8 3/4 -- Hum...

[Gordon340]

I don't think I understand what I know - or think I know.

I picked up a "741" case with a 3.55 open diff in it at a local swap meet. It had a bad yoke on it. I had 2 other 8 3/4's with 741 cases, so I was just going to swap one over (there were all small joint yokes). I pulled a replacement yoke off of the one that came out of a C body, and as expected, it was a 10 spline yoke.

I cleaned it up and got it ready to transplant onto the 3.55. To my surprise, the 3.55 had a 21 spline with a larger pinion nut. I have found the yoke I need and it is ready to go.

My present understanding is that 741's all had the 10 spline yokes. Am also puzzled by the larger pinion threads. What gives?

My numbers for the "3.55" rear are as follows:

"2070 741"

Date 1021 2

Has a large X stamped on body of diff.

Thanks.
Brian

 

[rumblefish360]

I don't think I understand what I know - or think I know.

And never be tooooo sure of yourself or become a non-humble person to learn something new. I'm with ya on that. Ya never know what curve you'll be thrown next. He he he.

MoPar has a verity of yokes that should fit the bill. If not, theres randys ring and pinion, richmond, progears, or was that U.S. Gears, etc....

I'm not to up on this, but, I did have 742 stuff, put into my 741 case. There could be a difference there. And that last person could have done just that?!?

 

[Small Block]

Aint' it great to still be able to learn and by golly that's what i've been doing ever since i started tearing down my 489. The pinion on the 741/742 and the 489 are different and the 489 takes bigger bearings. I've got it shimmed to spec with a trial fit up and now i have taken and went back with the final including crush sleeve. The torque spec is a min of 210 lbs and it takes all of that to crush that baby and i'm not there yet. What's the best method to hold the pinion to keep it from turning? I went down and bought me a set of 3/4" sockets and breaker bar. I've got the book from Randy's but it is lacking in some areas. They jump from ford to chevy to mopar and back and forth and back and forth. Just a word of advice. Make a note of what went where when you take em apart. Just trust me. How does one hold the center section solid enough to get that kind of pressure on it?

 

[sweatybetty]

Aint' it great to still be able to learn and by golly that's what i've been doing ever since i started tearing down my 489. The pinion on the 741/742 and the 489 are different and the 489 takes bigger bearings. I've got it shimmed to spec with a trial fit up and now i have taken and went back with the final including crush sleeve. The torque spec is a min of 210 lbs and it takes all of that to crush that baby and i'm not there yet. What's the best method to hold the pinion to keep it from turning? I went down and bought me a set of 3/4" sockets and breaker bar. I've got the book from Randy's but it is lacking in some areas. They jump from ford to chevy to mopar and back and forth and back and forth. Just a word of advice. Make a note of what went where when you take em apart. Just trust me. How does one hold the center section solid enough to get that kind of pressure on it?

put a 2' long pipe on your torque wrench and go to 105lbs

 

['64 Cuda]

To keep the pinion from turning take a large pipe wrench & use it on the outside of the yoke. Brace it against the floor. This is if the third member is on the floor.

 

[340mopar]

Small Block, the 742 has a bigger (larger rollers) gear end bearing than the 489.


Chuck

 

[SGBARRACUDA]

Small Block, the 742 has a bigger (larger rollers) gear end bearing than the 489.


Chuck

The way I hold the yoke from turning when I crush the sleeve is to put the yoke in a vise that is bolted down to a good work bench.