Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit, Flowmaster mufflers, 18,500 miles on the odometer.
Replaced with Motive Performance Plus 4.10 gears, #21103 (Motive Performance #F888410) from Americanmuscle.com. Installed at local garage with Royal Purple Max. diff. gear oil, 75w90, also from Americanmuscle. Used their Master bearing kit, #21201.
Terrible gear whine, especially at 45~55 MPH, accelerating and decelerating. I was told everything was set up correctly. Is this normal with Motive Performance gears? Is there a better choice of diff. gear oil? I was told there would be gear noise, but this is excessive. The factory installed 3.55 gears gave no gear whine.
Thx in advance............ :(
.boB - 29 Jul 2007 16:43 GMT
> Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit, Flowmaster mufflers, 18,500 miles on the odometer.
> Replaced with Motive Performance Plus 4.10 gears, #21103 (Motive Performance #F888410) from Americanmuscle.com. Installed at local garage with Royal Purple Max. diff. gear oil, 75w90, also from Americanmuscle. Used their Master bearing kit, #21201.
> Terrible gear whine, especially at 45~55 MPH, accelerating and decelerating. I was told everything was set up correctly. Is this normal with Motive Performance gears? Is there a better choice of diff. gear oil? I was told there would be gear noise, but this is excessive. The factory installed 3.55 gears gave no gear whine.
> Thx in advance............ :(
Higher ratio gears do tend to be a little noisier,
because there is more meshing going on. But it
shouldn't be that bad. And it should be fairly
consistant - not noticable until you reach a certain
speed, then gradually gets louder.
Sounds like you're were not set up quite right.

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.boB
2006 FXDI hot rod
2001 Dodge Dakota QC 5.9/4x4/3.92
1966 Mustang Coupe - Daily Driver
1965 FFR Cobra - 427W EFI, Damn Fast.
Sarah Czepiel - 29 Jul 2007 23:07 GMT
:>Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit, Flowmaster mufflers, 18,500 miles on the odometer.
:>Replaced with Motive Performance Plus 4.10 gears, #21103 (Motive Performance #F888410) from Americanmuscle.com. Installed at local garage with Royal Purple Max. diff. gear oil, 75w90, also from Americanmuscle. Used their Master bearing kit, #21201.
:>Terrible gear whine, especially at 45~55 MPH, accelerating and decelerating. I was told everything was set up correctly. Is this normal with Motive Performance gears? Is there a better choice of diff. gear oil? I was told there would be gear noise, but this is excessive. The factory installed 3.55 gears gave no gear whine.
:>Thx in advance............ :(
Best advice I ever got for no gear whine is use Ford parts. I have
FRPP 4:10's in my 04 MACh 1 and have no whine in over 20,000 miles.
Same with my old 97 GT - put FRPP 3:73's and never had any whine.
Regards, Sarah
Big Al - 30 Jul 2007 00:30 GMT
> Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit, Flowmaster mufflers, 18,500 miles on the odometer.
> Replaced with Motive Performance Plus 4.10 gears, #21103 (Motive Performance #F888410) from Americanmuscle.com. Installed at local garage
with Royal Purple Max. diff. gear oil, 75w90, also from Americanmuscle. Used
their Master bearing kit, #21201.
> Terrible gear whine, especially at 45~55 MPH, accelerating and decelerating. I was told everything was set up correctly. Is this normal
with Motive Performance gears? Is there a better choice of diff. gear oil?
I was told there would be gear noise, but this is excessive. The factory
installed 3.55 gears gave no gear whine.
> Thx in advance............ :(
They were set up wrong. You need a new ring and pinion and someone competent
to install it. Not good news:)
Al
Richard - 30 Jul 2007 06:14 GMT
> > Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit,
> Flowmaster mufflers, 18,500 miles on the odometer.
[quoted text clipped - 13 lines]
>
> Al
Sometimes there are just bad gear sets. I had a set of Motive 4:10's that
were very quiet until I a chipped the pinion. Even then the whine was barely
audible. The shop doing the work shouldn't even hesitate to put in a new
gear set to make it right.
Richard
Big Al - 30 Jul 2007 07:20 GMT
> Sometimes there are just bad gear sets. I had a set of Motive 4:10's that
> were very quiet until I a chipped the pinion. Even then the whine was barely
> audible. The shop doing the work shouldn't even hesitate to put in a new
> gear set to make it right.
>
> Richard
His problem is a bad installation. No other excuse. If it was a bad or
mismatched gear set they should have caught it when they did the tooth
contact and other checks. Lots of people think setting up a rear end is
easy. They're wrong.
Al
rws - 30 Jul 2007 13:35 GMT
>> Sometimes there are just bad gear sets. I had a set of Motive 4:10's that
>> were very quiet until I a chipped the pinion. Even then the whine was
[quoted text clipped - 10 lines]
>
> Al
Yeah, this is what I figured. Not good news, well, back to the installer........!
My Name Is Nobody - 30 Jul 2007 18:57 GMT
> Car is a 2004 Mustang Mach 1, 5 spd. M/T, K&N cold air filter kit,
> Flowmaster mufflers, 18,500 miles on the odometer.
[quoted text clipped - 8 lines]
> factory installed 3.55 gears gave no gear whine.
> Thx in advance............ :(
Way too many people talk about gear changes like they were changing tires,
it is not that simple.
Anybody can slap a rear-end together, very few people do it well. Most
"Mechanics" can not setup rear-end gears correctly. It is truly more of an
art than a science. IT IS VERY HARD TO FIND SOMEONE WHO DOES IT CORRECTLY.
You could do the research and learn the details of the correct "Mesh
Pattern", and check it yourself. the proper gear alignment/adjustment here
is critical.
I would wager to say whomever set up your gears did not devote the time and
effort to getting this right, maybe never even checked the ring and pinion
gear tooth mesh pattern.
Here is a link to get you started.
http://images.ford-trucks.com/articles/9inch/GEARS.jpg
http://www.ford-trucks.com/article/idx/0/065/article/Ford_9_Inch_RebuildGear_Set
up.html
You may get 10,000 miles out of this mal adjusted rear-end before it finally
chews itself up, but if it is not set up right, it will chew itself up.
Good luck