8 3/4 ring and pinion swapout

[mopower440]

so i have a 741 case 8 3/4 rear that has a 3.23 suregrip (clutch style). I have purchased a 3.73 ring and pinion set along with all new bearings. This will be my first ring and pinion swap. I have been watching some videos on how to do it and am confused on a few things..First is the shimming of the pinion, is the reasoning to get the correct drag on the pinion or to get the depth into the ring gear correct? Next, being the bearings are pressed onto the pinion shaft, if i put it together and it needs more or less shims, is it going to ruin the new bearings by removing them and pressing them back on several times over until the shims are correct?? Im assuming that since this is a whole new ring and pinion set that the oem shims currently in it probably arent going to get it correct like it could be if i was just re-using the original ring and pinion..

 

[Illahe]

so i have a 741 case 8 3/4 rear that has a 3.23 suregrip (clutch style). I have purchased a 3.73 ring and pinion set along with all new bearings. This will be my first ring and pinion swap. I have been watching some videos on how to do it and am confused on a few things..First is the shimming of the pinion, is the reasoning to get the correct drag on the pinion or to get the depth into the ring gear correct? Next, being the bearings are pressed onto the pinion shaft, if i put it together and it needs more or less shims, is it going to ruin the new bearings by removing them and pressing them back on several times over until the shims are correct?? Im assuming that since this is a whole new ring and pinion set that the oem shims currently in it probably arent going to get it correct like it could be if i was just re-using the original ring and pinion.

Take an inner pinion bearing and hone it so it just slip fits over the pinion shaft and set the pinion depth. Place the outer bearing and yoke on the pinion, then assemble and check your pattern.

Once your good press the "new" bearing on the pinion and re assemble.

 

[RustyRatRod]

The shims are to set the pinion gear depth in relation to the ring gear.

Yes, if you aren't careful or don't have the right tools (A press and bearing separator) you can and in all likelihood mutilate bearings.

What I do is carefully remove the old large pressed on large pinion bearing. I then hone the inside of that bearing to a slip fit on the new pinion shaft. Then I start fitting shims and find my correct pinion depth. Once I find that, I remove the old bearing, leave the correct shim in place and press the new bearing on. The differences between the used and new bearing will be very minimal and will have a negligible effect on the pinion depth.

 

[RustyRatRod]

Take an inner pinion bearing and hone it so it just slip fits over the pinion shaft and set the pinion depth. Place the outer bearing and yoke on the pinion, then assemble and check your pattern.

Once your good press the "new" bearing on the pinion and re assemble.

Ya treed me! lol

 

[mopower440]

The shims are to set the pinion gear depth in relation to the ring gear.

Yes, if you aren't careful or don't have the right tools (A press and bearing separator) you can and in all likelihood mutilate bearings.

What I do is carefully remove the old large pressed on large pinion bearing. I then hone the inside of that bearing to a slip fit on the new pinion shaft. Then I start fitting shims and find my correct pinion depth. Once I find that, I remove the old bearing, leave the correct shim in place and press the new bearing on. The differences between the used and new bearing will be very minimal and will have a negligible effect on the pinion depth.

sounds good! What are you guys using to hone the center of the old bearing out? Also, when i use the old honed out bearing to set the pinion depth, im assuming i have to put the complete unit together, set the backlash and use the gear marking compound to be sure that pinion depth is correct, and once it is correct, tear it all back down and press on the new pinion bearing. OR, am i only assembling the pinion into the housing and getting the resistance setting correct on the pinion using the inch pound wrench and then installing the new bearing and THEN installing the ring gear and doing the backlash? Im asking because on the videos ive watched, it seems like they do it separately..They shim the pinion until the resistance while spinning it is correct, and then they are done with the pinion, THEN, the install the carrier and set the backlash and use the marking compound to check it all..Ive never seen any of them assemble it completely, check it with marking compound and then tear it all back down to remove or ad shims to the pinion..its like they always get the correct pattern by just changing the adjustment on those side bearing adjusters.. Just asking so i do this correctly so bear with me and thanks for any and all help!

 

[RustyRatRod]

I use a small three stone cylinder hone. It takes a little time, but it works.

 

[jas0162]

Ive been through several 8 3/4 gear changes over the years and have found if you use the shim or shims from your old gears in the same housing your pinion depth will most likely be good, if it was good before. That being said, the honed bearing can save time.

 

[Oldmanmopar]

Ya treed me! lol

He was using a trans brake. You were foot braking.

