Left Rear Vibration at Highway Speeds - Running Out of Ideas
Thread Starter
Joined: Jul 2014
Posts: 2,382
Likes: 419
From: Former S2KCA President
Left Rear Vibration at Highway Speeds - Running Out of Ideas
A quick synopsis...
Summer of 2020, I started to get a clicking sound in the left rear. Telltale sign of the axle nut. I was near 100,000. So, I replaced the left and right axle nut.
This is when the left rear vibration started.
In my attempt to diagnose it...I did the following
confirmed that the wheel and tires (I have two rear wheel sets (Summer and All-Season) are straight and true. I also swap my Summer tires yearly.
axle spacers on the original OEM axles
aftermarket axles (I still have the OEM axles)
axle bearing (left and right)
Other than the vibration at highway speeds (69-75 MPH is the worst), the car is fine. (the vibration lessens over 75-80)
In this state, I've driven over 30,000, from Ohio to...
Boston Mountains Spring 2021 (Branson, MO)
3000+ miles to Sheppard AFB, TX (Wichita Falls), through the Deep South (MS, AL, LA) TX and western NM (Tucumcari), then back I-40 and I-70 through MO, IL, IN OH.
2 trips to the Tail of the Dragon
S2KDays in Northern Michigan
Also, this is my daily. My other car is a 1985 Porsche 944.
The car just turned 130,000.
I'm running out of ideas on the left rear vibration. I'm sure the Differential is not the culprit. I'm even going the rabbit hole of drivetrain misalignment or motor mount replacement.
I plan to drain the Diff and Trans before Winter.
Anyone? Buhler??
Summer of 2020, I started to get a clicking sound in the left rear. Telltale sign of the axle nut. I was near 100,000. So, I replaced the left and right axle nut.
This is when the left rear vibration started.
In my attempt to diagnose it...I did the following
confirmed that the wheel and tires (I have two rear wheel sets (Summer and All-Season) are straight and true. I also swap my Summer tires yearly.
axle spacers on the original OEM axles
aftermarket axles (I still have the OEM axles)
axle bearing (left and right)
Other than the vibration at highway speeds (69-75 MPH is the worst), the car is fine. (the vibration lessens over 75-80)
In this state, I've driven over 30,000, from Ohio to...
Boston Mountains Spring 2021 (Branson, MO)
3000+ miles to Sheppard AFB, TX (Wichita Falls), through the Deep South (MS, AL, LA) TX and western NM (Tucumcari), then back I-40 and I-70 through MO, IL, IN OH.
2 trips to the Tail of the Dragon
S2KDays in Northern Michigan
Also, this is my daily. My other car is a 1985 Porsche 944.
The car just turned 130,000.
I'm running out of ideas on the left rear vibration. I'm sure the Differential is not the culprit. I'm even going the rabbit hole of drivetrain misalignment or motor mount replacement.
I plan to drain the Diff and Trans before Winter.
Anyone? Buhler??
Last edited by JoePhotographer; Oct 8, 2021 at 09:16 AM.
Moderator
Joined: May 2014
Posts: 7,984
Likes: 2,542
How certain is it that it is left rear? Many times we think a vibration is on the left because that is the side we sit on. Let a passenger ride along and do not tell them anything but to pay attention to the vibration, they very well may say it feels like it is coming from the right 
And could be that it is coming from the center of the car as well.
And could be that it is coming from the center of the car as well.
Thread Starter
Joined: Jul 2014
Posts: 2,382
Likes: 419
From: Former S2KCA President
How certain is it that it is left rear? Many times we think a vibration is on the left because that is the side we sit on. Let a passenger ride along and do not tell them anything but to pay attention to the vibration, they very well may say it feels like it is coming from the right And could be that it is coming from the center of the car as well.
And could be that it is coming from the center of the car as well.
Joined: Nov 2013
Posts: 6,338
Likes: 617
From: Norfolk UK
Just put front and rear discs on my bmw because of a vibration ,turned out to be built up rust on mating surface to hub .got it on a rolling road brake tester and showed a very slight issue. Cost me 4 tyres to get to the problem 
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Thread Starter
Joined: Jul 2014
Posts: 2,382
Likes: 419
From: Former S2KCA President
Yes. Two, in fact
Wheel (knuckle) bearings, per Bama Dave
@AaronCompNetSys and I did the following yesterday afternoon:
Re-torqued the axle nuts
Did an E-Brake check
We are going down the rabbit hole of motor/transmission mounts. We have not inspected them yet (ran out of time yesterday), but will do so, before ordering.
Wheel (knuckle) bearings, per Bama Dave
Re-torqued the axle nuts
Did an E-Brake check
We are going down the rabbit hole of motor/transmission mounts. We have not inspected them yet (ran out of time yesterday), but will do so, before ordering.
Joined: Sep 2007
Posts: 7,346
Likes: 112
Yes. Two, in fact
Wheel (knuckle) bearings, per Bama Dave
@AaronCompNetSys and I did the following yesterday afternoon:
Re-torqued the axle nuts
Did an E-Brake check
We are going down the rabbit hole of motor/transmission mounts. We have not inspected them yet (ran out of time yesterday), but will do so, before ordering.
Wheel (knuckle) bearings, per Bama Dave
@AaronCompNetSys and I did the following yesterday afternoon:
Re-torqued the axle nuts
Did an E-Brake check
We are going down the rabbit hole of motor/transmission mounts. We have not inspected them yet (ran out of time yesterday), but will do so, before ordering.