Has anyone seen a Gear Vendor Overdrive on newer 4L80e?
09-07-2012, 12:22 AM
#11
Yea you definitly have to pay to play.
And yes you are correct on how it splits every gear. My question is: once you split a gear, do you have to turn the gv off when upshifting? So if you are in 1st over and you shift it into 2nd, will it go strait to 2nd over if you don't turn the GV off?
And yes you are correct on how it splits every gear. My question is: once you split a gear, do you have to turn the gv off when upshifting? So if you are in 1st over and you shift it into 2nd, will it go strait to 2nd over if you don't turn the GV off?
09-07-2012, 12:32 AM
#12
TECH Fanatic
Yea you definitly have to pay to play.
And yes you are correct on how it splits every gear. My question is: once you split a gear, do you have to turn the gv off when upshifting? So if you are in 1st over and you shift it into 2nd, will it go strait to 2nd over if you don't turn the GV off? Or will it shift into 2nd normally
And yes you are correct on how it splits every gear. My question is: once you split a gear, do you have to turn the gv off when upshifting? So if you are in 1st over and you shift it into 2nd, will it go strait to 2nd over if you don't turn the GV off? Or will it shift into 2nd normally
I've heard the controllers tend to be on the unreliable side though, failing while both in and out of warranty.
01-06-2015, 06:34 PM
#19
I can answer any question you have about how these work.
As far as using it to reduce E/Ts, it's not practical. The PCM is completely unaware of the Gear Vendors OD and the GV is unaware what gear the transmission is in. Disengaging and engaging it are somewhat unpredictable as far as timing it goes. Don't even try to disengage it with WOT because if you get the timing wrong you can overrev your motor and bend some pushrods, or worse. Also, the hydraulic system in the GV OD is not pulse width modulated - it is full line pressure full time and can therefore feel violent at certain throttle positions. I always upshift mine with my foot off coasting, and I always downshift with throttle applied.
They do have a major weakness with their torque-holding ability with reverse input, it is only springs holding the conical clutch this way. You have to be careful not to overdo it in reverse (like backing a boat trailer with surge brakes uphill) or downshifting. You can downshift just about normally with the unit disengaged but engaged it doesn't have the strength to hold the reverse torque downshifting. I've smoked that overrun clutch in two units. I really wish they would fix that weakness, it would be about perfect.
Here's an old audio only file of the Tahoe (circa 2001), engaging the OD at the top of first and then the PCM shifts to second which is actually second/over. You have to get it just before the PCM would have shifted to second. Splitting the higher gears at higher speeds is more practical.
http://bertok.us/pics/gv0-70.mpg
As far as using it to reduce E/Ts, it's not practical. The PCM is completely unaware of the Gear Vendors OD and the GV is unaware what gear the transmission is in. Disengaging and engaging it are somewhat unpredictable as far as timing it goes. Don't even try to disengage it with WOT because if you get the timing wrong you can overrev your motor and bend some pushrods, or worse. Also, the hydraulic system in the GV OD is not pulse width modulated - it is full line pressure full time and can therefore feel violent at certain throttle positions. I always upshift mine with my foot off coasting, and I always downshift with throttle applied.
They do have a major weakness with their torque-holding ability with reverse input, it is only springs holding the conical clutch this way. You have to be careful not to overdo it in reverse (like backing a boat trailer with surge brakes uphill) or downshifting. You can downshift just about normally with the unit disengaged but engaged it doesn't have the strength to hold the reverse torque downshifting. I've smoked that overrun clutch in two units. I really wish they would fix that weakness, it would be about perfect.
Here's an old audio only file of the Tahoe (circa 2001), engaging the OD at the top of first and then the PCM shifts to second which is actually second/over. You have to get it just before the PCM would have shifted to second. Splitting the higher gears at higher speeds is more practical.
http://bertok.us/pics/gv0-70.mpg
