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Several years ago I had the original 2.73 gears and open carrier swapped out for 3.23 ring and pinion (USA Standard) and limited slip carrier (Yukon). These gears have always generated noise, both on accel and decel as well as coast. The shop I paid to install told me the reason was that they are aftermarket gears. After the fact, I discovered that the USA Standard gears are not marketed as "quiet" gears, but are their economy line. OK, so, my bad.
Recently I decided to upgrade to Yukon ring and pinion in the hopes of silencing the rear gear whine. I decided to tackle this myself with the help of a good friend with significant experience. After going through the gear swap, I have slightly MORE gear noise than before. Of course, after this I did a bit more research here on TGO and see that these Yukon gears aren't necessarily as advertised. I used the original pinion shim (.036) and set the pinion preload to 12 inch/lb. I wound up with .007 to .008 backlash and a total of 18 inch/lb preload. My factory manual specs .005 to .009 backlash for new gears; Yukon specs .006 - .0100, so I feel pretty good about my backlash. Not so sure about pinion depth (see photos).
I'm asking those here with experience to take a look at my gear pattern pics and recommend a course of action. I don't plan on doing anything until the recommended 500 mile oil change. At that time I feel I have several options to try, but would like to hear from the forum. I was on the fence as far as gear selection. Almost purchased a set of used OEM gears off EBay, but decided to try the new Yukon gear set instead. Thanks in advance for any and all advice.
I have the same problem (in a non-thirdgen) with a set of Motive gears. They whine on coast. So frustrating.
I'd like to know who makes gears that are as quiet as the factory stock gears...
Yes, mine are worst on coast. Pretty quiet below 35 mph and above 60 mph.
You guys can try what I did. Deburr the edges of every tooth (both ring and pinion) with a rotary tool (Dremel) and an appropriate bit.
I did this to mine and I have no noise. The noise increases with higher numerical ratios. I have 4.10s.
I can't promise anyone that this always works, but it did for me.
Okay, so I guess I'm starting over. I have determined that my pinion is a bit too deep and so will address that. I also re-checked my factory manual and it specs pinion preload on new gears/bearings at 25-35 in/lb. I only got to 12 (pinion only) before I gave up trying for more, so I'm assuming my pinion preload is insufficient as well. I have read that this is the most common cause of decel noise, which is my most obvious problem.
You guys can try what I did. Deburr the edges of every tooth (both ring and pinion) with a rotary tool (Dremel) and an appropriate bit.
I did this to mine and I have no noise. The noise increases with higher numerical ratios. I have 4.10s.
I can't promise anyone that this always works, but it did for me.
yeah your pinion is too deep (too close to the ring gear center). Meaning your contact pattern is too close to the bottom of the teeth. I would remove about .008 from the shim on the pinion. and see how that looks. FYI not quite expert advice.. I just finished my 1st gear install (learned a lot though). My gears came out nice and quiet..here is a pic of mine..
Okay, reduced pinion depth by .009 (backlash measures .008). These were obtained by rotating the yoke with axle installed and parking brake partially set to create some load on the gears. Opinions?
Me and my dad did mine with 4.10 motive gears over the course of a weekend or two (no rush) and like another user said, we learned alot. it tuened out super quiet, so the "noisey gears" thing seems more like an excuse in my experience.
I must have taken the pinion in and out a million times, and then after that experimentation of the depth, the pattern was suddenly perfect, it all cloicked together and looked picture perfect. Backlash is important as a final measurement, but only secondary to the pinion depth, it all starts with pinion depth and goes from there.
nother handy thing we did was get a sacrificial pinion bearing and used a carbide bur to open it up so I could experiment with different shims.
Step one get the "test" bearing, and then keep experimenting.
I can get my before and after photos if you want, yours look very familiar from my before photos.
Oh and I learned that only gear marking compound will work hahaha, everything else left me wondering, looks like your stuff is good.
Originally Posted by rt66er
Okay, reduced pinion depth by .009 (backlash measures .008). These were obtained by rotating the yoke with axle installed and parking brake partially set to create some load on the gears. Opinions?
