8 3/4 489 differential build

[AZMoparboy]

I just got done rebuilding my 489 case, rear end differential using specs from 1973 Chrysler Service manual. I even installed the correct crush sleeve. I have 20 inch. lbs preload on pinion, back lash on gear is about .007 and torqued carrier to 150 foot lbs. I think my tooth pattern is great, almost purfect on both sides of ring teeth. The assembly is very tight. Should it be really tight for a new setup? Just getting feedback, just a little understanding of the brake in.

Thanks Steve

[c00nhunterjoe]

Might take a little while to loosen up. .007 is tight but acceptable. How much rotational force does it take to turn the pinion?

[AZMoparboy]

 Thanks for replying , I have snap on torque wrenches and have a very accurate reading, 20 inch lbs. with a crush sleeve. Chrysler Manuel says  minimum of 210 foot lbs. on pinion nut, let me say it took more than that to get the sleeve to get tight enough to achieve the 20 inch. Lbs. I kept tightening the nut just a very little at a time and  all at once the  tension on the bearings started to come up and befor I know it, it as at 20 inch lbs.

The carrier was very touchy, it took lots of  attempts to set the backlash and achieve the 150 foot lbs. on the adjusters. Each time turning the ring and pinion through many full turns to set the bearings after each attempt. This was a very  physical job to complete .

So while waiting for response from someone here on the forum I went ahead and assembled it filled it with lube and took it for its first 15 miles.  I think it did OK, it' a little early to tell for sure, will just have to put more miles on it and see where it goes.

Thanks again
Steve

[ACUDANUT]

Tell us more about your 73 charger. Looks great from your username box.

[Bad B-rad]

most of the time I  use the older "beam" style torque wrench to measure rotational torque on pinion nut, but if it is in the car now, I do not know if the reading would be correct.

There is a spec that you can use to see if you rear is to tight or loose, based on how much torque it takes to make the pinion turn.

[Challenger340]

For break in.... we used to run the gear sets in with the rear wheels up on jackstands until hot a couple of times, cool overnight, then drive it, but no WoT / No max load runs right away.
Dunno if the above is the prescribed method ?
just say'in .... worked for us, but then again we were Drag Racing with LOTS of power and abuse the gears would be subjected to ?

[Bad B-rad]

 

That's how we have done the few we rebuilt(aprox ,I think that is exactly what Yukon Gears says to do, up on jack stands run for 20 min forward, five in reverse,and then let it cool.

We kinda took it easy for the first 40 or so miles but after that, its on.
But we have also done the jack stand thing, then just started making passes, and had no issues.

[cdr]

 the 150 foot lbs. on the adjusters.?  explain what you mean ?  The bearing cap bolts ? or the adjusters ?

[AZMoparboy]

The question is, did I torque the Bolts to 150 on the cap bolts or the adjusters for moving the carrier left and right to 150 foot lbs. to  establish preload to the carrier bearings? I torqued the carrier end caps bolts to 90 foot lbs. after I established the preload and back lash to 150 foot lbs on the carrier adjusters with a .007 backlash.

The exact way and process that I installed the ring and Pinion and bearing set was from a Yukon installation instructions pamphlet issued with the new gears that I had acquired some years before .  If you are interested in exactly the wordage of this instruction pamphlet just Google Yukon instructions for gear set


I managed to pull up the pamphlet myself and copy and paste the verbiage that I followed to  accomplish the preload on the carrier bearings of my third member assembly.


here is the easiest method uses screw adjusters to set the backlash and carrier bearing preload. Carefully oil the adjuster threads on both the housing and on the adjusters themselves. Note the order in which you tighten the adjusters so the backlash remains consistent, even when subjected to heavy loads.
The pinion gear always forces the ring gear away from itself whenever it transfers power. Start with a looser backlash setting than the axle's manufacturer calls for and always ensure that the last adjustment made to the left adjuster tightens it.
If the backlash becomes too tight, loosen the left adjuster first, followed by tightening the right adjuster. To reestablish the backlash setting, tighten the left adjuster. Ensure that the last adjustment made to the left adjuster tightens it to eliminate any space between it and its bearing race. Any space or looseness on the left side will let the carrier deflect when under load, and this will allow backlash to open up when driven under load.
Once the backlash approaches the manufacturer's recommendations, tighten both left and right adjusters evenly to increase carrier bearing preload. Set the carrier bearing pre- load to approximately 150 to 200 pounds/feet. It is difficult to damage bearings with exces- sive carrier bearing preload on a screw-adjusted differential.
Kit Installation Manual

[cdr]

I never heard of getting them that tight, I have a 12in spanner & I get them as tight as I can with that, that is how Dr Diff says to do it also.

