1st ride ---Broke----HELP

[Dusty1]

My first time out after 5 years of a complete build and the rear gears sound like theres no oil in it. Everyone says the gears weren't set up right , to loose, but it was checked and double checked by experienced men. Chunking sound, coming to a stop it rattles and clanks like the clutches sticking and jerking loose. 489 posi bought used, supposed to have been in good shape. 3:55 Richmond gears meshed great when they were set up. Sounds like something is about to break.
Can the posi unit make these sounds if its bad?  Any help would be appreciated!

[brads70]

Did you add the limited slip fluid?

[Dusty1]

I did, but thats the first thing I thought too. Sounds like their grabbing and jerking loose

[PlumCraZRT]

I did, but thats the first thing I thought too. Sounds like their grabbing and jerking loose

You may just need to add more.  I think my bottle said you may need to add the entire thing.

[BS CUDA]

You may just need to add more.  I think my bottle said you may need to add the entire thing.

I don't think that is your problem(been fooled before though). Normally the clutches will only react like that in a cornering situation if there is not enough posi lube / friction modifier - go ahead and dump another bottle in (won't hurt it) and see if it changes. I would grab hold of the pinion and see if it is loose - this could explain the chunky while coming to a stop. If it is tight then a flexible search magnet through the fill plug to see if any chunks come out with it. Does the rattling and clank disappear even on slight acceleration?

[Dusty1]

It will be hard to add any, its full to the top. I hear it when off the gas all the way to a stop. No whining just a lot rattling

[moparmaniac59]

You can definitely have two totally different sounds from a set of meshed gears in a drivetrain such as loaded vs. non-loaded. From the noise you've indicated; I would either drain the gear set or use the magnet to look for metal particles. If it were my car, and for peace of mind, I'd drop the drive shaft, pull the pumpkin and inspect the gear set for any damaged teeth or uneven wear/shiny spots, metal shavings ect. Maybe get some bluing and check your toe-to-heel tooth contact and go from there based on what you find! 


                                                                       Matt B.

[BS CUDA]

It will be hard to add any, its full to the top. I hear it when off the gas all the way to a stop. No whining just a lot rattling

 Just a suspicion but the crush sleeve may not have been crushed properly and the pinion is loose - noise would usually disappear when moving forward even under slight load as the pinion would be pulled into position. Noise would develop again on decel as the pinion would "relax". Tough to diagnose a sound without hearing it but...............

[Dusty1]

I know it is, just wanted ideas and got them. A mechanic (buddy) grabbed the pinion and said its loose. How, I don't understand. I'll pull it!

[moparmaniac59]

If you do end up having to re-set your pinion depth and want to get rid of the "crush sleeve", you can get a "crush sleeve eliminator kit" from Randy's Ring & Pinion for $36.75. It is easier to do (using a solid spacer & shims) than trying to get the crush sleeve at the right spot. I pasted the link below to Randy's if interested. Good luck!! 

http://www.ringpinion.com/b2c/ProductDetails.aspx?ProdID=8271&Product=SK_CSC8.75&Brand=Yukon_Gear_and_Axle


                                                                               Matt B.

[Dusty1]

I did use the crush sleeve eliminator

[tman]

Could the seller been deceptive on condition? "Good shape" could mean anything.........

[HP2]

That was my first thought. Bought used...."sure, its in good shape, just pulled it out of my car that ran great (except for this annoying clunking sound I could never figure out)."

You have a desireable set up, get it dialed in correctly and enjoy.

[Dusty1]

Thank you! My fault for putting a use part in when everything else in the car is new. But I don't know if the posi unit would make that kind of racket.

[moparmaniac59]

A few years ago I bought a used 4:10 center section. It had a sure-grip unit (Borg Warner made the sure grip which is now Auburn gears). The unit was operational when removed, but sat on a shelf for MANY years. The spring/clutches in the sure grip must have lost their elasticity or been 'stuck' as after I installed it, the unit made terrible noises whenever I turned a corner and also had a 'clunking' noise. It was a 489 case unit. So the rear diff. can absolutely make all manner of noises if there is a problem with the gears or the sure-grip unit! 


                                                                          Matt B.