Cherokee transfer case forks broken

I've got a '99 Cherokee Sport with ~90k miles. I was recently driving
in 4wd at around 80mph on a wet highway when I experienced a couple of
bumps from somewhere in the drive train. It felt just like a hit some
rough pavement, in fact that's what I initially thought had happened. I
got out and walked around the vehicle after feeling it again and
realizing that it wasn't the road. I saw nothing out of the ordinary.
About thirty minutes later I got the bump again followed by a horrible
grinding noise. I quickly slowed down and threw it into 2wd. The
grinding stopped, but I'm still getting intermittent bumps. The bumps
vary in intensity and frequency. It basically feels like the vehicle is
being bumped from behind or hitting a large pothole.

So, I took it to a local transmission shop and they opened the transfer
case. They're telling me that the problem is a broken shift fork. The
fork needs to be replaced along with some damaged bearings. Does this
sound right? I don't know much about 4wd since this is my first, but I
fail to understand how this happened or how it was causing the
bump/lurch/jerk. They want to charge me $900 to do this work which
seems steep. Again, I don't know what I'm talking about, so maybe it's
not steep.

Which transfer case do you have? If you have a part-time transfer case
("Command-Trac" or NP231), it is not designed to be driven on hard surfaces
at all, even if the surface is wet. Snow, sand, gravel, dirt is OK, but hard
surfaces are not. The full-time "Selec-Trac" or NP242 can be driven in
full-time mode on any surface.

If you're somewhat handy or have friends that are, you can find low-mileage
Jeep transfer cases on ebay for a couple of hundred dollars (including
shipping) and install it yourself in a day or 2. $900 sounds quite high to
me as well, just for replacing parts.

> wrote in message
oups.com...
> I've got a '99 Cherokee Sport with ~90k miles. I was recently driving
> in 4wd at around 80mph on a wet highway when I experienced a couple of
> bumps from somewhere in the drive train. It felt just like a hit some
> rough pavement, in fact that's what I initially thought had happened. I
> got out and walked around the vehicle after feeling it again and
> realizing that it wasn't the road. I saw nothing out of the ordinary.
> About thirty minutes later I got the bump again followed by a horrible
> grinding noise. I quickly slowed down and threw it into 2wd. The
> grinding stopped, but I'm still getting intermittent bumps. The bumps
> vary in intensity and frequency. It basically feels like the vehicle is
> being bumped from behind or hitting a large pothole.
>
> So, I took it to a local transmission shop and they opened the transfer
> case. They're telling me that the problem is a broken shift fork. The
> fork needs to be replaced along with some damaged bearings. Does this
> sound right? I don't know much about 4wd since this is my first, but I
> fail to understand how this happened or how it was causing the
> bump/lurch/jerk. They want to charge me $900 to do this work which
> seems steep. Again, I don't know what I'm talking about, so maybe it's
> not steep.
>

> wrote in message
oups.com...
> I've got a '99 Cherokee Sport with ~90k miles. I was recently driving
> in 4wd at around 80mph on a wet highway when I experienced a couple of
> bumps from somewhere in the drive train. It felt just like a hit some
> rough pavement, in fact that's what I initially thought had happened. I
> got out and walked around the vehicle after feeling it again and
> realizing that it wasn't the road. I saw nothing out of the ordinary.
> About thirty minutes later I got the bump again followed by a horrible
> grinding noise. I quickly slowed down and threw it into 2wd. The
> grinding stopped, but I'm still getting intermittent bumps. The bumps
> vary in intensity and frequency. It basically feels like the vehicle is
> being bumped from behind or hitting a large pothole.
>
> So, I took it to a local transmission shop and they opened the transfer
> case. They're telling me that the problem is a broken shift fork. The
> fork needs to be replaced along with some damaged bearings. Does this
> sound right? I don't know much about 4wd since this is my first, but I
> fail to understand how this happened or how it was causing the
> bump/lurch/jerk. They want to charge me $900 to do this work which
> seems steep. Again, I don't know what I'm talking about, so maybe it's
> not steep.
>


Yes, it sounds right. If you can do 80, you should not, that's NOT, be in
4WD. You exploded your tcase. While they are putting in the obvious parts,
you may as well get a new chain and sprockets too.

Ahh well.....

