Gear Install - Now Whines
08-06-2010, 08:09 AM
#1
Gear Install - Now Whines
I just had 3.90 motive rear gears put in my 2010 mustang. now it whines significantly, and is louder the faster you go. It whines under acceleration, deceleration. Its loudest when you are just coasting and in neutral or put your foot on the clutch, so there is no load. What could cause this whine?
The shop didnt follow the directions that came with the kit bc hes done it for years. He is saying it looks like the ring gear was lapped but the pinion gear wasnt, which doesnt make sense because they are lapped together as a set. I'm having him take it out to check the serial numbers. if they match, then its a good set. But the shop keeps saying its the gears.
He set the backlash at .005" when motive recommends .008"-.012" and stock it was .012". Could this cause it?
Right now I'm having the shop take it out and check the serial numbers on the gears to make sure they match. after that, I'm having him install it per the instructions that motive provides (with a new bearing) to see what happens. I just really want to know what could cause the gears to whine. Could it be the backlash?
The shop didnt follow the directions that came with the kit bc hes done it for years. He is saying it looks like the ring gear was lapped but the pinion gear wasnt, which doesnt make sense because they are lapped together as a set. I'm having him take it out to check the serial numbers. if they match, then its a good set. But the shop keeps saying its the gears.
He set the backlash at .005" when motive recommends .008"-.012" and stock it was .012". Could this cause it?
Right now I'm having the shop take it out and check the serial numbers on the gears to make sure they match. after that, I'm having him install it per the instructions that motive provides (with a new bearing) to see what happens. I just really want to know what could cause the gears to whine. Could it be the backlash?
08-06-2010, 08:41 AM
#2
I googled it and saw a few threads in different forums where guys had similar problems and they had their backlash around .006-.007 and going from that to .010-.011 helped a ton. I called the shop and asked him to adjust the backlash to around .011-.012 and see how it sounds. ford recommends .012-.015 and motive recommends .008-.012.
08-06-2010, 09:03 AM
#3
5th Gear Member
Join Date: Dec 2006
Location: Redding, CA
Posts: 4,552
Sorry to hear about the gear whine.
Not everygear installation is the same on every car and companies recommend certain backlash and specs because it's what their products work best with.
I recently had my gears switched to 4.10s from 3.55s. They are absolutely silent and make zero noise.
A backlash adjustment will hopefully change your noise.
Not everygear installation is the same on every car and companies recommend certain backlash and specs because it's what their products work best with.
I recently had my gears switched to 4.10s from 3.55s. They are absolutely silent and make zero noise.
A backlash adjustment will hopefully change your noise.
08-06-2010, 11:50 PM
#4
5th Gear Member
Join Date: Jul 2008
Location: ......
Posts: 2,057
The guy who did my last gear install said 8.8's need minimum backlash. He sets them a .008".
Unfortunately 3.90's have a rep for making noise. It has to do with the number of pinon and ring gear teeth and how they mesh.
Noisy gears suck. Sorry to hear about your misfortune.
Unfortunately 3.90's have a rep for making noise. It has to do with the number of pinon and ring gear teeth and how they mesh.
Noisy gears suck. Sorry to hear about your misfortune.
08-07-2010, 06:05 AM
#5
yeah well i wish i had known that before. the gears are still loud being set to .012" (factory setting). its annoying and i wont let it stay like this. I'll most likely be getting some 3.73 FRPP gears and having a different shop install them. and spend another $600 
08-07-2010, 06:53 AM
#6
Join Date: Jan 2010
Location: MA
Posts: 18
Sorry to hear that Ice. I just finished installing my 4.10's this week. I used FRPP gears. All of the Ford Service manuals call for .008-.015 backlash, with .012-.015 preferred. I'm right at .012, and all seems well, no noise yet. Another thing to check would be the pinion height, this is very critical. Unless you have the right tools to set this, it is very difficult to get it right. Before changing the gears again, check the wear pattern, that may be able to tell you what's going on.
08-07-2010, 07:42 AM
#7
5th Gear Member
Join Date: Jul 2006
Location: New Orleans
Posts: 4,491
You're the victim of a bad install. If he had set the backlash correctly the first time, you would have no whine. Unfortunately, after you drove with them in for a while at the improper backlash setting, they established a wear pattern that caused the noise to continue even when adjusted to the proper backlash (if the mechanic even reinstalled them, which I am suspicious of). There is no "noisy" gear ratio. All gears should operate silently and any mechanic who tells you otherwise does not deserve your business.
