Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Transfer Case Question

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Neko H, Jun 1, 2000.

  1. Neko H

    Neko H Registered Member

    Joined:
    May 31, 2000
    Posts:
    21
    Likes Received:
    0
    Location:
    Texas
    First off this is GREAT !!! I just got my 79 Jimmy and what a gold mine of information. I'm looking forward to keeping up with the posts and getting to know some of you.

    Ok now for the question (remember I'm a newbie this is my first 4x4, so you diehard's keep down the chuckles ... OK).
    The 79 has full time 4 wheel drive my transfer has Low Loc, Low, Neutral, High & High Loc. I read that for regular driving it should be run in High .... right? And the Auto tranny should be in neutral when changing the transfer case ..... right? However I seem to only have Low, Neutral, and High there does not appear to be a Low Loc or High Loc available. Do you think it just needs adjusting? And is this a royal pain in the butt or easly done? Any insight would be greatly apperciated on this matter.
    Can it be converted so that it is not 4 wheel all the time cheap and easy (have a wife and three daughters so hence the cheap & easy .... not a lot of money or time).

    Neko H
    79 GMC Jimmy 4x4
    (If I'd only win the Lottery, it would be Cherry)
     
  2. Blazer79

    Blazer79 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,816
    Likes Received:
    0
    Location:
    Guatemala, Central America
    I have a NP203 transfer case as well. Sometimes it's VERY hard to shift to the LOC positions. What I've found is that the more you use them the softer they get. I used to have to slam the shifter in order to get it to shift. Also check the oil level. This transfer case uses grade 30 engine oil. Find a trail where you can practice shifting (off-road, not paved) through all five positions. That way you'll be ready for when you really need it. My Blazer turns on a light in the dashboard indicating "4-wheel LOC" when I finally shift into a LOC position. You can shift into and from a LOC position while driving. You MUST stop to shift from Hi to Lo or viceversa.

    This is from an old post I wrote a while ago:

    What you have there is a very fine piece of metal. I love my NP203. It makes your truck handle better on-road. There are some people that convert it to part-time with a kit looking to improve mileage, but many have discovered that the changes are minimal, while they loose the benefits of full-time-4x4.

    This transfer case originally has HI-HILOC-N-LOLOC-LO on the shifter. When you are in Hi or Lo, both driveshafts will receive power, but there's a differential (like the one in an axle) between both driveshafts. This means that the driveshaft with the least resistance is the one that spins the most. So if you raise only one tire of the ground, and you don't have a locker or posi in your axles, only that tire will spin and your truck will not move.

    When you shift into HiLoc or LoLoc, both driveshafts get locked and must turn at the same rate, no matter what. This is the equivalent of 4Hi and 4Lo found on other transfer cases. In these positions at least one tire of each axle must turn (if you they don't have locker/posi), just like the 4wd position of other transfer cases.

    On hard surfaces, you must use the non-loc positions because not all tires turn at the same rate when you make a turn. There's no point in locking your tires on hard surfaces anyway, and something might break. So, you should use Hi for highway. Use Lo when moving around in tight spaces or when backing with a heavy trailer, or when you simply want to go really slow. Use the Loc positions when you're losing traction off-road.

    I'm not so sure about the part time kit, but from what I've read, it makes your Hi and Lo positions be 2wd (no differential and no power to the front driveshaft). I don't know if they remain in the same order, tough. They also include the locking hubs for the front axle, so 4wd is operated like the other transfer cases.

    Hope this helps you understand your truck and make better decisions when using it.


    <font color=black>//////
    What the heck!...Drive it like gas is $0.50/gal!!!
    </font color=black>[​IMG]
     
  3. Executioner

    Executioner 1/2 ton status

    Joined:
    Feb 22, 2000
    Posts:
    1,530
    Likes Received:
    0
    Location:
    Temp. Ft. Walton Beach Fl. home=Tucson, Az.
    My shop manuel say's that the NP203 can be shifted from LOW to High, or High to Low at speeds below
    35,or 45 MPH, the trick is enginge speed(PRM) needs to be very close.
    Please post why you say "MUST stop "
    Thanks alot
     
  4. Blazer79

    Blazer79 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,816
    Likes Received:
    0
    Location:
    Guatemala, Central America
    Seems like the Executioner is trying to execute me!LOL

    I've never actually tried shifting from LOW to HIGH or viceversa while moving. I don't have the factory manual, so I didn't know that. The reason is that I feel there will be a big "clunk", kind like the one you get when you shift into drive while in high RPM. I don't want to mess my drivelines or blow a U-joint. Besides, I'm never in a hurry when I need Low gears, so I guess it's a "better safe than sorry" thing. Have you ever done that kind of shifting? If so, is there a clunk after all?

    I've shifted to and from Loc positions quite often, and haven't had any problems.

    <font color=black>//////
    What the heck!...Drive it like gas is $0.50/gal!!!
    </font color=black>[​IMG]
     
  5. Neko H

    Neko H Registered Member

    Joined:
    May 31, 2000
    Posts:
    21
    Likes Received:
    0
    Location:
    Texas
    Hey Executioner

    On My drivers side visor on the Jimmy it say's to stop and put the vehicle in neutral before shifting into High or Low from either or neutral with the transfer case, and it does confirm what Blazer79 said about shifting from High to High Loc (and back)or from Low to Low Loc (and back) while in engaged. I have an automatic transmission, is yours standard? That might make a difference.

    Also Blazer79 Thanks for all the GREAT info and digging out the former post for me. I am hoping to hit the dirt roads tonight and see if I can get the thing into a Loc position (after checking the oil).

