Mustang Mach 1 differential gears

mufflers, 18,500 miles on the odometer.

#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.

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.

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.

:>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

Flowmaster mufflers, 18,500 miles on the odometer.

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.

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.

They were set up wrong. You need a new ring and pinion and someone competent to install it. Not good news:)

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

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

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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.

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