Results 1 to 8 of 8

Driveline vibration

This is a discussion on Driveline vibration within the Drivetrain forums, part of the LSx Technical Help Section category; Long story short, I had to replace my u-joint in my stock driveshaft. This gave me a great excuse to ...

  1. #1
    Sold: LS1 '85 El Camino ls1camino's Avatar
    Join Date
    Dec 2005
    Location
    Laurel, Maryland
    Posts
    4,977

    2000 Grand Prix GTP
    2000 Trans Am WS6 M6

    Driveline vibration

    Long story short, I had to replace my u-joint in my stock driveshaft. This gave me a great excuse to install the ACPT Carbon Fiber Driveshaft that was sitting in my garage for over ayear. Now that I have that in, I have a vibration like the driveshaft isn't balanced, but carbon fiber shafts are balanced from the factory. From ACPT's website: "The balance of the job is handled by ACPT's primary distributor, Inland Empire Drive Line Service, in Ontario, CA. Here the driveshaft is fitted with U-joints and yokes, and is balanced. The balancing act differs from that of a conventional shaft since weights can't be welded on. Instead of adding weight, material is ground off the end fittings directly opposite of where weight is needed, until the shaft is in perfect balance." A friend said I may have tightened the end caps onto the u-joint too far and I'm crushing the needle bearings. I doubt that since All I used was a 13mm wrench and an allen key, and I am not THAT strong.

    I might also mention that I messed with the rear suspension as well. I did the heater hose mod (removed the rubber disc from the top of the rear springs and replaced it with heater hose wrapped around the top of the spring. I then centered the rear wheels using my adjustable LCAs and PHB. I checked the pinion angle of the torque arm when I was done and adjusted that back to 3* (where it was before the adjustments and the adjustments put it at 1*).

    I'm completely lost as to what is going on here.

  2. #2
    Super Moderator
    pajeff02's Avatar
    Join Date
    Feb 2009
    Location
    Mansfield, PA
    Posts
    21,567

    Black & Blue
    '02 WS.6 / '07 Suburban

    The stock driveshaft runs a damper -- could be that the vibration had been there all along but was not as noticeable. How bad is it?

  3. #3
    Super Moderator
    pajeff02's Avatar
    Join Date
    Feb 2009
    Location
    Mansfield, PA
    Posts
    21,567

    Black & Blue
    '02 WS.6 / '07 Suburban

    You went 3* negative (nose pointing down), right?

  4. #4
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    You're running a 9" aren't you, Jeremy? Is the CF driveshaft set for the stock length? I know when I swapped to the 9", it was mentioned that a few people experienced a vibration issue which was resolved by going to a longer driveshaft. I have the same driveshaft, and swapped u-joints for the 9". I don't have a vibration issue, but I'm just wondering if that might be the issue for you.....

  5. #5
    Sold: LS1 '85 El Camino ls1camino's Avatar
    Join Date
    Dec 2005
    Location
    Laurel, Maryland
    Posts
    4,977

    2000 Grand Prix GTP
    2000 Trans Am WS6 M6

    Quote Originally Posted by pajeff02 View Post
    You went 3* negative (nose pointing down), right?
    Err...no...3* nose up. I looked it up and I thought it said 3* up angle. Are you sure about that?

    Quote Originally Posted by Knight View Post
    You're running a 9" aren't you, Jeremy? Is the CF driveshaft set for the stock length? I know when I swapped to the 9", it was mentioned that a few people experienced a vibration issue which was resolved by going to a longer driveshaft. I have the same driveshaft, and swapped u-joints for the 9". I don't have a vibration issue, but I'm just wondering if that might be the issue for you.....
    9" has been in for over 2 years. Yes it's a stock length.

    As an update, the vibration is gone. I think some driving around worked out whatever it was. Did a 50-140 pull and it was smooth all the way.

  6. #6
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    Jeff is correct. You should have the pinion angle set to around -2. The pinion should be pointing slightly down from the driveshaft.

  7. #7
    Super Moderator
    pajeff02's Avatar
    Join Date
    Feb 2009
    Location
    Mansfield, PA
    Posts
    21,567

    Black & Blue
    '02 WS.6 / '07 Suburban

    J -- picture your car taking off from the driver side. The back wheel is rotating counterclockwise and the force of the wheel against the pavement is trying to rotate your axle in the opposite direction -- clockwise -- thereby lifting the nose of your driveshaft. That means that you need a negative angle on the pinion and it should point down.

  8. #8
    Sold: LS1 '85 El Camino ls1camino's Avatar
    Join Date
    Dec 2005
    Location
    Laurel, Maryland
    Posts
    4,977

    2000 Grand Prix GTP
    2000 Trans Am WS6 M6

    Quote Originally Posted by pajeff02 View Post
    J -- picture your car taking off from the driver side. The back wheel is rotating counterclockwise and the force of the wheel against the pavement is trying to rotate your axle in the opposite direction -- clockwise -- thereby lifting the nose of your driveshaft. That means that you need a negative angle on the pinion and it should point down.
    Ok, I'll have to fix that then...good thing it's an easy adjustment.
    2000 Pontiac Trans Am WS6 M6: 427ci LS3, Built T56, Moser 9" w/ 4.11 Gearing, Full Suspension, and 6-point Cage.
    2000 Pontiac Grand Prix GTP: Twincharged w/ a T67 Turbocharger
    2007 Chevrolet 3500 Dually Duramax: 3" Downpipe, Dual 4" Exhaust, EFILive Tuning

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Driveline problems
    By Andys04GTO in forum Manual Transmission
    Replies: 0
    Last Post: 07-26-2010, 03:20 PM
  2. Question: driveline upgrades?
    By Left_Slick in forum Drivetrain
    Replies: 2
    Last Post: 01-16-2010, 02:51 PM
  3. Driveline Vibration Problem
    By AborTivE in forum Manual Transmission
    Replies: 8
    Last Post: 01-26-2009, 10:05 AM
  4. Help! Sound coming from driveline!
    By LS1Formula01 in forum Drivetrain
    Replies: 0
    Last Post: 08-09-2007, 07:14 AM
  5. Help! Sound coming from driveline!
    By LS1Formula01 in forum Drivetrain
    Replies: 0
    Last Post: 08-09-2007, 07:12 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •