Different Kind of Carnage (at least for me)
08-13-2008, 02:53 PM
#11
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Time = .250 (if memory serves)
Pressure = stock & lower (depends on gear)
Pressure Control Solenoid (PCS) = physically not modified
Lower than stock pressure setting allowed for "slipping" effect during downshift transition... The PCS tried to raise fluid pressure to satisfy setpoint (detected by PSA) before PCM commands downshift. Pressure setpoint was eventually satisfied (coincidentally whilst I started to let off the "go" pedal), and PCM commanded the gear change. Unfortunately, higher pressure buildup was already in the works, PCM got the go-ahead for downshift, but me letting out surpassed that requirement & allowed 3-4 fluid feed (de-energized B solenoid) for harder 3rd/4th apply (with the 2-4 band not being applied to the reverse input drum yet). I strongly suspected the apply force (surge of pressure) ultimately compressing the apply plate, steels and clutches against the retaining ring is what killed the "tangs" on the drum.
As for me thinking to adjust pressure settings to soften shifts, that probably wasn't the best route to go (obviously, right?). Vac mod would eliminate "hunting" (IMO), and should give me a faster pressure response. Who's to say the solenoid operates as it should at all times? I have some time to think about this. Remember, I'm no pro, so I gotta study this longer than those who've done this for over a decade.
BTW, trans shifted PERFECT at WOT. The problem was always at part throttle and downshift transitions.
Pressure = stock & lower (depends on gear)
Pressure Control Solenoid (PCS) = physically not modified
Lower than stock pressure setting allowed for "slipping" effect during downshift transition... The PCS tried to raise fluid pressure to satisfy setpoint (detected by PSA) before PCM commands downshift. Pressure setpoint was eventually satisfied (coincidentally whilst I started to let off the "go" pedal), and PCM commanded the gear change. Unfortunately, higher pressure buildup was already in the works, PCM got the go-ahead for downshift, but me letting out surpassed that requirement & allowed 3-4 fluid feed (de-energized B solenoid) for harder 3rd/4th apply (with the 2-4 band not being applied to the reverse input drum yet). I strongly suspected the apply force (surge of pressure) ultimately compressing the apply plate, steels and clutches against the retaining ring is what killed the "tangs" on the drum.
As for me thinking to adjust pressure settings to soften shifts, that probably wasn't the best route to go (obviously, right?). Vac mod would eliminate "hunting" (IMO), and should give me a faster pressure response. Who's to say the solenoid operates as it should at all times? I have some time to think about this. Remember, I'm no pro, so I gotta study this longer than those who've done this for over a decade.
BTW, trans shifted PERFECT at WOT. The problem was always at part throttle and downshift transitions.
I SEE U STILL HAVING TROUBLE WITH THE TRANNY U SHOULD OF BOUGHT A BUILD UNIT FROM CHUCK AND WOULD HAVE BEEN DONE WITH IT ALREADY HOPE TO MEET U DEC. 13 AT HOUSTON AND UR TRUCK CAN MAKE A COUPLE OF PASSES
08-13-2008, 08:43 PM
#12
formerly 1BADC10 (12/14/2011)
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why don't ya start a charity fund to giveaway a built trans on the quarterly basis for one year, and help those strapped for cash! 
08-15-2008, 07:48 AM
#15
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Ive measured line pressure with and without vac mods. The pressure response with the vacuum mod is waaaaay faster the with the pc sol. The PC sol will delay when downshifted and fluctuate at part throttle. I recommend the vac mod for all performance trannies I build. I run one in my truck and its held up about 15,000 miles no prob. Line pressure at wot is about 235.
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