junior supercar

ok, I think this is starting to wear on me, literally as my fingers hurt from all the measuring and removing and installing. not to mention I had no idea how sharp those teeth are on the gears. my measuring got a little sloppy today also as I tried to tweak the carrier shims for the backlash. prolly shoulda left it alone. but I got it back to .008 backlash. anyway, enough with my sob story

first in an attempt to help everyone, here's some pics of the pinon, showing the two chips that I noticed. the pics are in focus actually. also a few pics of the ring gear. nothing seems out of the ordinary with it, but then again this is the first ring and pinon I examined closely.

100_3854_zpsec8d52b7.jpg

100_3855_zps1781a192.jpg

100_3857_zps61ae4e82.jpg

this one is a little blurry sadly
100_3858_zpsf851f6ec.jpg


and the ring gear

100_3859_zps88343544.jpg

100_3860_zps04086a99.jpg

100_3861_zps38c46cc5.jpg

100_3862_zps92415554.jpg



Now again, for sharing purposes and some education, like for me, here are the carrier shims from the original housing this setup came from. I believe these to be GM shims as they look identical in style to the type of shims I removed from a 70 Olds type O 3.23 open rear.

100_3863_zps1a1ba04b.jpg


and the pinon shim from the housing this setup original came from. I would assume this is a factory GM shim also. ironically when I measure it in several spots, it came up .038 and .039, only one spot was it .040

100_3865_zpsa8019fa9.jpg


Now on to the gear pattern. as mentioned above in this post, backlash is .008. pinon shim is a .030, although it came up .0295 in some spots also

100_3869_zps810b9096.jpg

100_3870_zpsa30c94af.jpg


thoughts on whether I should try a .028/.027? I measured shims already just in case, so I should be able to get that. I probably have one more shot before I run out of marking compound too, fwiw.

Thanks again for all the feedback as this has definitely been a learning experience

Steve g

.030 is still at the bottom of the gear, bottom meaning root to crown. Try .027, but I think the .025 was optimum.

Look at the photo of the 030. That is right in the bottom.
030_zps0269b59f.jpg

Steve g

monzaz

IT IS TOO DEEP. PERIOD. do the .027 button it up and be DONE.

WHEN you get the .027 in play with the backlash from .007-.010. YOU very well may have to set this gear set up on the wide side.009 ish.010

I KNOW what you are going through with the sharp gears I have hamburger hand some days from all the set-up on USED gears. YOU Can dull those top edges and would be a VERY smart process to make the pattern true up . use 180 grit 2" 90 degree air grinder and knock off the sharp edges. DO NOT reform the gear just debur. Jim

monzaz

I feel like ***** Wonka - THE SUSPENSE IS KILLING ME! lol. Jim

junior supercar

lol, thats good

oldstata

Just looking to learn great feed back thanks

Steve g

For the sake of those following along out of interest, this is where where my position comes from.

There is a tendency to want to set patterns looking at the heel to toe position. That works ok on a new gear set because with a new gear set with heel to toe centred, so is the root to crown. But really what should be done is you centre the root to crown, and on a new gear set that centres heel to toe. If you look at this page of acceptable patterns you will see the heel to toe is all over the map. But what is constant in all of the examples is the root to crown.
patterns_zps1edc68c2.jpg
If you go back and find the Richmond gear diagrams, which depicts new gear patterns you will see a couple of examples of acceptable patterns, and at a glance appears to be telling you that there is a bit of leeway when centering heel to toe and that's what you should be doing. But if you look at the root to crown on the examples you will see that they are in exactly the same spot on all of the examples. What they are, in fact, telling you is that once you have your root to crown centred, your heel to toe can fall in any of these areas. The US gear shows a wider range of heel to toe positions in a centred root to crown because that's what happens as the gear wears. The depth stays the same and the pattern moves down the length of the tooth.

Another thing that's not quite right about the procedure used here, but is done all the time, is the backlash. All pattern tests should be done with the backlash set the same. You don't let backlash change alter your pattern and you don't alter your pattern with backlash changes. If you decide it's to be .008 that's where it should be. So you change your pinion shim from 25 to 30 and set that in. Then set your ring gear in and adjust the backlash with the carrier shims to .008. Change your pinion shims to 34, set that in and reset your backlash to .008. This is much easier said than done with a carrier using shims, but on a Ford 9" where you're just spinning the adjusters, that's exactly what you do. But because it's such a pita to adjust backlash with these we tend to live with small changes to backlash with different pinion depths, as long as we are within spec.