    Neko H
    79 GMC Jimmy 4x4
    (If I'd only win the Lottery, it would be Cherry)
     
  6. ken

    ken 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,244
    Likes Received:
    0
    Location:
    Anaheim, CA
    If you stop and shift into neutral in the case, then try to shift into another position, it will grind. The way I've always shifted my 203s (for 23 years now!) is to not stop the movement between case gears, meaning do not stop in neutral, pass by it as quickly as you can...you can be stopped or moving when you shift this way, you may get a slight grind, but nothing compared to if you pause in neutral and THEN try for another range!!

    ken
     
  7. Jeff427

    Jeff427 1/2 ton status

    Joined:
    May 22, 2000
    Posts:
    1,186
    Likes Received:
    0
    Location:
    Gladwin, MI
    Hello. I had a 3/4 ton GMC with a 203 transfer case and a 400 sb that got 14 mpg when I had it all tuned good. I also know of four 203 cases that were converted to part time, and would no longer stay in four wheel drive. I know this is not the case with everyone, but in my experience changing them to part time seems to mess something up (over time, all of the cases that had problems had been run a while before they started popping out). I know a couple of people that didn't convert to part time and have had no problems.
    I do like the added control of full time 4x4, most of the time while wheeling I don't even have to lock it in.
    the only reason that part time might be of benefit is if you have to travel long distances regularly.
    Another benefit of full time is the power is always divided between the front and rear so it is easier on your drivetrain (some people complain that it prematurely wears out the front axle assembly but the money you save in rear u-joints will probably make up for it [not to say that you won't break a rear u-joint, you'll be less likely to]).
    Another thing to consider is how cheap 203s are. Most people don't like them so you can usually get them real cheap. I've had three of them given to me, two have nothing wrong with them, one has been converted to part time and pops out of four wheel drive. I've also seen ads for surplus 203s for $150.
    Sorry for the long reply.
    Jeff427
     
  8. ken

    ken 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,244
    Likes Received:
    0
    Location:
    Anaheim, CA
    Yeah, I wouldda left my 203 full time, but with 12" of lift, the front driveshaft wouldn't live very long!!!!

    ken
     
  9. Neko H

    Neko H Registered Member

    Joined:
    May 31, 2000
    Posts:
    21
    Likes Received:
    0
    Location:
    Texas
    Well I didn't get to check the oil last night, it rained buckets. But I did get out in it and tried to get it into a loc position by trying to go from Neutral and slaming it down to Loc only found High and Low no matter what. Thought I was going to break the shifter.

    Still think it might be an oil problem or need adjusting?

    If it is adjusting any insights or tips? I have both a Chilton's and Hayes manual.

    Neko H
    79 GMC Jimmy 4x4
    (If I'd only win the Lottery, it would be Cherry)
     
  10. Blazer79

    Blazer79 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,816
    Likes Received:
    0
    Location:
    Guatemala, Central America
    I'm not really sure if it's simply an adjustment problem. Mine never got that bad. The first time I used the other positions I felt like I was going to break the shifter too. Apparently there was something seized in there. With time, and continuous use, it is softer to shift.

    I have the Chilton's too but instead look for older posts, I'm sure there's a better description on how to adjust the NP203 shifter on a post about a month old.

    Could it be that you're actually going all the way into the LOC positions and your dash indicator is out? Mine are pretty close to each other, well at least the HI-HILOC ones. I have to be careful when going from anything else into any of those two. I have to return the shifter slowly (but with a very strong grip) to H in order to not go back to N.

    Anyway, it's a good idea to replace the oil if you haven't in a long time. A few months ago I replaced the oil in my T-case for the first time in 20 years! The old oil smelled like rotten food or something! and it was liquid as water!

    How many miles on your T-case anyway? Mine has about 110,000 with no rebuilds. Maybe yours is asking for a rebuild (hope not).

    Good luck. If you have any more questions just ask.

    <font color=black>//////
    What the heck!...Drive it like gas is $0.50/gal!!!
    </font color=black>[​IMG]
     
  11. paul_cfh

    paul_cfh Registered Member

    Joined:
    Apr 22, 2000
    Posts:
    82
    Likes Received:
    0
    Location:
    OH (for school) NH to live
    neko i would say that you need to adjust the linkage .........mine was the same way when i first got my 78 blazer ...i had to beat the shifter to get it to move .......and no matter how hard i tried i could not get it into low lock .....haynes explains how to adjust it (it will tell you to go buy a pin from a dealer just use a nail) i did that and now it shifts so smooth .....no problems ........FYI it took about 20 min to do it



    [​IMG]<font color=blue>where the road ends the fun begins</font color=blue>[​IMG]
     
  12. Neko H

    Neko H Registered Member

    Joined:
    May 31, 2000
    Posts:
    21
    Likes Received:
    0
    Location:
    Texas
    Well .............. I checked the linkage set the pin with the NP203 in neutral. The levers from the transfer case pointing down at 6:00. All is well there, checked the oil pulled the fill plug oil seeped out so all is well there. BUT I STILL have only Low, Neutral, & High NO Loc that I can find.

    ANY Ideas??????

    Neko H
    79 GMC Jimmy 4x4
    (If I'd only win the Lottery, it would be Cherry)
     
  13. Brady

    Brady 1/2 ton status

    Joined:
    May 6, 2000
    Posts:
    628
    Likes Received:
    0
    Location:
    Parachute,Co
    Does the rig have hubs in front maybee autolocks.Might have been converted already by previous owner?The problem with converting these to part time is in 2wd it will not lubericate all of the bearings so you need to put it in 4wd at least once a month if not more and drive it.to get oil to all the bearings.Actually any 4wd should be put in 4wd and driven to get oil on all the bearings not used in 2wd.Chevy says on a parttime rig should be driven with the hubs lock for 10miles once a month.This will keep the gears and bearings lubed.Brady
     

Share This Page