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8-3/4 Conversion Open to Sure Grip (how to) & Questions

Danny Boy

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Thanks in advance for your comments as I'm trying to get educated before plunging into working on my 8 3/4

1. In process of converting 741 from open to Sure Grip.

Will be keeping same 323 gears and only want to convert to Sure Grip.

What is required to perform this conversion besides purchasing the Sure Grip and it's bearings?

Hopefully it's a DYI and won't required many tools/effort necessary as when changing ring & pinion

2. Here's a link from Cass at Dr. Diff regarding ring/pinion install
https://www.pirate4x4.com/d1/tech/b...Ring and Pinion installation instructions.pdf

3. Also, saw this on Ebay and have a question regarding the mesh pattern.

Maybe I'm not seeing correctly but it appears that there is no mesh pattern - looks like face of tooth has been wiped clean. Please help me as I don't get it...

Is this an acceptable pattern? (or lack of)

s-l1600-jpg.jpg
 
I just swapped from a 742 open to a 489 cone type and had the ring and pinion set up by a professional.
If you're using the same 741 carrier and adding to that you will need the tools to set up pinion depth and then get the pattern correct on the ring gear. Takes a bit of know how to get it all correct. RUFFCUT
 
You’ll need:
Spanner wrench
Dial indicator mounted on a magnetic base
Large bench vice is helpful
Bearing press
Gear pattern marking grease
Copious amounts of patience and a few cold beers.

luckily you won’t need to r&r the pinion, which is the most involved aspect of setting one up. In a nutshell it should go something like this:
Measure your backlash as it is now with the dial indicator set up in multiple spots, making note of what you find (should be somewhere in the .007-.010 range); Mark the main-caps for location (L & R). Mark the appropriate positions of the adjuster-discs; Remove the carrier with the ring gear and remove the ring gear; swap the ring gear onto the new sure-grip carrier with new bearings pressed on (heating the gear from the backside with a butane torch and gentle persuasion with a rubber mallet are often helpful here); place the races onto the new bearings, and gently lay it into the case, mating the ring gear and pinion; replace the caps in the correct locations, start the bolts but leave them loose.; place the adjuster discs back into the case on either side of the carrier, and tighten the bolts enough now only to hold it all together.; place the mag-base with dial indicator back on the case in the same location you had it prior. Now start the tedious process of moving the carrier with the adjuster discs in attempt to find the same backlash you had prior (this process cannot be described, it has to be experienced.... be patient!). Once you think you have the right backlash, apply the pattern grease and check your pattern. Since you didn’t move the pinion, It should be mighty close to correct as long as your backlash is back to where it was. Normally, this is adjust, check, adjust, check, adjust.... and so on for the better part of 2 or 3 beers. Once you think you have it, post a picture of the pattern and get ready to do it all over again. You’ll eventually get there. Torque the caps down and install the adjuster locks, and you’re ready to install.
I think that’ll be pretty close to the process. I probably completely forgot something, but I’ve set up more than a few... I think I’m close.

ps: the pattern in the picture isn’t real clear. I wouldn’t look at that.
 
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You’ll need:
Spanner wrench
Dial indicator mounted on a magnetic base
Large bench vice is helpful
Bearing press
Gear pattern marking grease

