89 S15 Jimmy differiental problem

'89 S15 jimmy 4X4 140,000 miles.
sometimes when starting from stop making a left turn, and it breaks loose, after I straighten up it pulls to the right when I accelerate. when I let off the gas, it stops pulling to the right. to correct it I have to gas on it starting from a stop in a right turn. I thought it might be the bearings but when I got it all apart the wheel bearings looked good. any ideas?

Under the battery tray there is a vacuum actuator. When you select 4WD, vacuum is applied to the actuator and a cable operates a clutch mechanism on the right front axle shaft. When the cable is pulled, the outer axle shaft is locked to the inner axle shaft and the front differential becomes "live". There is a vacuum switch on the transfer case with 3 vacuum lines to it. One comes from the intake manifold to supply vacuum to the system. The second line goes to the actuator, and the third line goes to a filter and vents to atmosphere when 2WD is selected. If the vacuum switch fails, it can suck transfer case fluid into the lines and the actuator. If this happens, the actuator may not release, or release very slowly. If the vent line is restricted, it will have the same effect. If the vacuum switch is faulty, most auto parts stores have them in stock. Check it out and post your results.

It is not the front dif. that is currently out of the vehicle, it is the rear dif. Could it be the wheel bearings in the front passenger side going bad?

Probably not a wheel bearing, but it could be a problem IN the differential, spider gears etc. (not with ring or pinion gears). If you pull the cover off, you might see some metal shavings, (or even chunks) in the oil. Just gonna have to get in there and look around for wear or damage. Post what you find.

there are tiny shavings on the magnet, dust size. No visable damage or wear.

Is there a rear brake hanging up? Possibly the parking brake stuck on?

I never use the parking brake.

could it be the clutch packs on the passenger side going bad?

If it has them, yes. Some differentials don't have them. Check your RPO codes and see which differential your vehicle has. Rear axle RPO's usually start with "G" and have two other characters following it. Here is a list of MOST of the RPO codes and what they mean: http://www.marshu.com/images-website/car/gm-firebird-camaro-rpo-car-door-manufacturer-codes/gm-firebird-camaro-GM-RPO-car-codes.pdf You can find the sticker either in the glove box, or door jamb. It's a white 3x5 sticker.

G80 axle positraction, limited slip
GU6 axle rear, 3.42 ratio

Your axle does have clutch packs so it's a real possibility that's what's causing the problem. The fluid used in them is different than those without the packs. Your owners manual will tell what fluid type to use, and it may require a friction modifier additive. You might get lucky by just changing the fluid. The alternative is overhaul the differential.

If it is the clutch packs and I don't do anything, what happens?