little update on my vibration problem.

[AWDTerror]

little update on my vibration problem.*Update*

Well just got back from the dealer, they put in a completely NEW rear differential in my car, and guess what, still vibration at 75mph on up.
Dealer is going to call mazda USA in the morning to see what else can be done.

So far here is what we know:
This all started a month or 2 ago and was getting progressively worst, and has leveled off and has not gotten any worst or better.
The vibration only occurs on acceleration, little or a lot, above 75mph.
Vibration from what appears to be from the rear of the car, increasing in frequency as the car goes faster.
The vibration goes away when the light for the emergency brake comes on.(I've even rigged up the ebrake light switch to a 12v switch to rule out any possibility of the actual ebrake interfering)
There is a clicking noise from the rear of the car that comes and goes(seems almost random), it sounds like a cv joint that is bad. But that(cv joint) has also been checked and ruled out.

Here is what has been done:
New tires and balanced
New rear diff

My suggestions:
Checking u-joints, carrier bearing, and driveshaft balance.
I have requested the dealer to ask mazda what actually occures when the ebrake light is activated.
The vibration only being caused on acceleration 75mph and faster still leads me to believe that it is a problem is in the drivetrain and how the power/load is transfered to the rear.
My thought is that even though the ebrake light is activated that the rear just free spins and no load is placed on the driveshaft of the rear components, hence why the vibration goes away.

and if anyone else has any suggestions feel free to add and i'll let the dealer know.

also they gave me a new subaru wrx...fun little car in the recent snow and mud.

Also if anyone would like to see what items they installed I can just copy them from my work order.

 

[silver_speed6]

Got a question for you. Is the vibration constant? Because I have been experiencing some vibration myself. It starts around 70mph or so and is like a pulsing vibration. It seems to be isolated to the rear of the vehicle also and it increases in frequency as I accelerate. Is this similar to what you experienced?

 

[AWDTerror]

yes it is constant and feels like it is coming from the rear of the veh. and also increases in freq as the speed increases, almost feeling like your driving on the shoulder of the interstated at 100mph

 

[coondogg]

I was going to guess that you got her new batteries...

 

[AWDTerror]

lmao

 

[Reyan]

Check the drive shaft to the rear differential, maybe that universal join (it looks like a cross) is probably worn.

 

[AWDTerror]

that's my though also, seeing that it still could be the rear diff it's best to start looking forward toward the front of the car also

 

[Reyan]

I know from experience that will vibrate at higher speeds when they go bad.

 

[bova80]

are you sure your wheels are balanced correctly? most vibration with incorrectly balanced wheels is around 65+mph

 

[USAFVMI08]

Is it possible for a driveshaft to become off balance? Have you bottomed out or struck anything in the recent past that might've struck the drive shaft?

 

[AWDTerror]

are you sure your wheels are balanced correctly? most vibration with incorrectly balanced wheels is around 65+mph

wheels are balance correctly. I have swapped rims and changed tires, still same issue, also activating the ebrake light makes the vibration go away ruling that out even further.

 

[AWDTerror]

Is it possible for a driveshaft to become off balance? Have you bottomed out or struck anything in the recent past that might've struck the drive shaft?

It is possible but i have not struck anything and have checked the driveshaft visually for anything of that nature. plus the drive shaft sits so high in the driveshaft tunnel that it makes it nearly impossible to cause damage to the driveshaft, you will crush your exhaust and underbody before the drive shaft gets touched.

But i have seen balance weights come loose and fall off, and that is an issue we are going to check.

 

[bova80]

if it goes away when pulling the ebrake it is something with the drive shaft or rear diff.

 

[AWDTerror]

if it goes away when pulling the ebrake it is something with the drive shaft or rear diff.

yep that is my thought also, but since they replaced the rear diff we are going to start looking at the other stuff

 

[bova80]

check all the bolts on the driveshaft.

 

[AWDTerror]

they did that yesterday when the installed the new rear diff

 

[kalonov]

interesting .... by activating the e-break will it disable the AWD (rear diff) is this why the vibration stops in the rear end?

 

[bgibb68]

i remeber on my friends old jeep grand awd it had that too but it was just there....nothing wrong....i think it was just to the gear set for the awd....kinda weird

 

[AWDTerror]

interesting .... by activating the e-break will it disable the AWD (rear diff) is this why the vibration stops in the rear end?

Per the technical manual it stops sending power to the rear wheels.

 

[kalonov]

Does it mean it will save me some gas if I disable the power to the rear wheels and drive th car with the ebreak pulled to the first click? LOL.