Humming Sound between 40-45 and 50-55mph

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mikegrannis@gmail.com - 11 Dec 2007 15:37 GMT

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?

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Stephen B. - 11 Dec 2007 23:18 GMT

> I have a 2004 Saab 9-3 Linear with 68K.
>
[quoted text clipped - 5 lines]
>
> 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?

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hippo - 12 Dec 2007 03:37 GMT

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

<mikegrannis@gmail.com> wrote

>> I have a 2004 Saab 9-3 Linear with 68K.
>>
[quoted text clipped - 5 lines]
>>
>> 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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mikegrannis@gmail.com - 12 Dec 2007 13:22 GMT

On Dec 11, 10:37 am, mikegran...@gmail.com wrote:

> I have a 2004 Saab 9-3 Linear with 68K.
>
[quoted text clipped - 5 lines]
>
> 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?

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hippo - 27 Dec 2007 08:17 GMT

mikegrannis@gmail.com Dec 12, 2007 at 05:22 AM

>On Dec 11, 10:37 am, mikegran...@gmail.com wrote:
>> I have a 2004 Saab 9-3 Linear with 68K.
[quoted text clipped - 6 lines]
>>
>> 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
[quoted text clipped - 3 lines]
>is shifting too early. Possible reprogramming of transmission
>software?

Whoa! Is it that long since I last logged in...?
Sounds like a sympathetic vibration of some sort.
(My typing is crap tonight but the Shiraz Malbec that caused it is quite
pleasant...) Check oil and auto trans levels are ok before doing anything
else (cheap option) and then start hunting. If tyres *are* a prob, then
swapping them iwll at least eliminate any secondary issues they are
causing. Cheers

--
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