GMC Hauler
08-30-2007, 16:49
I recently updated my transmission. I had an issue while under medium throttle, in OD with the torque converter locked and vehicle speed around 45 MPH, the torque converter would shudder. I have the electronic shift control, and I adjusted the knob for more line pressure. However, I don't like driving around like that, because the full power shifts are harsh.
So, I installed a shift kit. I used the Transco HP shift kit (4L80E-HD2). It is the third shift kit I have installed, and the most extensive. I have heard on this forum before that adding a shift kit while having a performance PCM can cause extremely harsh shifts. I have overcome this problem. The shift kit has you drill holes in the separator plate to adjust the shift firmness for 1st-3rd gears: .076" soft, .086" average, and .096 firm. I drilled the holes at .092".
I turned off the electronic shift kit to allow the kit in the transmission to do its part.
There were several upgrades I made. The second one was a new separator plate. The plates tend to wear.
I removed the stock cooler and installed a 29K Btu cooler. Trans temp's are now under control while towing.
I also added a remote filter mount and a 1 Qt filter to clean the fluid even further.
The final upgrade was TCC regulator valve kit (K33887). It came from Sonnax industries. It prevents leakage around the valve, which is a cause of the TCC slipping. The instructions also show you how to adjust TCC lockup firmness. You must peen a hole shut in the separator plate and drill it to .025". It took me a while to find this bit. My hope was that this in combination with the shift kit would fix my TCC woes before it was beyond repair.
When I took the vehicle down for these modifications, I cut the trans cooler line for modifications and to drain the trans as much as possible. I started the vehicle. As soon as fluid stopped coming out of the hose, I shut the Sub down. There was plenty of fluid in the pan after removing it. I let it drip for several hours.
This was a good time to update to synthetic, so with the help of Greg Landuyt, I used Amsoil synthetic trans fluid. I ended up adding 3.75 gallons of fluid to fill the trans, lines, and the filter. According to the service manual, this (minus the amount for the line and filter and cooler) is pretty close to a full change with draining the torque converter.
Have a few cans of carb cleaner handy. There was plenty of dirt in the passages of the valve body.
Towing with this was incredible! Before when I had only the electronic kit, shifts under load towing were harsh and made the vehicle "hop" (set on 4). The kit in the transmission reduced the harshness of this shift, while keeping the firm shift. Shifts feel better now, and there is no slippage.
Verdict: Forget the electronic shift kits, go with the valve body kit!
So, I installed a shift kit. I used the Transco HP shift kit (4L80E-HD2). It is the third shift kit I have installed, and the most extensive. I have heard on this forum before that adding a shift kit while having a performance PCM can cause extremely harsh shifts. I have overcome this problem. The shift kit has you drill holes in the separator plate to adjust the shift firmness for 1st-3rd gears: .076" soft, .086" average, and .096 firm. I drilled the holes at .092".
I turned off the electronic shift kit to allow the kit in the transmission to do its part.
There were several upgrades I made. The second one was a new separator plate. The plates tend to wear.
I removed the stock cooler and installed a 29K Btu cooler. Trans temp's are now under control while towing.
I also added a remote filter mount and a 1 Qt filter to clean the fluid even further.
The final upgrade was TCC regulator valve kit (K33887). It came from Sonnax industries. It prevents leakage around the valve, which is a cause of the TCC slipping. The instructions also show you how to adjust TCC lockup firmness. You must peen a hole shut in the separator plate and drill it to .025". It took me a while to find this bit. My hope was that this in combination with the shift kit would fix my TCC woes before it was beyond repair.
When I took the vehicle down for these modifications, I cut the trans cooler line for modifications and to drain the trans as much as possible. I started the vehicle. As soon as fluid stopped coming out of the hose, I shut the Sub down. There was plenty of fluid in the pan after removing it. I let it drip for several hours.
This was a good time to update to synthetic, so with the help of Greg Landuyt, I used Amsoil synthetic trans fluid. I ended up adding 3.75 gallons of fluid to fill the trans, lines, and the filter. According to the service manual, this (minus the amount for the line and filter and cooler) is pretty close to a full change with draining the torque converter.
Have a few cans of carb cleaner handy. There was plenty of dirt in the passages of the valve body.
Towing with this was incredible! Before when I had only the electronic kit, shifts under load towing were harsh and made the vehicle "hop" (set on 4). The kit in the transmission reduced the harshness of this shift, while keeping the firm shift. Shifts feel better now, and there is no slippage.
Verdict: Forget the electronic shift kits, go with the valve body kit!