rear diff. thud

[Task125]

I am trying to figure out if there is a problem with my rear. diff. . that is. when ever I drive strait for a long period, then make sharp turns slow I hear something going on in the diff. clonk type of noise. is this normal with posi rear?

don't really want to go to stealler with bombs.

mike

 

[craftybigdog]

I had that happen once on my chevy and actually it was a tooth on my ring gear let go I was only backing up and I was getting on it I hope this didnt happen to you it popped a pin hole in my diff cover!

 

[Shovelhead]

My old '84 Dodge had the same noise, clunk in the rear while turning after highway driving. My '90 did the same, thought it was just the nature of the posi.

Then while talking to a buddy who works at the stealer, he gave me a package of the "friction modifyer" for the rear lube.

PRESTO... ... no more clunk.

It seems that the aftermarket lube I was using didn't have the "correct" additives for the Dodge posi.



HTH

 

[Task125]

Thanks for the help,I am calling the stealer this morning,I hate taking out the EZ and I guess I should take out Megacannon.

Mike

 

[Shovelhead]

You should be able to purchase the additive at the parts counter, and add it at home instead of letting the stealer get their hands on your ride.

 

[Task125]

Thats the plan,just called they have it in stock. whats the word on synthetics. yes no maybe?

 

[LSMITH]

Mike, refill it with synthetics, but don;t buy them at the dealer. You can get Valvoline or Mobil 1 at just about any parts house, and might be able to find Redline, Amsoil or Royal Purple if you do a little calling around. I use Mobil 1 and like it, well worth the money to have it in there.

 

[Tim1]

My posi was making a clunk sound, and I was using High Performance Valaoline withthe friction modifier already in there. Finally jammed up and pulled the cover (easy job) to find a busted pinion tooth. Changed ring and pinion, goood to go! Tim

 

[wtrenholm]

On clutch pac style limited slips (the word POSI is a 60's GM term for a limited slip) there is a series of friction and steel plates loaded by a heavy spring. The spring keeps the pacs loaded so the assembly resists slipping, some torque will hopefully be transfered to the wheel without traction. They do provide quiet operation as compared to some other diffs, like falling block style for example.



When the clutches friction and steel plates don't slip smoothly on each other the "clunk" is the pac "breaking free" to allow the wheels to turn differents speeds on corners. Some gearlubes will come with additives and some do not. The friction modifier will help this, but it may also make the unit less aggressive for normal operation. This style of limited slip is kind of a joke in some respects because the clutches are prone to wear quickly when abused making the unit useless. On my trail beater I've had to replace the clutches numerous times. Some day I'll upgrade to a better diff setup.



HTH

Wayne

 

[Task125]

Thanks for the help guys,

just got done changing oil in diff. no chunks or any other junk in oil or base of diff. added mopar additive. waitting to go to work on wed. 50 miles straight parkway driving . then i'll see if that worked.

thanks again ,Mike

 

[LSMITH]

Mike, go out and do some tight figure 8's to mix the new oil and modifier into the clutch packs or you will have the same problem as before for a long time. The 8's make the clutches slip letting the oil into them. Don't be surprised to get some pretty good chatter out of the diff on the first few. I would do at least 6 of the figure 8's. Good luck.



EDIT: Forgot to say do them slowly with the wheel all the way turned, then back the other way. Going slow does not let the tire slip and forces the clutches to slip instead.

 

[Task125]

good Idea,as soon as I defrost my fingers and warm up a little . I will go for a ride . cold and wet in the N,east. I love doing this stuff in my driveway.