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Gear Pattern check - Chry 8.25

zthang43

NAXJA Forum User
Location
WA state
It's a 29 spline Chrysler 8.25; I'm installing 4.56 gears. I tried a couple different patterns, looking for some opinions from those of you who know more than I do.

The first try (which seemed to give the best pattern) was with the original .028" pinion shim, and .007" backlash:

Img_2947a.jpg


Img_2948a.jpg


Img_2950a.jpg


Img_2952a.jpg


I thought this pattern looked just barely too deep on the pinion for both coast and drive sides, so I moved the pinion out a little for the second try.
I used a .024" pinion shim, and .006" backlash:

Img_2960a.jpg


Img_2958a.jpg


Img_2956a.jpg


Img_2954a.jpg


On this pattern, it looked like the pinion was too shallow on the drive side, but still deep on the coast side. The coast side is also biased towards the toe in both cases.

My pinion shims are .008, .010, .012, .012, .021, and the original .028, so I can't get between .024 and .028 without getting some new shims. Any opinions?
BTW these are Superior gears from Rusty's.
Oh, and I'm using setup bearings on the pinion so I will have to reset the backlash when I put the good bearings in.
 
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On you second try the pinion is too far out and you can see the half moon shape on the face of the gear on the drive side. Adjust it further in just a bit. The heel to toe pattern isn't that crucial that it is centered and sometimes impossible to obtain anyway.
 
Try your first pattern and loosen up the BL by .002". can't hurt cuz it takes all of what? 2 seconds? don't forget to enjoy another bottle of that Hornsby Draft Cider...
 
Thanks Rawbrown.
That's what I ended up doing. (.028" pinion shim, .008 BL). It still looks like the pinion is just a hair deep to me, but I'm probably just being picky.

When I installed the pinion for final assembly, I torqued the pinion nut down just barely too much, so the torque to rotate the pinion is 18-19 in-lbs to get it started, and right at 15 to keep in rotating. The yukon instructions I have say pinion torque should be at 12-15 in-lbs. Am I OK, or do I need to take it apart and put in a new crush sleeve?
This is on dry bearings by the way, no oil or grease.
 
Should be ok on the pinion bearing preload. just pay attention to diff temps during break in. the pattern in either pics was so broad that its hard to get a perfect idea of what its doing. Thats a good thing. how smooth does it feel when your turning the ring gear into the pinion?
 
It felt very smooth rotating the ring gear, but a little stiff, especially after I tightened up the backlash adjusters. I assume that's pretty normal on a new setup? No binding whatsoever though.
I went ahead and put the No-Slip in too; I'm planning to get it under the jeep today, so we'll see how it works.
Thanks for your help Rawbrown, it's much appreciated.
 
Just thought I'd post up my results; got the axle under the XJ last night and drove it around a bit.
I'm pretty pleased with it so far. I had a little bit of gear whine when coasting at about 20mph, but that seemed to quiet down as I drove it. No other gear noises other than a little more clunk from the extra backlash the locker causes.
I'm very impressed with the No-Slip locker too. Haven't wheeled it yet of course, but in driving on the roads around my house I can't even tell it's there unless I'm on the gas in a corner. I do have an uphill corner right out of my driveway so I notice it there, but it's a much steeper hill than most roads so it takes a little more power to go up the hill. I can't hear or feel it unlock in a corner. I do feel it lock up when I hit the gas in a corner, but it's not bad. We'll see how it does in the rain soon.
 
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