 

[RustyRatRod]

He was using a trans brake. You were foot braking.

 

[Sterling]

In the 741, there are shims to set the pinion bearing preload, and shims for the pinion depth. I would remove the old bearing from the 3.23 pinion, and start with the shim under the bearing for pinion depth. And if you don't ruin the bearing removing it, you can hone the old bearing and use that for mock up.

 

[mopower440]

Take an inner pinion bearing and hone it so it just slip fits over the pinion shaft and set the pinion depth. Place the outer bearing and yoke on the pinion, then assemble and check your pattern.

Once your good press the "new" bearing on the pinion and re assemble.

so the outer pinion bearing (one closest to the pinion nut) can be pressed on, and then hone the other pinion bearing (inner) to slip on and off for checking?

 

[Illahe]

so the outer pinion bearing (one closest to the pinion nut) can be pressed on, and then hone the other pinion bearing (inner) to slip on and off for checking.

No. Inner bearing need to me honed because the shims stack under the inner bearing for pinion engagement.

I use a magnet on the pinion and a parallel ground ruler to check the initial depth of the pinion gear in the case, with a set of calipers. The measurement is +/- .001`.003 and it will get you in the ball park to check the ring gear pattern.

Be patient, the pinion engagement will come in to the correct pattern, one you get the "feel of the shim stack" effect.

 

[66fs]

They sell a special bearing to use for setup.

 

[mopower440]

No. Inner bearing need to me honed because the shims stack under the inner bearing for pinion engagement.

I use a magnet on the pinion and a parallel ground ruler to check the initial depth of the pinion gear in the case, with a set of calipers. The measurement is +/- .001`.003 and it will get you in the ball park to check the ring gear pattern.

Be patient, the pinion engagement will come in to the correct pattern, one you get the "feel of the shim stack" effect.

? which one are you saying is the inner that needs to be honed?

 

[RustyRatRod]

? which one are you saying is the inner that needs to be honed?

There are two bearings on the pinion. The big bearing and the small bearing. The big bearing gets honed to a slip fit so you can easily slide off to change the shim(s). The big bearing is the inner bearing.

 

[Illahe]

? which one are you saying is the inner that needs to be honed?

Yes, the bearing against the pinion gear. "The large bearing." Don't get confused by the shim stack if your not running a "crush sleeve" that does not set pinion depth. Just bearing pre-load.

 

[mopower440]

Found an excellent video on rebuilding the 741 case like i have! Pretty straight forward except for one thing..So he shims the pinion and gets the preload correct, the assembles the sure grip with ring gear and sets the backlash and all and sees that the contact pattern needs the pinion depth to be deeper, so he has to take it all apart and CHANGES the shims on the pinion to get it deeper..ok what i dont understand is, if the preload on the pinion was correct , how does that preload STAY correct when he changes the shims to get the pinion deeper? Seems that when he changes the shims to make the pinion deeper it would throw off the preload that he had correct..?

 

[340six]

The shims are to set the pinion gear depth in relation to the ring gear.

Yes, if you aren't careful or don't have the right tools (A press and bearing separator) you can and in all likelihood mutilate bearings.

What I do is carefully remove the old large pressed on large pinion bearing. I then hone the inside of that bearing to a slip fit on the new pinion shaft. Then I start fitting shims and find my correct pinion depth. Once I find that, I remove the old bearing, leave the correct shim in place and press the new bearing on. The differences between the used and new bearing will be very minimal and will have a negligible effect on the pinion depth.

That's best way. And you are cheap like me. Old bearings made into set up bearings. They sell them, but you can make your own.

 

[Illahe]

Found an excellent video on rebuilding the 741 case like i have! Pretty straight forward except for one thing..So he shims the pinion and gets the preload correct, the assembles the sure grip with ring gear and sets the backlash and all and sees that the contact pattern needs the pinion depth to be deeper, so he has to take it all apart and CHANGES the shims on the pinion to get it deeper..ok what i dont understand is, if the preload on the pinion was correct , how does that preload STAY correct when he changes the shims to get the pinion deeper? Seems that when he changes the shims to make the pinion deeper it would throw off the preload that he had correct..?

He adds the same thickness shim to the preload that he takes out of the shim stack under the inner pinion bearing. Or vise versa if the pinion is too deep. He removes the shim thickness that he adds to the pinion inner shim stack.

