Check my gear pattern :)

[superhondaz50]

These look good? Need a seasoned builder to give me a thumbs up, it's been about 10yrs since I rebuilt a rear. Backlash is at .007, .040 shims on pinion, 3.73 fat gear in a 3 series. Thanks.
Drive:


Coast:

[superhondaz50]

Anybody?

[Hotcorner]

Never built a rear end, but I understand it to require some major skills. Which rear end?

[superhondaz50]

12 bolt

[Wrenchbender Ret]

It looks a little too deep. Try moving the ring gear away from the pinion a little & retest.
George

[6T7 C10]

For whatever it is worth I did my first GM 12 bolt truck this summer and changed all the bearings, seals, ring 3.73, pinion, and added a Truetrac. So far it has been silent, running cool, and everything works so far. I think it looks just slightly too deep as well. Your backlash measurement is very good but when you change any of the shims on the carrier or pinion it all goes back out the window to try again. I had to fit and refit mine many times to get it the best I could in all directions with the shim set I had. I don't remember using so much on the pinion. I recall mine was around .026-.028 but each one is an individual and yours will vary. I admire your efforts, best of luck to you and you are getting close.

[88fordf150]

Maybe a little deep but not too bad in my opinion.

[superhondaz50]

Ok cool, too deep as the markings are darker towards the bottom correct? Shim in it is at .042, the next size down I could make was .040 which moved the marking alot closer to the top if that makes sense. Will I have a catastrophic failure running it as is?

[superhondaz50]

Here it is with .002 thinner shim

[6T7 C10]

My no answer answer. Hard to tell by pictures alone but you are very close. If it is too close it will run hot and bind.

Is this a gear ratio change or not? If it is the same ratio then the original shim thickness on the carrier and pinion is a good place to start as a baseline but rarely do they every end up being exactly the same when finished. Use as many shims as you can on the carrier sides using a gentle tap of a hammer to get them in. When using your marking paint make sure to give the carrier some resistance when turning. Also with it all assembled when you spin the pinion/driveshaft yoke by hand the resistance should be even and smooth to the feel through the full rotation of the ring gear. If there are any tight spots or something does not sound right I would then go with a thinner pinion shim but then your backlash will probably grow but if it stays under .010 you are good.

[6T7 C10]

Yes, I like that much better in my opinion.

[superhondaz50]

I think I'm on it with these, they have a more football shape on the bottom. Backlash was still at .007.

[superhondaz50]

Yes, gear change from 3.08 to 3.73

[superhondaz50]

So would y'all say I'm good to go? Gonna install the bearings and button it up today.

[OBS454]

Um, pinion still looks a little deep into the ring .....

[superhondaz50]

Originally Posted by OBS454

Um, pinion still looks a little deep into the ring .....

What part of the markings show that? I'm still re-learning this haha

[superhondaz50]

So I was looking at this PDF, under face hobbing I can see the the pattern for coast, decrease shim, looks similar to mine, although my pattern is more centered. My drive side I think looks ok correct? Am I like .001-.002 off? I also see for the correct pattern, it says my coast pattern can be closer to the toe, what y'all think?

[OBS454]

Originally Posted by superhondaz50

Here it is with .002 thinner shim

In the second pic the contact pattern is still too far "in" the pattern should be more centered on the face of the gear tooth. Like someone mentioned before, be sure to apply pressure in the opposite direction of the force you are applying to get your pattern.

[superhondaz50]

Originally Posted by OBS454

In the second pic the contact pattern is still too far "in" the pattern should be more centered on the face of the gear tooth. Like someone mentioned before, be sure to apply pressure in the opposite direction of the force you are applying to get your pattern.

Sounds good, I clamp a 2x4 to the pinion and use wrench on the carrier to get good leverage on the two. You think about .002 off the shim stack should get me closer or go thinner?

[OBS454]

That might be enough - you're really close. Make sure to abide by your manual specs on lash. Be particular because you don't want a rear end lockup - especially if your girl or a younger person is driving and doesn't heed the warning signs of differential problems

Don't mean to insult but the crush sleeve is very important and changing the shim(s) a lot can damage the tension qualities of the sleeve. Be careful with that.

[superhondaz50]

Originally Posted by OBS454

That might be enough - you're really close. Make sure to abide by your manual specs on lash. Be particular because you don't want a rear end lockup - especially if your girl or a younger person is driving and doesn't heed the warning signs of differential problems

Don't mean to insult but the crush sleeve is very important and changing the shim(s) a lot can damage the tension qualities of the sleeve. Be careful with that.

Excellent thanks, it's getting a new sleeve and nut for final assembly. This truck needs to be super safe and reliable since it'll be carrying my wife and son on long trips.

[superhondaz50]

Ok, got two shim packs built, current was a .039, I have a .037, and .035. hopefully .037 does it, hopefully backlash will still be good. I'll find out Friday.

[superhondaz50]

Ok, new pattern fellers, started with .037, then .035, no good, my shims would only allow for the next size down, .034 or .032.

I was thinking using .034, put went with .032 instead.

Backlash is .009

Here it is with .032, please give me some good news!

[A1971Blazer]

Originally Posted by superhondaz50

Ok, new pattern fellers, started with .037, then .035, no good, my shims would only allow for the next size down, .034 or .032.

I was thinking using .034, put went with .032 instead.

Backlash is .009

Here it is with .032, please give me some good news!

That pattern will run just fine....just make sure the backlash is in tolerance..

[superhondaz50]

Originally Posted by A1971Blazer

That pattern will run just fine....just make sure the backlash is in tolerance..

Got backlash at .009, spec is .006-.10 so on the higher end but in range, I'll measure shims and see if I can get it to .007 or .008