Two Cherokees

[Edbrooks]

I have an 88 Cherokee and an 89 Cherokee. Both are 4.0 engine, and four speed auto, with Command Trac.

Somewhere I read, but can't find it now, that shifting into 4WD High above a couple of miles an hour, would cause severe damage to the drive train. Probably the shift collar in the shift motor.

However, the owner's manual on the 89 ( I don't have one for the 88) says it can be shifted into 4 wheel high at "any legal speed."

These two vehicles have pretty much identical drive trains. Why the difference? Or am I just dreaming that the 88 cannot be shifted into 4wh high at "any legal speed?"

Ed

[AlohaBra]

Originally Posted by Edbrooks

I have an 88 Cherokee and an 89 Cherokee. Both are 4.0 engine, and four speed auto, with Command Trac.

Somewhere I read, but can't find it now, that shifting into 4WD High above a couple of miles an hour, would cause severe damage to the drive train. Probably the shift collar in the shift motor.

However, the owner's manual on the 89 ( I don't have one for the 88) says it can be shifted into 4 wheel high at "any legal speed."

These two vehicles have pretty much identical drive trains. Why the difference? Or am I just dreaming that the 88 cannot be shifted into 4wh high at "any legal speed?"

Ed

Hey...I have two Cherokees also a 97 with Command Trac and a 2001 two wheel drive. I also had an 84 with Selc Trac. Anyway, the Cherokee usually has the Command or the Selec Trac. The difference is the Selec Trac is considered full time because it has a (silicone)viscous unit between the front and the rear diffs. The Command Trac (CT) is considered "part time" because the transfer case is mechanically linked internally.

The problem with putting the CT into 4 wheel drive is not the speed but the condition of the pavement (I use it on the freeway in the rain at 70 Mph sometimes). On drive pavement, because there is no viscous unit, the front and the rear (from friction and engine power etc.) will cause the transfer case to lock up so it won't disengage from 4WD. The CT should only be used when there is slippage between the front and the rear such as gravel or heavy rain or snow. The Selc Trac that I had, an early one, should only be engage or disengaged when stopped and with the engine running for the vacuum motors to work properly. The Selc Trac can be used on dry pavement all the time for more neutral handling, but at the expense of lower fuel mileage and tire wears.

At any rate, do not use the 4WD high range on CT on dry or "mostly" dry pavement. If you do lock it up, try backing up or jack the front axle unit up with the Jeep turned off. You will also find that if you don't shift out of 4WD when turning at slow speed the front end will steer "funny" and could lock up or break something, so basically the CT should be out of 4wd hi at slow speeds, like turning in and out of your driveway or in a parking lot.

[Edbrooks]

Thanks. What I want to know, more precisely, is why the 88 (I do not have the owner's manual for it) is not supposed to be put into 4wd-high, at any speed above a crawl as "extreme damage may result" but the owner's manual on the 89 says it can be put into 4 wd high at any legal speed.

It has been my practice, with the 88, to always come to almost a dead stop, pull the lever into 4wd high, and roll forward a few feet to engage the shift motor. Only then would I accelerate to cruising speed (I live on dirt roads so 40-50 mph in 4wd-h is not a problem.)

Yet the manual on the 89 indicates I do not have to come to a near stop, but can engage 4WD high while cruising at 50 mph or so. I'm not talking about paved roads, though the same would apply on snowy or icy roads.

Incidentally I also had an earlier Eagle, which had an interlinking system to prevent one from putting it into 4wd (there was no low) without coming to a stop. That Eagle, and my two Cherokees, are the only remotely controlled hub vehicles I have ever owned. All previous ones have been manual hubs.

Hope this helps. My interest is why must I nearly stop on the 88 to engage 4wd and can (supposedly!) engage 4wd at cruise speed on the 89, when the two are about identical.

[AlohaBra]

Originally Posted by Edbrooks

Thanks. What I want to know, more precisely, is why the 88 (I do not have the owner's manual for it) is not supposed to be put into 4wd-high, at any speed above a crawl as "extreme damage may result" but the owner's manual on the 89 says it can be put into 4 wd high at any legal speed.

It has been my practice, with the 88, to always come to almost a dead stop, pull the lever into 4wd high, and roll forward a few feet to engage the shift motor. Only then would I accelerate to cruising speed (I live on dirt roads so 40-50 mph in 4wd-h is not a problem.)

Yet the manual on the 89 indicates I do not have to come to a near stop, but can engage 4WD high while cruising at 50 mph or so. I'm not talking about paved roads, though the same would apply on snowy or icy roads.

Incidentally I also had an earlier Eagle, which had an interlinking system to prevent one from putting it into 4wd (there was no low) without coming to a stop. That Eagle, and my two Cherokees, are the only remotely controlled hub vehicles I have ever owned. All previous ones have been manual hubs.

Hope this helps. My interest is why must I nearly stop on the 88 to engage 4wd and can (supposedly!) engage 4wd at cruise speed on the 89, when the two are about identical.

OK...so I made the jump from an 84 to a 97...on the early Jeep Cherokee they used the vacuum motor on the front axle....and they also used CV joint axles...If you can, check the one on yours and let me know which one you have on the 88, since i don't have one in front of me.

Then they made a better one with no CV joints and that one is used in the later model. I am thinking that the 89 is the year they made that change. If you can look under the newer one and see that the new front axle is there, then that is what happened. This axle goes all the way across and the U-joints are on the ends only, I would like to know this for my own information (I used to be an auto tech).

On the new one, since there is no vacuum motor to engage the front axles, the CT can be engaged at highway speeds.

[Edbrooks]

Nope. Not it. The 89 has a shifter motor. However the owner's manual assures me it can be put into 4wh at 'any legal speed." Darned if I'm gonna try it!!

Thanks