My primary problem was pinion preload. It was basically none (maybe 5 inch/lb). Once we got the pinion depth, got the pinion preload to ~25 inch/lb, I also made a "test" bearing out of the old one for pinion depth experimenting. Much quieter now; not totally silent but you only notice if you listen real hard. Pics of what we settled on...
Okay, so I'm back asking for opinions. After ~600 miles I decided to tear into the diff again to see if I can find out why this SOB is making progressively more noise. New photos of drive/coast patterns look pretty good to me. Backlash measures .008, which is right in the middle of spec (.006 - .010). Only thing I can find that's suspect is preload. Total preload (pinion and carrier) measures 12 inch pounds. With "used" bearings I would expect something more in the 20 inch pound range, as I believe spec for pinion alone is 15 inch pounds. Could this small lack of preload be the culprit? I'm going to pull the carrier and check pinion preload, but I wanted to see if anyone had anything to contribute at this point. Edit: Pinion preload by itself is ~10 inch pounds...
Pattern looks definitely better, yet difficult to read on the pics. Contact pattern is high, towards the heel. I would tighten up the back lash to move it more towards the toe.
10 in/lbs is on the low side after only 600 mls. I would expect it to be in the 12 to 15 range, assuming it was set at 20 to 25 initially.
Keep in mind that if the pattern was setup incorrectly in the beginning, it might have worn in incorrectly and remain noisy.
Thanks, hopefully it isn't past the point of no return. I tightened up the backlash (as you suggested) and it helped the pattern, but with only .005 backlash I worry about problems after it gets warmed up. I decided to pull the pinion (ugh, that means crush sleeve again!) and go from .029 to .031 on pinion shim and recheck. Hoping .031 pinion will allow a little more backlash. Pics are .029 pinion shim and .005 backlash:
It for sure moved the pattern in the right direction, but the pattern is very shitty to read. Try turning the mesh by axle while putting pressure on the ring gear with your other hand. Wouldn't change anything till I have a readeable pattern.
Disclaimer: I am NOT WORTH A CRAP at evaluating patterns. I don't even bother to try anymore because I never get it right.
That said, I have NEVER worked on a GM rear axle newer than the late 70s or so (they must have cleaned up their machine work by then) that needed ANYTHING BUT a .035" shim under the pinion head bearing. NOT ONE. Granted I haven't worked on all that many, maybe 10 or so, butt still...
Another thing to keep in mind is, good quality gears (yeah I know) are precise to within a .001" or 2 anyway. They're ALL THE SAME SIZE. What that means is, the thing you are REALLY shimming - the thing with all the tolerance in it - is THE HOUSING. Meaning also, if you take out a particular thickness of shim, then NO MATTER WHAT gear you're putting back in, it'll need THE SAME THICKNESS shim. Assuming good quality gears of course; and also, NOT the Richmond drag race gears. Those are different in MANY ways from street gears, and should NEVER be used if the car will EVER be on the street, even ONCE. They are specific-purpose, for that one purpose (drag racing) ONLY, and will not survive nor give satisfactory service on the street, regardless of how well they may handle their true intended purpose.
Virtually all "gear" noise I've ever come across has actually been bearing noise. Usually pinion bearings but not always. Usually a result of either not enough preload, or the nut backing off because of the general crappiness of the whole crush sleeve principle. Which I guess are really both the same thing, in effect.
When I build a 7½", I prefer to use a crush sleeve eliminator and a .035" shim; and using a honed-out tail bearing so that I can easily put it together and take it back apart, find the CSE shim that gives me 22 - 25 in-lbs on the pinion (new bearings) WITHOUT the seal and WITHOUT the carrier; then reassemble it one last time WITH the seal and a new un-honed tail bearing, and tighten the pinion nut until it screams for mercy. I've found that a crush sleeve seems to take around 150 ft-lbs or so on the nut to crush it; but you can tighten a CSE WWWWWAAAAAAAYYYYYY more than that if you want. I won't even bother putting one together with used bearings so that's a non-issue. New vs old gears don't matter because the parts you're actually concerned with when setting up all this are the BEARINGS and the HOUSING, not the gears.
