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.

Should I rebuild my TC NP241? Got some vibs...Update Fixed!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by tch777, Sep 29, 2003.

  1. tch777

    tch777 1/2 ton status

    Joined:
    Jan 15, 2003
    Posts:
    244
    Likes Received:
    0
    Location:
    Colorado Springs, CO
    My 91 burb has 127,000 on it now. The guy who swapped my gears for me said the chain was a little loose then.

    I have just lowered the T-case by shimming it down, and I replaced both u-joints on the rear driveshaft. The eliminated a low vibration by 70% that we have been having. Now it is very bearable and I almost don't notice it. But if I am cruising at like 60 MPH and I pull very slightly out of the throttle I get a rough vibe and groan from the driveline. And when I put it in drive or reverse it pauses a makes a clunk.
    Is there a way to tell if the chain is too stretched?
    Is there a way to diagnos the TC as the noise source?
    If I have to do the chain I will also do the rebuild kit from JB conversions while I am in there.
    I just want to make sure I really need to do the chain. I don't want to blow 240.00 and a weekend and fix something that doesn't need fixed.

    Thanks

    Tim

    Well it turns out the Pinion bearing was wasted by an out of balance driveshaft! I got both of these items fixed and went thru the TC, the TC was fine. Driveline shop said whenever you take out the factory u joints that are held in by the plastic retaining clips you HAVE to balance the drive shaft. I don't know but for 70.00 bucks I will probably balance the driveshafts on everything I own. The Burb drives soo smooooooooth now it is scary!

    HTH
     
  2. sdavid

    sdavid 1/2 ton status

    Joined:
    Aug 5, 2002
    Posts:
    244
    Likes Received:
    0
    Location:
    Livingston, TX
    Re: Should I rebuild my TC NP241? Got some vibs...

    Sounds like you have problems with your rear gears, not your T-Case. The 241 will not be spinning in 2 wheel drive. When ever you let off the gas and hear noise, it is normally problems in the rear drive line. Is your pinion loose?
     
  3. tch777

    tch777 1/2 ton status

    Joined:
    Jan 15, 2003
    Posts:
    244
    Likes Received:
    0
    Location:
    Colorado Springs, CO
    Re: Should I rebuild my TC NP241? Got some vibs...

    How do I check for that? Do I need to take the Ujoint back off and check the pinion nut on the flange the ujoint mounts too?

    Thanks

    Tim
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Joined:
    Aug 28, 2002
    Posts:
    9,095
    Likes Received:
    144
    Location:
    california
    Re: Should I rebuild my TC NP241? Got some vibs...

    I also have a 241 and are you aware that it is NOT a full time 4wd like the 203? The chain doesn't spin unless the TC shifter is in 4wd. I get that funky sound too when I start to let off the gas but goes away when I take my foot all the way off. It only makes the noise in a sertain spot when letting off the throttle. I had a pinion bearing problem when I swapped my 14BFF in and Had it fixed after a 100miles or so. The guy at the shop told me the rearend might make a little noise because the R&P wasn't wearing right. He also said it should still last for a LONG time. I wouldn't worry a lot about especially if it's not a 10 bolt.
     
  5. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Re: Should I rebuild my TC NP241? Got some vibs...

    Just bring it by the house and we'll check it over. /forums/images/graemlins/cool.gif
     
  6. K5 NUTT

    K5 NUTT 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,611
    Likes Received:
    0
    Location:
    Grand Junction Colorado
    Re: Should I rebuild my TC NP241? Got some vibs...

    Best answer i was able to get out of gm that 1/2 of slop in the chain was ok...which holds true for superduty flywheels...would still like a better answer than that though. Our 90 has the same problem...around 65-70 we get a vibration...new motor...new trans...i rebuilt the xfer...replaced the driveshaft yoke..new u joints...and had the driveshaft balanced..next i had the tires rebalanced...suppose its time to pull the rear end cover and take a peak see...as the vibs are still with me...

    DW
     
  7. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Re: Should I rebuild my TC NP241? Got some vibs...

    [CONTINUE THREAD HI-JACK]

    MY '89 V2500 has this SAME freakin vibration. ITS STARTING TO GET ON MY NERVES. Mine is more drastic though I think... around 60-65mph, I get a cyclic vibration. It goes:

    vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr... well you get the idea. At some point in there though, its riding smooth. I've had the tires balanced, replaced the u-joints, replaced the rear shocks too. MY 241 I just rebuilt before I put the truck on the road about 5000mi ago. I would ASSuME that isn't the problem.