08-07-2010, 11:55 AM
#8
^ diabolical i have heard that so many times. and it sucks bc now i have to spend anohter $170 on gears (im gonna get 3.73 frpp) and i dunno who to take it to. this guy has been doing trannys and gears for many many years, but he messed up on this. there is another local guy who will do it for $400 but i dont have another $600 to spend on gears right now.
08-07-2010, 12:45 PM
#9
2nd Gear Member
Join Date: Jun 2009
Location: California
Posts: 277
The drive line shop I used would not guarantee FRPP gear sets to not whine. If I wanted a guarantee of no whine, I would have to allow them to choose the parts. Wound up with a FORD OEM 3.73 gear set which is absolutely quite. They tried a US Gear set first but it whined. So they redid the job under their warrantee. I paid more for the job than some report although much less than the Ford Dealer wanted.
08-07-2010, 08:07 PM
#10
2nd Gear Member
Join Date: Jul 2008
Location: Billings, MT
Posts: 462
It is in the install, and any shop that tells you different is just covering their own butt.
Your BEST bet starting out is to locate a shop who will work under the following circumstances:
1) Set a price, complete, and have them buy the parts so they can warranty them
2) For agreed price, they will guarantee there will be no rear end noise when finished.
3) If there is any noise at all, you will return and have them re-do it for no charge to you, including fluids, parts, or labor.
4) They will make it right, regardless of how many tries it takes, at no additional cost to you.
When I set out to find a shop willing to follow those rules, I encountered a lot of places unwilling to guarantee their work. Eventually, I found a shop who was willing to do it. The price was at the top of the spectrum, but if I had done this to begin with, I would have saved thousands. The first install by that shop was perfection, and after 600 miles on the new gears, still quieter than stock. (3.73 frpp gears btw).
Previously, I went through 2 sets of gears and 4 reinstalls. One swap was to go from 4.10 to 3.73. I paid for full labor 2 times (initial 4.10 swap and initial 3.73 swap), after which the shop paid labor for reinstall but charged for parts and fluids (gets expensive with royal purple each time). Regardless of the fact that the mechanic who did all those installs and reinstalls had done over 1000 rear ends in his life, in the end it was his failure that caused the noise. The first install showed a perfect pattern, which we rechecked after 500 miles, and I witnessed the pattern myself. Everything was in spec according to the instructions. Despite this, there was noise.
The last mechanic to work on it (the one who did it right), was able to point out many flaws, including the necessity to shim the pinion bearing, something the first mechanic never did.
I would let the shop you had do the gears have one more shot at it, and then look elsewhere for a better mechanic, one who will guarantee his work. If the shop is associated with one of the big parts stores, they may have an insurance program that will allow you to take it elsewhere and have all labor covered (as well as any parts that store sold to the mechanic, hence the reason to have the mechanic buy the parts).
Good luck, there is NOTHING more irritating than whining gears, I put up with it for over a year, and never should have had to.
Your BEST bet starting out is to locate a shop who will work under the following circumstances:
1) Set a price, complete, and have them buy the parts so they can warranty them
2) For agreed price, they will guarantee there will be no rear end noise when finished.
3) If there is any noise at all, you will return and have them re-do it for no charge to you, including fluids, parts, or labor.
4) They will make it right, regardless of how many tries it takes, at no additional cost to you.
When I set out to find a shop willing to follow those rules, I encountered a lot of places unwilling to guarantee their work. Eventually, I found a shop who was willing to do it. The price was at the top of the spectrum, but if I had done this to begin with, I would have saved thousands. The first install by that shop was perfection, and after 600 miles on the new gears, still quieter than stock. (3.73 frpp gears btw).
Previously, I went through 2 sets of gears and 4 reinstalls. One swap was to go from 4.10 to 3.73. I paid for full labor 2 times (initial 4.10 swap and initial 3.73 swap), after which the shop paid labor for reinstall but charged for parts and fluids (gets expensive with royal purple each time). Regardless of the fact that the mechanic who did all those installs and reinstalls had done over 1000 rear ends in his life, in the end it was his failure that caused the noise. The first install showed a perfect pattern, which we rechecked after 500 miles, and I witnessed the pattern myself. Everything was in spec according to the instructions. Despite this, there was noise.
The last mechanic to work on it (the one who did it right), was able to point out many flaws, including the necessity to shim the pinion bearing, something the first mechanic never did.
I would let the shop you had do the gears have one more shot at it, and then look elsewhere for a better mechanic, one who will guarantee his work. If the shop is associated with one of the big parts stores, they may have an insurance program that will allow you to take it elsewhere and have all labor covered (as well as any parts that store sold to the mechanic, hence the reason to have the mechanic buy the parts).
Good luck, there is NOTHING more irritating than whining gears, I put up with it for over a year, and never should have had to.