[c00nhunterjoe]

Holy crap, you are going to burn it up. The factory has NO spec for carrier bearing preload. 250 ft lbs is way too much. Run them as above stated, snug, then a little more, which will probably come out to around 50-60 ft lbs roughly.

[AZMoparboy]

Hi everyone that has responded, I have found another on line tech help article  with similar verbiage describing the technique of torquing carrier side adjusters.  It comes from Randy's worldwide,

There are several types of rear ends that use a threaded side adjuster be it a single adjuster or one on both sides of carrier. The most commonly known rears with this type of carrier adjustment are the Chrysler 7.25-8.25-8.75-9.25, Ford 9", GM 8.25" IFS, Suzuki Samurai, & Toyota. The GM 9.5" is a little different than most as one side uses shims but the other side is the threaded adjuster. Randy's has tools that work with a 1/2" drive ratchet or breaker bar that work much better than beating the heck out of the adjuster with a punch & hammer. These side adjuster tools are priced starting at $29.00. Most people are reluctant to really crank on these adjusters to preload the carrier bearings. It is perfectly normal to have 150-200 ft lbs of torque on the side adjusters. It is very important to obtain good preload to avoid damage to your differential. At Randy's, our service shop uses a 1/2" breaker bar, as shown in illustration 1A. The reason we do this is because as you accelerate, the pinion wants to make the ring gear deflect. The more power, the more it will tend deflect. Housings always flex, some more than others, depending on whether it's stock or an aftermarket nodular. If you put a lot of preload on the carrier bearings it also preloads the housing. Since the housing is already flexed, it is not likely to flex even more causing the ring gear to move away from the pinion resulting in broken teeth.

I try to read up on as much as possible on subjects such as this topic to get as wide of a  perspective and make a  decision based on information that I found.  It does seem to me that there are many different ideas specifications torques and sometimes no information at all .  I'm never going to tell anybody there's a positive an undeniable way to do any such job.

I'm going to try to remember this thread so that I can inform everyone of the outcome as this differential case gears and bearings break-in. Good or bad, I'll post it.

Thanks again for all of your interest in this matter,
Steve

[ACUDANUT]

Cool. Thanks and good luck. 

[c00nhunterjoe]

Hi everyone that has responded, I have found another on line tech help article  with similar verbiage describing the technique of torquing carrier side adjusters.  It comes from Randy's worldwide,

There are several types of rear ends that use a threaded side adjuster be it a single adjuster or one on both sides of carrier. The most commonly known rears with this type of carrier adjustment are the Chrysler 7.25-8.25-8.75-9.25, Ford 9", GM 8.25" IFS, Suzuki Samurai, & Toyota. The GM 9.5" is a little different than most as one side uses shims but the other side is the threaded adjuster. Randy's has tools that work with a 1/2" drive ratchet or breaker bar that work much better than beating the heck out of the adjuster with a punch & hammer. These side adjuster tools are priced starting at $29.00. Most people are reluctant to really crank on these adjusters to preload the carrier bearings. It is perfectly normal to have 150-200 ft lbs of torque on the side adjusters. It is very important to obtain good preload to avoid damage to your differential. At Randy's, our service shop uses a 1/2" breaker bar, as shown in illustration 1A. The reason we do this is because as you accelerate, the pinion wants to make the ring gear deflect. The more power, the more it will tend deflect. Housings always flex, some more than others, depending on whether it's stock or an aftermarket nodular. If you put a lot of preload on the carrier bearings it also preloads the housing. Since the housing is already flexed, it is not likely to flex even more causing the ring gear to move away from the pinion resulting in broken teeth.

I try to read up on as much as possible on subjects such as this topic to get as wide of a  perspective and make a  decision based on information that I found.  It does seem to me that there are many different ideas specifications torques and sometimes no information at all .  I'm never going to tell anybody there's a positive an undeniable way to do any such job.

I'm going to try to remember this thread so that I can inform everyone of the outcome as this differential case gears and bearings break-in. Good or bad, I'll post it.

Thanks again for all of your interest in this matter,
Steve

We have a 155 mph super gas car with a dana 60 in it. It does not have 200 ft lbs of load on the carrier bearings. There has never been a ring gear movement problem. It has off the shelf parts in it, nothing special.