That doesn’t look good.

[dodgechargerfan]

I’m starting to pretend to make plans to get back to work on the Charher.

I was thinking I’d just need a rebuild kit for the rear end, but while trying to figure out which size pinion bearing I need I saw this.



So, I’m guessing I need to look at a ring and pinion set, too.
Not the greatest picture, but that leading edge of the pinion is chewed up on every tooth.

It’s a 489 case. Is there a way to determine which pinion is in there without taking it apart? Rebuild kits spec the gear size. So I want to know what to order.
or if I’m getting a new one anyway, can I put it in whatever I want? If so, I’m guessing the thicker, the better?

So, they list ring and pinion sets and spec the number of splines but not the gear size. Frustrating.

 

[dodgechargerfan]

Also, those chunks are f*cking heavy.

 

[dodgechargerfan]

And as often happens with me, as soon as I ask, I find the answer…

1 7/8” tapered is what should be in there.
Still not sure about the spline count, but I could go out there and count them. I guess. If I have to.

 

[b-body-bob]

Not the greatest picture, but that leading edge of the pinion is chewed up on every tooth.

So the shiny tin-foil looking area is the pinion teeth? Yep, that's pretty ugly.

The 489 uses the crush sleeve. In the past I've subbed in a non-crush spacer and used shims to set the depth. Seemed easier to me, but I'm a girly man unlikely to pull the torque needed to crush the sleeve without having to stand on the cheater bar and screwing it up.

 

[dodgechargerfan]

So the shiny tin-foil looking area is the pinion teeth? Yep, that's pretty ugly.

Yep.

 

[69.5CUDA]

id tell you its stampeed on the ring and useualy the pinion as well but thats some serious chunkage..sooooooo it may not be there anymore

 

[Dr.Jass]

I'm not sure what the actual question here is, so as is my tradition I'll write a long explanation with info that doesn't apply.

489-case gears only fit 489 cases, and 489 cases will not accept any other gears. There only differences are ratio and yoke spline. Your car, being the vintage it is, could have either a coarse or fine-spline pinion. You don't have to completely disassemble the chuck to determine this; once the pinion nut and washer are off you should be able to see the splines. The difference between 10 and 29 splines is significant and obvious.

All 741 (and 657) cases have a 1-3/8" pinion; yoke splines could be either 10 or 29, depending on year.
All 742 (and 985) cases have a 1-3/4" pinion with a 10-spline yoke.
All 489 (and 488) cases have a 1-7/8" pinion; yoke splines could be either 10 or 29 in 1969 and early 1970. This depends on assembly date and (I think) which diff was used. I've only seen 10-spline yokes on units factory-equipped with Spicer Trac-Lok (clutch-type) diffs. The 488/489 is the only tapered pinion shaft. All the others are straight.

Any 8-3/4" ring gear will bolt to any 8-3/4" differential. If you're using an original Trac-Lok, you will need to use a countersink to slightly chamfer the holes to accept new ring-gear bolts from an open/cone-type diff, or spend five times the money for single-use ARP ring-gear bolts that only work on that diff. All the ring-gear bolts are LH thread, and you cannot reuse ring-gear bolts. You're welcome to attempt proving me wrong on this. Let me know how many break.

All the bearing and seal numbers provided below are Timken.

Pinion bearings: 489 pinion bearings is 489 pinion bearings, period. M88048/M88010 for the outer, M804049/M804810 inner, with the pinion seal being 5126.

Side bearings depend heavily on which diff you're using.
Open or cone-type (Borg-Warner/Auburn) units use the side bearings listed for a 489 case (look them up for a 1971 car with a 1-7/8" pinion, since most places don't go by the casting number). The Timken numbers are LM104949 and LM104912, bearing and race respectively.
If you're using a clutch-type, Detroit Locker, or (I believe) Eaton Tru-Trac then you want side bearings for a 742 case, which means looking it up for a 1968 or older model with a 1-3/4" pinion diameter. The Timken numbers are 25590 and 25520, bearing and race respectively.
If I have to tell you to order two each of the side bearings and races, sell your car.

 

[69.5CUDA]

All the ring-gear bolts are LH thread, and you cannot reuse ring-gear bolts. You're welcome to attempt proving me wrong on this. Let me know how many break.

i did not know this
looks at 67 fish with docs old 5:33 gears with 3:23 bolts in it

 

[b-body-bob]

i did not know this
looks at 67 fish with docs old 5:33 gears with 3:23 bolts in it

I don't remember replacing the ring gear bolts on the two units I rebuilt either.

I did learn the hard way that the clutch-type carrier bolts are LHT though.

 

[Dr.Jass]

I've tried to re-use them twice. I broke multiple bolts both times merely attempting to torque them to factory specification, which ain't much (55lb/ft, maybe?). For the little they cost, I'm not risking destroyed gears and a wasted carrier. Those are considerably more expensive.

 

[dodgechargerfan]

I'm not sure what the actual question here is, so as is my tradition I'll write a long explanation with info that doesn't apply.

489-case gears only fit 489 cases, and 489 cases will not accept any other gears. There only differences are ratio and yoke spline. Your car, being the vintage it is, could have either a coarse or fine-spline pinion. You don't have to completely disassemble the chuck to determine this; once the pinion nut and washer are off you should be able to see the splines. The difference between 10 and 29 splines is significant and obvious.

All 741 (and 657) cases have a 1-3/8" pinion; yoke splines could be either 10 or 29, depending on year.
All 742 (and 985) cases have a 1-3/4" pinion with a 10-spline yoke.
All 489 (and 488) cases have a 1-7/8" pinion; yoke splines could be either 10 or 29 in 1969 and early 1970. This depends on assembly date and (I think) which diff was used. I've only seen 10-spline yokes on units factory-equipped with Spicer Trac-Lok (clutch-type) diffs. The 488/489 is the only tapered pinion shaft. All the others are straight.

Any 8-3/4" ring gear will bolt to any 8-3/4" differential. If you're using an original Trac-Lok, you will need to use a countersink to slightly chamfer the holes to accept new ring-gear bolts from an open/cone-type diff, or spend five times the money for single-use ARP ring-gear bolts that only work on that diff. All the ring-gear bolts are LH thread, and you cannot reuse ring-gear bolts. You're welcome to attempt proving me wrong on this. Let me know how many break.

All the bearing and seal numbers provided below are Timken.

Pinion bearings: 489 pinion bearings is 489 pinion bearings, period. M88048/M88010 for the outer, M804049/M804810 inner, with the pinion seal being 5126.

Side bearings depend heavily on which diff you're using.
Open or cone-type (Borg-Warner/Auburn) units use the side bearings listed for a 489 case (look them up for a 1971 car with a 1-7/8" pinion, since most places don't go by the casting number). The Timken numbers are LM104949 and LM104912, bearing and race respectively.
If you're using a clutch-type, Detroit Locker, or (I believe) Eaton Tru-Trac then you want side bearings for a 742 case, which means looking it up for a 1968 or older model with a 1-3/4" pinion diameter. The Timken numbers are 25590 and 25520, bearing and race respectively.
If I have to tell you to order two each of the side bearings and races, sell your car.

Thanks for all of that.


I think I’ve figured out where I went wrong.

I could swear that I saw listings for rebuild kits for 489 case and w different pinion sizes.
My eyes must have drifted down a row as I scanned across… or something.