I have the Command Trac NP231 in my Cherokee and the owners manual on
page 50 specifically says it is ok to drive on wet pavement with it.....

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Chuck Bremer wrote:
>
> Which transfer case do you have? If you have a part-time transfer case
> ("Command-Trac" or NP231), it is not designed to be driven on hard surfaces
> at all, even if the surface is wet. Snow, sand, gravel, dirt is OK, but hard
> surfaces are not. The full-time "Selec-Trac" or NP242 can be driven in
> full-time mode on any surface.
>
> If you're somewhat handy or have friends that are, you can find low-mileage
> Jeep transfer cases on ebay for a couple of hundred dollars (including
> shipping) and install it yourself in a day or 2. $900 sounds quite high to
> me as well, just for replacing parts.
>
> > wrote in message
> oups.com...
> > I've got a '99 Cherokee Sport with ~90k miles. I was recently driving
> > in 4wd at around 80mph on a wet highway when I experienced a couple of
> > bumps from somewhere in the drive train. It felt just like a hit some
> > rough pavement, in fact that's what I initially thought had happened. I
> > got out and walked around the vehicle after feeling it again and
> > realizing that it wasn't the road. I saw nothing out of the ordinary.
> > About thirty minutes later I got the bump again followed by a horrible
> > grinding noise. I quickly slowed down and threw it into 2wd. The
> > grinding stopped, but I'm still getting intermittent bumps. The bumps
> > vary in intensity and frequency. It basically feels like the vehicle is
> > being bumped from behind or hitting a large pothole.
> >
> > So, I took it to a local transmission shop and they opened the transfer
> > case. They're telling me that the problem is a broken shift fork. The
> > fork needs to be replaced along with some damaged bearings. Does this
> > sound right? I don't know much about 4wd since this is my first, but I
> > fail to understand how this happened or how it was causing the
> > bump/lurch/jerk. They want to charge me $900 to do this work which
> > seems steep. Again, I don't know what I'm talking about, so maybe it's
> > not steep.
> >

Thanks for the fast replies guys. It was definitely in full-time 4wd.
According to the manual I can drive in this mode all the time. I stress
that I'm a 4wd newbie, but I did consult the manual before ever using
it.

Installing a new case myself isn't an option. Unfortunately, I don't
have the tools/time. Just to clarify, the bumping sounds like it could
be caused by the transfer case damage to you guys?

Thanks, again.

just because you can doesn't mean you should ;-)


"Mike Romain" > wrote in message
...
> Ahh well.....
>
> I have the Command Trac NP231 in my Cherokee and the owners manual on
> page 50 specifically says it is ok to drive on wet pavement with it.....
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's
>
> Chuck Bremer wrote:
> >
> > Which transfer case do you have? If you have a part-time transfer case
> > ("Command-Trac" or NP231), it is not designed to be driven on hard
surfaces
> > at all, even if the surface is wet. Snow, sand, gravel, dirt is OK, but
hard
> > surfaces are not. The full-time "Selec-Trac" or NP242 can be driven in
> > full-time mode on any surface.
> >
> > If you're somewhat handy or have friends that are, you can find
low-mileage
> > Jeep transfer cases on ebay for a couple of hundred dollars (including
> > shipping) and install it yourself in a day or 2. $900 sounds quite high
to
> > me as well, just for replacing parts.
> >
> > > wrote in message
> > oups.com...
> > > I've got a '99 Cherokee Sport with ~90k miles. I was recently driving
> > > in 4wd at around 80mph on a wet highway when I experienced a couple of
> > > bumps from somewhere in the drive train. It felt just like a hit some
> > > rough pavement, in fact that's what I initially thought had happened.
I
> > > got out and walked around the vehicle after feeling it again and
> > > realizing that it wasn't the road. I saw nothing out of the ordinary.
> > > About thirty minutes later I got the bump again followed by a horrible
> > > grinding noise. I quickly slowed down and threw it into 2wd. The
> > > grinding stopped, but I'm still getting intermittent bumps. The bumps
> > > vary in intensity and frequency. It basically feels like the vehicle
is
> > > being bumped from behind or hitting a large pothole.
> > >
> > > So, I took it to a local transmission shop and they opened the
transfer
> > > case. They're telling me that the problem is a broken shift fork. The
> > > fork needs to be replaced along with some damaged bearings. Does this
> > > sound right? I don't know much about 4wd since this is my first, but I
> > > fail to understand how this happened or how it was causing the
> > > bump/lurch/jerk. They want to charge me $900 to do this work which
> > > seems steep. Again, I don't know what I'm talking about, so maybe it's
> > > not steep.
> > >

