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.

NP 205 Noise

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Texas76, Oct 26, 2000.

  1. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    I know that the NP205 is supposed to be noisier than the chain driven t-cases, but just how noisy? Before I installed the t-case, I replaced all of the bearings, checked the gears for wear, and even replaced the output shaft on the front driveshaft side. But this thing is really loud when 4wd is engaged and even when the hubs are locked and the t-case is in 2wd. You can even feel the vibrations in the floorboard (rhinolined).
    Any input would be great. Am I just paranoid or is this normal? Thanks.

    Ryan
     
  2. Shawn

    Shawn 1/2 ton status Premium Member Author

    Joined:
    Feb 17, 2000
    Posts:
    1,753
    Likes Received:
    5
    Location:
    5280'
    Do you have a lift? Are you sure your driveline angles are correct? My rear driveshaft never did align correctly and always caused a terrible sound from the 205 t-case. After I put a CV shaft in the rear, the 205 grinding/rattleing noise went away. You could always remove the rear driveshaft and run it in 4HI to see if this is the cause. Your angle on your t-case must be the same angle as your axle pinion angle (or not more than 2 degrees). If your axle pinion points up 10 degrees, then your t-case should point down 10 degrees.

    Shawn
    87 K5
    http://www.off-road.com/chevy
     
  3. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    If it was the angle of the rear drive shaft, wouldn't it make the noise in 2wd with the hubs unlocked as well? I will try your suggestion and double check. I do not have any lift on it, and I'm running 33 inch BFG Mud terrains. Thanks for the info Shawn.
     
  4. Shawn

    Shawn 1/2 ton status Premium Member Author

    Joined:
    Feb 17, 2000
    Posts:
    1,753
    Likes Received:
    5
    Location:
    5280'
    It would still make noise with the hubs unlocked mine did but I'm running a 7" lift. Since you're not running a lift, then it's probably not your shaft. It may be your 205 then. Sorry, I'm not sure what other advice to give. You might take it to a transmission shop and have someone go for a ride. They might have a better idea.

    Shawn
    87 K5
    http://www.off-road.com/chevy
     
  5. Thumper

    Thumper 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,582
    Likes Received:
    0
    Location:
    Alberta Canada
    Your noise is only in 4wd? Have you checked out your front driveshaft? The slip yoke splines wear and it may have some up and down play right where it slips. This will cause noise and vibes as well. You can try some grease in the yoke and see if the noise changes. Its a possibility.

    Mike


    <font color=blue>Thumper
    85 Fullsize Jimmy
    [​IMG]
    <font color=red>Lets Go Wheelin! </font color=red>
     
  6. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    Mike, my front drive shaft and the u-joints are brand new. I put the Jimmy on a lift and put it into gear with the 4wd engaged. With the transmission in drive and the engine at idle, it does not make the noise. As soon as you push on the accelerator, the noise starts. You can feel the vibration on the t-case itself. It sounds (and feels) like it is coming from the gears on the front output side. I'm the only person that I know around this area that has a 205, so I don't have anything to compare the noise to. But it seems excessive. Also, I only have about 700 miles on the engine(crate), transmission, and t-case (replaced a 203)since they were installed.
     
  7. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    I haven't had my 205 apart, but isn't the clearance on the gears adjustable? Maybe it too tight? Too loose?
    For comparison my 205 is dead quiet, no noise whatsoever in any of the ranges.

    Rene

    [​IMG]
     
  8. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    Rene, Thanks for the info on it being quiet through all of the ranges. When I put it back together, I don't remember there being any adjustment in the way the gears could be placed. I took it by a gear, clutch, and joint shop at lunch. The guys there listened to it and said that it was definitely not a normal noise. I guess I'll have the joy of taking it apart again. I'll be able to tell then if there is any adjustment.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    When I had the case at work cleaning it all up before installing it one of my co-workers pointed out these two things on the top of the case. He said this was the adjustment for the gears. Personally I have never had one apart, but it would make sense that there would be a way to adjust the gears.