Incidentally, another consistent problem is, stock pinion yokes are CRAP. Don't forget, the factory uses U-joints with a groove in the caps, and a matching groove in the yoke; they assemble the shaft to the yoke in a fixture that pefectly aligns and centers it; then they inject plastic into the grooves to retain it. The surfaces where us shadetrees out here in meatspace are going to put "C-rings", isn't even machined (because it doesn't need to be); it might, or might not, be the right distance apart, or might or might not be centered, or the surfaces flat, or even parallel to the rings, because it's AS FORGED. And, they're made of soft metal - just hard enough to get through the warranty period, after all why should they spend time money and effort making it any better - and they always get a groove where the seal goes, which obviously causes leeeeks. A new yoke solves or prevents MANY problems on down the road, and of course, NOW is the time that it has to be installed.
I also find that it's better to set the backlash at the high side of the spec, which would be around .010" or so in this model of rear. Reason being, gears GROW when they get hot; their tooth mesh CHANGES with temperature; and getting a "perfect pattern" at room temperature, is no guarantee that it will be perfect under load. Specifically, backlash GOES AWAY as the gears heat up. I'd MUCH rather have just a tiny sheet-of-paper "too much" backlash for the 1st couple of miles when cold, than 2 gears trying to occupy the same volume just when they're working their hardest. Again, new vs old gears doesn't really matter.
Since carrier bearings are tapered rollers just like pinion bearings or front wheel bearings, they ALSO need preload. That's a little harder to attain though. The standard "book" method for this is a "case spreader", which is a big frame sort of tool that bolts across the cover surface, and pries the case open, such that when you put the carrier in and take it back off, the case presses on the carrier bearings and gives them some preload. I don't have one, and the whole idea of bending on the case gives me the ******* anyway. I use 2 large C-clips on the bearing outer races to press them together CAREFULLY so I can drop the carrier in. Then the tight fit maintains that preload so that the backlash stays where I left it. I try to get AT LEAST .010" of preload on them (.005" too much shim on each side) and MORE if I can get it.
A girdle type of cover such as a T/A keeps the case from spreading open under load and all your carrier preload going away. I highly recommend one of those.
Last edited by sofakingdom; 02-11-2022 at 08:10 AM.
Thanks for all the input! Spent the entire day swapping shims. Pinion shims tried: .041, .036 (OEM), .031, .025, .020, .015, .010. Varied carrier shims to achieve .006 to .010 backlash with these pinion shims. I'll compile results and figure out where to go next. None of these combos got me where I think I need to be. Maybe I'm just being too particular with the patterns I'm getting.
Picture pressing the bearing cones onto the carrier, setting the outer races onto them, and putting 2 large C-clamps around the whole shebang. One on one side, one on the other, so that they press equally on both sides of both races. Then put all the shims into the housing, tighten the C-clamps, drop the carrier into the housing, loosen and remove the C-clamps as it gets close, and push or bolt the carrier the rest of the way in.
I stack up shims to get the desired backlash, as described; then add .005" to each side and try to put the carrier in. If I can get it to go without too much of a fight, I'll up it to .007" or something (.002" more), or whatever the particular shims I have on hand support. And so on, until I get so much shim in there that I can't get the carrier in anymore with any reasonable tightening of the C-clamps.
As a point of reference, the T-5 clutch gear bearing is supposed to have .012" of preload. About the same size bearings but a MUCH weeeeeker housing. I would expect the preload "spec", if there even is one, for the 7.5" rear, to be comparable.
For me, the last pic is easiest to understand, at least to get started.
You can then use the other pics to fine tune.
To my eyes, you need the .036" pinion shim.
And lighten up on the marking compound. You used enough for 10 rear ends.
Double-check the tightness of your ring gear bolts. RED Loctite is a must.
