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.

NP205 overhaul??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by jarheadk5, Sep 8, 2000.

  1. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    I recently acquired a 205 from a Blazer, don't know what year. I think it was attached to an auto tranny. While I decide what I'm ultimately going to do with it, I'm going to rebuild it. How hard is this? I've never attempted anything like this before, but I do have a pretty extensive mechanical background (duh...). Where would I get an overhaul kit from? Are there any specific things or places to look at to determine whether it's good or bad? Is there a book with a picture/drawing or two? Any special tools required? Thanks for the help!

    [​IMG] Semper Maintenance!
     
  2. Russ

    Russ 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    509
    Likes Received:
    0
    Location:
    Summerdale AL
    It is not a hard process to rebuild the case. You can take a look at most of the gears through the pto cover to see if they look allright prior to disassembling it. I bought a small parts kit from a local driveline shop here in San Diego, I'm sure you could find one around there, or order one over the internet. The kit will come with all the bearings seals and snaprings to rebuild it. That is really about all there is to replace as long as your gears are OK. If any of your gears have black spots or pitting on them then I would replace them. They have probably been in water, and the metal will continue to flake off if it is black. There is a good breakdown in the chevy shop manuals for the transfer case. I highly recommend that you get a GOOD set of snap-ring pliers before you start, that will make a huge difference.
    Russ
     
  3. Steve_87K5

    Steve_87K5 1/2 ton status

    Joined:
    May 26, 2000
    Posts:
    521
    Likes Received:
    0
    Location:
    central NC
    ditto ...get GOOD & LARGE snap ring pliers. Also check for slop in the front drive flange. It is easy to rebuild. JC Whitney sells a manual in their book section on the 203/205. It has a complete exploded view diagram in it. The only adjustment is the tension on the idler gear bearing. This is easily set by the tightness of 1 bolt. There are some 205 photos on my website. http://www.geocities.com/tneg50/ Hope this helps.

    SteveB
     
  4. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    EXCELLENT!! Keep the tips and advice coming, I've just about convinced myself to do it.

    [​IMG] Semper Maintenance!
     
  5. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    Anyone else with tips/advice? I know there's got to be a few more of you out there who've rebuilt 205's...

    [​IMG] Semper Maintenance!
     
  6. TX Mudder

    TX Mudder 1/2 ton status

    Joined:
    Jul 10, 2000
    Posts:
    2,514
    Likes Received:
    0
    Location:
    Houston
    Mine's slightly greasy (original 205 in a 76) and probably needs new seals, but it holds fluid so screw it LOL
    4WPW sells rebuild kits for the 205. Call them and ask how much.
    -- Mike
     
  7. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    OK, here's a couple more things. You need a thin wall 1 5/16" socket to get the rear output yoke off. Some normal sockets will fit inside the yoke, but most will not, it depends on the yoke and the socket. Hold the yoke with a big pipe wrench, and preferably use a 3/4" drive ratchet with the big socket (and probably a long cheater pipe) to get the yoke nut off. The front takes a similar 1 1/8" socket. I managed to borrow some tools from work for this. The cross shaft that the idler gears rides on also uses the 1 1/8" socket for its nut. You have to punch the roll pins that hold the shift forks to the shift rails out from the outside of the case before you can can finish dissassemby. There are holes through the top of the case for access to punch the pins out. Use a drift punch to punch the plugs that are in the holes into the case (retrieve them later), then line up the shift rails and punch the pins into the case also. These are really the only tricky parts. There are loose roller bearings in a couple of spots in the 205, but they do not pose much of a problem. Just pay attention when you take it apart, and use some axle grease to hold them in place for re-assembly. The end play in the idler gear is set by shims, you should be OK to just put them back in the way they came out. You do not set the end play by the torque on the nut, the shims do it. The nut just gets torqued to spec. I think the torque specs are in my factory service manual for the '70 Blazer.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  8. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    Oh yeah, I installed a complete rebuild and small parts kit in my 205 since I never had a chance to run it before I was going to install it in my Blazer. I would not have had to replace any of the bearings, and I don't think it is usually necessary in any 205, unless it has been severely thrashed, or underwater or something. Gaskets and seals would normally be all. The one thing I did do was replace the shift rails, as they had deep grooves where the seals sit when in 2WD HI. Good luck finding the Chevy style shift rails if you want new ones. My local truck parts place found a box of stuff in the back room (I kept pressing until they got the mechanic out to the counter), and there was a new set in there that the guy sold me for $10 a piece. Not sure if they are available from GM. This is a common leak point for this case.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  9. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    Is that enough info for ya???

