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transfer case problems

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Old 10-24-2009, 01:48 AM
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Default transfer case problems

i have 74 chevy blazer, dont have a shifter locator? showing me what gear my transfer case is in? 4 hi 4 hi locked? should i be in 4 hi when street driving? i have a hard time getting it to drive? i have to move shifter back and forth to find a gear, to get the tranny to engage! any help would be appreciate. james
 
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Old 10-24-2009, 07:20 AM
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When you say HI and HI-LOC, I am assuming that you have the NP203 transfer case which is a full-time 4wd transfer case. That is unless it has been part-time converted. If you have manual lock-out hubs at the front wheels, then your transfer case has likely been part-time converted. If this is the case, then you can do most of your driving in HI with the hubs unlocked. Periodically, you should run in HI-LOC to keep oil splashed up around the input and output bearings in the case. The chain does not spin in HI, only in HI-LOC.

Getting back to the part-time conversion. It is possible that someone would put lock-out hubs on and not do the conversion to the transfer case. If this is the case, then the truck should not move when in HI (or LO) with the front hubs unlocked.

Hope this helps!
 
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Old 10-25-2009, 04:10 PM
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Default Transfer case id

THANKS FOR THE HELP, how would i determine which transfer case i have? and 4 hi lock would be all the way towards engine, and 4 lo lock would be all the way towards rear of vehicle? i'm pretty sure its a full time 4 wheel drive, the previous owner had he front drive line out when i purchased it. one thing i did do once, i had the rear end jack up then i put it in drive, and the rear wheels spun(with front drive line in) while the front tires were on pavement and didnt move! so i'm a little confused? if it is full time 4x4 or not?
 
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Old 10-25-2009, 04:28 PM
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Try some google image searches for some images of the NP203 and NP205 transfer case. They look somewhat similar from the rear, but the controls are quite different.

With the NP203, there will be 5 detents for the transfer case. In order from closest to the firewall to furthest from the firewall:
  1. LO-LOC
  2. LO
  3. Neutral
  4. HI
  5. HI-LOC
 
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Old 10-26-2009, 01:12 AM
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NP203's have shifter linkage assembly... NP205's have two rods that slide directly into the case. Also - there is a round metal tag on the case near the output shaft that will indicate the model and date of build.
Either way, with a NP203 or a NP205... All the way back is HiLoc, one notch forward is Hi... Neutral is in the middle and Low Range is all the way forward (the opposite of a NP208 or NP241)
Note - If you have a NP203 fulltime case, you will be able to jack any one wheel off the ground and the truck will not go anywhere until you slap the t-case into HiLoc or Lowloc and tie both driveshafts together.
 
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Old 10-26-2009, 06:47 AM
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The NP205 only has 4 detents, not 5 like the NP203. This is due to it being a part time 4wd transfer case which does not have a differential inside, thus not requiring a LOC position for each range (HI & LO).

The shift pattern for the NP205 is as follows (again closest to the firewall to furthest from the firewall):
  1. 4LO
  2. Neutral
  3. 2HI
  4. 4HI


Originally Posted by bandidolenny View Post
Note - If you have a NP203 fulltime case, you will be able to jack any one wheel off the ground and the truck will not go anywhere until you slap the t-case into HiLoc or Lowloc and tie both driveshafts together.
Do not do this until you have verified that there is not a locker installed in the axle with one wheel off the ground. Sure way to drive off the jack.

An interesting note as well, if there is not a locker installed on the axle with one wheel off the ground, just the factory open differential, the wheel you have off of the ground will be traveling at 4 times the speed of the input shaft to the transfer case. So be careful. If the input shaft is spinning at a speed that would translate to 60MPH when driving down the road, the one wheel that is spinning will be doing 240MPH (extreme example).

Given the speedometer drive location, if you lift a front wheel, the speedometer will not move. If you lift a rear wheel, the spinning wheel will be going 1/2 as fast as the indicated speed on the speedometer.

This is all true for an NP203 transfer case in factory form. If it has been modified for part time operation, then the rear axle will be driven at all times and the LOC positions will drive the front and rear together.
 
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Old 10-26-2009, 06:49 PM
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Default transfer case

thanks for all the info! it helps! after further messing with t case, i think it is (damaged) not working properly, when i put it in low only the front drive shaft moves, when i put it in hi it kinda whines like its not catching! but when i put it in any loc position it will drive, but engages kinda hard, so i took front drive shaft out and put it in hi loc. so if i understand everything correctly i could get a np 205, and locking hubs, i would be able to drive in 2 wheel and save more gas?! anyway thanks appreciate the info james
 
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Old 10-26-2009, 08:45 PM
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Do you already have lock-out hubs on the front? They would be 1/4 turn dials in the center of each wheel. If so, then someone may have already done the part time conversion for you.

You can adjust the shift linkage which may correct the issue you are having.
 
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Old 10-26-2009, 09:14 PM
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Default transfer case

no there are no locking hubs, i can adjust shift linkage? interesting? something else i will have to play with!? what is happening now is alot viberation when accelerating, like something is loose? my tranny was loose, last week i had to tighten it! now it sounds loose again? so any way how would i be able to tell if transfer case is no good? thanks james
 
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