Spinning wheels with the NP229 ?

[dbell]

Hi all,

I have an 84 GW that has been converted to manual hubs and has the NP229 TC. I've owned 6 waggies in the past that all have plowed snow very well, all were 74-79 QT's. On the QT's, the "emergency switch" in the glove box says, "DO NOT SPIN WHEELS" !

I understand the potential ramifications of manual hubs with the NP229 TC, in terms of the viscous coupler. We all know that sometimes while plowing snow, a little wheel spin is unavoidable. My question is : Does occasional wheel spin (I try to avoid the best I can) in my 84 with manual hubs create harm to the VC ? I plow in low 4wd and in 1st gear. I've babied all my waggies.
Thanks,
Dan

[Billygoat]

99% sure that in 4 low the viscous coupler is locked out on the 229

[Ristow]

they don't want the wheels spinning when you flip the switch. once engaged you can spin all you want.

if the hubs are locked,and in 4x mode the 229 don't care if you're spinning or not.

[Carnuck]

99% sure that in 4 low the viscous coupler is locked out on the 229

That is correct. You can also move heavy loads with the hubs unlocked in low range 2wd.

[FSJunkie]

4lo locks the viscous coupler. It's like Quadratrac e-drive. The normal 4x4 position of the NP229 is not locked, however, and spinning would not be particularly good for it, but I imagine a few little spins here and there would kill it. Just get off the throttle when it happens.

[dbell]

That is correct. You can also move heavy loads with the hubs unlocked in low range 2wd.

Carnuck,

Senario,

So if I am going down a steep grade gravel road in the summer time (very dry,hard road), and I DON'T lock the hubs in, I can put the rig in 4wd low so I can just creep down the road so I don't have to ride the brakes ? This WON'T lunch the VC ? Note, the shift collar in the front diff has been welded to the shaft. Does that affect anything I've just mentioned ?
I do this with my 84, f-250 (manual hubs) and it sure saves brakes !

Thanks guys,
Dan

[acct21]

I don't know that I'd ever want to go through 4Hi with the front unlocked. Since you have to go through 4Hi to get to 4Lo, whenever you're driving that route and you'd like to coast down in 4Lo, lock the hubs before you leave the house. You can unlock 'em for the ride back. Obviously, locking them doesn't do anything more to the drivetrain than it came from the factory already doing.

[Tinkerjeep]

Carnuck,

Senario,

So if I am going down a steep grade gravel road in the summer time (very dry,hard road), and I DON'T lock the hubs in, I can put the rig in 4wd low so I can just creep down the road so I don't have to ride the brakes ? This WON'T lunch the VC ? Note, the shift collar in the front diff has been welded to the shaft. Does that affect anything I've just mentioned ?
I do this with my 84, f-250 (manual hubs) and it sure saves brakes !

Thanks guys,
Dan

I'm stepping out of my comfort zone here, I do not have any NP229 equipped vehicles, so I'm asking this: If you shift from Viscous-coupled 4WD, with the hubs unlocked, through locked 4WD, to 4WDlow while moving, aren't you already lunching the VC and your low-range? My NP208 will not shift into 4WD low when I'm moving. It grinds like a Noob trying to downshift into "Granny" at 20mph in an older Chebby.

Also: depending on how long the graded gravel road is, and how hot these rigs run (especially the later 80-90s versions) wouldn't you risk overheating stuff by relying on engine compression braking all the way down a hill? Wouldnt it save wear by using some actual braking and leaving it in 2WD and 1st gear?

And high engine speed, closed throttle, high vacuum, high spark advance makes engine heat that the cooling system may not be able to deal with long term. Any thoughts?

[dbell]

I've read and heard so many different conflicting opinions that I've decided to never use my jeeps current set up (lo or hi 4wd, hubs locked or unlocked) on hard, dry surfaces. Brake pads are easier and cheaper to replace than viscous couplers. I try to reduce issues like this to the least common denominator.

Dan

[acct21]

in 4Lo the viscous coupler isn't in the equation any longer, so no concerns there. It's getting to 4Lo that could be the problem.

I just wouldn't want to go into 4Hi (unlocked) without the front hubs locked in. The VC might survive it 100 times; it might go the first time.

[Ristow]

the VC is always slipping in use. the frailness of the VC is quite overstated. its an oil fiiled can with discs inside,that prevents freewheeling of the differential in the tcase. it's pretty tough. yeah,you don't want to try driving in 4hi with the hubs unlocked. it'll drive like the trans is slipping.

my wife long ago threw my old '91 GW with locking hubs in 4hi and drove it down a muddy road with the hubs unlocked. it survived issue free.

[JeepJeepster]

Im not understanding why some say its bad to spin the wheels while in 4hi.. It wont hurt the VC at all to spin while in 4hi. It will use the VC as its intended to be used. I guess if youre really worried about prolonging its life, you wouldnt want to spin the tires since it will put the VC to use.

I have 94 Grand Cherokee that works much like the 229 (called 249 in the ZJ) and its working fine after 21 years. Its not been offroaded hard, but its been used many times.

[Tinkerjeep]

My confusion here is whether or not the vehicle has fulltime hubs or a CAD in the front. I always thought The 229 was a fulltime 4WD... so it had drive flanges in the front hubs, like the older Borg Warner 1305/1339 Quadratrac rigs had. But is it more like the "automoatic 4WD" setting in the mid 1990s Suburbans? 2WD, fulltime/automatic 4WD limited slip, 4WD lock, 4WD low range lock? Those didn't have selectable hubs or CAD...AFAIK.

I know the clutchpacks in the limited slip dif inside the BWQT fulltime case would fry if you installed locking front hubs, unlocked them and drove around in limited slip 4WD. But not if you locked the QT into "Emergency" (locked) 4WD mode...then it simply acts as a RWD with a lot of parasitic front driveline load.

[dbell]

in 4Lo the viscous coupler isn't in the equation any longer, so no concerns there. It's getting to 4Lo that could be the problem.

I just wouldn't want to go into 4Hi (unlocked) without the front hubs locked in. The VC might survive it 100 times; it might go the first time.

Interesting. What I usually do when going from 4hi to 4 lo or vice-versa is, stop the jeep, shift the trans into neutral, kill the motor, and then shift the lever into 4hi or 4lo. This seems to eliminate the "grinding" associated with the "5 mph roll to shift". I lock the hubs in FIRST before 4hi or 4lo in all cases. Is there a problem doing this verses jeeps instructions to be rolling at 5 mph ? I just hate the grind !

Dan

[Carnuck]

That's the way I do it! Not sure on downhill coasting in lo with the hubs unlocked. I've only done it under load hauling trailer. The viscous coupler is locked out in low.