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203 transfer cases (some interesting things I found) LONG

Discussion in 'The Garage' started by Leadfoot, Feb 5, 2003.

  1. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Well as some of you know, my 78's tranny crapped out on me (bearing support in the middle of the case let go). While I had the tranny out, I dedided to rebuild the t-case (NP203 with MM shaft part time conversion kit) as it was a little sloppy. I ordered a rebuild kit (bearings, seals,etc) and a new chain. Once I got it apart I saw why it was "sloppy". The input gear, sliding clutch, and "intermediate shaft" teeth were worn on the "HI" side, which also explains why it was nowhere near as loose when in "LOW". In "HI" going from forward to reverse there was a solid clunk. When I first got the rig I rebuilt the driveshafts and checked the ring and pinion and found they were in good shape, which makes sense as it only happened in HI gear.

    I ended up getting 2 spare NP203's (3 total) to make 1 good one, and will hopefully make a second for a backup and write an article on it (didn't have time for this one as it had to go back in the plow truck ASAP...also daily driver).

    I have rebuilt several NP205's in the past and let me tell you the NP203 dwarfs it. The NP203 is huge and friggin' heavy ([high pitched voice]I think my balls are 2" lower after moving those 3 cases in and out of the back of trucks[/high pitched voice]). Upon comparison, I actually like the case (depending on application) as much as the 205. Until I actually saw the inside of them (which is a small engineering feat), I thought they were weaker than the 205. I would definitely have to dispute that now. People have said they are weaker due to the chain not being as strong as a gear. Granted both the 203 (gear box portion) and all of the 205 have huge hardened gears to transmit power (whether it be high or low) to the outputs and are constantly meshed, and yes they are "probably" (As I don't have a way to measure the amount of torque they would fail at) stronger than a chain, but each case has TINY (in comparison) teeth on the input and high/low gears that the sliding clutch engages to select high or low range. All that power is transmitted through these TINY teeth (you will know when you pull one apart) that I will guarantee are much weaker than the 203 chain (I don't know about the 208's, 241's, etc. as I have not worked on them).

    That being said. The 203 has it's pro's/con's. Most people know the cons (a misconception for a con is that it is inherently weaker than a 205), so here are some pro's.
    Pro's:
    Heavy (if you are like me and need all the weight you can get for winter traction.....also for pulling traction it is unmatched)
    Strength (as long as it is not neglected, it is as strong as a 205)
    Availability of full time operation (for maximum traction at all times and acceleration it can't be beat.

    The weight is a big drawback, overall length, and maintenence is slightly higher than a 205, but I just wanted to let everyone know it is not as "undesireable" or as "weak" as I (and most others) originally thought. By the time the chain becomes loose enough to notice (unless neglected), then a rebuild is in order anyway as the bearings and thrust washers should be checked (even in a 205).

    Is there anybody here that has SEEN a 203 chain break without neglect before something else in the case.

    Also the enginuity did not stop with the case (which is pretty impressive). I cleaned/lubed/rebuilt two of the shifters. The shifter itself has some nice engineering features in it. Think about the shift pattern (L Loc, L, N, H, H Loc) as the shifter moves front to back, and that both "Loc" positions are at opposite ends. The Lock feature on the case only moves from Open to Lock, not Lock to Open to Lock. The shifter has to account for this, and the way they "gate" the shifter with a pivot and a latch to accomplish bi-directional output from a uni-directional input is pretty clever (considering there are several ways to do it, the way they did it and in the space constrictions they were working with is pretty ingenious).

    I just want to clarify before I get flamed. The 205 is a great case and depending on weight and overall length requirements may be the only case you can use and is as strong as they come. I just wanted to let others who have a 203 and are thinking of going to a 205 for "strength" concerns, that they probably aren't gaining anything. For a trail rig that did not have any driveshafts yet, I would probably choose the 205 as it is shorter for better driveline angles and better parts availability, as well as the ability to twin stick, but if it already had a 203 and correct driveshaft lengths, I would be hard pressed to swap it out. Besides, I've seen guys go pretty far with a non-converted 203 before they even have to put the case into "Loc".

    OK, there's my two pennies. Do with them what you will. /forums/images/graemlins/thumb.gif
     
  2. m j

    m j 1/2 ton status

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    all I have ever heard is the cool sound the chain makes as it skips teeth.
    worn teeth is bad shifting, auto?
    the front 6" of a 203 is great, works good in front of a 205
     
  3. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    all I have ever heard is the cool sound the chain makes as it skips teeth.

    [/ QUOTE ]
    Not saying it didn't happen, but I highly doubt that is the case (no pun intended)
    If it did, it would have to be an isolated case.
    Have you actually torn one of these apart?


    I could see the range collar slipping on teeth and making a pretty cool sound.


