'96 SL1 Transmission Clunk When Shifting

1996 Saturn SL1. 125K miles. Has been a good car. Current problem when
shifting from Park into either forward or reverse. Engine moves violently
and loud clunk heard. Also experience the same loud noise when driving and
shifts between 2-3 and 3-4. It seems to shift much smoother from 1-2.

I have done some research and identified that the Torque Axis Mount may be a
problem. I looked at the mount and do not see any obvious problems with
cracked/aging rubber, etc. I see a slight spacing in the front and rear
between the rubber and the metal mount holder. When the car goes into gear
and the rubber gets compressed either to the front or rear of the metal
mount I can slip a large screwdriver (1/8 to 1/4") in the space between
them.

I have also seen and read stories about bad valve bodies, but am not sure
what the symptoms of a bad valve body would be. In any event, there are no
error codes and the transmission shift points seem to be normal. It is just
the loud clunking, possibly from too much engine movement that seems to be
the issue. As it is dark tonight and late, I have not had the chance to
crawl under the vehicle to look at any of the other motor mounts.

My question to the group is what is the most common cause so I can
investigate this further. The car is my son's and we need to get him safely
back on the road. How much space should there be in the Torque Axis Mount
and does the movement I am seeing seem right when going between gears while
the vehicle is at rest and the parking brake is applied? I am tempted to
take a quick look under the car if the other mounts look good to replace the
TAM since it seems easiest. Any advice or thoughts from those who may have
seen this problem before? Responses ASAP would be appreciated.

Bob

 

Update: I removed the torque axis mount and it looked like the rubber had
shrunk pretty badly so I went to the local dealer and bought a replacement
($73). it seemed much stiffer, so I was hopeful that it would resolve the
clunking.

Unfortunately, the replacement made little difference, although the engine
does not move as much anymore. But, the loud "clunk" when shifting is still
there and sounds like it is getting worse. The clunk is heard worst when
shifting between park and reverse, and then less noticeable, but still bad
between neutral and drive. I did not hear much going from drive to 3rd and
then 2nd, although there seemed to be a faint "buzzing" in 2nd while still
at a stop. When I take it out of the garage for a spin, the clunk is bad on
every shift and downshift too, but they appear to happen at the right
RPM/speed. When it is in a single gear, like 2nd, it drives perfectly and
sounds fine. It is only when it up and down shifts that it sounds like it
is getting torn apart and the shift is extremely harsh. .

Can someone who has had the auto trans "valve body" problem please describe
the symptoms and approximate cost of the part & difficulty of the repair?
Any other ideas? Thanks in advance.

Bob

 

Have you tried a drain and fill (or two) of the trans fluid? I started
having the signs of the valve-body problem (slippage, clunk/hard shift), but
a drain-and-fill with Mobil Synthetic Trans Fluid fixed the problem for
going on 8k miles.

 

After I replaced the Torque Axis Mount and saw no improvement I drained the
fluid and changed the filter hoping that would solve it, but again, no
improvement. (The previous fluid and filter had been replaced just about 18
months and 15K miles ago.) As a last resort, I even tried removing the
battery cable for 2 minutes to reset the transmission computer. Again, no
improvement.

At this point I'm researching a Saturn Fans web site that has an unorthodox
"cure" for the "reverse slam" posted. It involves running the vehicle in
reverse against a stationary object for 30 minutes to get the fluid hot and
force it through the clogged valve body. I figure there isn't too much to
lose at this point, but would like to verify that my symptoms are in fact
caused by the same fault since nowhere did anyone on that site mention
clunking when shifting forward gears.

Thanks for the thought. If anyone else can confirm this is the reverse slam
or provide other thoughts, let me know.

Bob

 

Is it slow to engage from reverse to drive and vice versa? If its not
the valve body it might be the retaining pin in the diff.

 

Thanks for the reply. It engages perfectly and seems to be at the normal
time when shifting from park to reverse. There is no noticeable delay. It
also shifts at normal times when driving or so it appears. The only symptom
is the extremely harsh nature and loud "clunk" that comes with the shift,
even when at a dead stop and engaging the gears for the first time when
attempting to back out of the garage.

Any other thoughts? My intention is to try to 30 minute reverse at idle
with the brakes holding the vehicle still. At this point I've already
changed the fluid and filter so all I need to do is add the trans cleaner
additive. So if it does not work, I will only have lost the time and gas I
burned.

Bob

 

I'm certainly no expert, but from your description, there appears to be
nothing wrong with the tranny. You say it shifts at the right time, and
with no noticeable delay or clunk. Have you considered "drive line play"?
In other words, if a CV joint has play in it, the tranny will appear to
clunk as the slack is taken up. This is particularly noticeable when going
from drive to reverse with brakes applied.
Just a thought!

 

I have been under the car with it up and when the shifter is moved between
reverse and park it the sound seems to actually come from the transmission
itself. I will take another look, but even though it is shifting at the
correct RPM torque points, it is definitely not right. Much too harsh and I
suspect this is what is causing the noise. This is why I thought that the
"reverse slam" was a good description. It does seem to be "slamming" into
gear too abruptly but this is with all gears, not just reverse and that is
why I was not sure if it was the same thing.

 

(Hopefully) Final Update on my '96 Transmission problem (the trans was
shifting extremely harshly between all gears and even when going from Park
to Reverse):

The lower motor mounts looked good - the engine moved less than 1/2"
laterally even during the harsh shifting, so I decided to go into the TAAT
transmission through the top valve body cover (which is located under the
12V battery holder).

After removing the outer cover (13 bolts) and then removing 19 more bolts
that held the internal solenoid cover in place, I was able to remove the
solenoids themselves. There were 5 in total and 4 of them measured 4.4 to
4.5 ohms each which agreed with the information that Bill Biggs had
provided (they should be 4-6 ohms when "cold"). The 5th solenoid however
measured just 0.6 ohms so appears to have an internal short. This solenoid
is the last in the string nearest the front of the vehicle and I presume the
one that modulates the fluid pressure. Since it was not working, the shifts
were getting full pressure which almost certainly would have caused a
catastrophic problem if we had continued to drive the vehicle and ignored
the "clunking" noise.

I plan to pick up a replacement solenoid tomorrow at the dealer along with a
new cover gasket and then put it all back together and have it back on the
road sometime later this week. Special thanks to Bill Biggs ( a.k.a.
webacraft on the SaturnFans Forum) for his assistance and to Blah Blah,
Steve, and Curmudgeon for their replies.

I hope that this thread may help someone else down the road if they
experience the same problem.

Bob