Steve g

Edit.

I should have added, the thing about as the gears wear, for a centred root to crown the pattern will move down the length of the tooth, this is where I'm coming from on the .025 setup in post #3. The coast side of that gear is pretty much centred in the root, and with it centred there the heel to toe is pretty close to centre as well. That tells me that side of the gear has very little wear. So if we leave that centred as it is, which has got to be pretty close to the original setuo if not dead on, the drive side pattern will be what it has worn into. That drive side pattern falls well into the acceptable range, Although a little deep and not centred heel to toe. But as the full sheet says, concentrate on the coast side on a used gear set.

507OLDS

Junior,
Your last post shows your pattern with the .0295" shim. Is this the same .0295" shim that you used back at the beginning,pictures 2 & 3? If it is the same thickness of shim,and same backlash,then the pattern should mimmick pictures 2 & 3,but instead,they are completely different.The latest one is too close,but getting better.
Since you are close to achieving the pattern,moving it in small increments,like .002" is good.I know it is time-consuming,but you will get there.
Jim,
You did a great job with your picture-pages.That is what I was trying to clarify with the .025" shim.It is too far away.You have a half-moon on the coast side,and only contact on the heel half of the drive side.
If you work with a lot of the GM gears,and Richmonds,you will deal with the sharp edges,and any type of burr can hinder you from getting the pattern,as it can keep the teeth from contacting.This is also why you want to do 5 or 6 teeth in various areas around the ring gear.
Some of the other gears,like Motive,have a better dressed gear,with more cuts in the machining process.It's like dulling a knife.
As for the illustrations above.I always concentrate on the top two,and have never had a problem achieving those.They are a drawing,and not an actual picture,but it shows you what to look for.I have never wanted or needed to try the lower 4 patterns.You also have to watch some of Richmonds illustrations because some of those are for the Pro-Gears.Different gear for a different purpose.
As for the backlash,the recommendations are .006"-.010". I always put it at .008",new or used.Setting the backlash is the easier half of the set-up.Once you determine the total thickness of shims needed to get the proper bearing preload,then you just split them.For example,Let's say your total shims is .484".You can take away from one side,and add to the other,to achive the backlash,and yet still have the correct preload.If you started with .250" on the right,and .234" on the left,and the backlash was too big,then take away .004" from the right side,and add it to the left.Your backlash will move about .007" for every .010" of shim,so it is not 1 to 1.
Mic ALL of your shims,regardless if they are stamped or not.Those GM shims might have been accurate when they were made,but usually end up thinner after having the bearing pressed on for 45 years.The new shims will sometimes have the thickness etched in them,but I mic them anyway.Otherwise you might end up scratching your head,wondering why something is not working,when it should.
So,you have crept down to .0295" shim,and it's still too deep,and the .025" is too far away.The .027" should do it. This also goes to show how every .001" can make a difference,so don't just guess & call it good.Take the time and get it right.I know you will get to try it yourself,so you could correct it later if needed,but for me,I send these all over the planet,so they have to be right the first time.I just shipped another one over the water.Do you think I would want to ship that back to correct it?No.
I will actually be doing a rear rear like you are working on shortly.I removed a 4-pinion posi,and original 3:90's,from a 69 GTO 8.2" 10-bolt houisng,that was heavily pitted,and not worth restoring,but the internals are absolutely mint.I have since found a correct housing,and will be doing the transplant when time permits.I'll nail it for sure.It can be more time-consuming than installing new gears,but the result will be the same.

junior supercar

I missed this in my reply last night, but the php software was nice enough to ***** out the, um, slang term ***** for those people who aren't logged into the board. a little excessive, but hey


Thanks for all the info guys. it's making some sense and I have a greater understanding and appreciation of the people who do this on a regular basis.

I'll set up the .027 and report back. stayed tuned

junior supercar

almost positive no, it's not the same .0295 tried before. Plus, the carrier shims are different from looking at my notes. not much, but enough to obviously change the pattern.