Last edited by NoEmissions84TA; 02-12-2022 at 04:41 PM.
Interesting. To my eye the coast side on the .036 is pretty bad (running off the toe). Maybe if I opened up the backlash a bit it would be better. I think the pics may be misleading as far as how much compound I'm using; I spread it as thin as I could and still get the tooth covered. I do really appreciate the input.
Since I can't easily draw curved lines, let's use the pics you posted.
Look at the left side (convex) pics only.
First you get pinion depth correct. Forget PATTERN at this point.
1st pic (.036 - setup 3) - look down into the tooth and see the solid line of marking compound? Now look at the outer edge and see a thinner solid line of compound.
Compare this to the rest of the pics where you reduced the pinion depth, by pulling the pinion gear out of mesh with the ring gear.
You now have a thicker line of compound at the root of the tooth, but you no longer have any line at the edge of the tooth.
With the pinion depth, you are trying to get the contact centered between the root and the edge. That's why I said .036" is correct.
YOU WANT THIS.
Last edited by NoEmissions84TA; 02-12-2022 at 06:15 PM.
OK, so I settled on the OEM .036 pinion shim. Set it up with ~16 in/lb of pinion preload (on existing bearings) and .008 backlash. Much better. Above ~60 mph, I can't hear any gear noise over road noise and below 60 is not bad. Most obvious is 40-50 mph decel. It's not terrible, but is audible. Below 40 mph, decel noise pretty much goes away. I guess it's as good as it's going to get. Pics are of final pattern before buttoning it up.
I would say that you are in the ballpark.
Personally, I might try for a little more backlash (.002").
I would rather err towards looser than tighter.
Unfortunately, most brands of numerically higher gears make noise in some way.
Well, that didn't work worth a ****. Still lots of whine, especially on coast. Gets worse as it warms up. Couple of photos here of a little experiment I performed prior to final (but obviously not really) install. This is comparing the OEM pinion (which used a .036 shim) to the Yukon pinion, indicating a difference of .014 from face of pinion to bearing surface. I was able to dismantle, set up and repeat these measurements. Logically, this would indicate a correct shim of .022 (.036 - .014).
Missed some messages unfortunately, since my last contribution but here it goes. No wonder it whines, the pattern shows the pinion is too deep in the mesh. I would pull 0.006 to 0.008 and recheck. You could also pull 0.010 to 0.012 to overshoot to the other side, so you can see the change clearly and work back from there.
Missed some messages unfortunately, since my last contribution but here it goes. No wonder it whines, the pattern shows the pinion is too deep in the mesh. I would pull 0.006 to 0.008 and recheck. You could also pull 0.010 to 0.012 to overshoot to the other side, so you can see the change clearly and work back from there.
Thanks. Pulling 0.007 would put me at 0.029 pinion shim, which is where I was before the most recent disassembly. Now I'm wondering if insufficient pinion preload was my problem all along. Would ~10 inch pounds of preload (10 instead of 20) be enough to make noticeable difference in noise? I'm not going to settle with what I have now. What's the prevailing opinion on used OEM gear sets?
I have done many gear swaps, mainly in Chrysler/Dana axles for customers (Jeeps, those guys love to regear) and never encountered the issues you are running into.
Did you get the master installation kit from yukon? Both Randy's and yukon will sell the master kit for any gear set that includes set up bearings. These enable you to pop the carrier in and out with set up bearings that don't need to be pressed onto the carrier to find the right carrier shimming. They will also include a pinion sleeve that enables you to find the correct pinion depth without destroying the crush sleeve in some cases. Otherwise, get a few (more) crush sleeves.
None of your grease patterns look great, and playing with the master kit to shim the carrier and pinion to get the right pattern without the gears permanently installed will take time. Bearing preload, while a decent measurement, matters little if the pattern is off. Once I find a pattern I like, I install the gear set with the shimming I like and leave it alone, even if the pinion bearing preload is out of specification. In this case, more is better, meaning that if you have the preload a bit over spec it will likely wear into spec as the gears go through their break in.
