FYI FORD - MustangSteve's Ford Mustang Forum
The Internet's Most Knowledgeable Classic Mustang Information
IF YOU HAVE A QUESTION ABOUT CLASSIC FORD MUSTANGS, YOU HAVE COME TO THE RIGHT PLACE!
MustangSteve has over 30 years of Mustang experience, having owned 30 of them and restored several others. With the help of other Mustangers, this site is dedicated to helping anyone wanting to restore or modify their Mustang.... THERE ARE NO DUMB QUESTIONS!!!!!
Visit MustangSteve's web site to view some of my work and find details for:
FYIFORD Contributors' PICTURES - Power Brake Retrofit Kits for 65-66 Stangs - Classic Mustang FAQ's by MustangSteve - How to wire in a Duraspark Ignition - Mustang Ride Height Pictures and Descriptions - Steel Bushings to fit Granada Spindles to Mustang Tie Rods - Visit my EBAY store MustangSteve Performance - How to Install Granada Disc Brakes MustangSteve's Disc Brake Swap Page - FYIFORD Acronyms for guide to all the acronyms used on this page - FYIFORD Important information and upcoming events

You are not logged in. Would you like to login or register?

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  » Vibration in 66 Mustang

    • 1 2  Jump to

       

    4/01/2026 11:41 PM  #26

    rpm
    Senior 24-7 FYI Addict

    Offline

    From: Bakersfield, Ca
    Registered: 9/17/2013
    Posts: 3,933

    Re: Vibration in 66 Mustang

    Interesting concept. And one I had never thought thought about trying.

    Bob. 69 Mach 1, 5.0 GT40P heads, SMOD Toploader, Armstrong  steering, factory AC.
     

    4/02/2026 5:22 AM  #27

    TKOPerformance
    Hyper FYIFORD ADDICT

    Offline

    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,965

    Re: Vibration in 66 Mustang

    What is the diameter of the driveshaft?  What material is it made from?

    Last edited by TKOPerformance (4/02/2026 5:23 AM)

     

    4/02/2026 2:30 PM  #28

    rpm
    Senior 24-7 FYI Addict

    Offline

    From: Bakersfield, Ca
    Registered: 9/17/2013
    Posts: 3,933

    Re: Vibration in 66 Mustang

    TKOPerformance wrote:

    What is the diameter of the driveshaft?  What material is it made from?

     
    Check post #11, first sentence.

    "I bought it from Street or Track.  3-1/2” aluminum. 1350 ujoints"

    Bob. 69 Mach 1, 5.0 GT40P heads, SMOD Toploader, Armstrong  steering, factory AC.
     

    4/02/2026 3:26 PM  #29

    TKOPerformance
    Hyper FYIFORD ADDICT

    Offline

    From: Newark, DE
    Registered: 12/15/2014
    Posts: 7,965

    Re: Vibration in 66 Mustang

    Hmn, it will be interesting to see how the changing of angles affects the vibration.  Clearly there was something going on with the shaft, so hopefully that 100% fixes it.  

     

    4/07/2026 2:26 PM  #30

    MS
    Forum Originator

    Offline

    From: Canyon Lake, Texas
    Registered: 1/24/2013
    Posts: 12,750

    Re: Vibration in 66 Mustang

    I will be driving from Canyon Lake, Tx to Montrose, Colorado next week.  Any speed below 80 it is smooth as glass. I will just have to keep the speed down. 

    I think my ultimate plan to set the engine at zero, rear end at zero and shaft sloping down about two degrees should fix it, but I don’t feel up to redoing things right now. The 4° rear shim on it right now is bolted to the spring pack and that will require more effort than just loosening u-bolts and removing shims.

    Right now am hoping the Apple car play 7” screen gets here before Monday so I can have a bigger nav screen on the trip. I plan to mount it in the console door in the 66.

