Correct differential yoke seal?

[koosh]

Moving on to my next project…69 Super Bee, currently has a 489 rear diff case, 8 3/4 rearend. Im going to be swapping the “chunk” with a 741 case. The current yoke is bigger than the 741 going in, so i will swap yokes. Id like to install a new seal ( guess its called pinion seal?). When looking on line, there are multiple choices, how do i order the correct one?
Rock Auto even lists one seal that fits both cases? I do not have my 489 case out yet, do both yokes require the same seal?
Thanks in advance…

 

[R413]

Same pinion seal in a 489 and 741 case.

All factory 741's are 10 spline yokes. 489 can be a 10 spline or 29 spline. It goes by the size of the socket needed on the pinion nut.
1 1/8" 10 spline
1 1/4" or 1 5/16" 29 spline

If it's stock 489 from the 69 bee it's most likely a 10 spline.

 

[khryslerkid]

Get the double lip seal from Dr Diff

 

[Fran Blacker]

Rather than change the yoke use a combination u-joint. Pinion preload could change. Just a thought.

 

[koosh]

Get the double lip seal from Dr Diff

So what do i ask dr diff for? Just an 8 3/4 seal?

 

[koosh]

Rather than change the yoke use a combination u-joint. Pinion preload could change. Just a thought.

Not sure ive heard of that? Where do i find?

 

[koosh]

Same pinion seal in a 489 and 741 case.

All factory 741's are 10 spline yokes. 489 can be a 10 spline or 29 spline. It goes by the size of the socket needed on the pinion nut.
1 1/8" 10 spline
1 1/4" or 1 5/16" 29 spline

If it's stock 489 from the 69 bee it's most likely a 10 spline.

So how do i order a seal then? By spline?

 

[koosh]

Rather than change the yoke use a combination u-joint. Pinion preload could change. Just a thought.

Is this what you are referring to?

 

[Fran Blacker]

Not positive this is the combination U-joint you need but spec's are there. Mopar Cars & Trucks > UNIVERSAL JOINTS > 7260 Series > Connect 7260 to 7290
Yes those are the one

 

[koosh]

Not positive this is the combination U-joint you need but spec's are there. Mopar Cars & Trucks > UNIVERSAL JOINTS > 7260 Series > Connect 7260 to 7290
Yes those are the one

That looks like the 2 I mentioned above, i have no clue if its right either! BUT- now im wondering how does my current ubolts fit both ends of that u joint?

 

[Fran Blacker]

If you go to the website I posted and click on the spicer u-joint and scroll down all the dimensions are there.

 

[koosh]

If you go to the website I posted and click on the spicer u-joint and scroll down all the dimensions are there.

Yes, saw that. But i must be missing something… when using this combination u joint, how do the u-bolts fit from the larger driveshaft end to the smaller yoke end?

 

[R413]

Straps fit the yoke. Big yoke 7290 small yoke 7260. The straps are different they don't interchange. You have the big straps on your car. You need the correct straps for the small yoke.

 

[Fran Blacker]

Do you have U bolts that have nuts on back of yoke? If you have straps you'll need different straps. I think with U bolts you'll ok. @R413 your thoughts.

 

[Fran Blacker]

7260 straps available from mancini $12. You'll need to scroll gown they're on left side. Search Results

 

[koosh]

Talked with knowledgeable Cass at Dr Diff today…he saud i have a very good chance my existing yoke will fit the just purchased 741 diff. Indicated early 69 489 cases had 10 spline yoke, and the 741 has same.additionally i should just swap the yokes as the 741 case does not have a crush washer, so not to worry about proper tightening. I ordered his pinion seal also.

 

[Fran Blacker]

My reason for not swapping yokes is pinion bearing preload. If yokes interchange the pinion bearing preload may not be right it could be to tight, to loose or just right. Judging by the questions this changing yokes isn't as simple as unbolting yokes and switching them! If you haven't ever done a rear setup you could have a mess by not having right pinion preload. I suggest doing the u-joint swap and buy the straps.