4L60E shift pressure
09-02-2010, 10:20 AM
#1
4L60E shift pressure My car has a medium built 4L60E, stock FM current table, I had my local shop address the weak links, I am no tranny man but they replaced the band, clutches, and sun shield,...I think that's what they called it...anyway I would like to have a nice smooth shift in the low rpm's and a good solid firm shift when getting on it, I have the pressure table set at about 3-7 above stock now and it feels about right in the lower rpm area but the higher is still way to soft for me, can I go up without to much worry? I know more pressure is usually more wear but can this tranny handle it? The shop that built it said they think these trannys are not as weak as most think and should handle it fine.
09-02-2010, 10:37 AM
#2
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The max is like 240 PSI. My car never did shift right at high rpm and high loads with the computer. I finally had a vacuum modulator tranny built. Yes they can handle the pressure if built correctly. On mine when you go into full throttle and the vacuum drops the trans has full line pressure. I'm not sure what value to put in the tables.
09-02-2010, 12:54 PM
#3
You should keep the force motor tables stock.
You HAVE TO have a mechanical gauge to tune the transmission.
The max line pressure is mechanically built into the transmission, the force motor just bleeds pressure off at lower loads. When your Max Shift Pressure is set to 90 the max line pressure references the 90 column in the force motor table.
If you want to make the shifts more firm you can raise the Base Shift Pressure and the Upshift Pressure Modifiers. This way you only have high pressure during a shift. When you watch a scanner (assuming hp tuners) you will see the force motor current value thats referenced shortly before, during, and shortly after the shift. Current will get lower (higher pressure)when you raise the base shift pressure and shift pressure modifiers.
The first thing you need to do though is find out what your maximum mechanical line pressure is with a gauge and a WOT run. It should be at least 190 psi at WOT.
You can buy a transgo .500 boost valve for around $20 and that should put you around 210 psi with the stock pr spring. If you get the SK kit in the small box it has three springs and the boost valve that, when used together, will give you 240 psi.
Once you get a scan you can look at it and see what force motor current is referenced during each shift. Then you can sit with the car in park and manually raise force motor current with the VCM controls to see what pressure is on the mechanical gauge and adjust it. You will notice when you raise the Upshift Pressure Modifier it will reference a lower force motor amperage (when driving) which means more pressure. After you note (or remember) each column of the force motor and what pressure corresponds with it on the gauge, you'll be able to tune without the gauge.
You may need a shift kit. I have the TransGo HD2 kit and have always had nice firm shifts at WOT, even with stock tuning. I used a gauge and tuning to get more feel in the part throttle shifts.
Hope this all makes sense, I never tried explaining it before.
You HAVE TO have a mechanical gauge to tune the transmission.
The max line pressure is mechanically built into the transmission, the force motor just bleeds pressure off at lower loads. When your Max Shift Pressure is set to 90 the max line pressure references the 90 column in the force motor table.
If you want to make the shifts more firm you can raise the Base Shift Pressure and the Upshift Pressure Modifiers. This way you only have high pressure during a shift. When you watch a scanner (assuming hp tuners) you will see the force motor current value thats referenced shortly before, during, and shortly after the shift. Current will get lower (higher pressure)when you raise the base shift pressure and shift pressure modifiers.
The first thing you need to do though is find out what your maximum mechanical line pressure is with a gauge and a WOT run. It should be at least 190 psi at WOT.
You can buy a transgo .500 boost valve for around $20 and that should put you around 210 psi with the stock pr spring. If you get the SK kit in the small box it has three springs and the boost valve that, when used together, will give you 240 psi.
Once you get a scan you can look at it and see what force motor current is referenced during each shift. Then you can sit with the car in park and manually raise force motor current with the VCM controls to see what pressure is on the mechanical gauge and adjust it. You will notice when you raise the Upshift Pressure Modifier it will reference a lower force motor amperage (when driving) which means more pressure. After you note (or remember) each column of the force motor and what pressure corresponds with it on the gauge, you'll be able to tune without the gauge.
You may need a shift kit. I have the TransGo HD2 kit and have always had nice firm shifts at WOT, even with stock tuning. I used a gauge and tuning to get more feel in the part throttle shifts.
Hope this all makes sense, I never tried explaining it before.
