Clunk when shifting from park to reverse (after sitting overnight)
12-13-2006, 10:14 AM
#1
Guest
Posts: n/a
Clunk when shifting from park to reverse (after sitting overnight)
Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
of 70,000 miles...
Seemed to notice this after the weather began to cool down... when
starting the vehicle after it has been sitting for more than 8 hours,
and shifting from park to reverse, there's a brief, one second delay,
then a loud clunk / thump, before it feels like it's in gear and
starts actually moving in reverse.
If I shift into drive first from park, then reverse, the loud clunk is
much less pronounced, but still there.
If I drive the vehicle within a certain window of time (ie: leaving
work in the afternoon or going to lunch), the transmission shifts just
fine from park into reverse - no loud clunking or delay before it
drops into reverse. This happens ONLY when the thing has been sitting
in the garage for a while.
Transmission fluid level is OK, and the color seems fine (light
reddish color).
Any ideas out there as to the cause?
Thanks in advance.
(please reply to the group - my e-mail address is munged to prevent
SPAM)
of 70,000 miles...
Seemed to notice this after the weather began to cool down... when
starting the vehicle after it has been sitting for more than 8 hours,
and shifting from park to reverse, there's a brief, one second delay,
then a loud clunk / thump, before it feels like it's in gear and
starts actually moving in reverse.
If I shift into drive first from park, then reverse, the loud clunk is
much less pronounced, but still there.
If I drive the vehicle within a certain window of time (ie: leaving
work in the afternoon or going to lunch), the transmission shifts just
fine from park into reverse - no loud clunking or delay before it
drops into reverse. This happens ONLY when the thing has been sitting
in the garage for a while.
Transmission fluid level is OK, and the color seems fine (light
reddish color).
Any ideas out there as to the cause?
Thanks in advance.
(please reply to the group - my e-mail address is munged to prevent
SPAM)
12-13-2006, 10:44 AM
#2
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Your Factory Service Manual should have a whole transmission section with
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 10:44 AM
#3
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Your Factory Service Manual should have a whole transmission section with
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 10:44 AM
#4
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Your Factory Service Manual should have a whole transmission section with
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
diagnosis charts.
Here is a link to the charts on a 2002 42re transmission.
http://s112.photobucket.com/albums/n...0Transmission/
"Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 10:49 AM
#5
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
You are describing the noise and feel of a blown u-joint.
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 10:49 AM
#6
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
You are describing the noise and feel of a blown u-joint.
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 10:49 AM
#7
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
You are describing the noise and feel of a blown u-joint.
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
If you block the wheels and put it in neutral to unload the drivetrain,
you can go under and check the driveshaft u-joints. You twist and push
at them as well as do a visual looking for rust stains around the caps.
One arm on one will likely be just flopping around.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)
Robert Giles wrote:
>
> Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> of 70,000 miles...
>
> Seemed to notice this after the weather began to cool down... when
> starting the vehicle after it has been sitting for more than 8 hours,
> and shifting from park to reverse, there's a brief, one second delay,
> then a loud clunk / thump, before it feels like it's in gear and
> starts actually moving in reverse.
>
> If I shift into drive first from park, then reverse, the loud clunk is
> much less pronounced, but still there.
>
> If I drive the vehicle within a certain window of time (ie: leaving
> work in the afternoon or going to lunch), the transmission shifts just
> fine from park into reverse - no loud clunking or delay before it
> drops into reverse. This happens ONLY when the thing has been sitting
> in the garage for a while.
>
> Transmission fluid level is OK, and the color seems fine (light
> reddish color).
>
> Any ideas out there as to the cause?
>
> Thanks in advance.
>
> (please reply to the group - my e-mail address is munged to prevent
> SPAM)
12-13-2006, 01:20 PM
#8
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Let me take a stab at this:
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
12-13-2006, 01:20 PM
#9
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Let me take a stab at this:
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
12-13-2006, 01:20 PM
#10
Guest
Posts: n/a
Re: Clunk when shifting from park to reverse (after sitting overnight)
Let me take a stab at this:
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
Your 42re doesn't circulate fluid through the torque converter when it
is in park -- the logic from the factory was to minimize parasitic
losses when the vehicle wasn't "in use". When the front pump bushing
has worn a bit, you get converter "drainback" (whether or not you have
a check valve in the cooler line). The transmission pump circulates
through the converter and cooler when in any position but park -- so
there's the one-second delay from extended shut-down. You're not
gassing it during the delay, are you?
On top of it all, that transmission uses unregulated, full-pump
pressure when in reverse. Hotter fluid -- therefore thinner and easier
for the torque converter to move through -- would make for a softer
engagement. I'm supposing that all these factors lead to the harsh
reverse engagement -- and therefore the louder clunk than from another
gear or a quick restart. So I'm with the others on bad u-joint/worn
spiders/bad motor or transmission mount potentially making the audible
clunk after a rougher than usual shift from park.
Take a walk over to alt.autos.dodge.trucks, there's a handful of guys
(i.e. Tom Lawrence) who are very knowledgeable about this transmission.
Jon
billy ray wrote:
> Your Factory Service Manual should have a whole transmission section with
> diagnosis charts.
>
> Here is a link to the charts on a 2002 42re transmission.
>
> http://s112.photobucket.com/albums/n...0Transmission/
>
> "Robert Giles" <KeepTheSPAMrgilesAWAY@mail.utexas.edu> wrote in message
> news:b560o2lf38cshsn68bggnf1jv7ohfdb3bm@4ax.com...
> > Howdy folks - I have a 2000 WJ, 2WD, 4.0L, 42RE transmission, just shy
> > of 70,000 miles...
> >
> > Seemed to notice this after the weather began to cool down... when
> > starting the vehicle after it has been sitting for more than 8 hours,
> > and shifting from park to reverse, there's a brief, one second delay,
> > then a loud clunk / thump, before it feels like it's in gear and
> > starts actually moving in reverse.
> >
> > If I shift into drive first from park, then reverse, the loud clunk is
> > much less pronounced, but still there.
> >
> > If I drive the vehicle within a certain window of time (ie: leaving
> > work in the afternoon or going to lunch), the transmission shifts just
> > fine from park into reverse - no loud clunking or delay before it
> > drops into reverse. This happens ONLY when the thing has been sitting
> > in the garage for a while.
> >
> > Transmission fluid level is OK, and the color seems fine (light
> > reddish color).
> >
> > Any ideas out there as to the cause?
> >
> > Thanks in advance.
> >
> > (please reply to the group - my e-mail address is munged to prevent
> > SPAM)
