Moparts

8 3/4 carrier bearing preload spec

Posted By: pishta

8 3/4 carrier bearing preload spec - 11/10/11 01:14 AM

Hard to find on the net. Someone got an FSM that shows spec for the carrier bearing preload by the threaded adjusters, NOT the caps? 75 fy/lbs? HELP! It can't be "snug" or "feel some drag"...?
Posted By: pishta

Re: 8 3/4 carrier bearing preload spec - 11/10/11 02:24 AM

c'mon..anyone? Im sure its in the FSM....
Posted By: cjs69mope

Re: 8 3/4 carrier bearing preload spec - 11/10/11 02:48 AM

it has been a while but it i think you just seat the ring gear side into the pinion and tight the crap out of the opposite side until you get 6-8 thou back lash i think .
because the whole carrier will move over away from the gear and the preload is set at the same time .
Posted By: Cab_Burge

Re: 8 3/4 carrier bearing preload spec - 11/10/11 02:50 AM

Quote:

c'mon..anyone? Im sure its in the FSM....

FSM says to adjust both adjusters until you get zero preload(not tight and not loose )and then adjust both sides equally so the ring gear ends up with .0010(one thousands) to .0015 backlash , (checked in three to four places, depending on which year FSM instructions your reading) and then adjust the right side(passenger side) only until you get the recommended backlash for that gear set. The backlash should be marked on the gear set, if your using OEM or Mopar replacement gear sets I use to shoot for .004 backlash maximum on a factory new OEM gear set on a dry gear set, no marking compound, grease or oil on the gears. That was for drag racing only, not a street and strip car
Posted By: 383man

Re: 8 3/4 carrier bearing preload spec - 11/10/11 03:03 AM

Most of the manufactors want 75 ft lbs on the carrier bearings. We had a tool at the dealer for the 8-1/4 and 9-1/4 rears that slid down the axle tube and you could put a torque wrench on it. I think you can buy the adjuster spanner wrench for the 8-3/4 that will adapt for use with a torque wrench. I myself dont have the adapter but I put enough torque on the bearing to try and be close to 75 ft lbs when done and backlash is in the .005 to .008 area. Some manufactors (Ford is one) actually has you measure the distance between the caps so you can see a change of a few thousand when bearing has proper load. In other words you measure the distance from one side to the other side of the caps and it will measure how much spread for bearing preload. But if we dont have all the tools many out there make do to try and hope they get close to the 75 ft lbs Mopar says. The important thing is they (carrier bearings) need some preload. You dont want them without any preload. Ron
Posted By: pishta

Re: 8 3/4 carrier bearing preload spec - 11/10/11 03:08 AM

OK, I made this in anticipation.....Ill get on that preload tomorrow..
Posted By: cjs69mope

Re: 8 3/4 carrier bearing preload spec - 11/10/11 03:37 AM

i don't think that tool is heavy duty enough i would made one out of 1/8 thick steel stock and 5/16 bolts and it bent when tightening the adjusters to get 6-to 8 thousandths back lash .
the main thing is you want to tighten the side opposite the ring a lot i don't think 75 ft pounds is enough IMO
Posted By: cjs69mope

Re: 8 3/4 carrier bearing preload spec - 11/10/11 03:48 AM

Check out this mopar muscle tech how to this is how i did mine and it works great 5 yrs now .
web page mopar muscle
Posted By: pishta

Re: 8 3/4 carrier bearing preload spec - 11/10/11 05:01 AM

Yeah, itll probably bend but its not going to bend before I get some sort of preload on the adjusters. My other option was grinding 3 teeth out of an old 2.5 hole saw. I was using an old pushrod and a hammer to tighten the adjusters after I got the .007 backlash set! I read that article too and didnt believe "good and tight" was quite accurate. Thanks.
Posted By: cjs69mope

Re: 8 3/4 carrier bearing preload spec - 11/10/11 06:08 PM

Well if you are setting the back lash before the preload then you are not doing it right. the preload is what sets the back lash !
As you tighten up the opposite the ring gear adjuster you will see change in the back lash the more preload the more back lash so to speak to a point .
Posted By: John_Kunkel

Re: 8 3/4 carrier bearing preload spec - 11/10/11 07:31 PM

There is no specified torque to be applied to the adjusters and no factory FSM mentions a specific carrier bearing preload.
Posted By: a12rag

Re: 8 3/4 carrier bearing preload spec - 11/10/11 07:48 PM

Ask the man - Doctor Diff . . . if anyone is gonna know, it would be him ! Cass . . . where are you on this ????

Cheers

Mark
Posted By: DoctorDiff

Re: 8 3/4 carrier bearing preload spec - 11/10/11 09:28 PM

Get the carrier bearings as tight as you can with a 12" spanner wrench, when the adjuster threads are lubed and the cap bolts are finger tight.

TIGHTEN the adjuster to acheive the correct backlash.

BTW, I sell a nice, Mopar specific spanner wrench for $35.
Posted By: pishta

Re: 8 3/4 carrier bearing preload spec - 11/11/11 10:53 PM

finally, thanks Doc. I thought just about everything torquable had a spec, but I was wrong. Ill do it like that. On a Dana its 75...(?)
Posted By: Cab_Burge

Re: 8 3/4 carrier bearing preload spec - 11/12/11 04:24 AM

The torque specs on the Dana 60 carrier bolts (the bolts that hold the center section in the housing) is 75 ft. lbs, theres no torque specs on the carrier bearings themselves There is a rotational torque spec on the pinion bearing preload with no pinion seal installed, just like there is for the 8 3/4 pinion bearing preload
© 2024 Moparts Forums