2002 Pontiac Trans Am Rearend gear noise

Tiny
GATORDUDE96
  • MEMBER
  • 2002 PONTIAC TRANS AM
  • V8
  • 2WD
  • AUTOMATIC
  • 91,000 MILES
I recently purchased this car and knew it had bad wheel bearings. I figured that while I was replacing the wheel bearings I might as well go ahead and replace the carrier and pinion bearings as well. I replaced all bearings and re-assembled everything to specs as best I could. I took the car for a test drive and as long as I give it gas it is fine but when I coast I hear a whinning noise from the gear set. I had.008 backlash on the ring gear and thought this may be too much so I went to.005 and still had same noise. Got any ideas on what this may be? Would like an answer by someone who is a reputable mechanic who knows rearends please.
Friday, June 4th, 2010 AT 9:45 PM

3 Replies

Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Backlash only accounts for part of the equation. Was the pinion depth measured and adjusted, as well as pinion and total assembly preloads? What was the final gear tooth contact pattern like?
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Friday, June 4th, 2010 AT 11:01 PM
Tiny
GATORDUDE96
  • MEMBER
  • 2 POSTS
Alright gstacey, I have done more research and have learned that pinion preload for my stuff should be 24 inch pounds. Exactly how is this performed? Also, I learned that my carrier bearings should also have a preload to which it should not just slip into the bearing/race holders but should actually have to be forced in. Is this correct? Please advise, thanks
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Sunday, June 6th, 2010 AT 4:11 PM
Tiny
FACTORYJACK
  • MECHANIC
  • 4,159 POSTS
Pinion bearing preload is set with the flange nut, and the crush sleeve that was on the pinion shaft should be replaced. Any time the sleeve is crushed, it should be replaced. The actual spec on the pinion preload is 15-30 in lbs, and total assembly preload is usually 30-50 in lbs. To achieve preload, you are going to have to use some force when putting the differential case into the housing, that is correct.
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Sunday, June 6th, 2010 AT 11:58 PM

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