luckily you won’t need to r&r the pinion, which is the most involved aspect of setting one up. In a nutshell it should go something like this:
Measure your backlash as it is now with the dial indicator set up in multiple spots, making note of what you find (should be somewhere in the .007-.010 range); Mark the main-caps for location (L & R). Mark the appropriate positions of the adjuster-discs; Remove the carrier with the ring gear and remove the ring gear; swap the ring gear onto the new sure-grip carrier with new bearings pressed on (heating the gear from the backside with a butane torch and gentle persuasion with a rubber mallet are often helpful here); place the races onto the new bearings, and gently lay it into the case, mating the ring gear and pinion; replace the caps in the correct locations, start the bolts but leave them loose.; place the adjuster discs back into the case on either side of the carrier, and tighten the bolts enough now only to hold it all together.; place the mag-base with dial indicator back on the case in the same location you had it prior. Now start the tedious process of moving the carrier with the adjuster discs in attempt to find the same backlash you had prior (this process cannot be described, it has to be experienced.... be patient!). Once you think you have the right backlash, apply the pattern grease and check your pattern. Since you didn’t move the pinion, It should be mighty close to correct as long as your backlash is back to where it was. Normally, this is adjust, check, adjust, check, adjust.... and so on for the better part of 2 or 3 beers. Once you think you have it, post a picture of the pattern and get ready to do it all over again. You’ll eventually get there. Torque the caps done and you’re ready to install.
I think that’ll be pretty close to the process. I probably completely forgot something, but I’ve set up more than a few... I think I’m close.

ps: the pattern in the picture isn’t real clear. I wouldn’t look at that.
One Thing, Before You put the ring gear on Plop the sure Grip in the case with bearing installed and measure the Flange runout. I think 1 maybe 2 Thou will be good. Other than that send it back.
 
People still run sure grips? I've been building my diffs with Detroit tru-tracs and will never spend money on a clutch differential again! No clutches to wear, no additives needed, lays 2 black lines and is quiet on turns!
Sorry just had to..... I have nothing against clutch units, just taking smack.
Have fun with the swap, it's pretty easy. Measure backlash on old setup before you teardown and match that with the new unit. Your gears already have a pattern worn into them, you'll want it back the exact way it is now!
 
Lemon Wedge -

Thanks very much for your instruction. You've been the only one to have explained it. The only guidance I'vppe received to date is for rebuilding the entire diff including re-setting the pinon - ugh
I knew it had to be simpler and you explanation is exactly what I needed
Really appreciate the time you took work up these instructions.

Also 65-440
People still run sure grips? I've been building my diffs with Detroit tru-tracs and will never spend money on a clutch differential again! No clutches to wear, no additives needed, lays 2 black lines and is quiet on turns!
f"
Thanks for your input. Very informative...

A top priority for me is what you've experienced: quiet and no additives.

Hadn't heard about Detroit tru-tracks will check them out

I used the term sure-grip generically to denote Mopar as opposed to the dreaded "posi-grip" used by non-mopar types.

I'll look into the Detroit

The differential I've been considering is the Dr Diff Sure trac II, which is quite pricey starting at $545.

https://www.doctordiff.com/8-3-4-helical-gear-sure-grip-sure-trac.html

Danny
 
Lemon Wedge -

Thanks very much for your instruction. You've been the only one to have explained it. The only guidance I'vppe received to date is for rebuilding the entire diff including re-setting the pinon - ugh
I knew it had to be simpler and you explanation is exactly what I needed
Really appreciate the time you took work up these instructions.

Also 65-440

f"
Thanks for your input. Very informative...

A top priority for me is what you've experienced: quiet and no additives.

Hadn't heard about Detroit tru-tracks will check them out

I used the term sure-grip generically to denote Mopar as opposed to the dreaded "posi-grip" used by non-mopar types.

I'll look into the Detroit

The differential I've been considering is the Dr Diff Sure trac II, which is quite pricey starting at $545.

https://www.doctordiff.com/8-3-4-helical-gear-sure-grip-sure-trac.html

Danny
The true tracs are in that same area....Cass at Dr
Diff is a good dude. I ordered I sure grip from him a few years back and had nothing but trouble with it. Once warmed up it chattered really bad in tight turns. After a few back and forths and new clutches it still did it. He took it back and I bought a true trac from him. I've already ran those on my jeeps and others cars, I love them. Torsen style helicut gears.
 
