan
12-15-2009, 11:26 PM
#46
Now that we have clarified that the transmission in the Aussie V8 Supercar is a "dog ring" box (still not sure if it is an H pattern or a sequential pattern), I watched the video a couple more times to try to learn something. The interesting thing that I noticed about Greg Murphy's upshifts down the straight beginning at 0:59 is that it looks like he is not lifting off the accelerator at all while using the clutch lightly to make the upshifts. Am I seeing this right? If so, what is providing the momentary ignition (or fuel) cut to release the tension off the driveline to enable the upshift to happen?
Let me give you some additional background -> I do understand that sequentially shifted dog ring boxes can relatively easily use an electronic sensor to sense when the shift lever is pulled towards the rear of the car to make upshifts and correspondingly cut the ignition and/or fuel. However, it would seem that such and electronic sensor would be difficult to implement on an H pattern dog ring box. So I guess my real question is this -> How do you electronically cut the ignition and/or fuel to enable you to shift an H pattern dog ring box without lifting your foot off the accelerator pedal?
Jeff
Let me give you some additional background -> I do understand that sequentially shifted dog ring boxes can relatively easily use an electronic sensor to sense when the shift lever is pulled towards the rear of the car to make upshifts and correspondingly cut the ignition and/or fuel. However, it would seem that such and electronic sensor would be difficult to implement on an H pattern dog ring box. So I guess my real question is this -> How do you electronically cut the ignition and/or fuel to enable you to shift an H pattern dog ring box without lifting your foot off the accelerator pedal?
Jeff
12-15-2009, 11:46 PM
#47
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12-15-2009, 11:59 PM
#48
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My understanding is you can do it either way, with or without the clutch. 1- If no clutch, you need to be extra precise. 2- As Mike P. said, it is probably pretty hard on the tranny w/out clutch.
12-16-2009, 12:13 AM
#49
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Jeff
12-16-2009, 01:38 PM
#50
I was thinking more about the flat upshifts...
I don't think it would be too hard to have a strain gauge on the shifter (like a sequential box) and program some logic into the ECU like: if wide open throttle and gear lever moved -> then cut ignition.
I have a friend who owns a couple of the PTG built world challenge E46 M3's and those cars use a Hewland H-pattern dog-ring box. He has told me that they have flat upshift capability, but he doesn't like to use it because it's hard on the car.
I don't think it would be too hard to have a strain gauge on the shifter (like a sequential box) and program some logic into the ECU like: if wide open throttle and gear lever moved -> then cut ignition.
I have a friend who owns a couple of the PTG built world challenge E46 M3's and those cars use a Hewland H-pattern dog-ring box. He has told me that they have flat upshift capability, but he doesn't like to use it because it's hard on the car.
12-16-2009, 04:48 PM
#51
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As long as we are now on the subject of H pattern dog-ring boxes, and to tie this thread back to Cup cars, does anyone happen to know if any of the 996 Cup cars use dog-ring boxes? Or, do they use H pattern synchromesh boxes?
Jeff
Jeff
12-16-2009, 06:56 PM
#52
Drifting
The 996 Cup Car uses an H-pattern gearbox with synchros. In the US, Alex Job Racing debuted the sequential in the 2003 ALMS season. Sequentials were later standard equipment in the 2004 RSR.
