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  •  » Vibration solution

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    9/02/2025 8:59 AM  #1

    Michael H.
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    From: Laurel, MS
    Registered: 4/01/2013
    Posts: 914

    Vibration solution

    Years ago I had many posts about chasing a vibration problem in my 1967 coupe with T5 swap.
    I had tried all of the common things with no improvement.  I had the driveshaft balanced, checked pinion angles (and added 4 degree shims), balanced tires, etc. 

    The vibration was cyclical and only happened around 60mph.  After years of chasing this issue, in 2017 "Glens 1965 50" recommended that I try a T5 tailshaft dampner weight it got rid of the vibration about 90%.  At that point I figured it was as good as it was going to get - and it was good enough that I could live with it.

    Recently I saw where someone else with the same setup as me - Ron Morris motor mounts and T5 swap - reported the same issue.  They said their issue was solved by going to the 1/2 in lowering plates for the Ron Morris mounts.
    So, I installed a set of the 1/2 in lowering plates and removed my 4 degree axle shims and Finally the vibration is gone!!!

    I just thought I'd share in case someone else finds themself battling this problem.

     

    9/02/2025 10:14 AM  #2

    MS
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    From: Canyon Lake, Texas
    Registered: 1/24/2013
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    Re: Vibration solution

    Can you measure what your resulting engine, drive shaft and pinion angles turned out to be?

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

    9/02/2025 10:48 AM  #3

    Michael H.
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    From: Laurel, MS
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    Re: Vibration solution

    I can do that, but it may be a few weekends before I get a chance to.

       •Thread Starter
     

    9/02/2025 4:17 PM  #4

    MS
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    From: Canyon Lake, Texas
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    Re: Vibration solution

    No rush, but I would sure like to get the info

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

    9/04/2025 4:53 AM  #5

    Nos681
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    From: Atlantic Mine, Michigan
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    Re: Vibration solution

    Michael, do you still have the tailshaft dampener attached to T5?

    Last edited by Nos681 (9/04/2025 4:54 AM)

     

    9/04/2025 5:24 AM  #6

    RTM
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    From: Cape Coral FL
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    Re: Vibration solution

    Has to be a satisfying feeling to finally solve that issue.   I would guess the added 4 degree shims were too much.  Be interesting to see what the pinion angle is now.

     

    9/04/2025 7:32 AM  #7

    Michael H.
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    From: Laurel, MS
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    Re: Vibration solution

    Nos681 wrote:

    Michael, do you still have the tailshaft dampener attached to T5?

    Yes, it's still attached.  I'm not sure if it's still needed, but I haven't taken it off.

       •Thread Starter
     

    9/04/2025 7:39 AM  #8

    Michael H.
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    Re: Vibration solution

    RTM wrote:

    Has to be a satisfying feeling to finally solve that issue. I would guess the added 4 degree shims were too much. Be interesting to see what the pinion angle is now.

    Definitely very satisfying... I chased it for years!
    I used the Tremec app to measure my angles and it showed in spec with the 4 degree shims... but I'll admit I always struggled to find a good flat place to take the readings.

    When I installed the 4 degree shims it went from having a vibration at 60mph and up to having a vibration only at 60mph (you could accelerate through it and it would go away once you got a couple mph above 60mph).

    When I installed the tailshaft dampner it made the vibration at 60mph much more subtle, but it was still there.  My hat is off to Glen for that tip.  It's the only thing that made the vibration bearable all these years.

    Last edited by Michael H. (9/04/2025 7:46 AM)

       •Thread Starter
     

    9/12/2025 11:36 AM  #9

    Glens 1965 50
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    From: Tomball,Tx
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    Re: Vibration solution

    Thanks for the update.  This is always an issue. 

     

    9/12/2025 12:24 PM  #10

    Michael H.
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    From: Laurel, MS
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    Re: Vibration solution

    Thank you Glen!  I was at the end of my rope with this issue until your suggestion made it bearable.

    Also, I've been gone for a few years, and last time I was on you were battling cancer.  I was so glad to see that you beat cancer and are still around!

       •Thread Starter
     

    9/13/2025 7:47 AM  #11

    Glens 1965 50
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    From: Tomball,Tx
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    Re: Vibration solution

    Yes me too!!  It did leave a scar but nothing I can't deal with.

     

    10/11/2025 2:05 PM  #12

    Michael H.
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    From: Laurel, MS
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    Re: Vibration solution

    As promised, here are the resulting driveline angles.

    Slip Yoke -> 4.4 degrees


    Rear -> 4.0 degrees


    Driveshaft -> 2.9 degrees

       •Thread Starter
     

    10/12/2025 9:50 AM  #13

    MS
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    From: Canyon Lake, Texas
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    Re: Vibration solution

    I don’t think I can get those angles on my car due to ride height.  What is the distance between the center of the wheel and the quarter panel wheel opening on yours?  Looks like it is 67 or newer as well, which will have different dimension than 65-66 ride height.