 

[1WildRT]

Found an excellent video on rebuilding the 741 case like i have! Pretty straight forward except for one thing..So he shims the pinion and gets the preload correct, the assembles the sure grip with ring gear and sets the backlash and all and sees that the contact pattern needs the pinion depth to be deeper, so he has to take it all apart and CHANGES the shims on the pinion to get it deeper..ok what i dont understand is, if the preload on the pinion was correct , how does that preload STAY correct when he changes the shims to get the pinion deeper? Seems that when he changes the shims to make the pinion deeper it would throw off the preload that he had correct..?

He made a video, he must know what he's doing.... Not.... You are correct, he screwed the pooch on his bearing preload...

Or, as Illahe assumes, he made an adjustment to his preload shim pack.. If he did, he should have told his viewers about that step...

 

[mopower440]

well, i believe i screwed myself good this time. I spent all this money buying a new gear set and bearings and tools to re-gear my chunk and i can NOT get the pinion nut loose for nothing! I dont have air or air tools, have always done everything by hand but this will not come loose. I wish i would have just got another chunk. . I Bought a yolk holder from mancini and it takes a darn 3/4 ratchet to hold it, which i also dont have and surely not very common..? I tried sticking an old ratchet between the yolk holder and the snubber and put a long piece of exhaust pipe on the ratchet on the pinion nut and tried to loosen it and it literally broke the old ratchet in half that was wedged between the holder and snubber! I could take the thing somewhere and loosen it with an air gun but when im assembling it i will have to torque it to 240 ft lbs. also and maybe have to do it several times trying to get the preload and depth correct.

 

[DartManPlum340]

well, i believe i screwed myself good this time. I spent all this money buying a new gear set and bearings and tools to re-gear my chunk and i can NOT get the pinion nut loose for nothing! I dont have air or air tools, have always done everything by hand but this will not come loose. I wish i would have just got another chunk. . I Bought a yolk holder from mancini and it takes a darn 3/4 ratchet to hold it, which i also dont have and surely not very common..?

View attachment 1716510081

View attachment 1716510082

In stock at my local H.F. This one is 20". but you might need a longer one or a cheater pipe on the end. https://www.harborfreight.com/3-4-q...MDQu68Ab9fURbClpf3cXym4EJ1pD2bxEaAo1kEALw_wcB

Here's a 40". Pardon Our Interruption...

 

[Sterling]

I have used the handle from my floor jack and a 1/2 " breaker bar already. And I have broken my Snap -On 1/2" breaker bar. Might be able to rent or borrow a cordless impact to loosen. I did set up a 8 3/4 489 housing for a friend once, that I had the pinion nut torqued to 450' lbs and still had no pinion bearing preload. I tried tightening more, and pulled the threads out of the nut.

 

[mopower440]

I have used the handle from my floor jack and a 1/2 " breaker bar already. And I have broken my Snap -On 1/2" breaker bar. Might be able to rent or borrow a cordless impact to loosen. I did set up a 8 3/4 489 housing for a friend once, that I had the pinion nut torqued to 450' lbs and still had no pinion bearing preload. I tried tightening more, and pulled the threads out of the nut.

I have a cordless impact but it didnt phaze it

 

[Illahe]

well, i believe i screwed myself good this time. I spent all this money buying a new gear set and bearings and tools to re-gear my chunk and i can NOT get the pinion nut loose for nothing! I dont have air or air tools, have always done everything by hand but this will not come loose. I wish i would have just got another chunk. . I Bought a yolk holder from mancini and it takes a darn 3/4 ratchet to hold it, which i also dont have and surely not very common..? I tried sticking an old ratchet between the yolk holder and the snubber and put a long piece of exhaust pipe on the ratchet on the pinion nut and tried to loosen it and it literally broke the old ratchet in half that was wedged between the holder and snubber! I could take the thing somewhere and loosen it with an air gun but when im assembling it i will have to torque it to 240 ft lbs. also and maybe have to do it several times trying to get the preload and depth correct.

View attachment 1716510081

View attachment 1716510082

A) do you have access to a welder?

B) be patient.

Weld a 3-4' piece of 1 1/4' black pipe to the Mancini yoke tool by slotting the pipe and welding on both sides.

Then get a 3/4 drive breaker at HF and the proper socket. Place the yoke tooling extension against your abdomen and fix the 3/4 breaker with pipe extension so you pulling towards yourself. Or rent a 3/4 drive impact from a tool yard.

Differentials are not scientific, they are just a pain in the ***.