I got a stack of shims (both carrier and pinon) in the Yukon gear kit from Randy's Ring and Pinon. None of them are marked, so like you said, I mic them all. Then put some together to get the thickness I need. I was thinking/debating, perhaps I should mark them with a sharpee marker so I don't have to keep re-measuring them. but I obviously haven't figured that out yet.

junior supercar

.008 backlash and the .027 shim

100_3871_zpsae2cae9c.jpg

100_3872_zps07513ee5.jpg

Steve g

I still like the .025. Coast side on either is okay, altho the 25 is closer to centre heel to toe. But look at the drive side on your 27. It's right down in the bottom of the tooth. it's practically removed all the marking from the bottom. The 25 leaves only slightly less distance between the bottom and the pattern and the top and the pattern. Runs further to the heel, but that's far better than running into the bottom.

From Westcoast Differentials

"Pinion depth is indicated by the position of the pattern between the face and flank of the ring gear teeth. Backlash must be kept within specifications, and will therefore only slightly affect the pattern between the heel and toe of the ring gear teeth. Housing alignment and pinion bearing bore alignment can also affect the pattern from heel to toe and can not be corrected without machine work. In some cases an ideal heel to toe pattern can not be achieved. If the backlash is within specifications, you may disregard the heel to toe pattern. A contact pattern that is centered from face to flank always indicates correct pinion depth even if a pattern that is centered from heel to toe can not be obtained."

Facing and flank are root and crown. The differing opinions here seem to stem from where one places the importance, centre root to crown or centre heel to toe. I was taught root to crown if job 1.

Steve g

507OLDS

The .027 is the better pattern than the .025. There is more contact on the drive side,which look a lot like the shiny area of a clean tooth,where the pattern was riding before.Just remember,it will change slightly with the load of the car.
The coast side also has a wider/longer contact,without the straight line at the top.
Stick a fork in it.

Run to Rund

It is your diff; if it was mine, I would say the drive side is too far to the heel and would try at least .032 to .035 or so would be better to see what happens.

507OLDS

He did do a .032" and a .034" on the previous page.

Steve g

Am I the only one seeing that drive side pattern sitting in the root of that gear? There isn't an example pattern I've ever seen that wants the pattern running off the top or into the bottom.

The 025 keeps it out of the bottom and only moves it slightly to the end, but not running off. The coast side almost perfectly centred in all directions with a nice long pattern. And in keeping with objective of centring top to bottom not end to end, the 025 is the closest on both sides.

.027 may not whine, but it's certainly not the best best example of a gear set centred root to crown.

Steve g

monzaz

The sharp edge on the drive side is most likely from the PINION sharp edge as you BRIAN stated...It is just one of the things that experience only can conquer. On the used gears and even NEW I deburr the peak 90 degree edges to quiet and make sure there are no burrs leading into the pattern as again Brian stated in a previous post. Try that on the pinion and ring and see the pattern. I would run the .027 BUT also deburr those peak gear teeth. I bet it will help a lot on the pattern after it is completed. Jim

Steve g

We're going to have to agree to disagree on this one.

I'm not totally without experience, having held an InterProvincial Journeyman's ticket since the mid 70's. Now I don't do diffs solely, but I've done enough of them over those years to qualify as experienced. But forget that. This is the internet and anyone can be anything they want. So I Googled setups and posted supporting documents. Will someone show me an acceptable pattern that runs into the root of the tooth?

Yes, you can take your grinder and remove the part that's troublesome, but moving that coast side pattern back to the centre lifts that drive side out of the bottom and leaves you with a nice contact pattern that fits in the acceptable patterns range.

Where we seem to differ on our approach is in what takes priority, heel to toe or root to crown. I was taught root to crown and posted two different sources supporting that.

My take in summary, on a used gear set, focus on the coast side. Centre top to bottom. A new or little worn gear set of reasonable quality will centre heel to tow once top to bottom is centred. Look at your drive side. Centred top to bottom? Heel to toe not off the map? Good to go.

But, we live in a democracy .

Steve g

Edit. The burr on the bottom didn't increase the space above the pattern.

Run to Rund

OK. I like the .034" best, and fiddle with backlash a little from .006 to .010". Note that the backlash will probably vary as you turn the ring gear and measure not just every 90 degrees but through more than one revolution as different pinion teeth mesh with a given ring gear tooth each revolution of the ring gear.

The drive side should not run off the heel end or the toe end, and be biased some to the toe under such light load.

Steve g

Copied and pasted from West Coast Differentials, who probably have more experience in this than all of us collectively times 10.