From Dr Diff, "Due to inconsistent quality issues, I no longer carry the 8.75" True Trac. Please consider the 6 helical gear Sure-Trac"
 
From Dr Diff, "Due to inconsistent quality issues, I no longer carry the 8.75" True Trac. Please consider the 6 helical gear Sure-Trac"
Interesting, I'm running 3 right now that work flawlessly. Wonder what people had issues with that returned them to him.
Did a quick internet search and came up with nothing, nothing at all....at least not when abused and nothing recently. Regardless of why Cass decided to stop selling them, I still highly recommend them.
 
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Last one I built had an Eaton True Trac, it was abused whole summer with slicks and 782Horses, 489 Nodular house.
 
Thanks in advance for your comments as I'm trying to get educated before plunging into working on my 8 3/4

1. In process of converting 741 from open to Sure Grip.

Will be keeping same 323 gears and only want to convert to Sure Grip.

What is required to perform this conversion besides purchasing the Sure Grip and it's bearings?

Hopefully it's a DYI and won't required many tools/effort necessary as when changing ring & pinion

2. Here's a link from Cass at Dr. Diff regarding ring/pinion install
https://www.pirate4x4.com/d1/tech/billavista/PDFs/Yukon Gear Ring and Pinion installation instructions.pdf

3. Also, saw this on Ebay and have a question regarding the mesh pattern.

Maybe I'm not seeing correctly but it appears that there is no mesh pattern - looks like face of tooth has been wiped clean. Please help me as I don't get it...

Is this an acceptable pattern? (or lack of)

View attachment 1064863
 
Next winter he invested in a Dana 60 but yes hold together a whole summer of abuse, I told him no slicks and no spray but he didn't listen to that.
 
It sounds like you're only adding a sure grip so you don't have to do anything with the pinion as long as your wear pattern looks good, the unit runs quiet and the bearings look to be in good shape. Of course you won't be sure the pinion bearings are in good shape unless you spin the pinion nut off and take the pinion out to do a visual on them. The side bearings being in good condition has no bearing on whether the pinion bearings are in good shape and really they should be looked at.
Without the pinion bearing inspection it is as simple as removing the open diff, swapping the ring gear onto the suregrip, install the side bearings on the suregrip and install it into the carrier. Then you set your backlash (pretty simple but a service manual is handy) and then runout.
You will need a dial indicator and 1 or 2 torque wrenches depending on if you pull the pinion gear out or not.
 
If using same case and gears and the ring & pinion are originally set up right, and your not removing the pinion to just change carriers...
Just measure the original ring back lash and record it. Swap ring gear to new carrier, and replace with the same backlash adjustment.
 
I won money in a class action lawsuit last year and rebuilt my 8-3/4. My charger originally has a 742 sure grip with 3.23 gears. I rebuilt the 742 pumpkin ball and installed Yukon 4.11 gears. I did everything myself with harbor freight hand tools and it took a few months and 50+ attempts to set the gear mesh. Came out perfect, but I might swap it for a Dana if I get serious racing it on weekends.
 
Thanks in advance for your comments as I'm trying to get educated before plunging into working on my 8 3/4

1. In process of converting 741 from open to Sure Grip.

Will be keeping same 323 gears and only want to convert to Sure Grip.

What is required to perform this conversion besides purchasing the Sure Grip and it's bearings?

Hopefully it's a DYI and won't required many tools/effort necessary as when changing ring & pinion

2. Here's a link from Cass at Dr. Diff regarding ring/pinion install
https://www.pirate4x4.com/d1/tech/billavista/PDFs/Yukon Gear Ring and Pinion installation instructions.pdf

3. Also, saw this on Ebay and have a question regarding the mesh pattern.

Maybe I'm not seeing correctly but it appears that there is no mesh pattern - looks like face of tooth has been wiped clean. Please help me as I don't get it...

Is this an acceptable pattern? (or lack of)

View attachment 1064863
How far are you from me in Deming? I might be able to give you a hand if not to far.
 
Thanks Runcharger and 451 Mopar!

Wagonman, I live next door in Las Cruces and will contact you regarding your assistance.
I would definitely love to learn how to do this!

Best regard to all in FBBO for assisting!
 
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