|
|
|
Welcome to Automatic Transmission Service Group
ATSG is the largest, Employee-Owned, technical support service in the Automatic Transmission Industry. We offer a Technical Hotline, Books, Software, Bulletins, Seminars, and Technical Courses to the Automatic Transmission Professional. Please use the links on the left to find out more or obtain products or services.
|
|
|
Click Below to Visit Our Sponsors
|
|
|
|
 |
A blast from the past, 4T40E
welds by Wayne Colonna |
For those of you who remember the Slim Jim (Roto 10) years,
the weld on the tube going to the fourth coupling would crack. Depending
on the severity of the crack , the transmission would either slip or neutralize
going into fourth gear. That was then. Today, we have a similar problem
with welds cracking in General Motors 4T40-E oil feed tube assembly (Figure
1). Lube failure to the Forward Clutch Support assembly, a slipping or
a loss of reverse, a loss of engine breaking in manual low, and a slipping
or a loss forward are all possible with weld failure of the oil feed tube
assembly.
If you loose forward, you will need to be careful not to pull the unit
right away. What I mean by that is being a good diagnostician, you may
place a gauge on the line pressure tap only to discover that line pressure
is high. A P0730 pending code Gear Ratio Error may be set. With line pressure
being more than sufficient to apply the forward clutch, it may lead you
to believe that the Input Sprag or Lo Roller Clutch is not holding. So
you pull the unit only to find that they are both OK. This is upsetting
when all along it was a Forward Clutch leak at the pipe weld (See Figure
2) which is accessible by dropping the bottom pan.
The fluid going through the pipe to the forward clutch must first pass
through a .090" orifice in the spacer plate
(Figure 3). Line pressure feeding this orifice comes from the manual valve
and the pressure tap for line pressure is
located in the circuit before the manual valve. The feed pressure on the
Tap side of the orifice via the manual valve
was not affected by the pressure drop on the pipe side of the orifice.
And this is why a line pressure check could mislead you to think there is enough pressure to apply the forward clutch.
More>>
PDF or Web page |
|
|
Newly Updated 41TE/42LE Codebook now available for download. Click Here.
