3.73's Installed Noisy When Decelerating

[Funny5.0]

I just had my gears swapped from 3.31's to Ford Racing 3.73's. It was done by a reputable performance shop that claims to have done many gear swaps. I'm not mentioning the business name without giving them the chance to resolve this issue...

I immediately noticed when in gear and decelerating there is a wurring and or whine noise. The pitch goes down as the speed decreases. The noise is still there when in neutral and decelerating as well.
When cruising or accelerating everything feels and sounds normal, it's only when lifting off the gas. I've had gears swapped in 2 prior cars and have never heard this sort of sound. The noise is loud enough to here over my radio and is not normal.
I have a busy schedule and won't have time to take my car in for a few days but need to drive as my daily to work and back...
Couple questions:

Is it safe to drive in this condition?

Any ideas to what's going on?

On a side note,
These gears feel perfect combined with the Ford Racing tune as a daily driver. Quite an improvement over the 3.31's:beer:

 

[alex12gt]

Take it back and i would avoid driving it if you dont have to

 

[Funny5.0]

Take it back and i would avoid driving it if you dont have to

This is really my primary mode of transportation.
I called the performance shop and they said from what it sounds like it is safe to drive and to bring it by at my earliest convenience.
He said nothing will come apart don't worry.
What's the worst that could happen?

From a quick google search based off my car's symptoms I came up with these as possible solutions :shrug::

• tighten down the pinion
• re-adjust the backlash of the pinion and gear
• bad pinion bearings or loose pinion bearing preload

 

[Back N Black]

It is definitely not right. Take it back. Don't let any shop tell you that all gears make a little noise.

I went through this bullshit with a shop here in Texas. When the gears were finally done right by a different shop, no noise at all.

 

[Funny5.0]

It is definitely not right. Take it back. Don't let any shop tell you that all gears make a little noise.

I went through this bullshit with a shop here in Texas. When the gears were finally done right by a different shop, no noise at all.

Thank you and that is what I figured. I will not be able to take it back in until next Monday or Tues (major work commitments).
I'm just posting on here to see if I can get some extra info on this issue in the meantime.

 

[try03venom]

yup not right not enough preload.

 

[runs2rch]

Not set up right. Drive it easy. You're not going to hurt the gearset with a little light driving. Sounds like the shop will make it right on Monday.

 

[Get some 5.0]

It's not right, I had 3.73 installed and mine are quite!!!!!

 

[BRNG ITT]

Do you still have all OEM bushings/suspension in back? I have the factory installed 3.73s which were quiet until I installed my billet LCAs with poly bushings. Now I get noise in the same circumstances as you, and it sounds almost like television white noise/static.

Here's a similar circumstance dealing with the adjushment of backlash to solve the problem:

Gear whine problem - Team Shelby - Page 2

 

[five.slow]

Mine whine too but I did my gears myself so it was expected from the start that something wouldn't be perfect bc iv never done it before. I had a perfect pattern and near perfect preload and Backlash was .010.

 

[me32]

Mine whine too but I did my gears myself so it was expected from the start that something wouldn't be perfect bc iv never done it before. I had a perfect pattern and near perfect preload and Backlash was .010.

Your backlash is too lose that's why. Should be .06-.08 because they will loosen up over time.

 

[me32]

To OP..BAD news is the gears will never be the same now..you may not be able to to fix the issue and gears already worn a pattern from the 1st time you drove it. you may end up having to get a new set of gears. Good luck

 

[Funny5.0]

To OP..BAD news is the gears will never be the same now..you may not be able to to fix the issue and gears already worn a pattern from the 1st time you drove it. you may end up having to get a new set of gears. Good luck

Well I just talked to the owner of the shop and he was very friendly and reassuring. He explained to me that they do gear swaps in a few cars per week and they have one guy that does all of them. It sounds like they know what they're doing. The same install technique is used for all of the gear installs and something like 2 out of 10 make noise with the rest being whisper quiet. He said we can open it up and re-adjust ect ect but the only way to fix the noise is really through a new set of gears:bored:.
He said their guy heard the noise on the test drive(before I initially picked it up) and that the sound was a variation of the norm.
He wants me to bring the car back and see if anything serious went wrong but he has a hunch it didn't and the noisy gears wont harm anything but my ears...
He sounded pretty confident in his gear guy and said if my rear were to blow up on me he'd send the tow truck and cover the rear.
The noise isn't crazy loud but it's there(like a 4-5 out of 10). I can live with it as long as it isn't harming anything.

 

[Funny5.0]

Your backlash is too lose that's why. Should be .06-.08 because they will loosen up over time.

Are you saying five.slow is screwed too since he has already been driving his with the loose backlash?:shrug:

Backlash may or may not have been my issue but according to my installer it's the gears themselves.

Do you agree that this sound is more intrusive than harmful to the rear end (if supposedly installed generally right)?

 

[CPRsm]

The only fix IS a new set of gears. They let you take it while being set up wrong. If they uad reset them before the gear warmed up and seated incorrectly they could have been saved. But now they have faced and hardened with the wrong contact pattern. I havent had a set of FRPP set of gears make a noise ever. Even quiet gears can be set up wrong. It has to be pretty far off to make noise.

 

[davidhuff]

To OP..BAD news is the gears will never be the same now..you may not be able to to fix the issue and gears already worn a pattern from the 1st time you drove it. you may end up having to get a new set of gears. Good luck

I agree 100%,you will need a new gear!

 

[Funny5.0]

The only fix IS a new set of gears. They let you take it while being set up wrong. If they uad reset them before the gear warmed up and seated incorrectly they could have been saved. But now they have faced and hardened with the wrong contact pattern. I havent had a set of FRPP set of gears make a noise ever. Even quiet gears can be set up wrong. It has to be pretty far off to make noise.

Assuming this is correct and my shop is blowing smoke up my ass
Will this harm my car/rear end other than sounding annoying?

 

[FreddieG]

It is definitely not right. Take it back. Don't let any shop tell you that all gears make a little noise.

I went through this bullshit with a shop here in Texas. When the gears were finally done right by a different shop, no noise at all.

Since I live up the road from you...who should I avoid? Who did you take yours too to have it done right?

Thanks

 

[Funny5.0]

I agree 100%,you will need a new gear!

I don't exactly have another $1000 for another set of gears and labor...

 

[BPatterson]

I don't exactly have another $1000 for another set of gears and labor...

WTF??????????