"If the backlash is within specifications, you may disregard the heel to toe pattern. A contact pattern that is centered from face to flank always indicates correct pinion depth even if a pattern that is centered from heel to toe can not be obtained."

Face to flank = root to crown. See their diagram.

Steve g

507OLDS

I've heard the whole "I have more experience than you" spiel before,and I am not directing this to you Steve,West Coast,or anyone else.Sure,there were people that were doing this before I was born,but I can safely and confidently say that I know what I am doing.I stopped counting the number,when there was a comma in it.I have also fixed some diffs that came from what were supposed to be reputable shops.That doesn't make me Jesus Christ,just experienced.There was a full-blown diff shop here,that did everything around for a good 30yrs,but I also found myself fixing some of their diffs,and now the co-owner now works at AutoZone.I have worked on cars since age 3,and I am extremely mechanically inclined,and have an degree in mechanical engineering.Again,not a big deal,but I know what I am doing.The reason I started doing these in the first place was when I had one of my that needed gears.I took it to the so-called expert,where he finally gave up after a week,and could not get it to stop howling on the coast.I then decided to do it myself,as I have done for everything else on this planet.I ordered the tools,with a great 2-hr video,from a place in Texas.The video could teach a monkey how to do it.Upon my my first try at this axle repair,which was an 8.8" Ford,I had it figured out in less than 2hrs.Still running fine 17 years later.I then began building rears for the rest of my cars,then friends,then people around town,then strangers that knew people,then word got out around the Internet,and the next thing I was shipping them all over the planet.I have seen a lot and done a lot.This is all something I do on the side,and it has been great,but my free time has become very limited,and there are other things that I need to do.Someone like Jim does this as a job,when he starts his day.I don't do 60+ a year,like I did,but I still know how to get it done.No,I am not an old man,I am only 37,with plenty of other things to do,but I can look at any pattern,new or used,and determine what to do with THAT particular gearset.It comes with the experience you learn along the way.Something a book,video,or random genius can't teach you.
I think the .027 shim will give you the best all around pattern,quiet and drive anywhere.If it was going behind huge power,and beat the **** out if it,I would put the .032" or .034" in it,to get as much strength out of it.You are flirting with the possibility of making noise,and they are used gears,so I would rather not.
Enjoy your day gentlemen.

Steve g

Just so we don't get off on the wrong foot here, or offend anyone, I did not claim to have anymore experience than anyone else here. My comment about my background comes on the heel (excuse the pun) of Jim's comment about some things only experience can conquor. The intent was simply to let you know I'm not a 12 yr old troll on my Mom's puter who's only experience was what he'd read on the internet.

My opinion is based on what I was taught in trade school, almost 40 years ago (when you could only view a video in a movie theatre ) and what I picked up since then. I admit that I am a by the book guy and have no experience with ultra high performance drag racing setups. However, the L88's and Hemi's back in the day ran the same setup as the diff just under it in the stack that was going in a 396 or a 440. And the factory service manuals don't differentiate between the two when describing setup of the diff, where they do make distinctions in other areas. Although my ticket and most of my experience was in the automotive side, I now deal with components in ag applications that see as much or more torque thrown at them through the wonders of deep gear reductions in frt of (behind) them. I have a frt diff from a MF 3545 on my stand as we speak. The principles are the same. And I know what has always worked for me and what has worked for me is consistent with what's in the books and published by the manufacturers. Just so no one is faced with wondering whether to trust the word of an anonymous name on the internet, I backed up my convictions with supporting documents. Search as I might I can not find a setup that shows a tooth running into the root or off the crown in the acceptable patterns, but I can find lots where it runs off the heel or toe.

At the end of the day I respect your right to your opinion. I've voiced mine and gave my reasons and supporting docs. I stand squarely behind the .025 setting being superior to that of the .027. Hopefully no hard feelings anywhere.

Steve g

507OLDS

None here.

monzaz

Only person that really can make the decision here is the man with the ring and pinion set. I think we have MORE than given all the best answers and reason why we think what we think. HE will just have to make a decision and go for it.

I STILL think after looking at the pinion you need to deburr that pinion gear so you are reading the gear true and not a sharp edge at the peak...WHICH is what I really believe is happening in the .027 shim. You deburr it the gear face will engage better and BAM... nice pattern too. Jim

Steve g

Based on the amount of real estate untouched above the pattern I tend to think the pattern isn't too wide (burr marking), just moved down.
The 025 does show a pretty wide (top to bottom) pattern, but it is moved up the tooth into that area that's unused in the other patterns and is not even close to running off the top.

