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.

Driveline Vibration help needed

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blue85, Nov 30, 2001.

  1. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,084
    Likes Received:
    486
    Location:
    Grand Rapids area
    OK, I could use some suggestions here. I am getting driveline vibrations sometimes. It occurs either when I am off the gas or almost off the gas. It almost sounds like I'm using a big rig compression brake. It only occurs in 4WD.

    Here's the story: I put on a 14B rear and with it a new adapter U-joint. I got a little vibration every once in a while while just barely applying the gas at speed. Then I put a matching gearset in the front and put new U-joints in the axleshafts while I had them apart. Then while driving in 4WD to break in the new gears I started getting this nasty vibration. So I changed the rear driveshaft front joint and the front driveshaft front joint. I rechecked the front pinion bearing preload and it is not loose.

    Now I can hardly get any vibration in 2WD no matter what I try, but it is just as bad as ever in 4WD.

    Where does this come from? Is it from the C/V joint? It still moves smoothly. Is it my loose slip yoke or the chain inside the T-case. Is it really a rear end problem that is only showing up under the load conditions caused by using 4WD?

    Soon I will try taping a plastic bag over the rear T-case output and driving in front-wheel-drive and I will also recheck the rear pinion bearings for looseness. I just don't know if I should take the plunge and rebuild the C/V.

    <font color=green>Oh man, 4:10's are sure better than 3.08's!</font color=green>
     
  2. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Do you have the T-case lowered for a lift? And if so what size lift is it?

    Mine did the same thing only when letting off the gas in 4HI. But since I put in a rear CV and raised the T-case back up it no longer does this.

    Surgeon General's Warning:
    Viagra and steroids may be harmful to your spouse![​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     
  3. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,084
    Likes Received:
    486
    Location:
    Grand Rapids area
    Oh yeah. I have 4" front springs, a rear shackle flip, T-case lowered 1" (for now), 6 1/2 degrees of shim under the rear spring packs. The C/V has just a little bit of grinding done to it (which didn't seem to help) It doesn't seem like my past experiences with incorrect u-joint angles, but I'm not ruling that out.

    So you also had the problem only in 4WD and it was essentially changes to the rear driveline that fixed it. That's interesting. Thanks.

    <font color=green>Oh man, 4:10's are sure better than 3.08's!</font color=green>
     
  4. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Well, not necessarily changes to the rear, but the T-case riaed back up to the stock height fixed it. It seemed that with the T-case lowered it caused the front CV shaft to reach its upper limits. My front CV joint very well could be worn out too.
    Jesse at High angle sells a front cv for K5's that works at higher angles which could rememdy your problems.
    Try taking a big mouth gatorade bottle to plug the rear of the t-case and wrap it with lots of duct tape. Raise the T-case back up to the stock height. And drive it in front wheel drive like you said and see what happens. Also try it in front wheel drive with the T-case dropped and see if you have a difference.
    Then reverse all this and try it with the front shaft out and only using the rear shaft. I think with the 4 options here you should be able to narrow down the possibilities.

    Surgeon General's Warning:
    Viagra and steroids may be harmful to your spouse![​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     
  5. TXsizeK5

    TXsizeK5 1/2 ton status

    Joined:
    Aug 26, 2001
    Posts:
    2,518
    Likes Received:
    0
    Location:
    College Station, TX
    What exactly does driveline vibrations feel like.. is it real noticble and unconfortable?

    6in 87' K5 w/ 35" BFG muds.
    305/Sm465/ NP208
    Kn, 4.56's.
    In desperate need of a rebuild.
    Next- Eaton mech locker... Flows.
     
  6. ftn96

    ftn96 1/2 ton status

    Joined:
    Sep 26, 2000
    Posts:
    3,238
    Likes Received:
    0
    Location:
    Nashville Tn
    Yes it is noticable and unpleasant. But it can also be mild and tolerable!

    Surgeon General's Warning:
    Viagra and steroids may be harmful to your spouse![​IMG]
    <a target="_blank" href=http://www.nashvillek5.freeservers.com>www.nashvillek5.freeservers.com</a>
     
  7. 2Dogs

    2Dogs 1/2 ton status Premium Member

    Joined:
    May 4, 2001
    Posts:
    3,470
    Likes Received:
    35
    Location:
    Ca
    Fixed mine by about 98% this weekend. The yoke on my 14FF was apparently worn out. You could not feel
    slop in the yoke by hand but when we replaced - AAAAHHHHHHH, what a relief. Still some very slight vibes but I think they are due to pinion angle being just out of specs.

    Will post this as its own topic. Jeez was that a good fix!

    Dave

    Horn Broken... Watch For Finger.
    <a target="_blank" href=http://coloradok5.com/gallery/Daves-Pics>http://coloradok5.com/gallery/Daves-Pics</a>
     
  8. Wheels

    Wheels 1/2 ton status

    Joined:
    Aug 18, 2000
    Posts:
    638
    Likes Received:
    0
    Location:
    Native Floridian living in Oklahoma, USA
    4" lift, ground the CV...Did you check the slip joint on the front shaft? And also, check the length of the front drive shaft. Mine did the same thing after the lift (4") and I had the rear lengthened and a new slip joint put in. The vibe went away in 2wd but was there in 4wd. Rebuilt the front shaft and it quit. Of course the 700R4/NP205 install null and voided the drive shafts. Had to get a shorter rear and a longer front. Anyway just my nickel.
     
  9. Blue85

    Blue85 Troll Premium Member

    Joined:
    Jul 26, 2000
    Posts:
    9,084
    Likes Received:
    486
    Location:
    Grand Rapids area
    Well I know that the front C/V is not limiting out on the street because I can disconnect it from the front yoke and spin it around just underneath the yoke.

    I have also had this little "shimmy" when taking off from a stop in various degrees since I did the first lift. I somehow improved that quite a bit this weekend just by taking out one of my overload leafs. See, one rear spring has more arch than the other, so I pulled the overload from that side to even it out and now the shimmy is reduced, but even better: the whole truck rides better! It's smoother and much better on the bumps. From just a 3/4" adjustment.

    So I'll have to try it in 4WD again. I will probably start another post on the benefits of a level truck later.

    Everything drives really good, except for when I let off the gas to slow down in 4WD. So I don't really suspect the front slip joint. I'm not really sure of how to check it, either. It seems solid...

    <font color=green>Oh man, 4:10's are sure better than 3.08's!</font color=green>
     

Share This Page