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  10. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    Thanks Tim, I appreciate it. One more thing; I pulled the PTO cover off and looked inside, everything looks good. I squirted some 80-90W gear oil in to coat everything and closed it back up. I found a silver metal tag with the following on it:

    6261465
    3 25 69 205

    Does this mean it came off a SM465 tranny? I assume the date-looking sequence is the build date.

    [​IMG] Semper Maintenance!
     
  11. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    Not sure if the "465" in the tag # means it came off a 465. If it has a 10 spline input shaft, it is from a manual tranny (SM465). If it has a 27 (I think) spline input, it is from a TH350. TH400 had 30 spline, I think.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  12. Steve_87K5

    Steve_87K5 1/2 ton status

    Joined:
    May 26, 2000
    Posts:
    521
    Likes Received:
    0
    Location:
    central NC
    I agree with Tim on the idler gear bearing preload, but there is some taper on one end of the shaft, and if the
    shims are not correct, it is possible to add preload by adding torque. Roll Pins: if you dont have the right
    size drift punch a large nail ground off is just right. To get the drive yoke nut off I use an impact wrench and
    hand hold the yoke itself. If the nut and washer are messed up, they are not in the kit. The part numbers are:
    nut, rear output shaft NE 97864. Washer, rear end yoke TW 334-150. I believe these are TRW p/ns. On reassembly it is possible to get the shift rods sequenced improperly, and have to R&R the roll pins again.

    SteveB
     
  13. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    Hey, I used a big nail with the end ground off when I did mine too!

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  14. Nike

    Nike Registered Member

    Joined:
    Feb 17, 2000
    Posts:
    93
    Likes Received:
    0
    Location:
    Jefferson City, Missouri
    I got a video from a place in Wisconsen. It is really informative and takes you through disassembly, evaluation of parts, and reassembly. The place advertises in most of the 4wd publications or send me an e-mail and I will get you the address. Nike in Mo.

    Blue
     
  15. TX Mudder

    TX Mudder 1/2 ton status

    Joined:
    Jul 10, 2000
    Posts:
    2,514
    Likes Received:
    0
    Location:
    Houston
    I always assumed the first set of numbers on the plate was a serial number.
    You are ussming correctly, the second set of number is a build date. Your 205 was probably OE in a '70 vehicle.
    -- Mike
     
  16. Blazer1970

    Blazer1970 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,600
    Likes Received:
    0
    Location:
    Old Mission, MI
    What fun would it be if you had a video? I did mine without any kind of instructions, or even an exploded view of the case. It was easy in comparison to the SM465 tranny that I did the same way.

    Tim

    1970 Blazer CST 4X4 350 SM465 NP205
    1987 Suburban 4X4 350
    1988 Chevy Pickup 4X4 350
     
  17. 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.
    Is that video for NP205 only, or does it cover the NP203 as well ?
    if it does cover the NP203, can you please give more info...........
    Thanks alot
     
  18. jarheadk5

    jarheadk5 1/2 ton status

    Joined:
    Mar 6, 2000
    Posts:
    4,389
    Likes Received:
    0
    Location:
    PA
    Thanks for all the info folks, I'll be getting started on this soon!

    [​IMG] Semper Maintenance!
     
  19. Nike

    Nike Registered Member

    Joined:
    Feb 17, 2000
    Posts:
    93
    Likes Received:
    0
    Location:
    Jefferson City, Missouri
    The video I have covers the 205 only - and it is informative. I think they have one for the 203 - Name of company etc. Technical video, 16325 E. Lincoln Drive, Fall Creek Wisconsen 54742-4813. I called them one morning, but I can't find the phone # now, put the video on a credit card, and got it the next day through regular snail mail - absolutly amazing. Nike in Mo

    Blue
     
  20. BlazerGuy

    BlazerGuy 3/4 ton status

    Joined:
    Apr 20, 2000
    Posts:
    9,206
    Likes Received:
    0
    Location:
    abcde
    Any tips for rebuilding a NP208? Mine is leaking so it's time for a rebuild.

    [​IMG] YEEEE HAWWW!!! [​IMG][​IMG]
     

Share This Page