I'm presuming what you don't like about the .025 is the heel to toe on the drive side? Curious as to why you guys feel it better to sink the tooth off the bottom than move it towards the end?

Steve g

junior supercar

yep. lots of great feedback. My intent in this thread was a person who has never done this before to post his results and get the feedback from people with more experience who have done this before. In addition it seemed to have provided information for those that have little or no experience with setting up a ring and pinon with (what I hope) is some good info should they decide to tackle this themselves. I know I have certainly learned things and if/when I decide to tackle the Type O 588 carrier rebuild/reshim and then installing the 4.66 ring and pinon (I got this loose, so no pattern what so ever to go by) into the 70 Type O 3.23 open housing I have, I feel I can do it. Or at least start it. Then obviously post my progress here and again ask for advice.


Jim, thanks for the pic with details on deburring the edges. That was going to be a next question. It's just a debur, not a reshaping of the teeth.

junior supercar

well, I got the pinon deburred. now starting on the final assembly and having a hell of a time trying to get the pinon nut to crush the sleeve. I should be able to just spin the pinon nut on by hand until it contacts the washer and then I start tightening until I get the bearing preload, right?

monzaz

That is a small crush sleeve....lol. you should try Chevy 12 bolt or chevy 10 bolt 8.2...

I use the air gun till I get close... Just have to work through it. Are you using a NEW nut? If so be sure it is the correct one chevy and BOP use DIFFERENT pinion nut thread count so that will make it nearly impossible by hand.

you can show pictures of it also . Use the OLD nut and some oil to start the crush to the point where there is almost no in out movement...then use the new nut after removing the old nut. That might help too. Jim

oddball

The pinion nuts I've been getting in kits have one or two crimps in them, so they will not spin on. Should hold better in case you forget the locktite, too.

junior supercar

well, I figured out the issue. It's one that I thought/feared too. The kit I bought contained two pinon nuts. two different pinon nuts. so you guessed it, I used the incorrect one. Why the 8.2 BOP kit contained two pinon nuts (and several pinon seals) I don't know. (well, actually I have an educated guess, but that's for another time). I dropped it off with a rear end guy (same guy I used years ago to set up the 3.90 thats currently in the car) this morning and he was able to fix it. (the guy also said the correct pinon nut in the kit (I showed it to him - big hex nut with a dimple on the side, not like "normal" pinon nuts we've probably all seen before) is junk, as are the ring gear bolts. I didn't use them however, didn't need too, but that is good info for future). He also wanted to see the 4 pinon cone style saf-t-trac (aka posi). He took it apart while I was there and said there is some wear but it should be good. He's going to clean it and check the breakaway torque.

monzaz

Every mechanic thinks all parts are JUNK unless they are the ones they use. lol. There is nothing wrong with the parts. We use ALL kinds of kits and they all have there issues. IT is the person that does not do the install enough to know what is what and really no fault of theirs. Mechanics spend way too much of the customers money on UNNEEDED, or what they think are superior parts STILL made out of the country or worse yet made in our country by employees that can not even pack the import parts in the correct box.

ASSEMBLED IN THE USA... I always find wrong part number parts in the wrong kits... please raise all your kids to give A DAMN ABOUT WHAT EVER JOB THEY DO. From the menial to the most desirable of jobs... Just do it well with integrity.

If that posi unit has bottomed out on the cones it will need machining and reshimming to work correctly. Do you have pictures of the parts and wear areas? Jim

junior supercar

Sorry Jim, I do not.

oddball

Do the Auburns wear in the same area, or just on the case?

monzaz

i DO NOT UNDERSTAND YOUR QUESTION PLEASE REWORK AGAIN- Crap sorry for the caps

oddball

How does one determine the amount of wear - or for more practical interest, the amount of remaining life - in an Auburn posi? They don't have the raised center ring that the side gears can it, so I assume it's just how close the wear patter as reached the outer edge of the case.
I have an auburn of unknown life and use, so I don't know if it'll be good for another month or a decade. From what I could see, the wear patern on the case is about 0.050" from the edge.
(sorry for the thread hijack)