    </font><blockquote><font class="small">In reply to:</font><hr />
    the front 6" of a 203 is great, works good in front of a 205

    [/ QUOTE ]
    /forums/images/graemlins/tongue.gif /forums/images/graemlins/thumb.gif
     
  4. m j

    m j 1/2 ton status

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    yup I have one apart
    the range fork would kick out of gear and not reengage,
    this Ford would crunch and pop and front shaft would kick back

    you refer to 'neglected', I assure you that every 205 and 203 out there has been neglected.

    the tiny teeth are not much smaller then are found in a semi tractor tranny that can transmit 2000ft#

    cant wait to see a write up(if I get to see it)
     
  5. Waxer

    Waxer 1/2 ton status Author

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    My 203 also did the "popping thing" with the chain. It also kept jumping out of 4low on me every chance it could get. So I took it to a professional to have it rebuilt. New chain, bearings, seals, etc...

    First trip out wheeling with the fresh case and it wasn't clicking, seemed like it was fixed. But once I really leaned on it while doing an uphill climb, I started to hear the chain skipping teeth again. It just got worse and worse after that point.

    I finally decided that a 205 was in order. Installed it and have had no trouble ever since. I'm sure that there were probably gears that the chain rode on which were worn and could have been replaced, but after the second time I was done with 203's. I will use the gear reduction for a doubler one day but that is about it for me.

    Glad they are working out for you tho.
     
  6. BorregoK5

    BorregoK5 1/2 ton status

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    Very cool. So did you end up putting the new chain on?
     
  7. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    I put in a new chain only because I ordered a new one. The "old" one was not sloppy.
     
  8. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    the range fork would kick out of gear and not reengage

    [/ QUOTE ] I this the same one that the chain was skipping teeth?
     
  9. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    the tiny teeth are not much smaller then are found in a semi tractor tranny that can transmit 2000ft#

    [/ QUOTE ]

    I agree, but strength wise they will bite the dust before the 2.5" chain would. The reason I said neglected is that "anything" is possible. Just because one chain goes does not mean it is an inherent weakness of the case. I agree that the teeth are strong.....that is all the 205 has to transfer the power and those things take abuse. My point was that the 203 uses the same size/shape/cut teeth to transfer power, and that they "should" fail before a good chain and chain sprockets would.
     
  10. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Not saying it wasn't but again I highly doubt it was the chain. My old 205 did the same thing (no chain). I had it rebuild (before I knew how to). New bearings and seals, new shift forks and new clutch collars. Worked ok for a couple of months and started again. That's when I decided to "try" and rebuild one. Found out the engagement teeth were worn causing it to pop in and out rapidly. ONLY cure for that was a new shaft and new Low gear (both have engagement teeth machined on/into them). That was $$$$$, and probably why most shops don't replace them.

    I will try to post pics by the end of the month on the pieces I'm talking about and then show the chain and sprocket gears and let you decide in a side by side comparison.
     
  11. Waxer

    Waxer 1/2 ton status Author

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    Well on the first 203, it was a combination of the chain and the gears. How I know the chain was a factor was I hung it side by side with a new one and the old chain hung about an inch lower, meaning it was stretched.

    Those pics would be great.

    On another note, I just received the extra 205 I purchased off a member here and I'm going to be rebuilding it (so I can learn how). Any tips for me at this point?
     
  12. ZonkRat

    ZonkRat 1/2 ton status

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    Like you said neglect is the biggest cause of chain driven case failures.It doesn't take long to ruin one either.I got water{prob mud too}in my 241 and like dummy waited week before i ccanged it{didn't know it was that full}.Ruined the fluid pump and another six weeks the bearings went.Front drive would quit at first,then got to jumping into neutral{shifter didn't move}even in 2WD.Ireplaced it and will build it for future use.KEEP the lube right and clean and there's nothing wrong with chain drives. /forums/images/graemlins/crazy.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/thumb.gif
     
  13. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    Well on the first 203, it was a combination of the chain and the gears. How I know the chain was a factor was I hung it side by side with a new one and the old chain hung about an inch lower, meaning it was stretched.

    [/ QUOTE ]
    That makes sense (chain neglect). Something you wouldn't have to worry with a 205....yes.


    </font><blockquote><font class="small">In reply to:</font><hr />
    On another note, I just received the extra 205 I purchased off a member here and I'm going to be rebuilding it (so I can learn how). Any tips for me at this point?

    [/ QUOTE ]
    I have a half-assed write-up now that I will send you. I'm hoping to spend some time to edit it as well as pull apart another 205 and get some better pics (my first attempt with a digital camera was pathetic). My best advice is invest in a good set of heavy duty snapring pliers. Not the kind with the needle type points, but the kind that transmission rebuilders use. Lay everything out, take your time inspecting the shaft teeth and the hi-low engagement teeth as well as the clutch rings. MJ has some pics on his site, I have a few posted, and I have an exploded view that I have been using and it works. There was also a link to a well written 205 rebuild and the link was just reposted in the last day or two. A search on 205 should yeild it for you. If you have any specific questions, feel free to PM/Email me.
     