The biggest factors that I have encountered when installing gear sets that determine best operation are lash and pattern. Lash in this case is measured by the pinion yolk rotational movement when fully installed from power to cruise, which should be around 1/8". Grease pattern should be solidly in the middle, think a box in a box. Sometimes moving the carrier does more than screwing with the pinion, especially on deeper gear sets.
All that being said, sometimes larger carriers don't play nice in a worn differential case. Check the races for the pinion if they were not replaced, I have found spun bearing races that took out a good portion of the case which relegated the axle to the scrap pile.
Thanks for the reply. This particular car only has 21,xxx miles on it and all the bearings/races have been replaced twice. The first time when I paid a shop to install the first set of 3.23 gears and Yukon posi, the noise of which I attributed to the low-end gears I purchased. The second time was about a year and 800 miles ago when I decided to try the more expensive (and supposedly better quality) Yukon gears. After a year of those gears getting progressively more noisy, I decided to tear it out and, along with a friend, take another shot at it. The only resource I'm lacking is a pinion depth tool, but it's hard to justify the cost of such equipment for one car. FWIW, I worked many years in a USAF PMEL (precision measurement equipment lab) as a mechanical dimensional calibration tech, so I'm not unfamiliar with using these tools. I have purchased a used OEM 3.23 ring and pinion and will give it a try. Stay tuned....
Okay, so here's the used ring and pinion. This is a factory 3.23 set. It came with the bearing and shim still installed. I pulled the bearing and the shim is .033 (etched on the factory shim). So I tried both the .033 and the .036 (original shim from this rear end). I have read that with used gears you try to get the best pattern you can on the coast side. Does anyone here know what kind of tolerance there is for pinion depth? .001? .003? IOW, is a difference of .003 pinion depth going to mean the difference between quiet and not so quiet operation? Should I go to the trouble of trying, say, .031shim? I tried a .026 and it was very obviously too shallow.
I can't answer your questions, but the .036" setup is the one I would choose.
Berlinetta00, I like your "box-in-a-box" analogy.
Edit: so I stared and stared at the diagrams above, and I cannot match your patterns to any of them.
The closest match is this diagram for your .033" shim. This says you need to move the pinion closer to the ring gear.
Does anyone else agree?
Last edited by NoEmissions84TA; 03-06-2022 at 08:23 PM.
Success. I guess it was the Chinesium gears. Set up the used OEM gears with the .036 shim and .009 backlash. Got a decent pattern and put it back together. Quiet as stock. I should be mad, but I'm really more relieved at this point.
Success. I guess it was the Chinesium gears. Set up the used OEM gears with the .036 shim and .009 backlash. Got a decent pattern and put it back together. Quiet as stock. I should be mad, but I'm really more relieved at this point.
Congrats! A friend with a ton of experience rebuilt my rear (which was previously rebuilt with an aftermarket gear seat and noisy), and when the new Yukon set came it was made in China or India and I sent it back. Good call it seems. I went with a used set of GM OEM 3.42 gears and it's silent.
The moron in that post told you to set it up at .035" and something toward the high side of the "spec" backlash; which would be something around .010". With if course, the caveat of
good quality gears
He did fail to mention, being of course the idiot and epsilon-double-minus-submoron that he was bred to be, that all of these "specs" he gave, were based exclusively on the use of "good quality gears", and that EVERY WORD he said (such as about noise being caused by bearings rather than gears and all that) was applicable ONLY to "good quality gears". If the gears are CRAP, all guarantees as to results are equally CRAP. Maybe if he wasn't so stooooooopid, he could have come out and told you that, despite your protestation that you had "good quality gears". Not that used OEM are really all that "good quality"; but evidently there are some that are QUITE A BIT worse.
Now as we all know, the poster of that post, is well and widely known around here to be a complete total effing idiot and moron, because he doesn't read magazines, doesn't bow to the marketing hype of the latest "trends", and so on. What a bonehead. So you can be forgiven for spending no telling how much time and money in ignoring his "advice", since he OBVIOUSLY doesn't know what he's talking about.
