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#1
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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. |
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#2
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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. > |
#3
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> 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. |
#4
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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. > > |
#5
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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. |
#6
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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. > > > |
#7
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> 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. |
#8
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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). |
#10
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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). > |
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