01M automatic gearbox modification

Here is an easy, free mod you can do when you service your auto transmission for fluid and filter change, or whenever you have the pan off. I found this while developing my new plug-in "tuning box" for these transmissions (an ugly but functional working prototype is in my car right now)

Here is a picture of the valve body from underneath the car, with the pan and filter removed:

Here is a closer view of the area around the adjustment:

The funny cap srew with the "star-shaped" notches is what you will turn to make the adjustment. Here is a picture of the hex wrench in the appropriate location:

About the only "special" tool you need is this shortened 3mm hex wrench. I ground mine down to about half the length onthe short end so it would fit. The fitting is actually for a T-20 torx, but it is a very tight fit unless you want to remove the valve body from the transmission, not recommended. 3mm hex works in a pinch if it is shortened.

***Warning***

DO NOT TURN THIS "SCREW" IN THE OUT DIRECTION TO TRY TO LOOSEN IT. YOU WILL BREAK THE LOCKIING TABS THAT LOCK IT IN PLACE.

Here is a fuzzy closeup picture of the star-shaped adjustment, from the valve body on my workbench. Note the locking tabs are broken.... Here's your chance to learn from my mistake, do not try to loosen them, only turn this in the righty-tighty direction.

How far do you turn it? On the workbench I got about 30 "clicks" out of it- you will see what I mean. In the car only about 20 clicks. Maybe I could get more if the wrench was ground a little shorter to get in there better, but it was enough.

The result: much more positive shifts. you need to see for yourself. [img]/images/graemlins/cool.gif[/img]

Ratcheting End Plug Installation and Adjustment

1. To install the end plug, thread into the bore until the pre-measured height is again achieved.

2. Adjustments to the base setting may be required due to variations in the plug, valve body or improvements from either regulator

bore. Initial setting on average OEM parts is .940", measured from the end of the valve to the outer face of the plastic adjuster.

Turning the adjuster clockwise will increase boost pressure, line pressure and create firmer engagements as well as upshifts and downshifts. Turning counter clockwise reduces line pressure at idle and results in softer shifts. Each turn is approximately 8 psialteration.

One turn is drastic and we suggest you go by 1/2to

1/4turns. The outcome of this adjustment is monitored at line pressure tap.

3. A 5/16" socket may be used while threading the plug into the bore. However, the tool will be needed to turn the plug back out

while adjusting to the correct setting.

4. It is very important to verify line pressure when installation is complete. OEM line in Drive is generally 50-56 psi. Reverse is 95-110

at idle. To obtain firm engagements or reduce flare, increase to line in Drive 60 (1/2-turn clockwise). Readjust if not within

this range.

Note:OE line pressure port is a straight 10 x 1.0mm thread with a flanged plug. A line pressure adapter can be made from a

common 1/8th NPT 45-degree adapter. Chase male thread on the adapter with 10 x 1.0 thread die. Gently screw adapter into

the case and then screw pressure gauge into adapter.

Adjustment Tool

119940-TL9

Ratcheting

End Plug

119940-22

Boost Regulator Valve Bore