    I can angle the tranny down more and the rear end up more, but my drive shaft will still be nearly horizontal. 
    Worth trying, though.

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

    10/12/2025 7:08 PM  #14

    Michael H.
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    From: Laurel, MS
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    Re: Vibration solution

    You are correct.  It is a '67 coupe.  The rear axle has no shims (anymore) so it is the stock pinion angle.
    From the center of the wheel to the quarter panel opening in the front is about 13 1/2" and in the rear it is about 14 1/4".

       •Thread Starter
     

    10/12/2025 7:55 PM  #15

    MS
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    From: Canyon Lake, Texas
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    Re: Vibration solution

    Thanks for posting the dimensions. 
    Unfortunately I have my convertible on the lift for an extended project.
    Any changes to my 66 will just have to wait.

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

    10/13/2025 5:46 AM  #16

    TKOPerformance
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    From: Newark, DE
    Registered: 12/15/2014
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    Re: Vibration solution

    I've been following this, and wonder if anyone ever tried using a double carden joint in the driveshaft?  Its common practice in lifted off road trucks where its impossible to get the angles right.  

     

    10/13/2025 7:35 AM  #17

    MS
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    From: Canyon Lake, Texas
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    Re: Vibration solution

    TKOPerformance wrote:

    I've been following this, and wonder if anyone ever tried using a double carden joint in the driveshaft?  Its common practice in lifted off road trucks where its impossible to get the angles right.  

    If it ever comes down to building a fifth drive shaft, that is my plan.  My daughter’s 460hp Mercedes has that and it is soooo smooooth.

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

    10/13/2025 9:36 PM  #18

    Nos681
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    From: Atlantic Mine, Michigan
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    Re: Vibration solution

    I do not believe the double Cardan is the secret to the smooth driveline.

    The opposite end of the newer driveshafts use a large “Lovejoy” type joint.

    Another factor is a better designed transmission mount assembly…even Foxbodys have a better setup.

     

    10/14/2025 4:23 AM  #19

    Nos681
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    Re: Vibration solution

     

    10/14/2025 3:06 PM  #20

    TKOPerformance
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    From: Newark, DE
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    Re: Vibration solution

    Well I have two thoughts: first the Germans are pretty good at what they do.  Second, I've seen all kinds of different setups used for off road vehicles, and generally they all work.  DC joints have been around for a long time, are stout, and seem to work.  Its rare to find a 4WD that doesn't use one for at least the front driveshaft.  

    The thing about the '16-'19 Explorer is that they are IRS.  The driveshaft doesn't have to account for much because the differential never moves.  

     

    10/14/2025 4:41 PM  #21

    Nos681
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    From: Atlantic Mine, Michigan
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    Re: Vibration solution

    Does the mentioned Mercedes have IRS as well?

     

    10/14/2025 4:56 PM  #22

    rpm
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    Re: Vibration solution

    Nos681 wrote:

    Does the mentioned Mercedes have IRS as well?

     
    Yep. And BMWs.

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    10/14/2025 9:10 PM  #23

    HudginJ3
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    From: Cedar Hill, TX
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    Re: Vibration solution

    I discovered a short while back that the shifter on my T5 is up hard against the shifter hole. I’m a little leary cutting a big hole in the bottom of the car. I don’t remember the dimensions but the drive line is within .2 degrees

    70, ragtop 351W/416 stroker Edel Performer heads w pro flow 4, Comp roller 35-421-8. T5
     

    10/14/2025 10:15 PM  #24

    rpm
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    Re: Vibration solution

    HudginJ3 wrote:

    I discovered a short while back that the shifter on my T5 is up hard against the shifter hole. I’m a little leary cutting a big hole in the bottom of the car. I don’t remember the dimensions but the drive line is within .2 degrees

     
    Drive train components making contact with the chassis is a verified way to cause vibrations.

    Bob. 69 Mach 1, 393W, SMOD Toploader, Armstrong  steering, factory AC.
     

    10/15/2025 4:41 AM  #25

    Nos681
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    From: Atlantic Mine, Michigan
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    Re: Vibration solution

    rpm wrote:

    HudginJ3 wrote:

    I discovered a short while back that the shifter on my T5 is up hard against the shifter hole. I’m a little leary cutting a big hole in the bottom of the car. I don’t remember the dimensions but the drive line is within .2 degrees

     
    Drive train components making contact with the chassis is a verified way to cause vibrations.

     
    I can confirm that.

    One 1/4-20 bolt on shifter trim ring touching the transmission makes a lot of noise.
    A shorter bolt solved the problem.

    RPM noticed it when my car was on the lift.

    Last edited by Nos681 (10/15/2025 4:42 AM)

     

     

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