Humming Sound between 40-45 and 50-55mph

"Stephen B." <spamtrashspam.TakeThisOut@verizon.net> Dec 11, 2007 at 11:18 PM


<mikegrannis.TakeThisOut@gmail.com> wrote
>> I have a 2004 Saab 9-3 Linear with 68K.
>>
>> I am hearing a humming/rumbling sound between 40-45 and 50-55mph. If
>> I hit the brakes to slow down it goes away and if I accelerate out of
>> it, it goes away. It sounds and feels like I am in too high of a gear
>> for the speed that I am going (if it was a manual). All I have to do
>> is accelerate past 45 and 55 and it goes away.
>>
>> What do you think?

>The only time I had a speed sencitive vibration was when I had a wheel
out
>of balance. It could be that you have 2 wheels out of balance to
different
>extents.

>Did both vibrations start at the same time?

>Was there a sudden onset of vibration?

I agree that 50-55mph is a classic speed for wheel balance vibrations, but
noise? Is it constant at those speeds regardless of the road surface or the
load in the car? If not, I'm thinking possibly tyre noise. Has *anything*
differnnet happened or been done to the car just prior to this starting?
Cheers


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 >> Stay informed about: Humming Sound between 40-45 and 50-55mph 

On Dec 11, 10:37 am, mikegran....RemoveThis@gmail.com wrote:
> I have a 2004 Saab 9-3 Linear with 68K.
>
> I am hearing a humming/rumbling sound between 40-45 and 50-55mph. If
> I hit the brakes to slow down it goes away and if I accelerate out of
> it, it goes away. It sounds and feels like I am in too high of a gear
> for the speed that I am going (if it was a manual). All I have to do
> is accelerate past 45 and 55 and it goes away.
>
> What do you think?

The tires are cupped and their is definite tire noise, but this is a
different issue. I did a little more testing yesterday and found that
when I switch the automatic transmission into the sudo-manual mode I
get the same humming/rumbling noise when the rpms are around 1500 in
fourth and fifth gear. My guess is that the transmission in automatic
is shifting too early. Possible reprogramming of transmission
software?
 >> Stay informed about: Humming Sound between 40-45 and 50-55mph