Hopefully someone can help out on this one but i was having problems setting pinion angle for awhile and finally got it to where it doesn't vibrate anymore. Now i hear a sort of whining noise out back only in fourth and fifth and only when i'm on the pedal. When i let off the pedal and let it cruise while in gear or neutral it stops. The setup for the rear is a ford 9" with the stock bracket locations. If anyone has an idea what to look for i would appreciate the help. Thanks.

 

Sounds like you may have a ring and pinion not properly adjusted/installed. The only thing that is throwing me off is that it only happens in 4th and 5th.- But that could just be speed related.
Is your driveshaft balanced?

 

yea had it rebalanced last week. about how much backlash do should you have for the 9"?

 

before i put it in i had .0010" backlash

 

ok i rechecked my tooth pattern and everything checks out. could it be possible that while im putting a load in those two gears that the driveshaft is going positive.

 

Did you check your gear pattern on the decel side? It sounds like that may be where your problem lies.

 

now is that coast side or drive side
of the ring?

 

Coast side. If thats where the noise is present thats where the problem is going to be.

 

the pattern is right in middle. its actually when im on the gas i start to hear it. i can only hear it in 4th and 5th gear. 5th gear is actually worse.

 

How much preload do you have on the bearings that hold the carrier? If it's too little the carrier could be moving around under load. Were all the bearings replaced?

 

i have preload set to about .0012"

 

Explain to me how you loaded the bearings (backlash).

 

if i want to reset backlash and preload before i put it in the car, do i have to reset pinion depth?

 

first i set preload with no backlash then i set backlash to about .0009"-.0010"

 

How did you set the backlash? That could be the problem. It's hard to explain but i always leave the bearing that is farthest away from the pinion alone and set the lash by cranking the other adjuster in essentially spreading the case and loading the bearings. If you don't have enough pressure on the bearings they will let the carrier move.

 

that does make sense. by leaving the furthest one alone do you mean with no backlash first then adjust with other?

 

Instead of loosening the adjuster on the opposite of the pinion to get your backlash, you force the ring gear away from the pinion with the opposite adjuster.

 

so you are setting backlash and preload at the same time? does the pinion depth have to be reset?

 

It shouldn't. That would be the last step.

 

im sorry for all the questions allen but could you explain exactly how you do it? im still fresh to suspension and drivetrain.

 

No problem. It's one of those hard to explain things and i would really have to show you. How did you set your bearing preload on the carrier? It sounds like you just don't have enough preload.

 

well i set it with no backlash in it to .0012" then turned to adjusters toward where the backlash needed to be set if that makes sense

 

How much pressure do you think you are putting on the bearings with the two adjusters?

 

iwill let you know now im going to set it now

 

ok my preload is at .0011" and my backlash is at .0010". how does that sound?