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2wd/4wd problem. + Bolt size inquiry

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Old 03-30-2010, 09:27 PM
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Default 2wd/4wd problem. + Bolt size inquiry

I recently bought a 79 k5 off a guy on craigslist. It checks out fairly well, cept it has an exhaust leak and the engine looks rough. The only other major problem I have is that I can't get it to drive in anything except 4 low loc or 4 hi loc. :/ The 4 wheel lock light is so dim, I didn't realize it was on till that night when I was driving it. I had taken it through some light mud in a washed out spot in a road that evening, made it through in 2wd just fine. I called the guy the next day, and he swore up and down it would drive in 2 wheel just fine, shift in and out, then he accused me of submerging the vehicle. The front drive shaft was out when I bought it, but it came with the old one and a new one.

So as to my question. Before I assume the pickle smoker sold me a vehicle that doesn't have 2wd and only has the drive shaft out for that reason, can someone confirm that i'm tryin' to shift out right? I put the vehicle in neutral, move the stick up into neutral, tried to shift it into reverse, and then nothing happens. Theres only 5 positions up and down on it, that I'm aware of. I see people mention 2 hi and 2 low, but all I see is 4 hi loc < 4 hi < N > 4 low > 4 low loc. I have my hubs out. I'm not aware of any shifting of it in any direction besides up and down. I can shift it up and down and make it run in 4 hi loc or 4 low loc, but no other gears. When I have it in hi, low, or N, I can kinda feel a grinding and it makes that really rough sound if I put it back in park.

I also need to know what size of bolts to use to hook the shaft up to the transmission. I have the bolts to hook the u-joint into the front end, but it didn't have any bolts to go into the trans. My uncle suggested I try to put the shaft back in, that it might help the 4wd gears disengage.

Any insight anyone can give would be much appreciated! Thanks!
 
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Old 03-31-2010, 07:39 AM
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You have the NP203 transfer case which is a full-time 4wd transfer case.

If you can only drive in HI LOC & LO LOC with the front driveshaft out, the transfer case is stock with no modifications and is doing exactly what it is designed to do. DO NOT put the transmission into park with the engine running and the transmission in HI or LO (ie not LOC). You are trying to stop a moving transmission with the park dog and can damage it.

There are part-time conversion kits that are available that you can then install lock-out hubs on the front axles to allow for 2wd operation when in HI or LO. Search for "NP203 part time conversion" on google and you should find what I am talking about.

As far as the bolts go that connect the driveshaft to the transfer case, the NP203 could come with a flange with 4 regular bolts connecting the driveshaft flange to the transfer case flange, or it could have come with a yoke that required two u-bolts and associated nuts. You need to determine what setup you have. Most autoparts stores should have the necessary hardware for either case.
 
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Old 03-31-2010, 12:17 PM
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Enough said. So he basically had the front shaft out and probably drove it in 4lock to have a 2 wheel drive truck
 
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Old 03-31-2010, 04:18 PM
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I was kinda wonderin' about that. So neither of my guesses were true. The guy knew nothing about it and fed me a load.

But as to my question on the bolts, I know its got the flange on it with 4 holes, I just don't know what kind of bolt to put in it. I've tried searching thread pitched and whatnot for 79 k5 front drive shaft, and other things like that, but I just can't find anything. It didn't come with any bolts for the shaft, Oreily's had the things to hold the u-joint in the front, I just need to know what kind of bolts I need, or if theres a way to find out.

Thanks for the other info though! Probably saved me a good $100 for some mechanic to pull it apart and tell me the same thing.
 
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Old 03-31-2010, 05:08 PM
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I believe the bolts are regular 7/16 or 3/8 bolts, but could be fine thread. Napa should have what you need. If you can drive it, get it there, go inside, grab a few bolts and try to thread them in. They need to be as thick as the two flanges combined. Should be roughly 3/4" long or so.
 
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Old 04-02-2010, 11:55 PM
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So, I've been reading around. I wondered why I had manual lockout hubs, a lot of my reading suggests the previous owner put a conversion kit in it. Which also suggest why my hubs look brand new.

So, with the conversion, it should be 4 low loc, < 4 low < N > 2 Hi > 4 Hi loc. I finally found the right bolts for my front drive shaft, and got it put in. It didn't fix the fact that it could only drive in the top and bottom positions. I didn't drive it around with my hubs locked, but I'd still like to be able to figure out why the two other gears won't work. I'm hoping my transmission isn't going out, but I'm all ears on suggestions. Does the t-case use a different weight of oil after the conversion is added, thus making it harder for the other gears to kick in? I put it where hi and low used to be, and it makes a really rough grinding sound with a little vibration still. I do this while in neutral then shifting into drive or reverse, no more park. I remember when my 87 silverado had a trans leak, the gears in it would take longer to shift in and after a bit just didn't shift at all (that sucked!).

But anyways, I'm open to ideas. Thanks again guys!
 
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