    One thing is that I am running a 14SF rear axle... anyone else? My last ditch effort is going to be to replace all 4 rims and tires... even though I am already running after market rims and decent tires.

    DAMN I wish I could figure that vibe out...

    -Dan

    [END THREAD HI-JACK]
     
  8. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Re: Should I rebuild my TC NP241? Got some vibs...

    [ QUOTE ]
    Just bring it by the house and we'll check it over. /forums/images/graemlins/cool.gif

    [/ QUOTE ]

    Harry-

    Which drive line do you have in your Burb? Does yours have any vibes? MAN I wish I could figure this one out!

    -Dan
     
  9. tch777

    tch777 1/2 ton status

    Joined:
    Jan 15, 2003
    Posts:
    244
    Likes Received:
    0
    Location:
    Colorado Springs, CO
    Re: Should I rebuild my TC NP241? Got some vibs...

    Harry,

    I will give you a call today. I really have my doubts that it is anything in my rear diff, I had the gears changed 2 years ago, and I got a whole new Eaton LS put in cause my old carrier was cracked. I had this done at a reputable shop here in town. Plus the vibe was there before hand and still there afterwards. I have checked everything I can think of and see for tightness. This just leaves motor mounts and the tranny mount for being worn out.

    But you know what the strut arm that goes from the NP241 to the bell housing is not attached. PO broke the bolt off in the housing so that end of the strut arm is dangling there. I think I will take that sucker off and go for a cruise tonight after work.

    Tim
     
  10. Mastiff

    Mastiff 1/2 ton status Premium Member

    Joined:
    Jul 21, 2002
    Posts:
    2,755
    Likes Received:
    48
    Location:
    Tucson, AZ
    Re: Should I rebuild my TC NP241? Got some vibs...

    [ QUOTE ]
    [CONTINUE THREAD HI-JACK]

    MY '89 V2500 has this SAME freakin vibration. ITS STARTING TO GET ON MY NERVES. Mine is more drastic though I think... around 60-65mph, I get a cyclic vibration. It goes:

    vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr vvvVVRRRRRRRrrrrr... well you get the idea. At some point in there though, its riding smooth. I've had the tires balanced, replaced the u-joints, replaced the rear shocks too. MY 241 I just rebuilt before I put the truck on the road about 5000mi ago. I would ASSuME that isn't the problem.

    One thing is that I am running a 14SF rear axle... anyone else? My last ditch effort is going to be to replace all 4 rims and tires... even though I am already running after market rims and decent tires.

    DAMN I wish I could figure that vibe out...

    -Dan

    [END THREAD HI-JACK]

    [/ QUOTE ]

    If you find out the problem, let me know! I've had the same type thing, a sort of pulsing in and out vibration, for 5 years. I have completely replaced the rear axle (10 to 12 bolt), the driveshaft (regular to CV) and all four tires and rims. Nothing has much effect.

    My leading theory is that it's coming from the exhaust. I replaced my exhaust system a while back (with headers plus all new pipes) and the pipes appear to be clamped rather tightly to the body. Most vehicles I see have the pipes hanging loosely from rubber, but on mine the pipes are firmly attached to the body with only a thin piece of rubber for isolation. I dremeled away a few of the pieces of wire/rod that clamped the pipes to the body and a think it quieted it up a little. I haven't gotten around to finding a muffler shop to completely hang the pipes from rubber yet.

    I also replaced by transmission a while back though (700 to 400 with adapter to 208) so there are other unpleasant possibilities.
     
  11. KRAZIE87K5

    KRAZIE87K5 1/2 ton status

    Joined:
    Feb 23, 2001
    Posts:
    3,369
    Likes Received:
    0
    Location:
    Chicago, IL
    Re: Should I rebuild my TC NP241? Got some vibs...

    My exhaust is on rubber mounts... and its not the cause in my case... /forums/images/graemlins/confused.gif

    -Dan
     
  12. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Re: Should I rebuild my TC NP241? Got some vibs...

    Dan, mine's a 700R4, 241. It didn't have any vibes when I bought it, but I haven't driven it on the highway since I swapped in the 14-bolt FF rear end.
     
  13. HarryH3

    HarryH3 1 ton status Author

    Joined:
    May 31, 2000
    Posts:
    10,384
    Likes Received:
    2
    Location:
    Georgetown, TX
    Re: Should I rebuild my TC NP241? Got some vibs...

    Tim, just give me a ring when you get time. We'll see what we can figure out. /forums/images/graemlins/cool.gif
     

Share This Page