489 vs 741

[68prostdart]

which is better and what are the differences between the 489 and 741 3rd members? And they will both bolt in to a 8 3/4 rear?

[68_Val_Sedan]

the 489 has a taperd pinion gear and is supposed to be the strongest of the 3 case styles,  a 741 style has the smallest pinion of the carriers.  they will both work in any housing

[oldkimmer]

In this case bigger is better....489 has 1 7/8 tapered pinion, which uses a crush sleeve to adj bearing preload, u can now get a solid spacer and shims to set the preload...............741 has a 1 3/8 pinion shaft, deemed weak because of its small size.......there is also a 742 with 1 3/4 pinion...all are interchangeable into the 8 3/4 housing..........there is a 7260 and a 7290 ujoint sizes......for just running around on the street u can use either 1 and b happy....kim........

[Ciscodog]

487 w/solid crush sleeve is the HEET baby!!!!!!!!!!!

[Tejas]

Where do you get the solid sleeve and shims for the 489 case?

[68prostdart]

Thanks for the info. I have a 489 and a 741. Was planning on building the 489 with 4.10's wasn't sure if it was better than the 741. 

[68_Val_Sedan]

Where do you get the solid sleeve and shims for the 489 case?

Mancini racing has them ... manciniracing.com

[Tejas]

 

[sr71mopar]

I've seen lots of pics of busted carriers and caps, but I don't recall seeing any of broken pinions.

[375InStroke]

It's not the pinion that makes the 741 weaker, it's the smaller pinion bearing.  All the pinions are the same size where the yoke bolts on.  Just for reference, the 741 case pinion is larger than the Ford 9" pinion.

[demon340v]

FYI if your looking for tall gears get rid of the 741 case.

only the 489 and 742 case have alot of gears offered for them.

I had a 741 case but the largest i coudl get was a 3.55 if i  rememebr correctly. i did nto have to worry to long since i blew the pinon out the back of my 8 3/4

[68prostdart]

It's not the pinion that makes the 741 weaker, it's the smaller pinion bearing.  All the pinions are the same size where the yoke bolts on.  Just for reference, the 741 case pinion is larger than the Ford 9" pinion.

I have a 742 case on my car I want to swap in my 489. If They are both 10 spline I can use the same yoke off the 742 for my 489?

[Winter]

Yokes fit if the splines are the same and the u-joint width is the same. The cap diameters are a clue, 1.078 found on the smallest pinion or 1.125 for the 7290 large series. Also the carrier bearings on the 498 & 742 are huge and will hold a spool. The small pinion is out for a spool or posi types so you need the big ones. I have a 3.91 stock single track from 1966Van, so they do have lower than the 3.55 I have left over from a 63 D100 pickup with the old splined axles. All open carries are interchangeable in the 1974,  8-3/4 "axle'd cuda for slalom runs to the coast. I use Posi for drags only, due to slipping in the turns. javascript:void(0);
drag tree

[375InStroke]

The yoke on the 489 can't be changed without rebuilding the assembly due to the crush sleeve design.

[smallbigblock]

Here is a pic of the three pinions for referance:



Left to right: 489 case 741 case 742 case

(10 spline yoke)

[rjsjea]

great pic smallbigblock............

[PureGTS]

I've always heard about the 741 pinions being thin and breakable. However I have only broken one and that was in trying to take the yoke off. It wouldn't go so I kept upping the size of the removal tool (hammer; it became a personal thing  ) When it did come off, it shot across the yard taking a part of the pinion with it. (oops!) But I got it off!    Did I mention I have a Neanderthal streak...

[375InStroke]

Yokes fit if the splines are the same and the u-joint width is the same.  The small pinion is out for a spool or posi types so you need the big ones.

Yokes may fit, but doesn't the pumpkin need to be rebuilt when changing yokes on a 489 case?  Why is the small pinion out for posi types?  My 741 in my 340 Swinger came with a posi.  I've found many 3.55 and 3.91 Sure-Grips in 741 cases in vans at junkyards.

[68_Val_Sedan]

I've always heard about the 741 pinions being thin and breakable. However I have only broken one and that was in trying to take the yoke off. It wouldn't go so I kept upping the size of the removal tool (hammer; it became a personal thing  ) When it did come off, it shot across the yard taking a part of the pinion with it. (oops!) But I got it off!    Did I mention I have a Neanderthal streak...

I have the same gene in me ... nothing wrong with a BFH when the time comes for it ...

[Winter]

Yokes fit if the splines are the same and the u-joint width is the same.  The small pinion is out for a spool or posi types so you need the big ones.

Yokes may fit, but doesn't the pumpkin need to be rebuilt when changing yokes on a 489 case?  Why is the small pinion out for posi types?  My 741 in my 340 Swinger came with a posi.  I've found many 3.55 and 3.91 Sure-Grips in 741 cases in vans at junkyards.

     At least you confirm that 3.91: 1 in a small pinion exist. You must be the ultmate  scrounge; to be so lucky, as to find the only small carrier bearing posi units from a by gone era; where only rust stops you from using your weak (lame) clutch type or was it modern cone type that you found? ANYWAY, you won't find any NEW posi's or spools with the option to use small carrier bearings. The chrush sleeve is what you guys are concerned with on the 489. Some times you can get away without a new one, by re-shiming the new pinion under it's case bearing, or shaft bearing(mine is holding tight). The stock mopar replacements are very hard to chrush with a 1/2 drive breaker bar so unless you have larger?... I am not the definitive expert in this field, just a user. go ahead blast me ..I've heard it all before...........................