How much trouble would you have saved if you had got yourself a set of "good quality gears", and set it up at .035" and .010" (less difference from his recommendations than the thickness of a sheet of rolling papers), a month or 2 ago? Or even, since the OE shim in your HOUSING was .036", and the above-mentioned yutz made the point over and over again that the shims go with the HOUSING, not the GEARS, and therefore if you have "good quality gears", you should simply put back in the OE shim thickness (or .035" if you don't know the OE thickness), and move on? WITHOUT trying to diagnose the "pattern"? I think that's exactly why the post #21 Neanderthal doesn't use "patterns", if I may be so bold as to extrapolate from his post.
I'm glad you finally got it sorted out. I hate to see anyone get put through such a wringer by GARBAGE parts, when the real SOLUTION is so simple. Our hobby is supposed to be FUN, and CRAP parts from the cheeeeeeeepest of the cheeeeeeeeep source (for example *cough*SkipWhite*cough*) do nothing but CORRUPT that, and turn FUN into a F***ING DRAG. As you can see, it's not really that hard, if you have "good quality gears". After all, it's just a car; one of some billion or whatever in existence JUST ON THIS MISERABLE PLANET (no doubt there are PLENTY more on others), not exactly the stuff of rarefied intelligence or ability. People all over this pitiful world, of every race creed color nationality religion language or gender preference, on every continent or island, of every imaginable level of education or sophistication from hunter-gatherer to ... whatever, seem to be perfectly able to put them together and have them work JUST FINE. Even the fool in post #21 can manage some of it occasionally, however staggeringly remarkable that may seem. But you're MUCH smarter than he ever could possibly be, like about everybody else. Did you end up using a crush sleeve eliminator, honed-out head and tail bearings, and leave the pinion nut cranked until it bleeds?
Last edited by sofakingdom; 03-10-2022 at 06:57 PM.
Did you end up using a crush sleeve eliminator, honed-out head and tail bearings, and leave the pinion nut cranked until it bleeds?
Yes, yes, yes and yes. FWIW, I didn't buy bargain basement EBay crap, I thought I bought good quality gears. In the end it didn't seem to matter. I would be curious to know what aftermarket gears (or any gears, as far as that goes) would be a better choice? Not everyone sells a 7-5/8 3.23 ring and pinion these days. It may be, anymore, no matter what brand you buy, it's a crap shoot.
Actually, yes, they do; it's quite a common ratio in fact. 3.73 is even more common because most people who are buying gears, much like yourself, are trying to improve their car's performance, which 3.73 is arguably the usual best compromise of acceleration, durability, noise, highway engine RPMs, and so on. But many other ratios are widely available.
I'm sorry you had all this trouble. It totally sucks, and I feel bad for you. I merely want to make the point that buying a "brand name" isn't a guarantee of gears being "good quality". Country of origin is usually the best indicator; not that "good quality" CAN'T come from China or India or Thailand or Vietnam or Malaysia, as if those people don't know how to do things right; rather, those places have a relatively low cost of labor, and if something is made there, it's usually because THE COMPANY that decided to use that labor, was looking for the lowest possible cost, and they usually tend to cut quality in any way possible to get to the lowest possible cost. Look for gears made in the US, Canada, Mexico even, Europe, or Japan. You won't generally find them advertised as such. Open the box and look when you get them, and if they say something cheeeeeeeeep, send them back and try something else. Good places to search as sources are companies that sell 4WD parts: the S trucks and various other similar things use the same model rear, and every imaginable ratio is widely available for that application, even if they're not listed for "Camaro". They're still the exact same part.
Also note that VIRTUALLY ALL 7½" gears sold today are actually 7.625" (7-5/8") in diameter. Again, it's the same model of rear, the factory merely increased the ring OD slightly in the mid 80s sometime, without making any material changes to anything else about it, and the aftermarket dropped the early, slightly smaller, size, in favor of the later larger one. The larger one fits all the early rears anyway.
03-13-2021, 08:29 AM