  14. u2slow

    u2slow 1/2 ton status

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    Anyone run a 203 as a "full-time" case anymore?

    Just wondering... since I have one I could use in a "trail-mostly" rig. Flanges are less fuss than lockouts. How about running it with lockers front and rear? /forums/images/graemlins/wink.gif
     
  15. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    You laugh but people do around here. Definitely NOT the majority, but it is sweet on slick icy/slushy roads and high speed cornering on dirt roads screwing around. You could get away with lockers front and rear too as the differential in the case would absorb SOME of the usual on pavement driveline bind (but then again if you have lockers front and rear it is most likely not a DD). Granted it wouldn't be ideal, but still useable.

    At one point I thought/ASSumed EVERYBODY had converted to part time because everybody said you should/have to do it........My question is why? Around here it is still 50/50. Most "kids" around here do as it is cheaper for fuel and less wear and it seems more hard-core, but most of the "plow guys" have left their case intact and installed lock-out hubs. Added traction with the plow on without having to drive around in "Loc" just to go anywhere is nice and is easier on the driveline in corners. Granted they have to run in "LOC" to move with the hubs unlocked, but the only "unnecessary" item spinning is the front driveshaft (and under no bind). Hubs locked, it's just like the factory. I have a feeling that's not what YOU use your rig for, but for others it may make sense and save some coin.
    Again for a trail rig, maybe not ideal, but for a daily driver/weekend warrior it is a good setup (except for the "hard-core" guys /forums/images/graemlins/rotfl.gif). It's all in perspective and application. By no means was I stating it should be the case of choice for ARCA competitions. Most "regulars" around here have already modified their rigs to a point and use them in such a way that the full-time aspect of the case is "obsolete". My point was for some of the Newbies that feel they have to modify their rigs a certain way because "WE" all have. It would be arrogant of us to believe that everybody is in the same boat we are and should modify their rigs the same as "WE" do. As it is, I use my rigs quite a bit differently than most here. It has given me a chance to see different uses and pro's and con's of different mods. Some are cool, but not necessary for what I do, and some are impossible. My 78 will stay stock height for plowing, so a crossover setup (although nice if I ever flexed it on a snow bank) is not an option for me without the lift.
     
  16. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    I have a 203 and cannot really complain about anything in particular. Its sometimes hard to shift out of Low Loc back into high, but it has never popped out of gear or made "funny" noises. On the trail it has worked flawlessly...so far.

    I would have to say that my experience with low and high (not "loc") has seemed like little more than 2wd off-road. i would imagine on the street or dirt roads there would be a noticable advantage. If you need those tires to grip, then better "loc" it.
     
  17. driney

    driney 1/2 ton status Premium Member

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    Any truth to the story I was told that sometime prior to 1978 the chain and sprocket design was changed to eliminate skipping if the chain stretched? All I know is my 78 PU with a 203 has not given me any trouble in over 200,000 full time (not converted) miles of abuse. Of course I never went with any larger than 12.00x16.5 tires and never towed more than 13000lbs.
     
  18. driney

    driney 1/2 ton status Premium Member

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    When my truck is hard to shift, it is a sign the shifter needs cleaned and lubed. One guy I know would just pull the boot off and pour diesel fuel down through the shift mechanism.
     
  19. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Glad somebody agrees with me about the 203. /forums/images/graemlins/thumb.gif
    I personnaly thing a lot of the problems that perople had with the 203 were not the 203's fault at all it was the owners fault. It was miss matched tires. You HAVE to replace all 4 tires at the same time and keep them rotated. If you don't the Diff is always slipping and it eats the gass millage. My 75 and 79 got the same MPG before my 75 took on some big stuff like lockers in both ends and 35's. The 79 has been converted since before I woned it and my 75 was still full time ti I put the front locker in and I had to convert it. I have seriously thought about pulling the front locker and going back to full time.
    Now I did have to replace the chain in the 75. It was jumpint teeth under heavy load. Guess where the replacment chain came from?....





    If you guess waxer your right. I got the chain and 501 kit off him. Never had an ounce of trouble till the lockers stressed the 501 kit. I put the shaft kit in and it's been great.
    I agree...if it already has a 203 then it isn't worth changing it. Yeah the shaft kit is pricy but the fact of the matter is it would cost more for new shafts to fit the 205 unless you just happen to have everything in one shot and since the 205 behind a auto was a pretty uncommon option in a 73-79 K5 your going to have to get a rear shaft done regardless. Bug staying with it means if you trash a shaft damn near every junk yard is going to have several.
     
  20. JeremyK5

    JeremyK5 1/2 ton status Premium Member

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    Last fall I decided to test the chain on my '76 203 (not rebuilt, well maintained), so I took out the rear driveshaft, put it in low-lock, and floored it on the pavement. /forums/images/graemlins/eek.gif Nothing slipped or popped, I just spun my 31" bfg's for about 15 feet till I let off the gas. /forums/images/graemlins/thumb.gif
     

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