school me on 8 3/4

[Vaanth]

so if i were to install the sure grip unit itself from my 741 unit into, say a 489 open diff center to make it positive traction, i would have to buy the outer axle bearings (wheel bearings) to install on my axles that would have been on the axles used in the 489 case? am i understanding this correctly? Im guessing there is not enough adjustment on the passenger side axle bearing adjustment? Or could i just use the green axle bearings for any of the 3 different carriers?

I should not have had the word "axle" in that sentence (removed in an edit). The outer axle bearings (wheel bearings) are not involved and do not change. Keep the axle bearings the same (if good), and just keep the carrier side bearings (inner, cone and outer, cup) with the '741' Sure Grip unit and place in the other housing with your new gears for that housing.

 

[1WildRT]

The aftermarket 741 3.73 set you posted uses a fine spline. (#16).

Hadn't even considered it...

 

[mopower440]

I should not have had the word "axle" in that sentence (removed in an edit). The outer axle bearings (wheel bearings) are not involved and do not change. Keep the axle bearings the same (if good), and just keep the carrier side bearings (inner, cone and outer, cup) with the '741' Sure Grip unit and place in the other housing.

wow that easy? so say i come up with a 489 case with 3.91 gears but its an open diff. I would just literally remove the carrier from the 489 case, install my complete sure grip unit INCLUDING its carrier side bearings and re-install into the 489 case..that easy?

 

[Vaanth]

wow that easy? so say i come up with a 489 case with 3.91 gears but its an open diff. I would just literally remove the carrier from the 489 case, install my complete sure grip unit INCLUDING its carrier side bearings and re-install into the 489 case..that easy?

Yes.

 

[1WildRT]

wow that easy? so say i come up with a 489 case with 3.91 gears but its an open diff. I would just literally remove the carrier from the 489 case, install my complete sure grip unit INCLUDING its carrier side bearings and re-install into the 489 case..that easy?

yup, but make sure there's bearing preload and keep the back lash the same as it was... Change the backlash & you'll probably have a new noise.....

 

[mopower440]

Yes.

Thanks sir!

 

[RustyRatRod]

There's nothing wrong with green bearings or tapered bearings. Both have been used in the industry for decades. If one was better or more durable than the other, we'd see huge failure rates of the other. We don't because it doesn't happen. Ford used green bearings in their rear axles in tens of millions of Ford trucks from the late 50s through the 90s and a little beyond. I'm not sure they're still not using them in some cases. Also, every single hub bearing ever made is an enclosed green bearing. Our 04 Ford Escape has 202,000 miles on it and still has the original wheel bearings. Green bearings. Run whatever you're comfortable with.

 

[halfafish]

I'm guessing all of those 3.23 and higher gears were oem Mopar, and not available new anymore. Last time I looked for a 741 gearset, all that was available was 3.55, 3.73, and 3.91. and I'm not sure about the 3.91.

I have a 741 with a cone SG and 3.91 gears. It's going in the wagon very soon.

 

[crackedback]

Thanks everyone, i appreciate it! So when i first bought this 741 with 3.23 that i am currently using, it was originally an open diff. I bought the clutch style sure grip unit and installed it in the center to make it positive traction. If im remembering correctly it was pretty easy. Let me ask, if i were to find a 742 or 489 center section that is open, can i install the clutch sure grip from my 741 case into it or will it not work because the case number is different?

Waste of money on the case swap. That strength bullshit again... LOL it's not the pinion size that is important or the weak point.

If you were to swap it over, swap the ring gear, take the complete unit with bearings and races and swap into other units, set backlash. Outer races are same diameter for 741/742/489. The bearings differ on ID for a clutch or cone SG unit .

 

[mopower440]

so if i do just a gear swap on my 741 case, does the pinion bearing have to be pressed on/off or no?

 

[1WildRT]

so if i do just a gear swap on my 741 case, does the pinion bearing have to be pressed on/off or no?

yes

 

[RustyRatRod]

so if i do just a gear swap on my 741 case, does the pinion bearing have to be pressed on/off or no?

A decent press is pretty cheap. If you do work on your own car, you really should have one.

 

[mopower440]

A decent press is pretty cheap. If you do work on your own car, you really should have one.

I have access to one at work, just was unsure of if it was needed. I need to find a video on the 8 3/4 gear swap.

 

[RustyRatRod]

I have access to one at work, just was unsure of if it was needed. I need to find a video on the 8 3/4 gear swap.

Yeah, you'll need one. You'll also need the pinion distance checking tool.

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