New rear end gears whine loud when I let off

[RedefinedGT]

So I put the gears in this past week, they seemed to be shimmed perfectley when we tested them out with some paint on them, dead center of the mark.... so I figured everything would be awesome. So I broke them in like they said I should driving for 20min or so over 55, let cool for an hour or so, and do that all over again.

They dont whine any when I am driving and on the gas, but as soon as I let off and coast it whines a bit, some times even buzzes..... WTF is going on? Are they out of alingment now, still braking in or what. I got like 150 miles on them now.....

 

[mrvax]

Hummm. Mine never whined & I did not break them in at all. I did get vibration that was cured with the aluminum driveshaft. Does this occur at high speed only? What if you coast w/ the tranny in neutral? What happens then?

 

[RedefinedGT]

It only happens when I cost.... I dont know if it does it as bad when I put the car in neutral, but I think it still did it....... I know that does it worse at higher speeds like from between 55 and 75mph.... but it does it down to about 35-40 and than stops after it drops past 30mph.

 

[dollarbill]

What type of gear lube did you use? Also what about the friction modifer? Maybe you should try synthetic lube, I know the Royal Purple already contains friction modifier.

 

[RedefinedGT]

We used Northland oil gear lube and ford additive for brake in..... than we where going to drain it and switch over to Mobile 1's stuff.

 

[MT1083]

It will do that if your backlash isn't set correct. Did you get a dial indicator to check the backlash? Ford specs call for .008 to .015. I set mine at .014 and I have no noise at all.

 

[dollarbill]

The guy that did my gears set them at .007 and I've never had a problem and I'm running convention lube with Ford friction modifier for now. Hey, are they FRPP gears? I've heard other brands are noisey compared to the Ford ones.

 

[trinity_gt]

Whining on overrun is coming from the front pinion bearing. What torque value did you set the pinion preload to? Did you use a new bearing or old? Did you use a new crush sleeve? Did you inspect the bearing races?

 

[RedefinedGT]

Used:
Ford Gears
New Bearing
Old Race
New Crush Sleve

 

[trinity_gt]

And what was the pinion preload torque?

 

[97gtblue]

i dont know much about gears but my gears whine,im guessing because i didnt use any tools to check the clearance or anything and could be because they are precision gears which the performanse guy said they are one of the best brands..but he might of just wanted my money

 

[RandyStinchcomb]

Used:
Ford Gears
New Bearing
Old Race
New Crush Sleve

theres your answer. "new bearing wth old race" never/ever mix new & used bearings and races. why skimp on a $10.00 part, it will only cost you in the long-run thats why I always preach, when you change a gear, get new bearings, races and seals

 

[crew_dawg16]

Since it only happens when he is coasting, I think it is backlash.

When you coast, power is transmitted from your wheels to your drivetrain, causing a different side or face of the gear to have load on it. Under power, the other side of the gear has load on it. Did you check the contact pattern on both faces?

And the reason it isn't as loud when you are in neutral is because it doesn't have to turn your engine, hence less load on the gears.

 

[BlackenedSVT]

Maybe you just need to re-shim the gears...

 

[RedefinedGT]

I was guessing that back lash had something to do with it.... we did check the pattern both ways I think and it was pritty much the same dead center spot..... but I dont know if we checked the back lash as well...

But would you guys say it is safe to make like a 80mi round trip tonight on the highway?

 

[Bill9000]

But would you guys say it is safe to make like a 80mi round trip tonight on the highway?

depends on how far off they are... they could be a little off and last for 6 months, or they could be a lot off an you won't make it 40 miles... just depends on how bad it is.

I've seen this happen before when people install gears in other cars, and they don't have enough experience, and don't have it set up right.

hope this helps.