Roasted Viscous Coupling?

[Dive 30]

OK, so a few weeks ago I was getting Gwen ready for a trip over the river and through the woods to Grand Junction. Upon inspection, I discovered that the Transfer Case (NP229) was low on fluid (none came out when I opened the speedo cable port). So I refilled it (Parts America has the coolest quart bottle pumps for like $5.00, that makes this super easy). So now, I'm pretty sure that the 4wd is not engaging (I visually verified that the 4wd shaft is moving) as it will not go into 4-lo. Plus, I noticed a weird intermitent vibration when traveling at 65 mph with the 4wd engaged (It was snowing as we came through Vail pass). What do you think, did I toast the Viscous Coupling? Or do I need to put it up on jack stands and see what wheels turn? I will say this though, last summer when I put all fours up on stands, even in 2wd, the front wheels turned (not forcefully though). I will say that last year and when mudding this last spring in IA, the 4wd performed flawlessly, any tips? Anybody got a Dana 18/20 or NP 205 they want to get rid of cheap?

Thanks,

Phil

[Crazy_Jeepman]

Well I think the Speedo Gear is above oil level to begin with. you need to check it at the plug above the drain plug. The vibration you feel is it shuddering like its going through the whole wag, or more of a harmonic vibration? Check all the joints in the drive shafts and front axles. The Dana 18/20 or NP 205 will not swap in, with out major changes. You would have to swap out the front axle, Drive shafts and transmission to make any of them cases work. NP208 would be your only choice, and you would need a rear driveshaft from a NP208 equiped Wag or Chero, or from a pre 80 Q-trac equipped rig.

[tuckers89GW]

I would think, that if it shifted into 4wd and the coupling was toast, you wouldn't go anywere. Sit and spin. You said that the shaft is moving. If it shifted the t/c into 4wd, whether the VC was bad or not, I would think you could still shift into 4-low. If I'm wrong, someone please let me know.

As Pete said, you need to check level at the fill plug, not the speedo.

[Ernzo]

I believe the test for a VC in a t-case on the vehicle is to test the torque bias. put it in 4H, raise one front wheel and rotate the wheel. A correctly operating VC ought to require a minimum of 45 ft.lbs. IF it is less, then perhaps the VC is weak or shot. IF it is at or more than 45, the VC checks out, according to the MR 253 book I use.

[Dive 30]

Thanks for the replies guys.

It was an intermittent shudder throughout the wag, but don't rule out the double cardan up front, the DSPO never greased anything on this rig, I've replaced all the rear u-joints and the front one, but not the double cardan.

As for the fluid level, typically with my wag sag, fluid will pour out the speedo cable port since it sits lower than the fill plug (but higher than the drain plug) if I am a bit low, but not empty.

Either way it is full of ATF now, and it won't shift into 4-lo, I'll have to raise a wheel this weekend and check the ft-lb. thing. How do you put the torque wrench on since mine has been converted to front hubs?

Thanks in advance,

Phil

PS: Crazy,

I do have my '77 sitting here waiting to donate parts (TH-400, Quadratrac, D44s front and rear) so if you have or know of someone who has a Dana 18, Dana 20, or NP 205 sitting around, I would be interested.

Thanks

[ November 18, 2002, 08:18 PM: Message edited by: Dive 30 ]

[Frankenstien]

Well I had a completely blown double cardan joint and my truck would still drive it just made a heck of a clanking noise. $160 later and I had a completely rebuilt 1 1/2 in longer driveshaft.

J