I have a 1998 Jeep Grand Cherokee 4x4 that is having issues with the front wheels. When I turn them, they turn way too sharp and end up spreading apart at the bottom. They also seem to rub the underside, stopping the vehicle from moving when the tires are turned too sharp. Any help?

SOURCE: FRONT END

Drive the car in a parking lot and make left and right hand turns.
If the noise goes away on either turn then the problem is a front hub bearing.
If the noise is still there, it could be possible front differential bearings.

SOURCE: Hose connection location

If you look under there you should find a steel or plastic line that runs up to a place inside the engine bay.( If it is connected directly to the differential) If it is connected to a box mounted on the right side axle it is part lof your 4x4control and should carry vacuum. With engine running you will hear vacuum leak and easily find connection point.
(but you didn't mention any driveline problem so it's likely the first, which is only a vent line. as long as it is not pointing foreward or straight up it is also ok to just secure it out of the way. (but not where it will become submerged in water etc.

SOURCE: Jeep Grand Cherokee 2004 front end clunking

It would be kind of hard to explain, but you may want to check your wheel bearings. Sounds like your wheel is binding. If you jack the front up, grab your tire, and shake. Sort of like you are trying to turn the wheel your self with out the steering wheel. Then do the same up and down. If you have a lot of play, then your wheel bearing is shot. And with a 4WD, you have to replace it because its sealed, where as on a 2WD, you can tighten them. For the pitman arm, and the gear box, you may have to get a haynes manual to find. But the gear box will be the box that your steering shaft goes into and connects to the tierods. Not too hard to find.

SOURCE: 1998 and 2000 jeep grand cherokee

This Info taken from Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Grand_Cherokee
Hopefully this will answer your question.

The redesigned WJ 1999 Grand Cherokee shared just 127 parts with its predecessor. The structure was stiffened by PorscheEngineering for sharper steering and lighter weight. The spare tire wasrelocated from the side of the cargo compartment to under the floor togreat relief of owners. The two heavy pushrod V8 engines were replaced by chrysler's first clean sheet V8 since the 60's (SOHC aluminium heads, plastic intake), Chrysler's then-new PowerTech. Although this engine produced less torquethan both previous V8s, it was lighter and got much better fuel economyand provided similar on road performance figures (the 23 gallon fueltank was replaced with one of a 20.5 gallon capacity). The Inline 6engine was also updated in 1999. 10 horsepower (7.5 kW) was added byredesigning the intake manifold. The manual transmission was dropped with this model.
While other Jeep vehicles used the Mopar 5 x 4.5 bolt circle, thiswas the first Jeep following the 1987 Chrysler buyout to receive awider bolt pattern — 5 x 5. The 5 x 5 bolt pattern (also 5 x 127 mm),although common to GM rear wheel drive vehicles and light dutytrucks/vans, has spread beyond its use with GM (and Ford with their 1973 to 1978 LTDs and Lincolns). Chrysler first used the 5 x 5 pattern on full-size half-ton Dodge Ram pickups and Dodge Ramcharger SUVs in 1986.
A notable feature available in this generation was the automatic four wheel drive option called Quadra-Drive II.With three viscous clutches, it was one of only a few four wheel drivesystems at the time with triple locking differentals, joining thecontemporary Mercedes Gelandewagen, Mercedes Unimog and Magna SteyrPinzgauer, and the only one of the four with fully automatic operation,although the axle differentials could not be manually locked like inthe other three vehicles.
The 45RFE and 545RFE automatic transmission in the WJ was notable. It included three planetary gearsets rather than the two normally used in a four-speed automatic. Thisgave it six theoretical speeds, and it would have been the firstsix-speed transmission ever produced in volume, but it was programmedto only use five of these ratios. Four were used for upshifts, with adifferent second gear for downshifts. Although five of the six ratioswere used, Chrysler decided to call it a "4-speed automatic". In 2001,the programming was changed to make use of all six ratios. Rather thanhave six forward gears, the transmission was programmed to act as afive-speed with the alternate second gear for downshifts. The RPM at70 miles per hour (110 km/h) on a 545RFE is 2000 rpm, 200 rpm less thanthe 45RFE programming. 1999 and 2000 model year WJ owners can havetheir 45RFE transmission's programming flashed to enable the extra gearas both transmissions are physically the same. The 42RE 4-speedautomatic remained the transmission for the Inline 6 engine. It was notchanged from the previous model Grand Cherokee's.

SOURCE: front-end noise on a 2001 Jeep Cherokee Sport

HI!! have somebody to help you star the car you outside put on drive turnthe whell to the side makes noisevery slow drive the truck and hear the noise if growglin noiise is detected is the hub bearing