    Rene

    [​IMG]
     
  10. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    Where on the top were the two things located? Do you think that it could be adjusted from that point without pulling the t-case? Fortunately, when I had the inside of my tub Rhino-Lined, they sprayed the access panel seperately. So I'll pull that off and look from the top to see if I can find what you're talking about. Thanks for the info.
     
  11. tom

    tom 1/2 ton status

    Joined:
    May 20, 2000
    Posts:
    157
    Likes Received:
    0
    Location:
    So. Cal
    Just a thought. Engage the hubs and drive at various speeds on smooth pavement with the t-case in 2wd. If it makes noise, you can be real suspicious of the front driveshaft or diff. If it is quiet, it suggests a look at the t-case.
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

    Joined:
    Jul 23, 2000
    Posts:
    36,169
    Likes Received:
    1,372
    Location:
    E-town baby!
    You'll have to bear with me this was about 2 1/2 years ago.
    If I remember these two things were on top like I said but were kind of angled and recessed a little, it looked like one was angled towards one gear and the other was angled towards the other gear.
    Ok (yuck I just got grease on my keyboard [​IMG]) I just went outside and had a good look at it. Sitting under the truck facing the front and looking at the back of the T-case, there is the round aluminum cover on the back, well directly above that on the top of the case is the adjusters and they are 90 degrees to one another. You'll know them when you see/feel them. They have some round rubber plugs that pull out (mine pulled out real easy). Also on the passenger side of the case are 2 more of these plugs, they are about 4" apart. These may also be a part of the adjuster set-up.
    Hope that helps, let me know what you find, I may have to do this someday.

    Rene

    [​IMG]
     
  13. BIGJ

    BIGJ 1/2 ton status Author

    Joined:
    Feb 17, 2000
    Posts:
    896
    Likes Received:
    0
    Location:
    Central Arkansas
    According to the Haynes manual as well as the Unit Repair manual from chevrolet, there are only two times you have to make an adjustment that can be measured. One is checking the endplay on the idler gear. It should be between 0.001 and 0.002-inch. The other measurement is on the rear output shaft. It can be between 0.002 and 0.027-inch. Unfortunately, the idler gear must be out of the transfer case to check the end play, which means taking it back apart.

    I get the same "grinding/rattling" noise that shawn described, but that is because I have a lift and the u-joints aren't angled correctly. No noise in 4hi or 4lo or in 2lo or 2hi, except at speeds of 60 mph or more (and definitely in 4wd at that speed). I can scan in some of the illustrations from my service manual if you want and e-mail them to you on monday.

    BIGJ
     
  14. Texas76

    Texas76 Registered Member

    Joined:
    May 24, 2000
    Posts:
    26
    Likes Received:
    0
    Location:
    Texas
    Rene, thanks for the info. I don't have my Jimmy with me this morning, so I'll take a look at it tonight. When I pulled the t-case out of a 3/4 ton truck, the two holes on the passenger side (that are 4inches apart) were used as part of a support brace. If you'll take a look, you'll notice that they are threaded (I think these are the same holes that you are referring too).

    BigJ, I dug out my Haynes and Chilton's this weekend. Thanks for the offer to scan them. I also got a "exploded diagram" of the t-case from the GM parts house as well.

    It will probably be later this week before I get a chance to get into it. I'm going to go ahead and pull the front output yoke off and the rear aluminum cover. I'm hoping that I'll be able to do all of this without pulling the t-case. But we'll see.
    I'll give you guys an update when I get it done. Thanks again for all of the info.

    Ryan
     
  15. TX Mudder

    TX Mudder 1/2 ton status

    Joined:
    Jul 10, 2000
    Posts:
    2,514
    Likes Received:
    0
    Location:
    Houston
    Did you ever figure out the noise?
    -- Mike
     
  16. jimmyjack

    jimmyjack 1/2 ton status

    Joined:
    May 11, 2000
    Posts:
    2,290
    Likes Received:
    0
    Location:
    Tucson Az
    My 1st truck had a 205 and the only time it made any noise, the drain plug had "fallen" out and all the fluid drained out. I plugged it back up, filled it up, and it didn't make a noise for years after. Hopefully, everything is ok inside of yours.

    creepin' and crawlin'

    Jim
     

Share This Page