> wrote in message
ups.com...
> Thanks for the fast replies guys. It was definitely in full-time 4wd.
> According to the manual I can drive in this mode all the time. I stress
> that I'm a 4wd newbie, but I did consult the manual before ever using
> it.
>
> Installing a new case myself isn't an option. Unfortunately, I don't
> have the tools/time. Just to clarify, the bumping sounds like it could
> be caused by the transfer case damage to you guys?
>
> Thanks, again.
>

Definitely.

The job of the tcase is to connect the front axle to the drive train. If the
tcase is toast, and the tires are turning, the tcase will be very noisy.
Bumps would be mild.

The bumps were usually mild, but they did vary. I just spoke with the
mechanic again and he clarified that the transfer case is being
completely rebuilt. This goes a long way to justifying the price I
suppose.

I'm a little confused by the disagreement on when you can and can't use
fulltime 4wd. To further explain my situation, I was driving out of
snow and into light rain. When the snow stopped I was able to go faster
on what were essentially just wet roads (no ice), but I kept the 4wd on
for increased traction. Was this a bad idea? I must admit it's the
first time I ever used 4wd at that speed, but I do use it occasionally
around town when the roads are wet at much lower speeds (40 -50 mph).

You have the full time and like you say it should be good for all the
time.

Lots like me only have the part time that locks things up so there is
debate if the wet is slippery enough to allow wheel scuff without
stressing things.

My old beast has over 300K km on it and I can feel the stress when on
wet so shift back to 2 wheel drive when I feel it.

I never have used it in the rain, but from patch of snow to patch on wet
is ok unless I feel it. I don't want to stress the old beast.

Not a bad price for a full rebuild. Then you know what you have vs a
used one.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

wrote:
>
> The bumps were usually mild, but they did vary. I just spoke with the
> mechanic again and he clarified that the transfer case is being
> completely rebuilt. This goes a long way to justifying the price I
> suppose.
>
> I'm a little confused by the disagreement on when you can and can't use
> fulltime 4wd. To further explain my situation, I was driving out of
> snow and into light rain. When the snow stopped I was able to go faster
> on what were essentially just wet roads (no ice), but I kept the 4wd on
> for increased traction. Was this a bad idea? I must admit it's the
> first time I ever used 4wd at that speed, but I do use it occasionally
> around town when the roads are wet at much lower speeds (40 -50 mph).

If you REALLY have Full Time 4WD, Part Time is more likely in your Sport,
then you can indeed do what you were doing.

There are two 4WD systems used, Command Trac and Select Trac. One is the
NP231 (P/T), and the other is the NP232 (F/T) - I can never remember which
is the Command- and which is the Select- Trac. With either, you can shift
into the 4WD mode at any speed, but the P/T system doesn't really like 4WD
unless the tires can slip on the road surface to release stress. So, the P/T
system says you can shift into 4WD at any "safe speed", but the safety is
dependent on other factors. Basically, if it is safe to do 80, then you
should not be using P/T 4WD. Actually, if it is safe to be doing anything
over about 40, you should not be in 4WD if you have a P/T system.

You should ask your rebuilder if he is getting parts for the NP231 or the
NP232. This will tell you what the safe operating conditions are.




> wrote in message
oups.com...
> The bumps were usually mild, but they did vary. I just spoke with the
> mechanic again and he clarified that the transfer case is being
> completely rebuilt. This goes a long way to justifying the price I
> suppose.
>
> I'm a little confused by the disagreement on when you can and can't use
> fulltime 4wd. To further explain my situation, I was driving out of
> snow and into light rain. When the snow stopped I was able to go faster
> on what were essentially just wet roads (no ice), but I kept the 4wd on
> for increased traction. Was this a bad idea? I must admit it's the
> first time I ever used 4wd at that speed, but I do use it occasionally
> around town when the roads are wet at much lower speeds (40 -50 mph).
>