    Money you enjoy wasting is NOT wasted money... unless your wife finds out.
       •Thread Starter
     

    4/08/2026 8:50 AM  #31

    Steve69
    Senior 24-7 FYI Addict

    Offline

    From: Madison Wisconsin
    Registered: 4/01/2013
    Posts: 2,814

    Re: Vibration in 66 Mustang

    MS wrote:

    I will be driving from Canyon Lake, Tx to Montrose, Colorado next week. Any speed below 80 it is smooth as glass. I will just have to keep the speed down.

    I think my ultimate plan to set the engine at zero, rear end at zero and shaft sloping down about two degrees should fix it, but I don’t feel up to redoing things right now. The 4° rear shim on it right now is bolted to the spring pack and that will require more effort than just loosening u-bolts and removing shims.

    Right now am hoping the Apple car play 7” screen gets here before Monday so I can have a bigger nav screen on the trip. I plan to mount it in the console door in the 66.

      Post some pics of the finished product.  Thinking of doing something like that with mine/ 
     

     

    4/16/2026 3:56 PM  #32

    jkordzi
    I FYI 24-7

    Offline

    From: Sequim, WA
    Registered: 12/28/2013
    Posts: 942

    Re: Vibration in 66 Mustang

    I just went thru a similar problem.  I had a cyclical vibration that started at 2,000 rpm and increased after that. Hard to describe but the pitch went up and down continuously.  New tires.  I checked the T5's output shaft angle and it was down 5 degrees, but the 9" pinion angle was only up 0.5 degrees.  So nowhere near parallel.  I installed a 3/8" shim under the T5's mount that decreased the angle to 4 degrees down.  That's as far up as the T5 will go.  BTW, measuring the downward angle off the crank pulley gave the same result, which makes sense to me.  I then made some wedges for the leaf springs that are 0.25" thick, tapering down to 1/16".  This increased the pinion angle to 3.5 degrees up.  The vibration is now almost gone.  My driveshaft is an aluminum one from an Explorer so I assumed it was already well balanced but will check that next.

    Cheap, Fast, Good:  Pick Any Two
     

    4/16/2026 11:48 PM  #33

    Ron68
    Senior 24-7 FYI Addict

    Offline

    From: Mukilteo, Washington
    Registered: 4/01/2013
    Posts: 1,759

    Re: Vibration in 66 Mustang

    jkordzi wrote:

    I just went thru a similar problem.  I had a cyclical vibration that started at 2,000 rpm and increased after that. Hard to describe but the pitch went up and down continuously.  New tires.  I checked the T5's output shaft angle and it was down 5 degrees, but the 9" pinion angle was only up 0.5 degrees.  So nowhere near parallel.  I installed a 3/8" shim under the T5's mount that decreased the angle to 4 degrees down.  That's as far up as the T5 will go.  BTW, measuring the downward angle off the crank pulley gave the same result, which makes sense to me.  I then made some wedges for the leaf springs that are 0.25" thick, tapering down to 1/16".  This increased the pinion angle to 3.5 degrees up.  The vibration is now almost gone.  My driveshaft is an aluminum one from an Explorer so I assumed it was already well balanced but will check that next.

    Are you going to the North Olympic Mustang Club show in Port Angeles on May 3rd? A group of us from Mustangs Northwest are going. 

    68 coupe - 351W, 4R70W, 9" 3.25 -- 65 convertible - 289 4v, C4, 8" 3.00
     

    4/17/2026 9:05 AM  #34

    jkordzi
    I FYI 24-7

    Offline

    From: Sequim, WA
    Registered: 12/28/2013
    Posts: 942

    Re: Vibration in 66 Mustang

    Hey Ron, PM'ed you.

    Cheap, Fast, Good:  Pick Any Two
     

     

    1 2  Jump to

  • Index
  •  » FYI Ford, Classic Mustang Tech Discussion
  •  »  Vibration in 66 Mustang

    • Board footera


    REMEMBER!!! When posting a question about your Mustang or other Ford on this forum, BE SURE to tell us what it is, what year, engine, etc so we have enough information to go on.