8 3/4 open to sure-grip swap

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60Powerwagon

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I’ve looked around, but haven’t found exactly what I’m looking for. I have a 8 3/4 open in my duster and just purchased a sure-grip unit to install. What all do I need and need to do to install it? I’ll be honest, I don’t have much experience with differentials. I can rebuild a engine, but changing diff oil is about as far as I’ve gotten so far. Any help is appreciated.
 
60Powerwagon said:
I’ve looked around, but haven’t found exactly what I’m looking for. I have a 8 3/4 open in my duster and just purchased a sure-grip unit to install. What all do I need and need to do to install it? I’ll be honest, I don’t have much experience with differentials. I can rebuild a engine, but changing diff oil is about as far as I’ve gotten so far. Any help is appreciated.
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1st make a stand or an adapter to mount the 3rd member on an engine stand, makes life a whole lot easier. Taking it apart is easy, bolting it up to the ring gear is easy, ***remember ring gear bolts are left hand thread.*** Getting the proper lash, can be the challenge. There are several videos on the "tube" showing how it is done. The service manual for your model will cover the set up.
Norm
 
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circlepilot said:
1st make a stand or an adapter to mount the 3rd member on an engine stand, makes life a whole lot easier.
Click to expand...
^^^^ This or a bracket bolted to the top 2 flange bolt holes and mount it in a vise.
Next is a dial indicator.Take the indicator reading before disassembly. Usually .008 backlash minimum.
You will find that a sure grip and the open take different side bearings.
There are many different ways to get side bearing preload. One is to adjust the side bearings to zero backlash,Then tighten the side bearing to push the ring gear away from the pinion achieving desired backlash..
A Factory service manual is your best friend.
 
Service manual and dial indicator have been ordered. Hopefully I’ll be able to get it done this weekend along with finishing the engine.
 
Mark both of the bearing caps prior to disassembly, so you know how to put them back in the correct spot when re assembling the diff.
 
my68barracuda said:
Mark both of the bearing caps prior to disassembly, so you know how to put them back in the correct spot when re assembling the diff.
Click to expand...
I've not found that to be very critical through the years, but I STILL do it regardless.
 
All great info. I just did my first one 3 months ago. Measured backlash...think it was 8. Marked the caps. Disassembled, removed ring gear. Sur-Grip carrier didn't have carrier bearings so I Installed bearings, then installed ring gear. I used a dab of red lock tite on the ring gear bolts. Installed carrier into chunk. Put the caps on with the bolts finger tight. Then spin on the adjusters. Cass (Doctor Diff) says to tighten as much as possible by hand with a spanner wrench. I bought the one he sells. I found myself going back and forth tightening caps and adjusting adjusters until backlash was perfect when caps were torqued. Install chunk, axles, brakes and you're done!

Don't forget friction modifier for the gear oil.
 
Thanks gentlemen. I’m more of a do it yourself kind of guy so I’ll take some scrap and a couple bolts and make my own spanner for $1 instead of $35, but other than that it seems pretty straight forward.
 
66fyssh said:
All great info. I just did my first one 3 months ago. Measured backlash...think it was 8. Marked the caps. Disassembled, removed ring gear. Sur-Grip carrier didn't have carrier bearings so I Installed bearings, then installed ring gear. I used a dab of red lock tite on the ring gear bolts. Installed carrier into chunk. Put the caps on with the bolts finger tight. Then spin on the adjusters. Cass (Doctor Diff) says to tighten as much as possible by hand with a spanner wrench. I bought the one he sells. I found myself going back and forth tightening caps and adjusting adjusters until backlash was perfect when caps were torqued. Install chunk, axles, brakes and you're done!

Don't forget friction modifier for the gear oil.
Click to expand...
Can you add more detail to the statement about tightening the adjusters as much ‘as possible’.
Thanks.
 
my68barracuda said:
Can you add more detail to the statement about tightening the adjusters as much ‘as possible’.
Thanks.
Click to expand...

I'll look for the info Cass gave. Not as much as possible, but as tight as you can by hand with the spanner wrench. It worked for me...been over 90 mph a number of times since and no whine.
 
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Here's one.

DoctorDiff said:
Your pinion is too close. I would decrease the shim thickness 0.005" and re-check the pattern.

Get the spanner nuts as tight as possible with a 12" wrench when the cap bolts are finger tight. After adjusting back-lash to 0.008", torque the cap bolts to 90 ft lbs.

[ame]RANDYS Worldwide | One Stop Differential & Drivetrain Shop

Note, the shape of the pattern is more important than where it lands on the gear tooth. You want a wide, wispy pattern that does not curve inward toward the peak or valley of the tooth. It must be centered between the peak and valley, but not necessarily between the inside and outside diameter of the ring gear.
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Which housing do you have?
 
agree with measure backlash before disassembly.

Reassemble and try to hit that number again.
 
I always just use a brass punch and a hammer and gently tap the adjusters until they're seated good and will tighten no further. I recommended the spanner wrench, because that's really the "correct" way, but my way works "for me". Has for almost forty years.
 
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